**4. Case studies introduction and objectives**

The aim of the following case studies is to demonstrate the capability of X-ray microtomography as a useful technique to study fat distribution and the percentage of fat in meat products such as salami. It also aims to help understand the correlation between the physical aspect and microstructural properties of these food products. It also aims demonstrates how the application of X-ray microtomography technique can aid in the study of cellular food microstructure such as coffee, breadsticks and biscuits with different porosity, by imaging and visualising the internal structure.

#### **4.1 Case study 1: Meat products such as salami 4.1.1 Materials and methods**

Five different types of Italian salami, chosen to exhibit variability in terms of visible structure of fat, were used for this experiment: Milano, Ungherese, Modena, Norcinetto and Napoli. They were purchased locally and were tested on the same day of purchase. Three samples were prepared for each type of salami, each 28mm in diameter and a thickness of 18mm. Each sample used for x-ray microtomography (µCT) analysis was wrapped with parafilm to avoid dispersion of moisture; the parafilm does not interfere with the x-rays. The same samples used for µCT analysis were also used for chemical analysis of fat composition.

#### **4.1.2 Results and discussion**

In order to verify the results of the µCT analysis, the percentage fat content obtained from the chemical analysis for each sample was compared to the µCT analysis results. Furthermore, the additional information gained from the µCT analysis i.e. the geometric parameters mentioned provided the required information to characterize and to see if there is any correlation between the microstructures of the different types of salami.

#### **µCT technique validation**

The percentage dark areas for each x-ray microtomographical image was calculated as a representation of the percentage total fat content within the sample. This value was directly derived from the geometric parameter, Percent object volume (POV). The percentage fat content was also calculated by chemical analysis on the same samples to verify the results obtained by µCT analysis. There were no statistical differences among the results obtained by chemical analysis and the POV values therefore suggesting that the POV calculated by µCT analysis for each sample is therefore a true representation of the percentage total fat content present within the sample. Therefore x-ray microtomography has proven to be a useful technique to quantitatively analyse fat content in meat products.

#### **Application of µCT technique**

344 Food Industrial Processes – Methods and Equipment

each point on the shadow image contains the integration of absorption information inside the three-dimensional object in the corresponding partial X-ray beam. The X-rays that are transmitted through the object are scattered and/or absorbed. The gray levels in a slice correspond to the X-ray attenuation, which reflects the proportion of X-rays absorbed or scattered as they pass through each voxel. X-ray attenuation is a function of X-ray energy and the density and atomic number of the material being imaged. Directing X-rays through the slice plane from multiple orientations and measuring their resultant decrease in intensity creates a µCT image. A specialized algorithm is used to reconstruct the distribution of X-ray attenuation in the slice plane. By acquiring a stacked, contiguous series of µCT images

The aim of the following case studies is to demonstrate the capability of X-ray microtomography as a useful technique to study fat distribution and the percentage of fat in meat products such as salami. It also aims to help understand the correlation between the physical aspect and microstructural properties of these food products. It also aims demonstrates how the application of X-ray microtomography technique can aid in the study of cellular food microstructure such as coffee, breadsticks and biscuits with different

Five different types of Italian salami, chosen to exhibit variability in terms of visible structure of fat, were used for this experiment: Milano, Ungherese, Modena, Norcinetto and Napoli. They were purchased locally and were tested on the same day of purchase. Three samples were prepared for each type of salami, each 28mm in diameter and a thickness of 18mm. Each sample used for x-ray microtomography (µCT) analysis was wrapped with parafilm to avoid dispersion of moisture; the parafilm does not interfere with the x-rays. The same samples used for µCT analysis were also used for chemical analysis of fat composition.

In order to verify the results of the µCT analysis, the percentage fat content obtained from the chemical analysis for each sample was compared to the µCT analysis results. Furthermore, the additional information gained from the µCT analysis i.e. the geometric parameters mentioned provided the required information to characterize and to see if there

The percentage dark areas for each x-ray microtomographical image was calculated as a representation of the percentage total fat content within the sample. This value was directly derived from the geometric parameter, Percent object volume (POV). The percentage fat content was also calculated by chemical analysis on the same samples to verify the results obtained by µCT analysis. There were no statistical differences among the results obtained by chemical analysis and the POV values therefore suggesting that the POV calculated by µCT analysis for each sample is therefore a true representation of the percentage total fat content present within the sample. Therefore x-ray microtomography has proven to be a

is any correlation between the microstructures of the different types of salami.

useful technique to quantitatively analyse fat content in meat products.

**4. Case studies introduction and objectives** 

porosity, by imaging and visualising the internal structure.

**4.1 Case study 1: Meat products such as salami** 

**4.1.1 Materials and methods** 

**4.1.2 Results and discussion** 

**µCT technique validation** 

Table 1 shows the average values obtained for the following six parameters using the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS) and Degree of anisotropy (DA) and the results of the statistical analysis carried out as reported below.


\* All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test (p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA).

Table 1. Values for the geometric parameters for the salami samples.

