Effects Of Feruloyl Oligosaccharides Producted By Fermentation On Nutrition And Flavor Of Flour Products

Feruloyl oligosaccharides(FOs)is an important component of cereal husk,which has antioxidant,anti-saccharification and prebiotic activities.However,FOs can reduce the taste and flavor of flour products.In the process of FOs production by fermentation,ferulic acid esterase(FAE)is involved in the hydrolysis of wheat bran to release FOs.At the same time,FAE acts on the ester bond in FOs,which has a great influence on the yield of FOs.In the early stage,the research group used comparative transcriptomics technology to analyze the strains with different fermentation time,and found that the expression level of FAE changed significantly at different fermentation time.Therefore,the correlation between the expression level of FAE gene and FOs yield under different fermentation conditions was analyzed by RT-qPCR,and the recombinant protein ApFAE? was obtained by heterologous expression to verify its effect on FOs yield,which laid a theoretical foundation for studying the regulation of FAE on FOs and efficient preparation of FOs.At the same time,FOs from fermentation was used to prepare the entrapment which released FOs in the kneading,baking and digestive stages.The effects of the entrapment FOs on the dough products qualities and nutritional characteristic of such as antioxidant,anti-saccharification and regulation of intestinal flora were studied,so as to clarify the mechanism of FOs in the production process of flour products,and provide the basis for the development of FOs flour products with nutrition and flavor.The main research contents and results are as follows:1.RT-qPCR was used to analyze the correlation between the expression levels of ApFAE?,ApFAE? and ApFAE? and FOs yield.The results showed that the R values of the correlation between the expression levels of ApFAE? and FOs yield under different p H,temperature and time were 0.658,0.933 and 0.810,ApFAE? were 0.976,0.881 and 0.865,ApFAE? were 0.909,0.902 and 0.837,respectively.Thus,the expression levels of ApFAE?,ApFAE? and ApFAE?were positively correlated with FOs production rate,and the expression level of ApFAE? was significantly correlated with FOs production rate(P<0.01).The ApFAE? gene was expressed in Pichia pastoris GS115 by heterologous expression method,and the recombinant protein with molecular weight of about 75 k Da was obtained.The results of ApFAE? functional verification showed that the hydrolysis efficiency of FOs was 2.11 ‰ within 12 h.Therefore,its ApFAE?can hydrolyze FOs,which indicates that C-type FAE plays an important role in the regulation of FOs synthesis.2.In order to study the effect of FOs on the quality of flour products in kneading and baking stages,?-Hydroxypropyl cyclodextrin(HP-?-CD),lipid and sodium alginate(SA)were used to prepare FOs encapsulations in kneading,baking and digestive tract,respectively.The results showed that the free sulfhydryl group,farinography and texture properties of lipid-FOs and SA-FOs were higher than those of cyclodextrin FOs(CD-FOs)and free FOs,which indicated that FOs destroyed the network structure of gluten protein and reduced the quality of dough;The quality of SA-FOs,CD-FOs,lipid-FOs and free FOs biscuits decreased in turn,The contents of?-dicarbonyl compounds,advanced glycation end products(AGEs)and baking characteristic flavor also decreased in turn,indicating that FOs inhibited the baking stage.The formation of?-dicarbonyl compounds,AGEs and baking flavor components.Therefore,FOs first destroyed the dough structure in the kneading stage to make the texture and taste of flour products,and inhibited it in the baking stage.The formation of ?-dicarbonyl compounds can reduce the contents of AGEs and baking flavor components,and reduce the flavor and glycosylation degree of flour products.SA-FOs did not release FOs in kneading and baking stages,which prevented FOs from destroying dough structure and retained FOs inhibition.Because of the interaction of?-dicarbonyl compounds and AGEs,the quality of SA-FOs flour products is the best.3.Free FOs,CD-FOs,lipid-FOs and SA-FOs were used to study the changes of antioxidant,glucose and lipid metabolism and intestinal flora of FOs before and after embedding.The results showed that DPPH,ABTS and hydroxyl radical scavenging power of CD-FOs,lipid-FOs and SA-FOs biscuits decreased in turn(P<0.05).The results showed that free FOs,CD-FOs,lipid-FOs and SA-FOs of 42 mg FOs / 100 g biscuit had higher T-SOD activity,GSH-PX activity and T-AOC than those of free FOs biscuit,which indicated that embedding treatment could maintain and promote the antioxidant activity in vivo;The results of different doses of SA-FOs showed that the antioxidant activity in vivo was concentration dependent(P<0.05),and the GSH-PX activity in the high-dose SA-FOs group was 2.25 times higher than that in the biscuit control group.In addition,free FOs and SA-FOs significantly reduced the body fat percentage,fasting blood glucose and serum AGEs concentration of mice,and decreased with the increase of FOs concentration(P<0.05),and also increased the diversity of intestinal flora and the abundance of probiotics such as akkermansia and Lactobacillus.In conclusion,the antioxidant activities of CD-FOs,lipid FOs and SA-FOs were higher than that of free FOs.Both free FOs and SA-FOs could regulate glucose and ester metabolism and intestinal microflora,but embedding treatment maintain and promote the physiological activity of FOs.