Pea yogurt alternative: flavor modification by starter selection and carbohydrate addition

Pea yogurt alternative integrates the physiological advantages of lactic acid bacteria (LAB) fermentation and the nutritional properties of pea proteins but the use of peas in yogurt like foods is limited due to their undesirable sensory attributes known as beany off-flavor. This study aims to improve flavor profile of the LAB fermented pea milks through regulating the off-flavor bio-transformation processes by applying different yogurt starter cultures and supplementing carbohydrates. Approximately 140 volatile organic compounds (VOCs) were detected using high-resolution two-dimensional gas chromatographic analysis combined with time-of-flight mass spectrometry (GC×GC-TOFMS). By changing starter cultures, adding glucose or lactose in different levels in LAB fermentations, 26, 27, and 26 critical differential VOCs were screened respectively. The up-regulated differential VOCs corresponded to the fermentation generated and biotransformation generated volatiles, whereas the down-regulated ones were basically off-flavor volatiles in pea milks. However, the quantitative patterns of the critical differential VOCs were starter culture and carbohydrate dependent. Effects of starter selection and carbohydrate addition on the sensory characteristics of fermented pea milks were assessed by summing up the relative odor activity values (ROAVs). The creamy, sweet and pungent odors were markedly enhanced by starters used for plant-based yogurt, while glucose or lactose addition at 3% or 5% levels enhanced creamy odor and inhibited the green odor. The findings of this study provide new ideas and methods for flavor modification to improve the quality of pea yogurt alternatives.