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index while on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. As the fat in salami is considered generally to be of a concave structure, it can be noted from the table that the FI is negative for all samples and there are no statistically significant differences among the samples for this geometric parameter. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the fat along a particular direction (Lim et al., 2004). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 1), the fat present in all samples have a fairly good degree of isotropy and there are no statistical differences among the samples. POV is the percentage of the total fat content present in the sample as proven above. It can be seen that the POV for the Ungherese salami and the Norcinetto salami are statistically equal and are also the highest. There are also no statistical differences in the POV values between the Milano salami and the Napoli salami. OSVR indicates the fat globule size distribution within the sample, the higher the value, the more finely distributed is the fat present in the sample. It can be seen from the table that the Milano salami has the highest value hence its fat content is more finely distributed. Whilst, the Modena salami and the Norcinetto salami are statistically equal i.e. having approximately the same type of fat globule distribution, their low values indicate that the fat globules are more largely distributed with respect to the Milano salami. The results also show that the Napoli salami and the Ungherse salami are statistically equal, hence they have a similar structure with respect to the fat globule size distribution. ST is the average thickness of fat present and SS is the average distant between the fat globules in the samples. The results for ST from table 1 show that Modena, Norcinetto and Ungherese salami are statistically equal, whilst for SS,

 POV OSVR FI ST SS DA Abbarcci MB 37.91±4.36ab 0.88±0.17a -0.08±0.03° 5.41±0.48ab 6.09±0.37a 0.36±0.02a Abbarcci C 39.76±5.18ab 0.85±0.15a -0.13±0.15a 5.89±1.52ab 6.03±1.17a 0.38±0.02a Campagnole C 38.02±3.33ab 0.92±0.10ab -0.12±0.10a 5.13±0.40ab 5.86±0.66a 0.37±0.06a Campagnole MB 31.23±5.04a 1.18±0.16b -0.02±0.06a 4.52±0.82a 5.74±0.36a 0.39±0.06a Traditional D 42.91±5.64b 0.74±0.19b -0.04±0.11a 6.72±1.34b 5.80±0.39a 0.35±0.09a Traditional OD 41.03±2.54ab 0.77±0.07a 0.03±0.03a 6.23±0.89ab 5.63±0.16a 0.33±0.01a \* All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test

341

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index while on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. From the results obtained for FI it can be said that the air cells observed in the samples are of a concave structure, as the FI is negative for all samples. It can also be noted that there are no statistically significant differences among the samples for this geometric parameter. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the air cells along a particular direction (Lim et al, 2004.). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 2), the air cells present in all samples have a fairly good degree of isotropy and there are no statistical differences among the samples. POV is the percentage of the total air cells present in the sample. It can be seen that the POV for both the Frollini samples although statistically there are little or no differences among the samples. OSVR indicates the cell size distribution within the sample, the higher the value, the more finely distributed are the air cell present in the sample. It can be seen from the table that the Campagnole MB has the highest value hence its air cells are more finely distributed, this can also be observed from the images obtained. Whilst, both the Frollini samples have the lowest OSVR samples hence their air cells are more largely distributed. ST is the average size of the cells in the samples and SS is the average distant between the air cells in the samples. The results for ST from the table show that there are larger air cells present in both the Frollini sample. From table 2 a correlation of the parameters is not evident therefore cluster analysis was performed on all the geometric parameters in order to group the salami in terms of similarity (results not shown); the results showed that there are three groups for terms of similarity. The Campagnole MB in terms of the geometric parameters cannot be grouped with any of the other samples, whilst, Abbracci C and Campagnole C are similar in terms of their geometric parameters and Frollini D, Frollini OD and Abbracci MB are also similar. Further investigation can be carried out to help achieve a better understanding of the relationships between the geometrical parameters, mechanical structure parameters and sensory

The three-dimensional geometrical parameters were calculated using the CTAn software (Skyscan). Table 3 shows the average values obtained for the following six parameters using

(p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA). Table 2.Values of the geometric parameters for all the biscuit the samples.

properties. **Breadsticks** 

Napoli and Norcinetto are statistically equal and also Milano and Modena. As reported above, in order to group the samples for each geometric parameter, a cluster analysis was run but only the results for ST are reported in this paper, as it could be considered the main explicative parameter for salami microstructure. As can be inferred from the results (not reported), the statistical analysis classified the 5 samples in 2 different groups. A group included Milano and Napoli salami and the other one all other samples. This second group was not homogeneous and could be divided in two different sub-groups: one for Ungherese and another one for Modena and Norcinetto salami. Also from table 1 a correlation of the parameters is not evident therefore cluster analysis was performed on all the geometric parameters in order to group the salami in terms of similarity (results not reported) The results of the cluster analysis showed that the Milano and Napoli salami are similar, this similarity occurs only between the microstructural parameters ST and POV (statistical figures not reported), therefore suggesting that the geometric parameters, structure thickness and percentage object volume are important parameters to consider when defining the microstructure of salami. Due to the lack of literature for this work, further investigation will have to be carried out to help achieve a better understanding of the relationships between the microstructure, mechanical structure and sensory properties of salami.

#### **4.2 Case study 2: Porous foods such as biscuits and breadsticks 4.2.1 Materials and methods**

Two different porous food products were used for this experiment, Italian sweet biscuits and breadsticks. Three types of Italian commercial sweet biscuits: 'Campagnole', 'Abbracci' and 'Frollini' were used for the first part of this experiment. Two types of brands were used for each types of biscuits: 'Campagnole' produced by Mulino Bianco and Coop, 'Abbracci' produced by Mulino Bianco and Coop and 'Frollini' produced by Ottimini Divella and Doemi. 'Campagnole' biscuits are made from rice flour and milk, 'Abbracci' are made from cream and chocolate and 'Frollini' are traditional made biscuits. A total of 30 samples were used for this experiment, 10 samples for each type of biscuit, i.e. 5 from each brand. Their dimensions were measured out of twenty to thirty random samples and were as following: 'Marie' thickness: 0.60 ± 0.07 (cm) and diameter 6.7 ± 0.03 (cm), 'Petit Beurre' thickness 0.61 ± 0.01 (cm), great and small axis: 6.23 ± 0.07 (cm), 5.45 ± 0.06 (cm), respectively. Biscuit diameter was measured as the average value of two orthogonal diameters. Thickness was measured with a digital micrometer. For each measurement the average of two to three readings was recorded. For the second part of the experiment, three different brands of breadsticks (Grissini) with the same typology were used: 'Mulino Bianco', 'Coop' and 'Bon'.

#### **4.2.2 Results and discussion**

#### **Biscuits**

The three-dimensional geometrical parameters were calculated using the CTAn software (Skyscan). Table 2 shows the average values obtained for the following six parameters using the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS) and Degree of anisotropy (DA) and the results of the statistical analysis carried out as reported below.

