Systematic Biological Evaluation And Application Of High Nucleotide Yeast Hydrolysate

As a new type of safe and green food additive,high nucleotide yeast hydrolyzate(HNYH)is of great nutrition and health.Previous studies have shown that HNYH is rich in a large amount of nutrients including: nucleic acids,nucleotides(AMP,CMP,GMP,UMP,IMP),oligopeptides,digestive enzymes,free amino acids and rich B vitamins and yeast cell wall polysaccharides.Having a variety of biological activities,HNYH plays an essential role in many ways such as bio-synthesis,carbohydrate synthesis,energy metabolism as well as protein bio-synthesis.Also it has several important functions like anti-oxidation,body immunity enhancement and gastrointestinal homeostasis maintenance.HNYH is widely used in medicine,health care products,condiments,and has great potentials of research significance and market value in the food field.This paper studied its systematic biological evaluation,including physical property evaluation,processing applicability and intelligent sensory evaluation for the food field,and constructed a cell evaluation model in order to study its ability to scavenge free radicals,antioxidants and anti-inflammatory.Furthermore,this study explored the mechanism of action of yeast nucleotides in the field of functional foods,and based on that,our team developed a meal replacement powder that will enhance people's immunity.The main contents are as follows:Under the national standard approaches,the nutrients of three yeast hydrolysates were determined;The five nucleotide contents and powder characteristics of yeast hydrolysate were compared and as well.As a result,the nucleotide content of HNYH was identified to be 13.6%,which was 63 times that of type II yeast hydrolysate,or 17 times that of Anqi FA31 yeast peptide,and HNYH powder has the best fluidity.The electronic nose were used to detect the complex odor and volatile components of the hydrolysate,and to obtain the odor fingerprint of the sample,so that different yeast hydrolysates can be effectively distinguished;The electronic tongue has also been used to perform pattern recognition and qualitative and quantitative analysis of the sample,and to obtain the sample's acidity,saltiness,freshness,bitterness,astringency,sweetness,richness,sharpness and bitterness.After evaluating the overall taste characteristics of the sample,reliable data can be supporting for the development of the product.Different samples were observed by electron microscopy.And different components in the sample underwent the qualitative and semi-quantitative analysis.Therefore,the comprehensive intelligent sensory evaluation of the raw materials was completed.This experiment employed the chemical method to determine the scavenging ability of DPPH on free radicals and hydroxyl radicals.The oxidative stress model of HepG2 cells induced by free fatty acid(FFA)was established.The results of vitro culture experiments showed that HNYH could relieve the FFA-induced oxidative stress in HepG2 cells,and the protective effect was positively correlated with HNYH concentration,and it significantly increased total antioxidant capacity and antioxidant enzyme activity as well as significantly decreased MDA content.When the dosage of HNYH was 1 mg/mL,the ROS level was close to the control level,indicating a significant antioxidant effect.The results of RT-PCR experiment also showed that the expression levels of antioxidant enzymes NQO1,Nrf2 and HO-1 mRNA in the experimental group were significantly increased while the expression level of keap1 mRNA decreased.The protein content of Nrf2 in the nucleus of HepG2 cells increased and the protein content in cytoplasm decreased,which clarified that HNYH can activate Nrf2 pathway to attenuate HepG2 oxidative stress injury induced by FFA.The well-grown RAW264.7 cells with lipopolysaccharide(1 ?g/mL)for 24 h was stimulated to establish an vitro cell inflammatory model.The results showed that HNYH significantly decreased the expression of inflammatory factors NO,TNF-?,IL-1?,IL-6 and its related mRNA in RAW264.7 cells induced by LPS,and decreased the expression of NF-?Bp65 protein in iNOS and nucleus.Showing a concentration-dependent relationship.The protective effect of HNYH on LPS-induced RAW264.7 macrophage inflammation was confirmed.The mechanism of action has also been found that it was related to iNOS protein expression and NF-?B pathway,which protected the body from inflammatory damage by inhibiting NF-?B activation and nuclear transport.The yeast peptide meal package was prepared,and the odor and taste of the meal package were rationally analyzed by electronic nose and electronic tongue.The odor fingerprint and taste evaluation were comprehensively evaluated.The mouse macrophage inflammation model was used to evaluate the function of the yeast peptide meal package.The results have shown that the yeast peptide meal package can inhibit the inflammatory response's action of LPS on RAW264.7 cells.