**6.3. Soup formulation**

In a soup formulation corn starch was gradually replaced with fenugreek gum (FG) till 0.9% wt. Pure systems of corn starch and fenugreek gum dispersions are also tested. Pure corn starch-FG mixtures and soups are subjected to rheological measurements after preparation. (Matia-Merino & Ravindran, 2009).

Final viscosities increase with increasing FG replacement levels. Soup containing FG (without starch) exhibit a dose–related pasting pattern and different pasting profiles than starch-FG soup formulations. Combined addition of starch-FG results in a synergistic effect of starch and FG. Thus, the viscosity increase is much greater than when the two ingredients are added individually. The viscoelasticity of the starch-FG systems and soups containing them is shown at the frequency of 1 Hz (Fig 7.a, Fig 7b). The viscous or loss modulus shows slightly more dependency with the elastic component being frequently independent and always over the viscous modulus through the entire frequency range. The main differences between starch-FG systems and soups containing them is: a) the higher viscoelasticity developed in all the soups with both G' and G'' being greater in value than in the pure starch/fenugreek mixtures, measured under similar conditions and b) both elastic and viscous moduli gradually increase with the substitution of starch by FG for all formulations.

## **6.4. Caramel sauces**

Caramel sauces can have tailored sensory, rheological and textural characteristics by using potato starch and xanthan gum combinations (Krystyjan et al., 2012). Potato starch and xanthan gum are selected among other starch-hydrocolloid combinations taking into account transparency and clear appearance for further use in caramel sauces as thickeners. Commercial sauce without any stabilisers received the lowest score in sensory evaluation. Samples were stored and among other rheological characteristics, storage and loss moduli

(a) 5% standard corn starch (P1), gradually replaced with fenugreek at 0.1% (P2), 0.15% (P3), 0.2% (P4), 0.25% (P5), 0.3% (P6), 0.5% (P7), 0.7% (P8), 0.9% (P9).

(b) soup formulations with 5% standard corn starch (S1), gradually replaced with fenugreek at 0.1% (S2), 0.15% (S3), 0.2% (S4), 0.25% (S5) and 0.3% (S6), 0.5% (S7), 0.7% (S8), 0.9% (S9). All measurements were carried out at 25 °C (From Matia-Merino & Ravindran, 2009, Food Hydrocolloids, 23(3), pp 1047-1053, with permission).

**Figure 6.** Storage modulus (*G*′), loss modulus (*G*″), and tan *δ* measured at 1 Hz and 1% strain

were measured. On the contrary to the assumptions in previous examples, the storage moduli of all sauces are much lower than their loss moduli. Sauces have very weak elastic and very strong plastic properties. This feature is considered disadvantageous, because the sauce can very easily flow down from the surface of the glazed products. An increase in xanthan gum amount results in moduli increase, both before and after storage. Controlled rheology can be achieved improving caramel sauces performance.

Concluding:

230 Viscoelasticity – From Theory to Biological Applications

retrogradation (Arocas et al., 2011).

network-like characteristic of the sauce.

(Matia-Merino & Ravindran, 2009).

**6.3. Soup formulation** 

**6.4. Caramel sauces** 

**6.2. Chilli sauce** 

sauce preparation as well as during the thawing process. Although the modified starch granules swell, little release of the starch components occurs. Thus, the differences between thawing techniques are related to their effect on structure changes related to starch

Chilli sauces investigated presented a dominant elastic behavior compared to the viscous behavior typically observed in suspensions with network-like structure (Gamonpilas et al., 2011). Weak gel-like characteristics are found in chilli sauces containing starch and hydrocolloids, as well as in white sauces mentioned above. The presence of starch/xanthan mixture in the commercial chilli sauces promotes their elastic properties. Furthermore, the sauce with low solid content and without xanthan gum has weak network structure and inferior flow properties. The addition of xanthan gum and/or modified starch can provide a

In a soup formulation corn starch was gradually replaced with fenugreek gum (FG) till 0.9% wt. Pure systems of corn starch and fenugreek gum dispersions are also tested. Pure corn starch-FG mixtures and soups are subjected to rheological measurements after preparation.

