Effect of ultrasound-assisted freeze-dried on microstructure,bioactive substances,and antioxidant activity of Flos Sophorae Immaturus

Flos Sophorae Immaturus(FSI)extract and its main active secondary metabolites have health benefits including antioxidant activity,but the drying process may negatively affect their quality and quantity.To investigate the effect of ultrasound-assisted freeze-drying(UAFD)on FSI,the drying rate,colour,and microstructure samples were analysed.Furthermore,the flavonoids and antioxidant activity of dried products were evaluated.The results showed that the drying rates were significantly enhanced with UAFD.At 600 W and 15 min,the drying time of UAFD was 40%shorter than that of freeze-drying(FD)alone.The micrographs showed that USAD created more porous structures that allowed water to migrate outward from inside the FSI tissue.Processing conditions of 600 W ultrasonic power and 5 min ultrasonication time produced better antioxidant activity in dried products than in other conditions.The highest characteristic properties were DPPH(75.51%),ABTS(95.14%),FRAP(83.05%),acceptable drying time(3 h),and low colour difference(1.09).Under these conditions,the contents of total flavonoids(298.34 mg/g),rutin(256.66 mg/g),quercetin(20.13 mg/g),kaempferol(19.64 mg/g),isorhamnetin(17.77 mg/g),and genistein(13.97 mg/g)were determined to be as indicated.The results confirmed the obvious benefits of incorporating the ultrasonic effect into the FD method.

In vitro characteristics of lactic acid bacteria probiotics performance and antioxidant effect of fermented soymilk

Lactic acid bacteria(LAB)are generally used for soymilk fermentation to improve its nutritional and health-related qualities.Twenty-five LAB strains isolated from soybeans and fermented dairy products(FDP)were screened for probiotic candidates.To obtain bacteria with probiotic properties and effective antioxidant activities for soymilk fermentation,their performance at pH(2.5-3.0)and bile salt(0.3-0.5 mg/100 mL)were evaluated,and two strains(Lactobacillus plantarum NCU001563 and Streptococcus thermophilus NCU074001)were selected.Further,the obtained strains showed excellent gastrointestinal fluid resistance ability,cell adhesion susceptibility,β-glucosidase activity,and were sensitive to the various antibiotics.LAB both strains and fermented soymilk supernatant(FSMS)displayed a strong inhibitory effect on pathogenic strains.Nevertheless,when treated with catalase and proteases at pH 6.2,FSMS demonstrated a significant decrease of antibacterial activity.Finally,the antioxidant results indicated fermented soymilk(FSM)has stronger antioxidant activity than non-fermented soymilk(NFSM)by evaluating 1,1-diphenyl-2-picrylhydrazyl(DPPH)radicals scavenging activity,2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulfonate)(ABTS)radical scavenging activity,and ferric reducing antioxidant power(FRAP).The results indicated that both LAB strains have excellent potential as probiotics and can have good application for soymilk fermentation products.

Effects of fermentation conditions on bioactive substances in lactic acid bacteria-fermented soymilk and its storage stability assessment

The consumption of fermented soymilk(FSM)is of great interest to consumers because of its many potential health benefits.Nevertheless,soymilk's unpleasant flavor and astringent taste are a major concern in consumption.To obtain the soymilk with good flavor and functionality profiles,fermentation is one of the alternatives,which is why Lactobacillus plantarum NCU001563 and Streptococcus thermophilus NCU074001 were selected and used through different fermentation conditions(DFC).The single-factor test and orthogonal experiment comprehensively determine the FSM production process.The parameters of optimal conditions include mixed fermentation agents,water ratio(1:5),sterilization time(15 min),sterilization temperature(105°C),160-mesh press cloth,carbon source(glucose),amount of glucose(10%),inoculum amount(0.03%),fermented soymilk temperatures(FSM3,37°C;FSM4,42°C),and fermentation time(24 h)were retained.The DFC significantly affects nutritional factors such as proteins,amino acids,and others.At the same time,the anti-nutritional components showed the opposite results,except the total phenolic content exhibited a significantly higher content after fermentation.However,the DFC significantly decreased aldehydes such as hexanal in non-fermented soymilk(NFSM)from 19.30%to 4.97%in FSM3 and 1.60%in FSM4,respectively.Furthermore,the fermentation produced a higher abundance of 2-butanone,acetoin,and acetic acids,thus improving the overall sensory acceptability.Over time,the fermentation has been pertinent to exert preservation effects,especially for FSM4 at 4°C.The results indicated that the optimized DFCs have a good application for FSM by improving its flavor,functional profiles with health-promoting effects,and soymilk product preservations.

