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SummaryThe proteolytic specificity of chymosin (EC 3.4.23.4) on bovine αs1-casein at 30°C in phosphate buffer, pH 6·5 and at pH 5·2 in the presence of 5% (w/v) NaCl was investigated. Peptides (pH 4·6-soluble) were isolated by reversed-phase HPLC and identified from their amino acid sequence; the identity of some peptides was confirmed by mass spectrometry and/or amino acid composition. The small peptides produced at pH 6·5 were Arg1–Phe23, Phe24–Phe28, Phe24–Leu40(?), Phe150–Phe153, Phe150–Leu156, Tyr154–Tyr159, Tyr154–Trp164, Asp157–Trp164 and Tyr165–Trp199. The same peptides, except Tyr154–Trp164, were produced at pH 5·2 in the presence of NaCl and, in addition, the peptides Arg1–Leu11, Phe24–Phe32, Lys102–Leu142, Ala143-Leu149 and Tyr165-Phe179. The rates of production of individual peptides differed under the two conditions studied but Arg1-Phe23 and Tyr165–Trp199 were the first and second peptides produced under both conditions. Pathways are proposed to interpret the proteolysis of αs1-casein in solution under the conditions of this study.

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Chesse flavor is a manifestation of complex interactions of volatile and non‐volatile flavor‐active compounds plus tactual perception. Numerous agents, including lactic acid bacteria, procece the flavou sensations. The effect of lactic acid bacteria is more dominant in cheese varieties with limited growth of secondary flora. This review describes the indirect and direct impacts of lactic acid bacteria in cheese with emphasis on carbohydrate fermentation, changes in oxidation‐reduction potential, interactions with non‐starter bacteria, autolysis, proteolytic and peptidolytic activities, transport of metabolites and flavor production.

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