AUTHOR=Xu Xifei , Liu Wenjian , Niu Honghong , Hua Mei , Su Ying , Miao Xinyu , Chi Yanping , Xu Hongyan , Wang Jinghui , Sun Mubai , Li Da 

TITLE=Study on the fermentation effect of Rhodotorula glutinis utilizing tofu whey wastewater and the influence of Rhodotorula glutinis on laying hens

JOURNAL=Frontiers in Nutrition

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1125720

DOI=10.3389/fnut.2023.1125720

ISSN=2296-861X

ABSTRACT=<sec><title>Background</title><p>Tofu whey wastewater (TWW) is the wastewater of tofu processing, which is rich in a variety of nutrients. <italic>Rhodotorula glutinis</italic> can make full use of TWW to ferment and reproduce yeast cells, produce carotenoids and other nutrients, improve the utilization value of TWW, and reduce environmental pollution and resource waste.</p></sec><sec><title>Methods</title><p>In this study, the nutrient composition changes of TWW treated by <italic>Rhodotorula glutinis</italic> were analyzed to reformulate TWW medium, and the optimal composition and proportion of TWW medium that can improve the biomass and carotenoids production of <italic>Rhodotorula glutinis</italic> were explored. Meanwhile, the <italic>Rhodotorula glutinis</italic> liquid obtained under these conditions was used to prepare biological feed for laying hens, and the effect of <italic>Rhodotorula glutinis</italic> growing on TWW as substrate on laying performance and egg quality of laying hens were verified.</p></sec><sec><title>Results</title><p>The results showed that the zinc content of TWW after <italic>Rhodotorula glutinis</italic> fermentation increased by 62.30%, the phosphorus content decreased by 42.31%, and the contents of vitamin B1, B2 and B6 increased to varying degrees. The optimal fermentation conditions of <italic>Rhodotorula glutinis</italic> in the TWW medium were as follow: the initial pH was 6.40, the amount of soybean oil, glucose and zinc ions was 0.80 ml/L, 16.32 g/L, and 20.52 mg/L, respectively. Under this condition, the biomass of <italic>Rhodotorula glutinis</italic> reached 2.23 g/L, the carotenoids production was 832.86 μg/g, and the number of effective viable yeast count was 7.08 × 10<sup>7</sup> cfu/ml. In addition, the laying performance and egg quality of laying hens fed <italic>Rhodotorula glutinis</italic> biological feed were improved.</p></sec><sec><title>Discussion</title><p>In this study, we analyzed the composition changes of TWW, optimized the fermentation conditions of <italic>Rhodotorula glutinis</italic> in TWW medium, explored the influence of <italic>Rhodotorula glutinis</italic> utilizing TWW on laying layers, and provided a new idea for the efficient utilization of TWW.</p></sec>