Synergistic effect of oregano essential oil fumigation combined with infrared heating on the inactivation of Aspergillus flavus

This study was aimed to evaluate the fungicidal effects of oregano essential oil (OEO) fumigation combined with intermediate-wave infrared (IWIR) heating on Aspergillus flavus (A. flavus ) in peanuts, and investigate the synergistic mechanism of the combined treatment (OEO-IWIR). Vitro experiments results indicated that OEO fumigation completely inhibited the A. flavus mycelium growth and aflatoxin production at a dose of 135 mg/L for 6 h. Meanwhile, the sterilization efficacy was assessed by inoculating peanuts with 6 log10 CFU/g A. flavus spores. OEO-IWIR exhibited synergistic effects and reached the 5-log reduction requirement by OEO fumigation at 135 mg/L for 6 h combined with IWIR heating at 65 °C for 1 h. Next, cultivability and spore viability tests of A. flavus were assayed. IWIR heating caused culturable sublethal spores, while the OEO-IWIR exhibited complete inactivation. Finally, the mechanism study confirmed that OEO-IWIR caused a higher degree of cell membrane permeabilization (from 17.0% to 65.6%), more significant alteration of cellular ultrastructure, and higher inhibition of ATPase activity than single treatments.

Inhibition mechanisms of wounded okra on theα-glucosidase/α-amylase

Okra has attracted increasing interests to be used as functional food ingredients due to various human health benefits such as the inhibition ofα-glucosidase andα-amylase in this paper.Results showed that theα-glucosidase(andα-amylase)inhibition capacity of polyphenols in wounded okra significantly increased by 31.6%(and 28.6%)when the wounding intensity was 1.87 cm2/g.The UPLC-MS analysis indicated that quercetin and catechin derivatives were the major polyphenols in wounded okra,of which quercetin 3-O-gentiobioside and epigallocatechin dimer were the most abundant compounds.Fluorescence quenching confirmed that wound and healing process promoted the affinity betweenα-glucosidase(andα-amylase)and polyphenols,which interacted with enzymes in a mixed type manner.Molecular docking suggested that quercetin-3-O-gentiobioside,quercetin-3-O-glucosyl-xyloside,isoquercitrin,querce-tin-3-O-(malonyl)-glucoside,epigallocatechin,and epigallocatechin dimer can interact with the activity cavities of enzymes by amino acids residues(Arg195,Leu162,and His305).The results of this study support the potentials of wounded okra to inhibitα-glucosidase andα-amylase in the food industries,without associated risks to consumers.

Improving the xanthine oxidase and adenosine deaminase inhibitory activities of Flos Sophorae Immaturus by ultrasound-assisted heating treatments

Flos Sophorae Immaturus(FSI)is consumed as a natural food rich in flavonoids and exhibits potential xanthine oxidase(XOD)and adenosine deaminase(ADA)inhibitory activities.Therefore,ultrasound and heating treatments were applied to improve the XOD and ADA inhibitory effects of FSI,and the mechanisms were revealed by tracking the changes of flavones.Results showed that ultrasound(480 W,60 min)assisted heating treatments(180℃,60 min)significantly improved the XOD(from 40.97%to 83.47%)and ADA(6.64%-23.28%)inhibition rates.Meanwhile,ultrasound and heat treatment caused significant variations in total polyphenols and flavonoid contents and altered the flavonoid composition of FSI.Specifically,rutin,kaempferol-3-o-rutinoside,and narcissoside of FSI converted to quercetin,kaempferol,and isorhamnetin during heating treatments.However,the model experiment revealed that ultrasound treatment did not cause the conversion of flavones and just promoted the dissolution of FSI flavones.Furthermore,quercetin,kaempferol,and isorhamnetin possessed better XOD and ADA inhibitory activities than rutin,kaempferol-3-o-rutinoside,and narcissoside at a concentration from 0.025 mg/mL to 1.0 mg/mL,implying de-glycosylation is a feasible approach for enhancing XOD and ADA activity.The present study provides a promising strategy for the processing of FSI.