Napoli and Norcinetto are statistically equal and also Milano and Modena. As reported above, in order to group the samples for each geometric parameter, a cluster analysis was run but only the results for ST are reported in this paper, as it could be considered the main explicative parameter for salami microstructure. As can be inferred from the results (not reported), the statistical analysis classified the 5 samples in 2 different groups. A group included Milano and Napoli salami and the other one all other samples. This second group was not homogeneous and could be divided in two different sub-groups: one for Ungherese and another one for Modena and Norcinetto salami. Also from table 1 a correlation of the parameters is not evident therefore cluster analysis was performed on all the geometric parameters in order to group the salami in terms of similarity (results not reported) The results of the cluster analysis showed that the Milano and Napoli salami are similar, this similarity occurs only between the microstructural parameters ST and POV (statistical figures not reported), therefore suggesting that the geometric parameters, structure thickness and percentage object volume are important parameters to consider when defining the microstructure of salami. Due to the lack of literature for this work, further investigation will have to be carried out to help achieve a better understanding of the relationships between the microstructure, mechanical structure and sensory properties of

**4.2 Case study 2: Porous foods such as biscuits and breadsticks** 

Two different porous food products were used for this experiment, Italian sweet biscuits and breadsticks. Three types of Italian commercial sweet biscuits: 'Campagnole', 'Abbracci' and 'Frollini' were used for the first part of this experiment. Two types of brands were used for each types of biscuits: 'Campagnole' produced by Mulino Bianco and Coop, 'Abbracci' produced by Mulino Bianco and Coop and 'Frollini' produced by Ottimini Divella and Doemi. 'Campagnole' biscuits are made from rice flour and milk, 'Abbracci' are made from cream and chocolate and 'Frollini' are traditional made biscuits. A total of 30 samples were used for this experiment, 10 samples for each type of biscuit, i.e. 5 from each brand. Their dimensions were measured out of twenty to thirty random samples and were as following: 'Marie' thickness: 0.60 ± 0.07 (cm) and diameter 6.7 ± 0.03 (cm), 'Petit Beurre' thickness 0.61 ± 0.01 (cm), great and small axis: 6.23 ± 0.07 (cm), 5.45 ± 0.06 (cm), respectively. Biscuit diameter was measured as the average value of two orthogonal diameters. Thickness was measured with a digital micrometer. For each measurement the average of two to three readings was recorded. For the second part of the experiment, three different brands of breadsticks (Grissini) with the same typology were used: 'Mulino Bianco', 'Coop' and 'Bon'.

The three-dimensional geometrical parameters were calculated using the CTAn software (Skyscan). Table 2 shows the average values obtained for the following six parameters using the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS) and Degree of anisotropy (DA) and the results of the statistical analysis carried out as reported

salami.

**4.2.1 Materials and methods** 

**4.2.2 Results and discussion** 

**Biscuits** 

below.


\* All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test (p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA).

Table 2.Values of the geometric parameters for all the biscuit the samples.

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index while on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. From the results obtained for FI it can be said that the air cells observed in the samples are of a concave structure, as the FI is negative for all samples. It can also be noted that there are no statistically significant differences among the samples for this geometric parameter. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the air cells along a particular direction (Lim et al, 2004.). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 2), the air cells present in all samples have a fairly good degree of isotropy and there are no statistical differences among the samples. POV is the percentage of the total air cells present in the sample. It can be seen that the POV for both the Frollini samples although statistically there are little or no differences among the samples. OSVR indicates the cell size distribution within the sample, the higher the value, the more finely distributed are the air cell present in the sample. It can be seen from the table that the Campagnole MB has the highest value hence its air cells are more finely distributed, this can also be observed from the images obtained. Whilst, both the Frollini samples have the lowest OSVR samples hence their air cells are more largely distributed. ST is the average size of the cells in the samples and SS is the average distant between the air cells in the samples. The results for ST from the table show that there are larger air cells present in both the Frollini sample. From table 2 a correlation of the parameters is not evident therefore cluster analysis was performed on all the geometric parameters in order to group the salami in terms of similarity (results not shown); the results showed that there are three groups for terms of similarity. The Campagnole MB in terms of the geometric parameters cannot be grouped with any of the other samples, whilst, Abbracci C and Campagnole C are similar in terms of their geometric parameters and Frollini D, Frollini OD and Abbracci MB are also similar. Further investigation can be carried out to help achieve a better understanding of the relationships between the geometrical parameters, mechanical structure parameters and sensory properties.

#### **Breadsticks**

The three-dimensional geometrical parameters were calculated using the CTAn software (Skyscan). Table 3 shows the average values obtained for the following six parameters using

They were purchased locally and all tests, microstructural and rheological, were carried out on the same day. Three 10ml samples were prepared for each type of mayonnaise; with

Table 4 shows the average values obtained for the following seven parameters using the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS), structure modelling index (SMI) and Degree of anisotropy (DA) and the results of the

**\*POV \*OSVR Av FI Av SMI \*Av ST \*Av SS Av DA**

0.19 5.18<sup>a</sup>

0.07 8.18<sup>b</sup>

0.18 4.69<sup>a</sup>

0.05 0.120.03

343

0.25 0.220.08

0.02 0.170.98

0.05 7.80b0.28 0.240.31

0.04 0.050.08 2.060.69 5.54<sup>a</sup>

0.30 0.170.10 2.491.64 4.76<sup>b</sup>

0.21 0.210.07 2.571.25 2.43<sup>c</sup>

0.18 0.150.04 2.640.31 2.45<sup>c</sup>

(p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA). Table 4. Values for the geometric parameters for the mayonnaise samples.

