Prediction of physiological functions of pasteurized yogurt using Capillary Electrophoresis Time-of-Flight Mass Spectrometry

Abstract

　In recent years, not only probiotics containing viable yogurt but also postbiotics, which consist of heat-killed lactic acid bacteria and/or their metabolites, have attracted much attention for their potential as functional foods. Therefore, the physiological functions of postbiotics are being thoroughly investigated. The physiological functions of non-live lactic acid bacteria have been reported in pasteurized yogurt but the role of related substances has not been clarified yet. In this study, we used Capillary Electrophoresis Time-of-Flight Mass Spectrometry to analyze trace components, including metabolites in fresh and pasteurized yogurt. Our results confirmed that the secondary pasteurization, the process of sterilizing lactic acid bacteria after fermentation, is involved in the physiological functions of pasteurized yogurt. We detected 221 substances, among which, the contents of nicotinamide, cytidine, 5′-deoxy-5′-methylthioadenosine, and N-acetylneuraminic acid increased after secondary pasteurization. Conversely, the levels of trans-glutaconic acid, malic acid, succinic acid, S-adenosylmethionine, and free amino acids decreased. However, based on the quantitative values, we conclude that the negative effects of secondary pasteurization on the physiological functions of pasteurized yogurt are negligible. Moreover, no significant differences were detected in the levels of several important molecules, including short-chain fatty acids. To the best of our knowledge, this is the first study to investigate the effect of secondary pasteurization on trace components and metabolites in yogurt. Our results suggest that the secondary pasteurization may positively affect yogurt's physiological function.