Whey protein is rich in cysteine residues that can be found in relatively high
amounts, compared to other protein sources. Cysteine, one of three amino acids are
delivered to the interior of each cell and there they are assembled into glutathione.
Using whey in preparing functional diet will exposed whey protein to different
environmental condition and may affect during heat processing on its stability
(denaturation) that leading to loss solubility and biological functionality. In this
research, many modifications for sweet whey concentrate by UF had been carried out,
after that exposed to different heat treatments and study the effect of modification and
heat treatment on the resultant whey components. Modifications had carried out with
keeping fixed total solids (6.4%). Treatments were the original whey, concentrate
sweet whey TS 8.4% and 10.5% were diluted to TS 6.4%. All samples had exposed to
different heat treatments (HT), 60, 70, 80, 90 and 100·C 110 min. free lactose, whey
protein nitrogen index, total and reactive sulfhydryl groups and major minerals
(monovalent and divalent cations) were assayed. Results showed that, with increasing
protein concentration, free lactose was decreased specially at 80·C. Modification
played role in retard of denaturation as obvious from WPNI. Total and reactive
sulphydryl groups has a positive correlation with protein concentrate and they
increased with increasing heating, whereas divalent cations decreased with increasing
HT until 80·C and rapidly increased with increasing HT to 90·C. Measurement of free sulfhydryl (SH) groups in both whey and modification
whey showed that the liberation of free SH is highly correlated to the change of the
heat degree. Modification high protein concentrate with phosphate buffer gave the
best result for sweet whey as antioxidant potential.