Optimization And Application Of Fermentation Process For Carotenoids Production By Red Yeast NCU-317

Carotenoids are a type of natural pigment that play an important role in the human body,such as enhancing immunity,reducing oxidative damage,preventing tumors and cardiovascular diseases,etc.However,since the human body cannot synthesize carotenoids autonomously,they must be obtained from external sources.In recent years,the production of carotenoids by red yeast has received widespread attention from researchers due to its advantages of short fermentation cycle,low cost,and easy scale-up production.However,there are still issues such as low yield in carotenoid production by red yeast fermentation,more research on liquid fermentation than solid-state fermentation,etc.Therefore,this paper optimized the process of carotenoid production by liquid fermentation of the red yeast strain NCU-317 in the laboratory and investigated its application in solid-state fermentation of orange peel powder.The main research content and results were as follows:1.The liquid fermentation process for the production of carotenoids by red yeast NCU-317 was optimized.Using carotenoid content as the optimization index,significant factors affecting carotenoid content were determined through Plackette-Burman experiments,which were sucrose,glucose,pancreatic digest of casein and yeast extract.Based on this,a central composite design experiment was conducted to further determine the optimized medium composition,which consisted of 20.00 g/L sucrose,25.00 g/L glucose,5.00 g/L pancreatic digest of casein and3.00 g/L yeast extract.After optimization,the carotenoid content of red yeast was125.424 μg/g,and the carotenoid production was 2.098 mg/L.Box-Behnken experiments were conducted to determine the optimized fermentation conditions,which were temperature of 20 ℃,p H of 6.5,fermentation time of 118 h and liquid volume of 10 m L/50 m L.The carotenoid content reached 238.428 μg/g,and the carotenoid production reached 3.966 mg/L after optimization,which was increased by 1.85 and 3.52 times compared with the non-optimized fermentation respectively.In addition,HPLC identification was performed on the optimized red yeast carotenoids,and it was preliminarily inferred that the carotenoids contained astaxanthin,lutein,lycopene,β-carotene and zeaxanthin.2.Optimization of the solid-state fermentation process of orange peel powder for the production of carotenoids by red yeast NCU-317 The amount of orange peel powder,moisture content,inoculation amount and fermentation time were determined by single-factor experiments to be 10 g,70%,15% and 96 h respectively.Nutritional composition and volatile compounds of the orange peel powder before and after fermentation by the red yeast were analyzed.The results showed that the content of carotenoids,crude protein,crude ash,and crude fat significantly increased by 75.72%,82.85%,17.17%,and 57.69% respectively after fermentation(P<0.05),while the content of reducing sugar decreased significantly by 41.76%.In addition,the aroma compounds in the orange peel also significantly changed after fermentation.The relative content of alkanes decreased from 31.7% to 10.98%,while the relative content of alcohols increased from 19.05% to 55.97%,and the relative content of olefins increased from 15.11% to 17.81%.These results indicated that the product of orange peel fermented by red yeast is rich in carotenoids,fungal protein and volatile compounds,which can increase the utilization rate and potential nutritional value of orange peel.3.The effects of adding red yeast NCU-317 fermented orange peel product on the production performance,physiological function and egg quality of laying hens were explored.The results showed that adding red yeast fermented product in chicken feed can significantly increase the weekly egg production rate and average egg weight of laying hens.At the same time,the content of carotenoids in egg yolk and Roche color fan value were also significantly higher than those in the control group(P<0.05).In addition,adding red yeast fermented orange peel product to the diet can significantly improve the antioxidant capacity and superoxide dismutase activity in the blood of laying hens,reduce the content of malondialdehyde(P<0.05),and have no significant effect on serum creatinine content.Therefore,adding red yeast fermented orange peel product in chicken feed can significantly improve the production performance of laying hens,improve egg yolk color,and significantly increase the content of carotenoids in egg yolk.At the same time,this treatment has a positive regulatory effect on the antioxidant capacity of laying hens,and has no negative effect on liver and kidney function.