Identification of the flavor profiles of Chinese pancakes from various areas using smart instruments combined with E-noses and E-tongues

In order to reveal the flavor characteristics of Chinese pancakes,the aroma and taste compounds of seven traditional Chinese pancakes were identified.The results showed that electronic nose(E-nose)analysis with PCA could successfully distinguish the aroma profiles of seven Chinese pancakes;the principal components PC1 and PC2 represented 75.74%and 23.2%of the total variance(98.94%)respectively.Meanwhile,the discrimination index of taste profiles of seven Chinese pancakes based on electronic tongue(E-tongue)analysis with LDA was 99.32%;the discriminant factors DF1 and DF2 represented 94.99%and 4.33%of the total variance respectively.Furthermore,GC-MS results demonstrated that thirty-threeflavor compounds were identified in seven Chinese pancakes,including aldehydes,alcohols,alkanes,acids,and aromatics.Among the flavor components,aldehydes with ROAVs higher than 1 contributed most significantly to the overall aroma,such as(E,E)-2,4-nonadienal present the largest contribution in Qingzhou pancake,Jinan and Yishui pancake;hexanal present the largest contribution in Shenxian and Gaomi pancake;nonanal and benzeneacetaldehyde present the largest contribution in Linqu and Tai’an pancake,respectively.The umami and sweet taste amino acids were the most abundant in all the Chinese pancake samples,and Qingzhou pancake had relatively high amino acid content.The content of glucose was higher than maltose in Gaomi,Shenxian,and Tai’an pancakes,whereas the content of maltose was higher than glucose in Linqu,Qingzhou,Jinan,and Yishui pancakes.These results indicated that the aroma and taste profiles of Chinese pancakes differed significantly in terms of their flavor compound composition.The presented results could be beneficial for providing a comprehensive method for flavor profile identification of traditional whole-grain-based staples such as Chinese pancakes.

Evaluation of probiotic yoghurt by the mixed culture with Lactobacillus plantarum A3

Lactic acid bacteria(LAB)fermentation is the simplest and safest way of food preservation,and the use of probiotics in yoghurt could provide dairy products with unique flavors,textures and health benefits.In this study,Lactobacillus bulgaricus,Streptococcus thermophilus,L.reuteri DSMZ 8533 and the potential probiotic strain L.plantarum A3 were used for the milk fermentation.Results found the texture properties such as hardness,consistency,and viscosity of the yoghurt were enhanced in the mixed culture condition.Furthermore,components like amino acid(leucine),vanilla(vanillin),C;(unsaturated fatty acids)were also accumulated in L.plantarum A3 fermented yoghut,which leads to the significant sensory profiling difference compared with the former plain yoghurt.All these results proved L.plantarum A3 is a potential probiotic stom winch could enhance the sensory and nutrition profiling of the fermented milk.Future work still needs to be done on the synergistic interaction between the traditional strains and the probiotics during the fermentation process.

Flavor profile variations of Huangjiu brewed in different traditional Chinese solar terms

Background:Through long-term research on Huangjiu fermentation,it has been found that the quality of Huangjiu is closely associated with Chinese 24-solar term.Therefore,this study was conducted to explore the characteristic and property index differences of Huangjiu,such as aroma and flavor profile,and physicochemical properties—brewed in different solar terms by choosing five representative fermentation times of Shaoxing Huangjiu.Results:Huangjiu samples in the current study all met the national standards of traditional semi-dry Huangjiu.There are significant differences in physicochemical properties such as acidity and amino nitrogen among different solar-term groups.Forty three detected volatiles were applied by principal component analysis and partial least squares discriminant analysis analyses to differentiate the main factors.Volatiles mainly loaded to four principal components,which accounted for 86.5%.Nineteen volatiles were discriminated to significantly differentiate solar-term groups.Odor activity values(OAV)analysis found 14 compounds with OAV>1,while correlation analysis between volatiles and the outcomes of sensory evaluation displayed the various properties of Huangjiu on aroma and flavor due to the various combinations of volatiles,reducing sugar,acidity and amino nitrogen.After a national wine inspector evaluated and scored Huangjiu fermented in different solar terms,Huangjiu brewed in Winter Solstice exhibited the highest performance,with a score of 91.0,and praised as a kind of gold medal product.Conclusion:The methodology of this study can help to produce more types of appealing flavor and aroma of alcoholic beverages to consumers,build varietal Huangjiu or other alcoholic beverages through fermenting guidance by solar term,and even expand the applications of the traditional Chinese 24-solar term.

