Characterization of the key aroma compounds in four varieties of pomegranate juice by gas chromatography-mass spectrometry(GC-MS),gas chromatography-olfactometry(GC-O),odor activity value(OAV),aroma recombination,and omission tests

P omegranate(Punica granatum L.)has attracted considerable attention in world markets due to its valuable nutrients and highly appreciated sensory properties.The aroma profiles of 4 varieties of pomegranate juice,including Dahongtian(DP),Jingpitian(JP),Luyudan(LP),and Tianhonngdan(TP),were investigated via gas chromatography-mass spectrometry(GC-MS)and gas chromatography-olfactometry(GC-O)analyses.A total of 43 volatile compounds were identified by using GC-MS.Among these compounds,16 were considered as potential aroma-active compounds as detected by GC-O.These compounds belonged to the classes of terpinenes,alcohols,and aldehydes.Eleven volatile compounds were defined as the main contributors to the overall aroma of pomegranate juice due to their high odor activity values(OAVs≥1).Aroma recombination and omission tests confirmed thatβ-myrcene,1-hexanol,and(Z)-3-hexen-1-ol were the key aroma compounds,and limonene,1-octen-3-ol,linalool,and hexanal were important aroma-active compounds in DP samples.

Sensory-directed flavor analysis of key odorants compounds development of French fries and oils in the break-in,optimum and degrading frying stage

The flavor is a decisive sensory characteristic that determines the popularity of French fries(FFs).During high-oleic rapeseed oil(RO)frying,the flavor development of FFs showed three noticeable stages including break-in(3.5%-7.5%of total polar compounds(TPC)),optimum(7.5%-22.18%of TPC),and degrading stages(above 22.18%of TPC).Further,in order to distinguish the key aroma compounds in each stage,the FFs prepared in RO at TPC of 3.5%(FF4),14.5%(FF15),and 26.96%(FF27)and their relevant oils(RO4,RO15,RO27)were selected for sensory-directed analysis.The results revealed that the FF4 had low contents of(E,E)-2,4-decadienal(deep-fried odor)which also caused lower sensory score in FF4 sample.The higher contents of(E,E)-2,4-decadienal in FF15 induced its higher deep-fried odor.The FF27 had higher hexanoic acid(sweaty odor),heptanoic acid,nonanoic acid,benzene acetaldehyde(stale odor),and trans-4,5-epoxy-(E)-2-decenal(metallic odor)compared with FF4 and FF15,thus leading to the undesirable flavor of FF27.Moreover,the decrease of 2,5-dimethylpyrazine and 2-ethyl-6-methyl-pyrazine in FF27 induced the lower roasty flavor,which may also lead to the decline of the sensory score.Similarly,the higher contents of(E)-2-undecenal,hexanoic acid,heptanoic acid,and nonanoic acid in RO27 lead to increase its rancid score and thus lower the sensory score.

A preliminary study on volatile organic compounds and odor in university dormitories:Situation,contribution,and correlation

Many dormitories have a high population density,and occupants exposed to volatile organic compounds(VOCs)could suffer severe physical and mental issues,so it is important to ensure good indoor air quality(IAQ).Currently,indoor VOC analysis using only chemical concentration cannot accurately reflect the effect of odor on human comfort.Therefore,the sensory evaluation of indoor odor acts as a supplementary method for an IAQ assessment.Here,we measured indoor VOC concentrations in 10 dormitories under occupied and unoccupied conditions.The contribution of building materials and human-related emissions was analyzed.An odor activity value(OAV)was calculated using the VOC concentration and odorant threshold.In addition,recruited sensory odor panel members assessed the odor intensity of each dormitory and the correlation between odor intensity and chemical measurements was analyzed.The indoor total VOC(TVOC)concentration under occupied conditions ranged from 242.2 to 1063.1μg/m^(3),with a mean value of 454.1μg/m^(3).The TVOC concentration under unoccupied conditions varied from 97.2 to 1055.2μg/m^(3),with a mean value of 342.2μg/m^(3).The TVOC concentration of 90% of the dormitories under the two conditions met the national IAQ standards.An average of 53.6% indoor TVOC emissions are related to building materials,the outdoor-related TVOC concentration accounts for 15.7%,and the average human-related TVOC emissions are 1519.4μg/(h·person),which accounts for 30.7%.Compared to TVOC concentration,odor intensity-OAV(OAV_(sum),OAV_(max))could better characterize subjective and objective correlations.However,the goodness-of-fit is not satisfactory.Weber–Fencher's law has limitations in characterizing the correlation between odor intensity and OAV when applied to the indoor air mixture,based on this small-scale study.

Enhancing antioxidant activity and fragrant profile of low-ethanol kiwi wine via sequential culture of indigenous Zygosaccharomyces rouxii and Saccharomyces cerevisiae

To explore a novel producing strategy for enhancing antioxidant activity and aroma of low-ethanol kiwi wine,kiwifruit juice was sequential fermentation with indigenous Zygosaccharomyces rouxii(Zr)and Saccharomyces cerevisiae(Sc)without adding sugars.The organic acids,bioactive compounds,volatile constituents,antioxidant capacities and sensory profiles were measured to evaluate the performance of different inoculation ratios.The results indicated that compared with pure fermentation of Sc,the sequential fermentations significantly increased the total flavonoids,total phenols,some mono-phenols and antioxidant activities of the low-ethanol kiwi wines,and resulted in a positive effect on organic acids mainly by reducing the content of malic acid.At the same time,sequential fermentations significantly enhanced the aroma profile of the low-ethanol kiwi wines.The higher inoculation ratio of Zr greatly increased the complexity of the volatiles,improving sweet odor of the wines.While the similar inoculation ratio of Zr and Sc significantly increased the volatile contents,intensifying the tropical fruity and kernel fruity.In addition,the partial least-squares regression analysis showed that aldehydes resulted in sourness,ethyl esters and acetate esters possessed a positive impact on tropical fruity and kernel fruity.

Contribution of non-Saccharomyces yeasts to aroma-active compound production,phenolic composition and sensory profile in Chinese Vidal icewine

To acquire candidate non-Saccharomyces strains for preparation of high-quality Vidal icewine,11 representative indigenous non-Saccharomyces strains were selected for analyzing their production of organic acids,phenolic compounds,aroma-active compounds and evaluating their sensory profile in Vidal juice.The results showed that the contents of organic acids in the wines were controlled and balanced well by the non-Saccharomyces strains as well as polyphenol concentrations were well improved during the fermentation.The strains differed from each other in their ability to produce aroma compounds,causing diversity and complexity of aroma characteristics in wine.Fermentation by Saccharomycopsis crataegensis YC30(Sc)and Hanseniaspora uvarum QTX22(Hu)could enhance the sweet and floral notes in Vidal icewine,especially Sc,which has never been reported before.It can not only enrich the aroma categories,but also increase the content ofδ-decalactone,γ-decalactone,ethyl isobutyrate,ethyl butyrate,phenethyl acetic acid,etc.The evaluation and optimization of non-Saccharomyces yeast strains could provide theoretical basis for the improvement of ice wine quality,and supply new ideas and strategies for the brewing of ice wine.