**3. Oxidative rancidity measured by TBARS test**

The initial TBARS values of the beef sample expressed as mg malondialdehyde/kg meat, were about two times greater than those of chicken sample. These results reflect the quality of the raw materials, which in the case of beef, it already had a high initial degree of peroxidation. Inappropriate storage conditions of meat, together with the action of light, oxygen and the presence of myoglobine probably accelerated oxidation.


Each value is the mean of three replicates.

\* Values within the same column with different subscripts denote significant differences (p< 0.05) between storage times according to LSD.

\*\* Values within the same row with different superscripts denote significant differences (p< 0.05) between the treatments according to LSD.

Table 1. Thiobarbituric acid reactive substances values (TBARS) expressed as mg malondialdehyde /kg meat for the raw and grilled burger samples during storage time.

It can be observed that TBARS values increased during the first month.The increase was higher in the chicken sample and those with olive oil than those of beef sample.These results might be explained by the fact that the fatty acids of these samples have higher degree of unsaturation when compared with those of beef.

carried out according to the method used by Sander, *et al.* (1988) and the trimethylsilyl derivatives (TMS) of cholesterol and cholesterol oxides were carried out according to the

The moisture, fat and protein contents for both beef burger treatments before grilling, were about 65.50%, 15.11%, and 18.20%, respectively. The moisture, fat and protein contents of both chicken burger samples before grilling were about 66.50%, 15%, and 17.50%, respectively.

The moisture loss percentage of the freshly prepared treatments due to grilling was between 20.37-25.62%, and fat loss was between 18.85-21.51%. On the other hand, the increase in protein contents was (96-116%) of the burger samples. Moisture and fat contents of the grilled samples were lower than those of raw samples, while protein content was higher.

The initial TBARS values of the beef sample expressed as mg malondialdehyde/kg meat, were about two times greater than those of chicken sample. These results reflect the quality of the raw materials, which in the case of beef, it already had a high initial degree of peroxidation. Inappropriate storage conditions of meat, together with the action of light,

> b1.21c a3.00c b1.20c

> b5.09a a7.04b c4.53a

\* Values within the same column with different subscripts denote significant differences (p< 0.05)

\*\* Values within the same row with different superscripts denote significant differences (p< 0.05)

It can be observed that TBARS values increased during the first month.The increase was higher in the chicken sample and those with olive oil than those of beef sample.These results might be explained by the fact that the fatty acids of these samples have higher degree of

Table 1. Thiobarbituric acid reactive substances values (TBARS) expressed as mg malondialdehyde /kg meat for the raw and grilled burger samples during storage time.

\*Treatment\*\*

b2.09b a2.59e b2.13b

b2.10c a3.68c c1.53c

olive oil

b2.27a a5.07b b2.59a

c0.38e a0.91e b0.79e

Chicken with olive oil

> b0.74d a5.23a b0.77d

> b3.76b a7.99a c3.12b

Beef Chicken Mixed Beef with

method used by Pie, *et al.* (1990).

Characterisic

Raw

Grilled

**2. Moisture, fat and protein content** 

This is mainly due to the loss of water and fat.

Time of storage (month)

> 0 1 3

> 0 1 3

Each value is the mean of three replicates.

between storage times according to LSD.

between the treatments according to LSD.

unsaturation when compared with those of beef.

**3. Oxidative rancidity measured by TBARS test** 

oxygen and the presence of myoglobine probably accelerated oxidation.

b2.26a a2.71d a2.62a

b0.57d a1.09d a1.03d

Melton (1985) reported that oxidized flavors were detectable at TBARS numbers of 0.3-1.0 in beef or pork, 1or 2 in chicken, and higher than 3 in turkey. The TBARS values obtained in this study, remarkably exceeded these ranges. So it can be assumed that these high values of TBARS could be attributed to oxidation as well as other interferences.

On the other hand, decrease in TBARS values noticed at the end of storage period were 85, 60, 47, 18 and 3% for chicken with olive oil, chicken, beef with olive oil, mixed and beef treatments, respectively. This behavior may be ascribed to the combination of aldehydes with other compounds and to the loss of volatile aldehydes (Severini, *et al*., 2003).

Different trends were observed on the effect of grilling on TBARS values, since TBARS values decreased in both beef samples, whereas they increased in both chicken samples. This finding may be attributed to the fact that chicken fat contains higher levels of PUFA, which are prone to higher level of oxidation.
