Metabolomics mechanism of traditional soy sauce associated with fermentation time

Given that fermentation time has significant impact on quality and flavor of soy sauce,a global understanding of the metabolic mechanism as fermentation time prolonged is essential for producing satisfactory and consistent quality of traditional soy sauce.Herein,the metabolic compounds changes of soy sauce associated with fermentation time up to 10 years were comprehensively investigated by using Chinese traditional fermented soy sauce(CTFSS)as a demonstration.Results showed that formaldehyde nitrogen,total soluble nitrogen(TSN),non-salt soluble solids,amino acids,free 5’-nucleotides and volatile compounds in CTFSS changed obviously during fermentation.Specifically,glutamic acid and aspartic acid were prominent in CTFSS.Continuous decrease in content of hypoxanthine(Hx)was found from 1 M(1-month soy sauce)to7 M(7-months soy sauce).Furthermore,a significant opposite tendency for changes between some volatile compounds and amino acids was indicated that there was a transformation between these two components.Therefore,a better understanding to the influence of fermentation time on soy sauce had been proposed.As the formation and conversion of amino acids and sugars might be mainly responsible for flavor formation in CTFSS,the ratio of these two reactions rate led the metabolism to be divided into three steps,degradation,conversion and balance.

Determination of Quality Properties of Soy Sauce by Support Vector Regression Coupled with SW-NIR Spectroscopy

The modern near-infrared(NIR) spectroscopy analysis is a simple, efficient and nondestructive technique, which has been used in chemical analysis in diverse fields. Shortwave NIR spectroscopy is also a rapid, flexible, and cost-effective method to control product quality in food industry. The method of support vector regression coupled with shortwave NIR spectroscopy was explored for the nondestructive quantitative analysis of the important quality parameters of soy sauce, including amino nitrogen content, total acid content, salt content and color ratio. In this study, the support vector regression(SVR) models based on subtractive spectra and positive spectra were found and compared, the results show that the subtractive spectrum was more excellent than the positive spectrum. Meanwhile, R and RSE were determined, respectively, by means of original spectra and pretreated spectra[standard normal variate (SNV), first-derivative and second-derivative], and the corresponding models were successfully established. The best prediction was achieved by a support vector regression model of the first derivative transformed dataset. In addition, the result obtained by the proposed method was compared with that of Partial Least Squares(PLS), which showed that the generalization performance of the classifier based on SVR was much better than that of PLS. The results demonstrate that shortwave NIR spectroscopy combined with SVR is promising for the quality control of soy sauce.

The Role of Nutrition Education in the Promotion of Iron-Fortified Soy Sauce in China

Iron deficiency anemia （IDA） is one of the most important nutrition issues in China. Data from the 2002 National Nutrition and Health Survey showed that the average anemia prevalence in China was 20.1% and the prevalence in women of child-bearing age and of children in some poor regions reached more than 50%; it has been estimated that more than 200 million Chinese people are suffering from anemia. Anemia significantly affects physical and mental development in children, decreases productivity in adults, and reduces immune function among the population at large, which leads to a lower health status and limits social development.

Visible and Near-Infrared Spectroscopic Discriminant Analysis Applied to Identification of Soy Sauce Adulteration

The identification of soy sauce adulteration can avoid fraud, and protect the rights and interests of producers and consumers. Based on two measurement models (1 mm, 10 mm), the visible and near-infrared (Vis-NIR) spectroscopy combined with standard normal variate-partial least squares-discriminant analysis (SNV-PLS-DA) was used to establish the discriminant analysis models for adulterated and brewed soy sauces. Chubang soy sauce was selected as an identification brand (negative, 70). The adulteration samples (positive, 72) were prepared by mixing Chubang soy sauce and blended soy sauce with different adulteration rates. Among them, the “blended soy sauce” sample was concocted of salt water (NaCl), monosodium glutamate (C5H10NNaO5) and caramel color (C6H8O3). The rigorous calibration-prediction-validation sample design was adopted. For the case of 1 mm, five waveband models (visible, short-NIR, long-NIR, whole NIR and whole scanning regions) were established respectively;in the case of 10 mm, three waveband models (visible, short-NIR and visible-short-NIR regions) for unsaturated absorption were also established respectively. In independent validation, the models of all wavebands in the cases of 1 mm and 10 mm have achieved good discrimination effects. For the case of 1 mm, the visible model achieved the optimal validation effect, the validation recognition-accuracy rate (RARV) was 99.6%;while in the case of 10 mm, both the visible and visible-short-NIR models achieved the optimal validation effect (RARV = 100%). The detection method does not require reagents and is fast and simple, which is easy to promote the application. The results can provide valuable reference for designing small dedicated spectrometers with different measurement modals and different spectral regions.

DETERMINATION OF ORGANIC ACIDS IN SOY SAUCE BY HPLC

Organic acids in 3 kinds of soy sauces were analyzed by HRLC.Column:C18 ()Bondapak(10μm,3.9mm i.d.* 30cm;mobile phase:0.5%(NH_4)_2HPO_4(pH=2.9);flow rate:1.0 ml/m.PT-C18 cartridge was used for the sample preparation.Recoveries of organic acids are between 96-111%.

