Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore 117542, Singapore.
Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore 117542, Singapore.
Food Res Int. 2022 Jun;156:111350. doi: 10.1016/j.foodres.2022.111350. Epub 2022 May 7.
Salted soy whey, a liquid by-product from salted tofu processing, is a source of valuable nutrients. However, it is often under-utilized due to its high salt content. The objective of this study was to investigate the feasibility of using different species of yeast to transform salted soy whey into a soy sauce-like condiment. Three yeasts were used for salted soy whey biotransformation: Zygosaccharomyces rouxii NCYC 1682, Candida versatilis NCYC 1433, and Torulaspora delbrueckii Biodiva. This study focused on the growth of the yeasts in soy whey added with different levels of NaCl and the physicochemical changes of salted soy whey after fermentation. The soy sauce yeasts (Z. rouxii and C. versatilis) grew by approximately 2 log CFU/mL in soy whey with 2% and 10% salt while the cell count of wine yeast T. delbrueckii increased by around 1.5 log CFU/mL at 10% salt and 1.78 log CFU/mL at 2% salt after 14 days of fermentation. Candida versatilis grew better at 10% salt with less glucose consumption (consumed 68.49% at 10% versus 94.05% at 2% salt) than at 2% salt. It was also found that all three yeasts converted isoflavone glycosides (bound isoflavones) into aglycones (free isoflavones), the latter having better bioavailability. C. versatilis showed the greatest ability to transform isoflavone glycosides in salted soy whey into higher amounts of aglycones (conversion efficiency of 23.04% at 2% salt and 15.05% at 10% salt). Salted soy whey fermented with different yeasts had different volatile profiles. Soy sauce yeasts produced more isobutyl alcohol, isoamyl alcohol and volatile phenols while T. delbrueckii generated a substantial amount of ethanol and esters. This study revealed the growth and flavour modulating potential of yeasts in salted soy whey fermentation, which provides a possible avenue to develop a soy sauce-like condiment using salted soy whey as a substrate.
盐水豆乳是一种来自盐水豆腐加工的液体副产物，是有价值营养物质的来源。然而，由于其高盐含量，通常未得到充分利用。本研究的目的是研究使用不同种类的酵母将盐水豆乳转化为酱油状调味料的可行性。使用三种酵母对盐水豆乳进行生物转化：Zygosaccharomyces rouxii NCYC 1682、Candida versatilis NCYC 1433 和 Torulaspora delbrueckii Biodiva。本研究重点研究了不同盐浓度的豆乳中酵母的生长情况以及发酵后盐水豆乳的理化变化。酱油酵母（Z. rouxii 和 C. versatilis）在 2%和 10%盐浓度的豆乳中生长约 2 个对数 CFU/mL，而酒酵母 T. delbrueckii 的细胞计数在 10%盐浓度和 2%盐浓度下分别增加了约 1.5 个对数 CFU/mL 和 1.78 个对数 CFU/mL，发酵 14 天后。C. versatilis 在 10%盐浓度下生长更好，葡萄糖消耗更少（10%盐浓度下消耗 68.49%，而 2%盐浓度下消耗 94.05%）。还发现，三种酵母都将异黄酮糖苷（结合异黄酮）转化为苷元（游离异黄酮），后者具有更好的生物利用度。C. versatilis 显示出将盐水豆乳中的异黄酮糖苷转化为更多苷元的最大能力（2%盐浓度下的转化率为 23.04%，10%盐浓度下的转化率为 15.05%）。用不同酵母发酵的盐水豆乳具有不同的挥发性成分。酱油酵母产生更多的异丁醇、异戊醇和挥发性酚类物质，而 T. delbrueckii 产生大量的乙醇和酯类物质。本研究揭示了酵母在盐水豆乳发酵中的生长和风味调节潜力，为利用盐水豆乳作为底物开发酱油状调味料提供了一种可能的途径。