\*All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index, on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. As it can be noted from the results the FI is positive for all samples and there are no statistically significant differences among the sample, therefore the fat structures in these samples have more or less disconnected solid lattices and therefore convex in structure. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the fat present along a particular direction (Lim et al., 2004). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 4), the fat present in all samples are isotropic and there are no statistical differences among the samples, this in accordance with Langton et al., (1998) whom found out that the fat droplets in mayonnaise samples had no orientation and could be regarded as isotropic. POV is the percentage of the total fat content present in the sample as proven above. It can be seen that the 'calvé' and 'kraft' mayonnaise samples have the highest POV values that are also statistically equal; therefore these two samples are similar in terms of fat content. On the other hand, the 'calvémayò' and 'kraft legeresse' samples have the lowest values and are also statistically equal. OSVR indicates the oil droplet/fat distribution within the sample. The higher the value, the more finely distributed is the oil droplet present in the sample. It can be observed from the table that the 'kraft legeresse' and the 'kraft' samples have the highest OSVR values that are also statistically equal; therefore they have a much finer dispersion of oil droplets compared

regards to µCT analysis, each sample was placed in a cylindrical tube.

**4.3.2 Results and discussion Application of µCT technique** 

Calvé 65.28<sup>a</sup> 1.45 0.48<sup>a</sup>

kraft 69.08a1.80 0.60<sup>b</sup>

Calvé-mayò 24.12<sup>b</sup>

legeresse 21.69<sup>b</sup>

kraft

statistical analysis carried out as reported below.

1.32 0.51<sup>a</sup>

0.04 0.61<sup>b</sup>

the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS) and Degree of anisotropy (DA) and the results of the statistical analysis carried out as reported below.


\* All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test (p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA).

Table 3. Values of the geometric parameters for all the breadstick samples.

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index while on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. From the results obtained for FI it can be said that the air cells observed in the samples are of a concave structure, as the FI is negative for all samples. It can also be noted that the FI for the Grissini B sample is statistically higher. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the air cells along a particular direction (Lim et al, 2004.). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 3), the air cells present in all samples are isotropic in nature and there are no statistical differences among the samples. POV is the percentage of the total air cells present in the sample. The Grissini C sample has the highest POV, hence a greater amount of air cells are present in this sample, whilst for Grissini MB and Grissini B the Frollini, statistically there are little or no differences among these samples. OSVR indicates the cell size distribution within the sample, the higher the value, the more finely distributed are the air cell present in the sample. It can be seen from the table that the Grissini B has the highest value hence its air cells are more finely distributed, this can also be observed from the images obtained. ST is the average size of the cells in the samples and SS is the average distant between the air cells in the samples. There are no statistical differences among the samples for ST and SS. From table 3 a correlation of the parameters is not evident therefore cluster analysis was performed on all the geometric parameters in order to group the salami in terms of similarity (results not shown); results obtained show that there are two groups in terms of similarity. The Grissini C in terms of the geometric parameters cannot be grouped with any of the other samples, whilst, Grissini MB and Grissini B are similar in terms of their geometric parameters. As for the case of the biscuits, further investigation can be carried out to help achieve a better understanding of the relationships between the geometrical parameters, mechanical structure parameters and sensory properties.

#### **4.3 Case study 3: Emulsions**

#### **4.3.1 Materials and methods**

Four different types of commercially produced mayonnaises, chosen for their variability of fat contents, were used for this experiment: 'kraft' 'calvé', 'kraft legeresse' and 'calvé-mayò'. They were purchased locally and all tests, microstructural and rheological, were carried out on the same day. Three 10ml samples were prepared for each type of mayonnaise; with regards to µCT analysis, each sample was placed in a cylindrical tube.

#### **4.3.2 Results and discussion**

348 Food Industrial Processes – Methods and Equipment

the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS) and Degree of anisotropy (DA) and the results of the statistical analysis carried out as reported

 POV OSVR FI ST SS DA Grissini MB 52.39±4.29a 0.58±0.05a -0.38±0.12a 10.17±0.46ab 4.38±0.15a 0.34±0.02a Grissini C 57.66±3.25b 0.67±0.67a -0.30±0.06a 9.65±1.02a 4.48±0.16a 0.42±0.02a Grissini B 50.26±4.81a 0.89±0.89b -0.58±0.18b 13.13±1.59b 4.37±0.13a 0.55±0.02a \* All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index while on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. From the results obtained for FI it can be said that the air cells observed in the samples are of a concave structure, as the FI is negative for all samples. It can also be noted that the FI for the Grissini B sample is statistically higher. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the air cells along a particular direction (Lim et al, 2004.). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 3), the air cells present in all samples are isotropic in nature and there are no statistical differences among the samples. POV is the percentage of the total air cells present in the sample. The Grissini C sample has the highest POV, hence a greater amount of air cells are present in this sample, whilst for Grissini MB and Grissini B the Frollini, statistically there are little or no differences among these samples. OSVR indicates the cell size distribution within the sample, the higher the value, the more finely distributed are the air cell present in the sample. It can be seen from the table that the Grissini B has the highest value hence its air cells are more finely distributed, this can also be observed from the images obtained. ST is the average size of the cells in the samples and SS is the average distant between the air cells in the samples. There are no statistical differences among the samples for ST and SS. From table 3 a correlation of the parameters is not evident therefore cluster analysis was performed on all the geometric parameters in order to group the salami in terms of similarity (results not shown); results obtained show that there are two groups in terms of similarity. The Grissini C in terms of the geometric parameters cannot be grouped with any of the other samples, whilst, Grissini MB and Grissini B are similar in terms of their geometric parameters. As for the case of the biscuits, further investigation can be carried out to help achieve a better understanding of the relationships between the geometrical parameters, mechanical structure parameters and sensory

Four different types of commercially produced mayonnaises, chosen for their variability of fat contents, were used for this experiment: 'kraft' 'calvé', 'kraft legeresse' and 'calvé-mayò'.

