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THE EFFECT OF DIFFERENT HEAT TREATMENTS OF CAPRINE MILK ON COMPOSITION OF CHEESE WHEY Zorana Miloradovic, Ognjen Macej, Nemanja Kljajevic, Snezana Jovanovic, Tanja Vucic, Igor Zdravkovic Institute of Food Technology and Biochemistry, University of Belgrade, Faculty of Agriculture, Serbia Introduction •The traditional view of cheese whey as a byproduct of dairy industry, with little value has disappeared, and now the whey is seen as a potential source of bioactive components that can be used in the formulation of multiple functional foods; •Although less explored than bovine whey, the caprine whey is gaining importance due to the worldwide increase in the production of dairy products based on caprine milk; •Among the different components of cheese whey, proteins are especially important in terms of biological activity, and the proteins of caprine whey possess a comparatively higher nutritional value than those of bovine whey; •The aim of this study was to give some basic characterisation of three caprine milk wheys derived from milk with three different thermal history, baring in mind that theese cheese wheys might be considered as different products; •The aim was also to provide an information of protein and fat losses from the point of view of cheese production. Matherial and methods •Caprine milk from the same batch was divided in three parts, and heated at three different regimes. Samples of whey were colected throughout draining and pressing of cheeses. •Three samples of whey were analysed acording to three heating regimes of milk: •W1 - 65°C/30 min, •W2 - 80°C/5 min, •W3 - 90°C/5min. •All three samples of whey were analyzed in terms of total solids, fat and protein content by the following methods: •Dry matter content - standard drying method at 102 ± 2º C (FIL IDF, 1987) •Fat content -by the method of Gerber-in (FIL IDF, 1981) •Protein content - Kjeldahl method (AOAC, 1990) •Protein composition - by SDS-PAGE according to Laemmli (1970), followed by subsequent densitometric analysis. •% of fat and protein recovery was calculated by the method of Lau et al., (1990) RESULTS Table 1. Basic composition of the whey samples obtained after the production of cheese from milk treated in the three heating regimes: 65°C/30 min (W1), 80°C/5 min (W2) and 90°C/5min (W3); Statistical analysis of data from Table 1 showed that heat treatment of milk significantly affected (p<0.05) all three parameters of whey composition. Whey samples From Table 2 it is clear that high heat treatment (80°C/5 min and 90°C/5 min) is more effective in terms of fat recovery (23.92% and 38.34%, respectively) than in terms of protein recovery (13.22% and 23.86%, respectively). W1 W2 W3 W* Proteins (%) 0,92±0,14 0,72±0,08 0,50±0,02 0,77 Fat (%) 1,05±0,10 0,58±0,17 0,35±0,05 0,51 Total solids (%) 6,78±0,17 6,16±0,26 5,78±0,15 6,61 Order of whey protein heat sensitivity, observed from the electrophoretogram (Figure 1), is as follows Ig≈LF>SA>β-lg>α-la Results in the table are the mean values of three replications ± standard deviation * Source: (Casper et al., 1998) Densitometric analysis of the electrophoretogram M W1 W2 W3 Figure 1. Electrophoretogram of milk (M) and whey samples (W1, W2 and W3) Figure 2. Protein composition of whey samples W1, W2 and W3 Table 2. Percentage of fat and protein recovery in whey obtained after the production of cheese from milk heated at 65°C/30min, 80°C/5min and 90°C/5min Whey samples W1 W2 W3 (%) of protein recovery 67,30±5,47 76,20±4,02 83,36±1,30 (%) of fat recovery 64,49±3,11 79,95±5,73 89,22±1,27 CONCLUSION According to presented results, it is clear that different heat treatments of cheese milk can produce completely different types of whey, in terms of basic chemical and protein composition. Further research could be pointed towards the investigations of technological and functional characteristics of such wheys. Obtained results could also provide the information about the effect of high heat treatments of caprine milk on distribution of milk components between cheese and whey. Results in the table are the mean values of three replications ± standard deviation The research was funded by the Ministry of education, science and technological development, as part of the investigations on the project 46009. The authors express their gratitude to Beocapra, Kukujevci for their generous donation of caprine milk.