Effect of wheat germination on nutritional properties and the flavor of soy sauce

Germination pretreatment of raw materials is an effective technique to improve the flavor and nutritional value of soy sauce.In this study,we aimed to investigate the effects of germinated wheat(GW-24h,GW-48h,and GW-72h)and un-germinated wheat(raw and fried wheat)on nutritional properties,flavor profiles,and microbial structure of soy sauce.The results showed that,the content of amino acid nitrogen,total nitrogen,reducing sugars,isoflavones,andγ-Aminobutyric acid(GABA)after germination was 15.4%,9.4%,176.7%,41.4%,and 238.0%,respectively,which were higher than that of un-germinated wheat.In addition,germinated wheat revealed a beneficial effect on antioxidant activity.Un-germinated wheat(e.g.,fried wheat)has a richer flavor profile but carries the risk of contaminants(e.g.,acetamide).In contrast,the germinated group has higher contents of acetoin,which contributes to desirable flavor and is a precursor to bioactive compounds of soy sauce.According to the microbial diversity,germinated wheat reduced bacterial diversity,which was favourable for soy sauce fermentation.Overall,this study approves that germinated wheat can effectively improve biological properties and flavor profile of soy sauce,providing new technical insight to improve soy sauce products.

Systematic analysis of key fermentation parameters influencing biogenic amines production in spontaneous fermentation of soy sauce

Biogenic amines(BAs),a class of toxic nitrogen-containing compounds,are commonly found in high-protein fermented foods.This study investigated whether,what and how the fermentation parameters influence the BAs accumulation in spontaneous soy sauce fermentation.The results showed that BAs accumulation in soy sauce fermentation throughout the year showed significant seasonal differences,which were closely related to temperature and pH value.Furthermore,different microbial communities were found in high-and low-BAs groups,indicating that seasonal fermentation factors affect BAs accumulation by influencing the microbial population.Following bioinformatic analysis,single-microorganism culture analysis,and simulated fermentation,it was found that lower temperature or higher NaCl concentration can reduce BAs accumulation,most likely by suppressing the proliferation of BAs-producing bacteria.This is a comprehensive study of the impact of fermentation parameters on BAs production,and will serve as a foundation for future research on BAs management.

Effect of salt concentration on Chinese soy sauce fermentation and characteristics

The effect of salt concentration on soy sauce fermentation was studied.Four groups of soy sauce samples with 8%,12%,16%,and 20%salt concentrations were prepared and their physicochemical parameters,non-volatile metabolites(organic acids,free amino acids,and biogenic amines),volatile metabolites,and microbial abun-dance were analyzed during the whole fermentation.The sensory characteristics of the final products were also assessed.Salt concentration significantly affected the microbial abundance and metabolite profiles during soy sauce fermentation,resulting in different characteristics among samples.The RT-qPCR analysis showed that the microbial abundance in lower salted soy sauce was higher.Correspondingly,the accumulation of total acid and the decrease of reducing sugar were observed in lower salted soy sauce,aggravating the sourness of soy sauce.The levels of free amino acids and biogenic amines(detected by HPLC)in lower salted soy sauce were higher,resulting in a taste of umami but making unsafe soy sauce.Additionally,HS-SPME/GC-MS analysis showed that several distinctive volatile compounds were absent in lower salted soy sauce.Sensory evaluation revealed that the highest total score for the quality of soy sauce was obtained through fermentation under 16%salt concen-tration.This study helped deepen our understanding of the effect of salt on soy sauce fermentation and provide a theoretical data reference for low salt soy sauce development.

Characteristics of the soy sauce taste and koji enzyme profiles as affected by soybean traits

Soybean is the main raw material for soy sauce fermentation and has a significant impact on the quality of soy sauce.Understanding the impact of soybean traits on the soy sauce quality is important for the development of the industry.The present study compared the traits of 12 soybeans and the quality of their fermented kojis and soy sauces,revealing the differences in total sugar and protein content may be the key factors responsible for differences in soy sauce characteristics.On this basis,6 representative soybeans including 3 high protein and low total sugar content soybeans(HPLS)and 3 low protein and high total sugar content soybeans(LPHS)were selected for further study.Results of the changes in enzyme activities during koji-making fermentation showed that neutral protease and beta-glucosidase activities were higher in HPLS kojis,while acid protease and xylanase activities were higher in LPHS kojis after 24 h of fermentation.Differences in enzyme activity further caused variations in the soy sauce quality and formed some correlations with soy sauce tastes,such as xylanase and umami(r=0.885),kokumi(r=0.916).The intensities of umami and kokumi were higher in LPHS soy sauces,which had a higher dipeptides content of X-Glu,X-Thr,X-Ser and Gly-X.

