Comparative characterization of whey protein concentrates from ovine, caprine and bovine breeds

Whey protein concentrates (WPC) obtained from ovine, caprine and bovine whe ys were studied in terms of chemical composition (concentration of lactose, protein, moisture, ash, calcium, sodium and potassium) and physical proper ties (onset denaturation temperature and viscoelastic behaviour). Ovine, ca prine and bovine WPC exhibited decreasing protein content and increasing la ctose content, in this order. The differences in ash content were relativel y small, but ovine and caprine WPC were quite different from bovine WC in t erms of calcium and potassium. Important differences in protein content hav e also been observed; ovine WPC showed the highest concentration in the pro tein beta-lactoglobulin, bovine WPC the highest concentration in the protei n alpha-lactalbumin and caprine the highest concentration in the protein im munoglobulin G. No significant differences existed in terms of denaturation onset temperature between the three types of WPC; however, differences wer e found within WPC types between those cases where NaCl was present or abse nt. The gel maturation at 85 degrees C was characterized by storage moduli that were close to one another for ovine and caprine WPC, but these were fa r from those of bovine WPC. Th, decrease in temperature from 85 to 20 degre es C had a strong effect on the viscoelastic moduli of WPC gels, but the in itial structure could be recovered by reheating the gels from 20 to 85 degr ees C. (C) 1999 Academic Press.