(p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA). Table 3. Values of the geometric parameters for all the breadstick samples.

below.

properties.

**4.3 Case study 3: Emulsions 4.3.1 Materials and methods** 

#### **Application of µCT technique**

Table 4 shows the average values obtained for the following seven parameters using the CTAn software (Skyscan): Percent object volume (POV), Object surface/volume ratio (OSVR), Fragmentation index (FI), Structure thickness (ST), Structure separation (SS), structure modelling index (SMI) and Degree of anisotropy (DA) and the results of the statistical analysis carried out as reported below.


\*All parameters obtained were submitted to one-way analysis of variance (ANOVA) and Duncan's test (p<0.05) through the statistic package Statistica for Windows (Statsoft, Tulsa, USA).

Table 4. Values for the geometric parameters for the mayonnaise samples.

Where FI is the index of connectivity and is a measure of relative convexity or concavity of the total solid surface, based on the principle that concavity indicates connectivity, and convexity indicates isolated disconnected structures (Lim et al., 2004). A lower FI signifies better-connected solid lattices and has a negative index, on the other hand a higher FI indicates a more disconnected solid structure and has a positive index. As it can be noted from the results the FI is positive for all samples and there are no statistically significant differences among the sample, therefore the fat structures in these samples have more or less disconnected solid lattices and therefore convex in structure. The degree of anisotropy (DA) is a measure of the 3D structural symmetry, i.e. in this case it indicates the presence or absence of preferential alignment of the fat present along a particular direction (Lim et al., 2004). A value of 0 would correspond to total isotropy, whereas a value of 1 would indicate total anisotropy. According to the results obtained for DA (see table 4), the fat present in all samples are isotropic and there are no statistical differences among the samples, this in accordance with Langton et al., (1998) whom found out that the fat droplets in mayonnaise samples had no orientation and could be regarded as isotropic. POV is the percentage of the total fat content present in the sample as proven above. It can be seen that the 'calvé' and 'kraft' mayonnaise samples have the highest POV values that are also statistically equal; therefore these two samples are similar in terms of fat content. On the other hand, the 'calvémayò' and 'kraft legeresse' samples have the lowest values and are also statistically equal. OSVR indicates the oil droplet/fat distribution within the sample. The higher the value, the more finely distributed is the oil droplet present in the sample. It can be observed from the table that the 'kraft legeresse' and the 'kraft' samples have the highest OSVR values that are also statistically equal; therefore they have a much finer dispersion of oil droplets compared

samples. These parameters give an idea of the emulsion stability. From the results obtained (not shown) the 'calvè', 'kraft' and 'kraft legeresse' samples showed statistically similar values of the z parameter and higher than that the 'calvè-mayò' sample. Therefore, the calvè-mayo light with higher z values has a more complex structure and contains more microstructural interactions with respect to the other samples. Regarding the A parameter all samples differ significantly. Moreover, the highest and the lowest A values were recorded for the 'kraft' and 'calvè' samples, respectively, therefore the 'kraft' 'sample was

345

Table 5 shows the results of the correlation among the microstructural parameters and

Av POV Av OSVR Av FI Av SMI Av ST Av SS Av DA A z

more stable (Peressini et al., 1998) with respect to the calvè sample.

rheological properties of the mayonnaise samples.

Av FI -0.21 0.83 1.00

Av SMI -0.51 0.98 0.87 1.00

Av ST -0.58 -0.22 0.09 0.00 1.00

consumer satisfaction to promote full product acceptability.

Av SS -0.68 0.94 0.74 0.97 0.06 1.00

Av DA 0.86 -0.71 -0.68 -0.84 -0.50 -0.90 1.00

A -0.10 0.68 0.97 0.75 0.19 0.59 -0.59 1.00 z 0.54 0.07 -0.30 -0.15 -0.97 -0.17 0.58 -0.41 1.00

\* The highlighted parameters indicate a strong correlation among the parameters for this the EXCEL

Table 5. Results of the correlation among the microstructural parameters and rheological

It can be noted from this table that a correlation exists among some of the following microstructural properties of the mayonnaise samples, OSVR, ST, SMI and FI. With regards to the microstructural and rheological relationship, there is a strong correlation among the coefficient A and FI and the coordination number z and ST, suggesting that the average thickness, i.e. the volume based thickness, of the fat structure present affects the level of microstructural interactions and the connectivity of the fat surfaces affects the magnitude of these interactions. The correlation thus confirms that as the fat structures in these mayonnaise samples have more or less disconnected solid lattices and being convex in structure there is an amplified level of microstructural interactions and the level of these interactions is correlated to the thickness of the fat structure, hence the results obtained demonstrate that there is a link between some microstructural features and rheological properties. As stated above, structure-property relationships can strongly affect the physiochemical, functional, technological and even nutritional properties of foods. For example, with regards to food emulsions like ice cream, yoghurt, spreads and dressings such as mayonnaise the consumer appreciation of these products is strongly linked to the texture. Therefore, this preliminary investigation allows us to carry out further study on the main process variables that affect the characteristics of mayonnaise that are involved in

**Correlation** 

Av POV 1.00

Av OSVR -0.38 1.00

statistic package for Windows was used.

properties of the mayonnaise samples.