Effect of co-inoculation of different halophilic bacteria and yeast on the flavor of fermented soy sauce

The flavor of soy sauce is closely related to the succession and interaction of the microbial community during fermentation.In this study,the selected potential flavor-producing microorganisms(7 species of bacteria and 4 species of yeast)were applied in the co-culture rapid fermentation model and their growth,physicochemical changes,volatile flavor compounds(VFCs),and sensory characteristics were investigated.Results showed that yeast promoted the growth of bacteria,while bacteria inhibited the growth of yeast in the co-culture model.Based on the results of VFCs and sensory evaluation,the combined fermentation of Zygosaccharomyces rouxii and Lactobacillus fermentum was the best strategy out of the 40 combinations.The effect of this combination was also validated in a 20 L fermentation application of soy sauce,which indeed enhanced the intensity of sauce-like,fruity,smoky,and caramel-like notes,as well as umami and kokumi tastes.These results provide a theoretical basis for the exploration and industrial application of flavor-producing microorganisms in soy sauce fermentation.

Screening and Characterization of Nitrite Degrading <i>Lactobacillus plantarum</i>in Chinese Traditional Pickles

A Gram-positive, non-spore, round ended, straight rod Lactic acid bacteria were screened. The strain was screened out from the traditional pickle jar in Yutang soy sauce garden of Jining. In order to degrade the nitrate content in the fermentation process of traditional pickles and improve the quality of pickles, it is necessary to screen out nitrite degrading strains from pickles, and preliminarily locate nitrite reductase, and find out the most suitable pH, temperature and culture time to degrade nitrite. Lactobacillus plantarum was screened by MRS medium in advance. After 48 hours of culture in a shaking table with Bacillus subtilis, the cell components were separated by centrifugation, wall breaking and other operations. After 20 hours at 30°C, the content of nitrite in each component was determined by the naphthalene ethylenediamine hydrochloride method (NIR). The culture conditions were as follows: inoculation amount 3%, 6%, 9%, 12%, 15%;salinity 2%, 4%, 6%, 8%, 10%;temperature 15°C, 20°C, 25°C, 30°C, 35°C for 20 h. The results showed that the best degradation effect of nitrite was obtained under the conditions of 9% inoculum, salinity 5% and 30°C. Under the conditions of 9% inoculum, 5% salinity and 30°C for 5 h, 10 h, 20 h, 48 h, 66 h and 78 h, the results showed that the degradation amount gradually increased with the extension of time, and gradually maintained a stable state. Lactobacillus plantarum JBA-3 is a new type of lactic acid bacteria which can degrade nitrite and produce nitrite reductase.

Evaluations of the Sensory Quality Indices and Freshness Assessment of Nile Tilapia Oreochromis niloticus Fillets Fed Recycled Food Waste Materials

This study was designed to evaluate the sensory quality indices, freshness assessment and safety of eating Nile tilapia fed recycled food waste materials [food industry waste （FIW） and soy sauce waste （SSW）] for 32 weeks using K values, IMP content and microbial viable cell count. Five experimental diets were formulated at 0% and 20%-22% inclusion level of recycled food wastes. The diets were designated as D 1： 0% of recycled food waste, D2： 20% inclusion of FIW, D3： 20% inclusion of FIW and SSW, D4： 20% inclusion of FIW and tryptophan, and D5： 22% inclusion of SSW. The result from the body composition shows that D I had higher carcass protein, while D3 had the highest lipid content and there was no significant difference in the carcass moisture and ash contents among all treatments. The results of microbial viable cell counts showed that no significant differences were observed among the dietary treatments and all the fish fed experimental diets still remained fresh four days after refrigerated storage at 5 ~C. In addition, no significant differences were noted among the K value concentrations of all the fish fed the experimental diets. From the result of this study, we concluded that using 20% inclusion of recycled food waste materials （FIW and SSW） in the diet of tilapia had no negative effect on the flesh of the fish; hence, recycled food waste could be a good alternative ingredient to aquaculture.

Comparison and application of the extraction method for the determination of enzymatic profiles in matured soybean koji

In this study,two methods of extracting crude enzymes from soy sauce koji were compared to investigate the effect of replacing the buffer extraction with distilled water extraction by measuring the enzyme activity.Results showed the enzyme activities of the two extracts in each koji sample were not significant differences.The stability of the different enzymes in the extracts varied.Acid protease,β-glucosidase and cellulase activities showed the best stability during the storage.Neutral protease,glucoamylase and aminopeptidase were moderately stable and their activities needed to be determined within 3 d of extract preparation,while xylanase activity was the least stable,decreasing by 40%on the second day of storage.Therefore,the recommended procedure for the analysis of koji enzyme profiles was as follows,xylanase was determined immediately after distilled water extraction,and then all other enzyme activity analyses need to be completed within 3 d to ensure the validity of enzyme analysis.This method was applied to the enzymatic analysis of 7 kojis made by different strains of Aspergillus oryzae,and to explore the association between the enzyme profile and the taste characteristics of seven fermented soy sauce.The results showed proteases were correlated with sour and richness,while carbohydrate-degrading enzymes were relatively more relevant to umami taste.