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Publication date: 2010-12-31
Pol. J. Food Nutr. Sci. 2010;60(4):353-362
Buffalo's milk protein products, total milk proteinate (TMP), rennet casein, and lactic acid casein were studied. The chemical composition was determined and some properties (water and oil absorption capacity, emulsion activity, foam expansion, and buffer capacity) of these products were also determined. The results indicated some differences in the chemical composition and electrophoresis bands of protein between total milk proteinate, rennet casein and lactic acid casein. The TMP was characterised by the lowest ash and moisture contents with highest protein contents compared to the other protein products. There is no remarkable effect of drying methods on the chemical composition within each type of protein products. Total milk proteinate contains some whey proteins which are high in alanine, cystine when compared with rennet casein. Lactic acid casein had high contents of amino acid proline. On the other hand, the rennet casein had a low content of sulfur containing amino acids cysteine and methionine. Differences between total essential amino acid (TEAA) of total milk proteinate and lactic acid casein were significantly (p<0.05) higher than those of rennet casein. Freeze dried total milk proteinate exhibited excellent foaming and emulsifying potential when compared with oven-dried caseinate. For all protein types, the maximum WAC can be seen for freeze-dried milk proteinates, whereas the minimum value was for oven dried rennet casein. The minimum value of emulsion capacity and surface tension was obtained at pH 4.5 and 2.5 in all types of proteinates, whereas the maximum values were found at pH 10.5. Relative viscosity of TMP solutions was higher than those of rennet and lactic acid casein. However, relative viscosity values tended to decrease with lowering or increasing the pH values of the solutions from the neutral pH value. Calorimetric analysis showed two major enthalpy changes in the tested caseinate samples. The first change occurred at peak temperature range of 92.2°C to 100.8ºC for the moisture removal, while the second change occurred between 273.9°C and 314.6°C for protein degradation. The enthalpy values ranged between 218.3 to 268.4 J/g for moisture removal. Total milk proteinate showed two major peaks for protein degradation indicating the presence of whey proteins and milk caseins.
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