to the other two samples. On the other hand, the samples, 'calvé' and 'calvè-mayò', have the lowest OSVR values and are also statistically equal i.e. having approximately the same type of fat distribution. Their low values indicate that the oil droplets present in these samples are more largely distributed with respect to the other two samples. ST is the average thickness of the fat structure present; this parameter calculates a volume-based thickness of the structure in three dimensions independent of an assumed structure type. It can be noted from table 4 that the samples, 'calvé' and 'calvè-mayò' have the highest ST values, therefore they have a similar fat thickness. While on the other hand the samples 'kraft legeresse' and the 'kraft' samples have low ST values that are statistically equal. SS is the average distant between the fat structures in the samples, it can be noted from this table that 'calvé' and 'kraft' have low SS values that are statistically equal. On the other hand the samples, 'kraft legeresse' and 'calvé-mayò' light have high SS values this could be due to the fact that the fat content in these samples are very low hence the average distant between each fat globule is greater with respect to the samples; 'calvé' and 'kraft'. No significant differences were found for SMI index in the different mayonnaise samples. SMI parameter, that is a topological index, gives an estimate of the characteristic shape of a structure in terms of plates and cylinders composing the 3D structure (Hildebrand & Rüegsegger, 1997) and is calculated using a differential analysis of triangulated surface of the structure under examination. The SMI assumes integer values of 0, 3 and 4 for ideal plates, cylinder and spheres, respectively. The SMI values calculated for all the samples ranged from 2.06 to 2.64, these values are fairly close to 3 therefore suggesting that the characteristic shape of the oil droplets present in these commercially produced mayonnaise are cylindrical in nature.

#### **Rheological analysis**

It was noted that for the rheological data, G' and G" values vs. the oscillatory frequency all samples exhibited a viscoelastic behaviour with storage modulus (G') greater than the loss modulus (G") (Subramanian & Gunasekaran, 1997; Rao & Steffe, 1992). As reported in literature (Ma & Barbosa-Canovas, 1995) emulsions with a greater fat content show higher values of G'. This was found for all samples except for the samples 'calvè-mayò' and 'kraft legeresse' that exhibited a higher storage modulus than sample 'calvè' in spite of their lower fat content. This could be due to the fact that the G' reduction was counterbalanced by the higher carbohydrate content of the 'calvè-mayò' and 'kraft legeresse' samples that structure the emulsions (Munoz & Sherman, 1990; Peressini et al., 1998).

It can also be stated from the results obtained that all the mayonnaise samples exhibited solid-like gel behaviour with rheological spectra resembling that of weak gel (Ross-Murphy, 1988; Richardson et al., 1989). Typical weak gel characteristics were observed: G′ was greater than G″ throughout the frequency range, and the moduli showed a slight dependence on frequency.

The experimental data on the frequency sweep tests were correlated using the following power law according to Bohlin's theory of flow as a cooperative phenomenon (Bohlin, 1980):

$$\mathbf{G}' = \mathbf{A} \cdot \mathbf{w} \exp\left(\mathbf{1}/\mathbf{z}\right) \tag{1}$$

On the basis of this theory, emulsions are modeled as a network of rheological units that interact for establishing system structure. The coordination number z gives the level of these interactions and the coefficient A their magnitude. The z and A values were obtained for all samples. These parameters give an idea of the emulsion stability. From the results obtained (not shown) the 'calvè', 'kraft' and 'kraft legeresse' samples showed statistically similar values of the z parameter and higher than that the 'calvè-mayò' sample. Therefore, the calvè-mayo light with higher z values has a more complex structure and contains more microstructural interactions with respect to the other samples. Regarding the A parameter all samples differ significantly. Moreover, the highest and the lowest A values were recorded for the 'kraft' and 'calvè' samples, respectively, therefore the 'kraft' 'sample was more stable (Peressini et al., 1998) with respect to the calvè sample.

#### **Correlation**

350 Food Industrial Processes – Methods and Equipment

to the other two samples. On the other hand, the samples, 'calvé' and 'calvè-mayò', have the lowest OSVR values and are also statistically equal i.e. having approximately the same type of fat distribution. Their low values indicate that the oil droplets present in these samples are more largely distributed with respect to the other two samples. ST is the average thickness of the fat structure present; this parameter calculates a volume-based thickness of the structure in three dimensions independent of an assumed structure type. It can be noted from table 4 that the samples, 'calvé' and 'calvè-mayò' have the highest ST values, therefore they have a similar fat thickness. While on the other hand the samples 'kraft legeresse' and the 'kraft' samples have low ST values that are statistically equal. SS is the average distant between the fat structures in the samples, it can be noted from this table that 'calvé' and 'kraft' have low SS values that are statistically equal. On the other hand the samples, 'kraft legeresse' and 'calvé-mayò' light have high SS values this could be due to the fact that the fat content in these samples are very low hence the average distant between each fat globule is greater with respect to the samples; 'calvé' and 'kraft'. No significant differences were found for SMI index in the different mayonnaise samples. SMI parameter, that is a topological index, gives an estimate of the characteristic shape of a structure in terms of plates and cylinders composing the 3D structure (Hildebrand & Rüegsegger, 1997) and is calculated using a differential analysis of triangulated surface of the structure under examination. The SMI assumes integer values of 0, 3 and 4 for ideal plates, cylinder and spheres, respectively. The SMI values calculated for all the samples ranged from 2.06 to 2.64, these values are fairly close to 3 therefore suggesting that the characteristic shape of the oil droplets present in these commercially produced mayonnaise are cylindrical in nature.

It was noted that for the rheological data, G' and G" values vs. the oscillatory frequency all samples exhibited a viscoelastic behaviour with storage modulus (G') greater than the loss modulus (G") (Subramanian & Gunasekaran, 1997; Rao & Steffe, 1992). As reported in literature (Ma & Barbosa-Canovas, 1995) emulsions with a greater fat content show higher values of G'. This was found for all samples except for the samples 'calvè-mayò' and 'kraft legeresse' that exhibited a higher storage modulus than sample 'calvè' in spite of their lower fat content. This could be due to the fact that the G' reduction was counterbalanced by the higher carbohydrate content of the 'calvè-mayò' and 'kraft legeresse' samples that structure

It can also be stated from the results obtained that all the mayonnaise samples exhibited solid-like gel behaviour with rheological spectra resembling that of weak gel (Ross-Murphy, 1988; Richardson et al., 1989). Typical weak gel characteristics were observed: G′ was greater than G″ throughout the frequency range, and the moduli showed a slight dependence on

The experimental data on the frequency sweep tests were correlated using the following power law according to Bohlin's theory of flow as a cooperative phenomenon (Bohlin, 1980):

On the basis of this theory, emulsions are modeled as a network of rheological units that interact for establishing system structure. The coordination number z gives the level of these interactions and the coefficient A their magnitude. The z and A values were obtained for all

G' A·w·exp 1 /z (1)

the emulsions (Munoz & Sherman, 1990; Peressini et al., 1998).

