B. Lieske et G. Konrad, THERMAL MODIFICATION OF UF-WHEY PROTEIN . 2. INFLUENCE OF THE NUTRITIVE PROPERTIES, Milchwissenschaft, 48(11), 1993, pp. 626-629
The effects of thermal treatments (90-degrees-C for 1 0 min) were exam
ined on ultrafiltered whey proteins under acid, neutral or alkaline co
nditions in relation to their nutritional properties. Therefore enzymi
c availability in vitro was investigated using physiological relevant
proteinases and subsequent investigation of proteolysates by gelchroma
tography on Sephadex G-25. The nutritive value was determined by a two
-step-digestion using pepsin and trypsin/pancreatin. The resulting pro
teolytic patterns were compared with those obtained by digestion of un
treated whey protein. It is shown that subtle modifications are not or
scarcely detectable under physiological relevant conditions. Further
investigations relating enzymic availability of whey protein fractions
by pepsin or trypsin made clear that the pepsin resistance of beta-la
ctoglobulin can be broken by thermal modification under alkaline condi
tions.