Unraveling the difference in flavor characteristics of dry sausages inoculated with different autochthonous lactic acid bacteria

The traditional dry sausage is highly appreciated in China because of its unique flavor characteristics.This study aimed to characterize and compare the flavor profile of traditional dry sausage,inoculated with lactic acid bacteria (LAB),including Lactobacillus plantarum MDJ2,Lactobacillus sakei HRB10,Lactobacillus curvatus SYS29,Weissella hellenica HRB6,and Lactococcus lactis HRB0 using headspace solid-phase microextraction gas chromatography-mass spectrometry coupled with electronic nose (E-nose).The control (non-inoculated) sausage presented higher water activity and moisture content compared to the inoculated sausages whereas,the inoculation led to decreased pH values and increased LAB counts during fermentation of dry sausages.Inoculation with LAB increased volatile compound contents and decreased total contents of free amino acids of sausages.E-nose and sensory analysis confirmed that inoculation with LAB,especially W.hellenica HRB6,Lb.sakei HRB10,and Lb.curvatus SYS29 enriched the pleasant odors of dry sausage.Correlation analysis demonstrated that sausages inoculated with W.hellenica HRB6 and Lb.sakei HRB10 showed a correlation with most of the key volatile compounds.In conclusion,W.hellenica HRB6 and Lb.sakei HRB10 are promising starter cultures to enhance the flavor characteristics of dry sausages.

Antioxidant,flavor profile and quality of wheat dough bread incorporated with kiwifruit fermented byβ-glucosidase producing lactic acid bacteria strains

This study aimed to investigate the effect of incorporation of kiwifruit substrate fermented by 3 highβ-glucosidase producing lactic acid bacteria(LAB)of Lactobacillus harbinensis(M12,M24)and Pediococcus pentosaceus(J28)on physicochemical and rheo-fermentation properties during proofing of wheat dough.Quality,sensory evaluation,antioxidant content and activity,and flavor profiles of bread was evaluated.Results revealed that LAB strains adequately adapted(J28>M12>M24)and produced enzymes during substrate fermentation.In dough,incorporation of fermented substrate increased acidity,soluble dietary fiber,β-glucosidase andα-amylase activity and gas retention during proofing,in a strain dependent manner(J28>M12>M24).The subsequent breads exhibited higher specific volume and had softer crumbs.Furthermore,total flavonoid,total phenolic,antioxidant activity,flavor content and intensity increased in breads incorporated with fermented substrate.Overall sensory acceptance was in order,bread containing substrates fermented by J28(KFB-J28)>M12(KFB-M12)>M24(KFB-M24)>wheat bread(WB)>bread containing unfermented substrate(KFB).Changes observed were attributed to biotransformation byβ-glucosidase which increasingly degraded dietary fibers into soluble dietary fiber,increased acidity,released glycosylated aroma compounds and phenolic compounds in substrate.When incorporated in dough,fermented kiwifruit substrates stabilized gluten network,increased yeast metabolism and gas retention during proofing.Subsequently,KFB-J28,KFB-M12,and KFB-M24 had higher antioxidant content and activity,higher flavor content and intensity,better quality and were more accepted compared to WB and KFB.This suggested the potential role played byβ-glucosidases through LAB fermentation on functionally enriching and adding value to kiwifruit substrate as a novel functional ingredient in bakery industry.