**Rheological analysis** 

frequency.

Table 5 shows the results of the correlation among the microstructural parameters and rheological properties of the mayonnaise samples.


\* The highlighted parameters indicate a strong correlation among the parameters for this the EXCEL statistic package for Windows was used.

Table 5. Results of the correlation among the microstructural parameters and rheological properties of the mayonnaise samples.

It can be noted from this table that a correlation exists among some of the following microstructural properties of the mayonnaise samples, OSVR, ST, SMI and FI. With regards to the microstructural and rheological relationship, there is a strong correlation among the coefficient A and FI and the coordination number z and ST, suggesting that the average thickness, i.e. the volume based thickness, of the fat structure present affects the level of microstructural interactions and the connectivity of the fat surfaces affects the magnitude of these interactions. The correlation thus confirms that as the fat structures in these mayonnaise samples have more or less disconnected solid lattices and being convex in structure there is an amplified level of microstructural interactions and the level of these interactions is correlated to the thickness of the fat structure, hence the results obtained demonstrate that there is a link between some microstructural features and rheological properties. As stated above, structure-property relationships can strongly affect the physiochemical, functional, technological and even nutritional properties of foods. For example, with regards to food emulsions like ice cream, yoghurt, spreads and dressings such as mayonnaise the consumer appreciation of these products is strongly linked to the texture. Therefore, this preliminary investigation allows us to carry out further study on the main process variables that affect the characteristics of mayonnaise that are involved in consumer satisfaction to promote full product acceptability.

decrease in bean density due to its increase in pore volume and simultaneous weight loss. This is in accordance with Dutra et. al (2001) whom found also a significant decrease in bean

(a) (b)

Fig. 1. Examples of the binary tomograph illustrating the separation of the air and structure phases: a) green coffee bean; b) roasted coffee bean at 2 minutes; c) roasted coffee bean at 5

10.0 mm

347

density with increase in roasting time.

(c)

minutes.

#### **4.4 Case study 4: Coffee 4.4.1 Materials and methods**

*Coffea arabica* var. S-795 from India, crop 2008-2009, has been used for this experiment. The green coffee beans were roasted with a Probat model BR74 (220°C, 100 g starting sample) and sampled during roasting process at 2, 3, 4 and 5 minutes. The roasting degree has been determined gravimetrically and expressed in terms of total weight loss (6.8, 10.7, 13.9, and 21.1 % w/w, respectively) it corresponded to very light, light, medium and dark, respectively. Five coffee beans at each roasting time were chosen for the experiment. Each coffee bean was weighed on a digital precision balance (± 0.1g) (Gibetini Eurpoe, Italy) to calculate the density of the sample. For x-ray microtomographical analysis, each sample was imaged under the same conditions, using the Skyscan 1172 high-resolution desktop X-ray microtomography system (Skyscan, Belgium).

#### **4.4.2 Results and discussion**

Figures 1a, 1b and 1c show as an example the set of flat cross sections that were obtained for these samples after binarisation of the images using the reconstruction software CTAn software (Skyscan), from these images the structure/air matrix is clearly visible. The threedimensional geometrical parameters were calculated using the CTAn software (Skyscan). From the images of above, it can be noted that the structure and the number of holes in the

samples changed and increased with increasing roasting time. Following data analysis, figure 2 shows the graph for the average distribution of the total volume of the holes present for the coffee bean samples at the five different roasting times.

The values of the total volume represented in the graph does not take into account the large central hole of the coffee bean, as this structure is only air it is therefore excluded in this micro-structural study. It can be noted from this graph that as the roasting time increases, the total volume of holes increases, with a significant peak at roasting time 3 due to the rupture of bonds in the internal structure of the coffee beans, this is in concurrence with Schenker et.al (2000). Statistical analysis, performed on the results of this graph confirmed that there are statistical differences for the total volume between roasting times t0 and t3 and roasting times t3 and t5, although there are no statistical differences between the total volumes at roasting time t4 and t5. On the other hand, the percentage hole volume, i.e. the geometric parameter POV, was calculated for each sample as a representation of the percentage total hole content within the sample. From the values obtained for POV (results not shown), it can be noted also in this case that the POV values increase with increasing roasting time. Statistical analysis, performed on the results of confirmed that there are statistical differences among all the POV values at the different roasting times. This result is in accordance with the results for the total volume, as an increase in total volume of holes results in an increase of POV.

Figure 3 shows the graph for the total number of pores present in the samples of coffee examined at different roasting times excluding the large central hole as before.

The trend of the graph shows that at roasting time 2 there is a significant peak due to the increase in temperature and therefore a change of the internal structure, this can also be noted from the images obtained. After roasting time 2 the increase of the total number of holes is gradual and statistical analysis performed on the results confirmed that although there is a statistical difference between the total number of holes at roasting times t2 and t5, there are no statistical differences among the values for roasting time t3 and t4. The average bean densities for the different roasting times are shown in figure 3. There is significant

*Coffea arabica* var. S-795 from India, crop 2008-2009, has been used for this experiment. The green coffee beans were roasted with a Probat model BR74 (220°C, 100 g starting sample) and sampled during roasting process at 2, 3, 4 and 5 minutes. The roasting degree has been determined gravimetrically and expressed in terms of total weight loss (6.8, 10.7, 13.9, and 21.1 % w/w, respectively) it corresponded to very light, light, medium and dark, respectively. Five coffee beans at each roasting time were chosen for the experiment. Each coffee bean was weighed on a digital precision balance (± 0.1g) (Gibetini Eurpoe, Italy) to calculate the density of the sample. For x-ray microtomographical analysis, each sample was imaged under the same conditions, using the Skyscan 1172 high-resolution desktop X-ray

