Comparative evaluation of commercial Douchi by different molds:biogenic amines,non-volatile and volatile compounds

To provide new insights into the development and utilization of Douchi artificial starters,three common strains(Aspergillus oryzae,Mucor racemosus,and Rhizopus oligosporus)were used to study their influence on the fermentation of Douchi.The results showed that the biogenic amine contents of the three types of Douchi were all within the safe range and far lower than those of traditional fermented Douchi.Aspergillus-type Douchi produced more free amino acids than the other two types of Douchi,and its umami taste was more prominent in sensory evaluation(P<0.01),while Mucor-type and Rhizopus-type Douchi produced more esters and pyrazines,making the aroma,sauce,and Douchi flavor more abundant.According to the Pearson and PLS analyses results,sweetness was significantly negatively correlated with phenylalanine,cysteine,and acetic acid(P<0.05),bitterness was significantly negatively correlated with malic acid(P<0.05),the sour taste was significantly positively correlated with citric acid and most free amino acids(P<0.05),while astringency was significantly negatively correlated with glucose(P<0.001).Thirteen volatile compounds such as furfuryl alcohol,phenethyl alcohol,and benzaldehyde caused the flavor difference of three types of Douchi.This study provides theoretical basis for the selection of starting strains for commercial Douchi production.

Effects of resistant starchⅢon the serum lipids levels and gut microbiota of Kunming mice under high-fat diet

Resistant starch III(RS3),as a prebiotic,provides health benefits.This study aimed to investigate the role of RS3 in lowering serum lipids and regulating gut microbiota by administering Novelose 330 to Kunming(KM)mice.The results demonstrated that RS3 intervention significantly decreased body weight,food intake,levels of serum total cholesterol(TC),triglyceride(TG),low-density lipoprotein cholesterol(LDL-C),and liver fat.RS3 could remarkably improve the quality of the entire cecum,quality of the cecal wall,and wall surface area of mice;enhance the moisture content;and reduce the p H value.Moreover,the decrease in the liver TC content and the increase in the fecal TC content were related to RS3 intervention.The concentrations of total short-chain fatty acids(SCFAs)in the colon and individual levels of acetate,propionate,and butyrate increased with RS3 supplementation.An Illumina-based sequencing approach showed that RS3 notably increased the Bacteroides/Firmicutes ratio in the mice fed a high-fat diet.At the genus level,the relative abundance of Bacteroides,Ruminococcus,and Bifidobacterium and the number of main SCFA producers increased in the mice fed an RS3 diet.These findings provided insights into specific gut microbiota shifts to the hypolipidemic effect of RS3.

Effects of different thermal processing methods on bioactive components,phenolic compounds,and antioxidant activities of Qingke(highland hull-less barley)

Qingke(highland hull-less barley)is a grain replete with substantial nutrients and bioactive ingredients.In this study,we evaluated the effects of boiling(BO),steaming(ST),microwave baking(MB),far-infrared baking(FB),steam explosion(SE),and deep frying(DF)on bioactive components,phenolic compounds,and antioxidant activities of Qingke compared with the effects of traditional roast(TR).Results showed that the soluble dietary fiber,beta-glucan and water-extractable pentosans of Qingke in dry heat processes of TR,SE,MB and FB had a higher content compared with other thermal methods and had a better antioxidant activity of hydroxyl radical scavenging and a better reduction capacity,while those in wet heat processes of BO and ST had a better antioxidant activity of ABTS radical scavenging and a better Fe^(2+) chelating ability.DF-and SE-Qingke had a higher content of tocopherol,phenolic,and flavonoid.Overall,6 free phenolic compounds and 12 bound phenolic compounds of Qingke were identified,and free phenolic compounds suffered more damage during thermal processing.Principal component analysis showed that SE had more advantages in retaining and improving the main biological active ingredients of Qingke,and it may be the best method for treating Qingke.