A fishy odor episode in a north China reservoir: Occurrence, origin, and possible odor causing compounds

A significant outbreak of fishy odor occurred in a reservoir located in Inner Mongolia, China, in the winter of 2011, and the odor rating, algal density and concentrations of some potential odorous compounds were monitored over a period of two months. The peak odor rating of the fishy odor was 7 according to flavor profile analysis. Among the dominant algal species （two diatom and one chrysophyte species） observed during the survey, the chrysophyte Dinobryon sp. was the most abundant species, with the peak density recorded at 88,520 cells/mL. Seven potential algal metabolites including heptanal, 2,4-heptadienal, 2,4-decadienal, nonanal, 2-octenal, 2,6- nonadienal and hexanal were detected. The principal component analysis result showed that n-hexanal, n-heptanal and 2,4-decadienal, possibly the metabolites of diatoms, and 2,4-heptadienal, possibly the metabolite of Dinobryon sp., might have contributed to the fishy odor episode. This study demonstrated that the fishy odor episode in this reservoir might be caused by the abnormal growth of chrysophytes and diatoms under the ice-cover.

Occurrence of odor problems in drinking water of major cities across China

A comprehensive investigation into the occur-rence of odor problem at 111 drinking water treatment plants （DWTPs） in major cities across China was undertaken using both flavor profile analysis （FPA） and gas chromatography-mass spectrometry （GC-MS）. Eighty percent of source water samples exhibited odor problems, characterized by earthy/musty （41%） and swampy/septic （36%） odors, while the occurrence rate was lower （45%） in the finished water. Source water from rivers exhibited more pollution-origin odors, such as the swampy/septic odor, while that from lakes and reservoirs exhibited more algae- origin odors, such as earthy/musty odors. The occurrence rate of 2-methylisoborneol （2-MIB） in the surface source water samples was 75%, with 7% of samples containing 2- MIB concentrations of over 10 ng.L-1. The earthy/musty odor in the lake/reservoir water samples was mainly caused by 2-MIB （linear regression coefficient, R2= 0.69）, while the correlation between 2-MIB concentration and the earthy/musty odor intensity samples was weak （R2= 0.35） in the river-source water These results will be useful for the management of odor-quality problems in drinking water of China.

Identification of odorous compounds in reclaimed water using FPA combined with sensory GC-MS

Odorous compounds in the influent of a reclaimed water treatment plant （RWTP）, consisting of coagulation, sedimentation, continuous micro-filtration （CMF）, and chlorination in succession, in a north China city, were identified by combining flavor profile analysis （FPA） with sensory gas chromatograph-mass spectrometry （GC-MS）. The sewery/swampy/septic odor with an odor intensity of 6.4 was found to be the major odor group in the RWTP influent, and the existence of well-known odorant including dimethyl disulfide, dimethyl trisulfide, indole and skatole were confirmed using GC-MS. The result of a spiking test showed that the intensity （3.6） of the sewery/swampy/septic odor caused by these four chemicals contributed to over 50% of the odor intensity of the influent. The FPA intensity for sewery/swampy/septic odor in the RWTP effluent was 3.8, showing that the treatment process was not efficient for the removal of odorants, particularly indole and skatole.

Addition of hydrogen peroxide for the simultaneous control of bromate and odor during advanced drinking water treatment using ozone

Complete removal of the characteristic septic/swampy odor from Huangpu River source water could only be achieved under an ozone dose as high as 4.0 mg/L in an ozone-biological activated carbon （O3- BAC） process, which would lead to the production of high concentrations of carcinogenic bromate due to the high bromide content. This study investigated the possibility of simultaneous control of bromate and the septic/swampy odor by adding H2O2 prior to the O3-BAC process for the treatment of Huangpu River water. H2O2 addition could reduce the bromate concentration effectively at an H2O2/O3 （g/g） ratio of 0.5 or higher. At the same time, the septic/swampy odor removal was enhanced by the addition of H2O2, although optimization of the H2O2/O3 ratio was required for each ozone dose. At an ozone dose of 2.0 mg/L, the odor was removed completely at an H2O2/O3 ratio of 0.5. The results indicated that H2O2 application at a suitable dose could enhance the removal of the septic/swampy odor while suppressing the formation of bromate during ozonation of Huangpu River source water.