Figures 1a, 1b and 1c show as an example the set of flat cross sections that were obtained for these samples after binarisation of the images using the reconstruction software CTAn software (Skyscan), from these images the structure/air matrix is clearly visible. The threedimensional geometrical parameters were calculated using the CTAn software (Skyscan). From the images of above, it can be noted that the structure and the number of holes in the

Following data analysis, figure 2 shows the graph for the average distribution of the total volume of the holes present for the coffee bean samples at the five different roasting times. The values of the total volume represented in the graph does not take into account the large central hole of the coffee bean, as this structure is only air it is therefore excluded in this micro-structural study. It can be noted from this graph that as the roasting time increases, the total volume of holes increases, with a significant peak at roasting time 3 due to the rupture of bonds in the internal structure of the coffee beans, this is in concurrence with Schenker et.al (2000). Statistical analysis, performed on the results of this graph confirmed that there are statistical differences for the total volume between roasting times t0 and t3 and roasting times t3 and t5, although there are no statistical differences between the total volumes at roasting time t4 and t5. On the other hand, the percentage hole volume, i.e. the geometric parameter POV, was calculated for each sample as a representation of the percentage total hole content within the sample. From the values obtained for POV (results not shown), it can be noted also in this case that the POV values increase with increasing roasting time. Statistical analysis, performed on the results of confirmed that there are statistical differences among all the POV values at the different roasting times. This result is in accordance with the results for the total volume, as an increase in total volume of holes

Figure 3 shows the graph for the total number of pores present in the samples of coffee

The trend of the graph shows that at roasting time 2 there is a significant peak due to the increase in temperature and therefore a change of the internal structure, this can also be noted from the images obtained. After roasting time 2 the increase of the total number of holes is gradual and statistical analysis performed on the results confirmed that although there is a statistical difference between the total number of holes at roasting times t2 and t5, there are no statistical differences among the values for roasting time t3 and t4. The average bean densities for the different roasting times are shown in figure 3. There is significant

examined at different roasting times excluding the large central hole as before.

**4.4 Case study 4: Coffee 4.4.1 Materials and methods** 

microtomography system (Skyscan, Belgium).

samples changed and increased with increasing roasting time.

**4.4.2 Results and discussion** 

results in an increase of POV.

decrease in bean density due to its increase in pore volume and simultaneous weight loss. This is in accordance with Dutra et. al (2001) whom found also a significant decrease in bean density with increase in roasting time.

(c)

Fig. 1. Examples of the binary tomograph illustrating the separation of the air and structure phases: a) green coffee bean; b) roasted coffee bean at 2 minutes; c) roasted coffee bean at 5 minutes.

image of large samples can be obtained with a voxel resolution of about 0.5 µm and image analysis of the full 3-D microstructure, measuring the size, shape, networking/connectivity and distribution of various phases is possible. These measurements represent the full 3-D microstructure, which is not always possible by 2-D image analysis using statistical

349

As stated above, the fat content in meat products is a very important compound and nowadays, lots of meat products with different fat contents and different physical and chemical features (protein network, moisture content, ingredients, additives and so on) are being manufactured. Consumers of today, require some of these information e.g. total fat content, types fat, ingredients, additives etc. to be stated. Therefore total fat content of meat products (e.g. salami, steak etc) is an important quantity used in numerous studies. X-ray microtomography has proven to be a very useful and sophisticated tool for the quantification analysis of fat in meat and meat products. Combined visualisation of the microstructure using X-ray microtomography and other microscopic techniques, extraction of quantitative data obtained by image analysis, and modelling of the microstructure based on characteristics of the structuring elements should point to the optimal food product. The consumer appreciation of solid food foams like bread, extruded cereals, biscuits and cakes is strongly linked to the texture. The control of the sensory properties of such products, which is still a challenge, requires a better understanding of relationships between composition, cellular structure formation mechanisms and the nal texture. For texture, sensory properties of solid food foams are related to both mechanical properties and cellular structure. In this context, determining the relationships between a given mechanical property and the cellular structure is thus of prime importance. Since cellular cereal products can be considered, from morphological and topological points of view, like metallic or polymeric foams, it is tempting to address this problem by referring to Gibson & Ashby's model. Such scaling laws are shown to be efficient to assess the effect of the relative density on mechanical properties like Young's modulus or strength of extruded starchy materials or bread. However, for the same density, mechanical properties and sensory

With regards to cellular cereal products, X-ray microtomography to date has proven to be a very useful technique for the non-invasive 3-D visualization and quantitative analysis of the microstructure of cellular cereal products. Further work can be carried out to study the inner cellular structure of the cereal matrix or to assess the integrity of moisture barriers applied on cereal product. The obtained quantitative information can be used as input for simulation models for moisture diffusion. The technique has significant benefits for the design, analysis, and processing science of certain food products. Such an advance in cellular food measurement will undoubtedly open up new horizons for the development of mathematical and computational models that link product microstructure to product mechanical

With regards to emulsions such as mayonnaise, the fat distribution could be observed and quantified in the microtomographic images, as well as fat droplets size. With µCT, a full 3-D image of large samples can be obtained with high resolution and image analysis of the full 3-D microstructure, measuring the size, shape, networking/connectivity and distribution of various phases is possible. These measurements represent the full 3-D microstructure, which is not always possible by 2-D image analysis using statistical techniques. The correlation of

properties are also sensitive to microstructural dispersions.

properties and rheology.

techniques.

Fig. 2. The average distribution for the total volume of the holes.

Fig. 3. The total number of pores.