Final viscosities increase with increasing FG replacement levels. Soup containing FG (without starch) exhibit a dose–related pasting pattern and different pasting profiles than starch-FG soup formulations. Combined addition of starch-FG results in a synergistic effect of starch and FG. Thus, the viscosity increase is much greater than when the two ingredients are added individually. The viscoelasticity of the starch-FG systems and soups containing them is shown at the frequency of 1 Hz (Fig 7.a, Fig 7b). The viscous or loss modulus shows slightly more dependency with the elastic component being frequently independent and always over the viscous modulus through the entire frequency range. The main differences between starch-FG systems and soups containing them is: a) the higher viscoelasticity developed in all the soups with both G' and G'' being greater in value than in the pure starch/fenugreek mixtures, measured under similar conditions and b) both elastic and viscous moduli gradually increase with the substitution of starch by FG for all formulations.

Caramel sauces can have tailored sensory, rheological and textural characteristics by using potato starch and xanthan gum combinations (Krystyjan et al., 2012). Potato starch and xanthan gum are selected among other starch-hydrocolloid combinations taking into account transparency and clear appearance for further use in caramel sauces as thickeners. Commercial sauce without any stabilisers received the lowest score in sensory evaluation. Samples were stored and among other rheological characteristics, storage and loss moduli


 Viscocelastic behavior of soups is similar to that of simple hydrocolloid-starch systems. However, viscous–like behavior is more pronounced in final soups than in starchhydrocolloids' systems.

Viscoelastic Properties of Starch and Non-Starch Thickeners in Simple Mixtures or Model Food 233

Adebowale, K. O., & Lawal, O. S. (2003). Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna

Achayuthakan P. & Suphantharika M. (2008). Pasting and rheological properties of waxy corn starch as affected by guar and xanthan gum. Carbohydrate Polymers, 71, pp.

Arocas A., Sanz T. & Fiszman S.M. (2009). Influence of corn starch type in the rheological properties of a white sauce after heating and freezing. Food Hydrocolloids, 23, pp. 901-

Acoras A., Sanz T., Hernando M.-I. & Fiszman S.M. (2011). Influence of corn starch type in the rheological properties of a white sauce after heating and freezing. Food

Ahmed J., Ramaswamy H. S., Ayad A. & Alli I. (2008). Thermal and dynamic rheology of

An, H.J., Yang H.S., Liu Z.D. & Zhang Z.Z. (2008). Effects of heating modes and sources on nanostructure of gelatinized starch molecules using atomic force microscopy. LWT-

Alloncle M. & Doublier J.-L. (1991). Viscoeleastic properties of maize starch/hydrocolloid

Atwell, W. A., Hood, L. F., Lineback, d. R., Varriano-marston, E., & Zobel, H. F. (1988). The terminology and methodology associated with basic starch phenomena. Cereal Foods

BeMiller J.N. (2011). Pasting, paste, and gel properties of starch-hydrocolloid combinations.

Bilbao-Sainz C., Burtler M., Weaver T. & Bent J. (2007). Wheat and starch gelatinization undermicrowave irradiation and conduction heating. Carbohydrate Polymers 69, pp

Biliaderis C., Juliano B. (1993). Thermal and mechanical properties of concentrated rice

Bowler P., Williams M.R. &AngoldR.E. (1980). A hypothesis for the morphological changes which occur on heating lenticular wheat starches in water. Starch/Stärke, 34, pp.

Chaisawang M. & Suphantharika M. (2006). Pasting and rheological properties if native and anionic tapioca starches as modified by guar gum and xanthan gum. Food

Dickinson E. 1992*. Rheology In: An introduction to food colloids*, Oxford University Press, pp

Doublier J.-L. & Cuvelier G. (2006). *Gums and Hydrocolloids: functional aspects in Carbohydrates* 

starch gels of varying composition. Food Chemistry 48, pp. 243–250

*in food*, ed. A.-C. Eliasson, CRC: Taylor &Francis, London

insoluble starch from basmati rice. Food Hydrocolloids 22, pp. 278-287

pruriens). Journal of the Science of Food and Agriculture, 83, pp. 1541–1546.

**8. References** 

9-17

907

Hydrocolloids, 23, pp. 901-907

World, 33, pp. 306–311.

224-232

149

59-62.

Food Science &Technology 41, pp. 1466-1471

Carbohydrate Polymers 86, pp. 386-423

Hydrocolloids 20 (5), pp. 641-649

pastes and gels. Food Hydrololloids, 5(5), pp. 455-467

 Thawing under heating of frozen ready to eat starch white sauces results in improved rheological characteristics of the final samples. In particular, thawing under microwaves leads to better products than those being thawed in a water bath.