Effects of microbial succession on the dynamics of flavor metabolites and physicochemical properties during soy sauce koji making

Koji making is a crucial stage of soy sauce production that affects the later fermentation efficiency and final product quality.However,little is understood about the dynamics and roles of microbiota throughout the koji making,especially the functional microbes responsible for flavor formation.In this work,high-throughput sequencing revealed that the top 3 bacteria were Weissella,Staphylococcus,and Bacillus,and the top 2 fungi were Aspergillus and Trichosporon.The fermentation process could divide into 2 stages based on microbiota succession:0 h and12-44 h.Additionally,6 organic acids,15 amino acids,and 30 volatile flavors were detected,of them,1-octen-3-ol and 3-octanone were the two characteristic volatile flavors of koji.Analysis of the corre-lation between microbiota,physicochemical properties,and flavors indicated that Weissella,Staphylococcus,Bacillus,and Trichosporon were the key microorganisms responsible for promoting environmental development and the formation of flavors.What’s more,Staphylococcus,Leuconostoc,and Pichia were identified strongly positively correlated with 1-octen-3-ol and 3-octanone,which probably play pivotal roles in the unique aroma formation of koji.These findings provide insight into the potential for developing profitable starter cultures for the manufacture of high-quality soy sauce products.

Lactic acid bacteria with anti-hyperuricemia ability: Screening in vitro and evaluating in mice

Hyperuricemia has become the increasing public health burden,which is a risk factor for gout,chronic kidney,cardiovascular diseases and diabetes.Lactic acid bacteria have been attracting considerable interest for the safe and effective treatment of hyperuricemia in recent years.In this study,Limosilactobacillus fermentum NCUH003018,Limosilactobacillus reuteri NCUH064056 and Lactobacillus gasseri NCUH066006 were preliminarily selected from sixty strains of lactic acid bacteria isolated from infant feces and fermented vegetables,and showed the ability of efficient degradation of inosine and guanosine,inhibition of xanthine oxidase activity,the tolerance to acid and bile salt,adhesion to epithelium cells,antibacterial activity,and antibiotic susceptibility in vitro.Then hyperuricemia mice model was established by high-yeast diet and intraperitoneal injection of potassium oxonate to analyze the uric acid-lowering effect of the three Lactobacillus in vivo.The results showed that Limosilactobacillus fermentum NCU003018 was the most effective in lowering uric acid level in mice,which prompted the decrease of serum uric acid by 30.77%compared with hyperuricemia model group.Therefore,the Limosilactobacillus fermentum NCU003018 is considered as a probiotic with anti-hyperuricemia ability,which could be used as a promising candidate in preventing and treating hyperuricemia,and the uric-acid lowering mechanism merits further investigation.

The inhibition mechanisms between asparagus polyphenols after hydrothermal treatment and tyrosinase:A circular dichroism spectrum,fluorescence,and molecular docking study

Asparagus contains high quantity of polyphenols,including gallic acid,coumaric acid,chlorogenic acid,quercetin,p-hydroxybenzoic acid,rutin,trans-4-hydroxycinnamic acid,and ferulic acid.An understanding of the antityrosinase capacity and polyphenols changes during hydrothermal treatments was crucial for the development of asparagus.The results show that hydrothermal treatments(HT)enhance the total polyphenols in asparagus,and HT-160 has the highest total polyphenol contents(5.321 mg/g⋅dw)and tyrosinase inhibitory rate(95.87%).Rutin content reach 1754.01μg/mL at 140℃.Increased polyphenols caused 7.5%,4.8%,2%decrease inα-helix,β-sheet,β-turn and a 7.4%increase in random coil using circular dichroism spectra.The fluorescence quenching of tyrosinase by HT samples(HT-80,HT-100,HT-120,HT-140,and HT-160)was accompanied by bigger ranges of red shift.Molecule docking analysis indicated that antityrosinase capacity was attributed to the capacity of polyphenols to bind to protein molecules and change the microenvironment of tryptophan or tyrosine residues.Conventional hydrogen bond,van der Waals,π-πstacked,π-σinteraction,andπ-alkyl interactions were generated between asparagus polyphenols(ASP)and residues.As a promising inhibitor of tyrosinase,ASP could be employed as a potential agent to reduce food browning.