| Chinese bayberry(Myrica rubra)is a subtropical evergreen fruit tree.It is widely grown in Southern China,especially with the higher quality in Zhejiang Province.Chinese bayberry fruit has a pleasant aroma,juicy and sweet-sour taste with high nutritional and commercial value,highly esteemed by consumers due to their unique flavor.Many current studies mostly focused on the fuctional compositions and health benefitial effects of bayberry fruit,however,there have been limited studies aimed to determine the character of bayberry concerning different cultivars,ripeness and storage conditions.The present study aimed to differentiate the flavor(taste and odor)profiles of different Chinese bayberry cultivars grown in Zhejiang Province.The flavor characteristics of bayberry with different cultivars,ripeness,and storage conditions were observed and characterized using the combination of chemometrics(PCA and PLS-DA)with GC-MS and E-nose.The main contents and results were summarized as follows:1.To differentiate the taste profiles and antioxidant capacities of different bayberry cultivarsThe differentiation of taste-related profiles and physicochemical characteristics in different cultivars of bayberry were studied by using chemometrics.The physicochemical analysis for taste indicated the bayberry cultivars were quite different in soluble sugars,organic acids,color,total phenolics and anthocyanin contents,and antioxidant capacities.The results showed PCA can differentiate the cultivars into 4 groups according to their physicochemical properties.The differences between BQ and other cultivars were mainly contributed by higher sugar and Brix:TA ratio,WD cultivar was contributed by higher TAC,and they could be significantly separated from other cultivars;BYM,FHZ,ZS,and CS could be separated into one group and BYM had the lowest TAC with the weakest antioxidant capacities.2.Sensory evaluation for different cultivars of bayberryThe sensory quality of different cultivars of bayberry juice was evaluated through sensory descriptive analysis."Fruity","sweet","sour",and "astringent" notes were found in all of the bayberry samples,there were significant different among different attributes in different bayberry samples.High intensities of the '"fruity","sweet",and "juicy" attributes were perceived in the BQ and DK cultivars.A common sensory profile was found for the "green","fruity","sour" and "astringent"descriptors,with high intensities among four cultivars,BYM,FHZ,ZS,and CS.3.Aroma-active analysis for different cultivars of bayberryHeadspace solid-phase micro-extraction(HS-SPME)coupled with gas chromatography-mass spectrometry(GC-MS)and olfactometry(GC-O)analyses were used to characterize the aroma-active profiles of 11 different bayberry cultivars.In addition,principal component analysis(PCA)and partial least squares-discriminant analysis(PLS-DA)based on the data of GC-MS and electronic nose was used to study and obtain the important volatile compounds contributed to the differentiation of the different cultivars of bayberry samples.The findings from analyses carried on bayberry samples showed a good agreement with the results obtained by means of GC-MS as they both separated the bayberry samples into different groups and suggested the usefulness of electronic nose as an identification tool for bayberry.The optimal HS-SPME extraction conditions were as follows:DVB/CAR/PDMS;incubation time,15 min;extraction temperature,50 ?;and extraction time,35 min.These conditions were applied during the extraction of volatile compounds from bayberry fruits.The detection frequency analysis(DFA)on the SPME extracts of bayberry identified 30 aroma-active compounds,including aldehydes(6),alcohols(6).esters(6),terpenes(9),and other compounds,which can be classified into seven classes:"green","mushroom","fruity","floral","cucumber","woody" and "pine" notes.The results obtained by PCA and PLS-DA indicated that the representative aroma-active components of the first group of samples(BYM,ZS,CS,and FHZ cultivars)were a-pinene(D2),?-pinene(D4),D-limonene(D7),and pinocarvone(E13),which contributed to the a stronger "floral","pine" and"cucumber" odors than the other groups of odors.The second group of samples(LZ,DA,BQ,SM,DK,and TM cultivars)had higher concentrations of ?-caryophyllene(D16)than the other cultivars,which were perceived as stronger "woody" odors.The group 3,however,showed higher levels of alchohol(B1),(Z)-3-nonen-l-ol(B9)and ethyl acetate(C2),which represents "overripe","fruity" and "cucumber" odors.According to the obtained results,the electronic nose can be used as a tool for quick analysis that can help to distinguish the different cultivars of bayberry samples.4.The flavor changes of different ripening stages of bayberry fruitThe present study intended to evaluate for the first time the effect of ripening stages(unripe,mid-ripe,and full-ripe)on the physicochemical properties,antioxidant activities,and aroma of bayberry fruits.The flavor of "green","sweet","sour",and"astringent" notes were found by sensory evaluation in all of the bayberry ripening stages.The weight,TSS,sugars(glucose,fructose,sucrose)and total anthocyanin content(TAC)increased up to the full-ripe stage of bayberry fruit.And the sucrose was the most abundant soluble sugar in bayberry fruit.Total phenolic contents(TPC)decreased across the same period and full-ripe fruit showed the lowest antioxidant activities(DPPH,FRAP,and ABTS).Eleven volatiles were identified in all the ripening bayberry and ?-caryophyllene was the most abundant compound.PCA allowed clearly differentiate all ripening stages,indicating that D-limonene(D3)with"lemon,citrus" note was most closely associated with the unripe bayberry,nonanal(A5,"citrus,flower" note),decanal(A7,"orange" note),p-ocimene(D5,"mushroom"note),and isocaryophyllene(D8,"wood" note)were associated with the mid-ripe bayberry,and the full-ripe bayberry fruit were characterized by hexanal(Al,"green"note),(E)-2-octenal(A4,"green" note),(E)-2-nonenal(A6,"cucumber" note),1-hexanol(B1,"green" note),(Z)-3-nonen-1-ol(B3,"cucumber" note),and methyl benzoate(C6,"herb" note).The results from E-nose to differentiate different ripeness staged for bayberry showed a good agreement with the results obtained by GC-MS.5.The flavor changes and off-flavor of bayberry during storageThe changes of the volatiles in different Chinese bayberry fruit in different storage conditions were observed and characterized.The volatile profiles at different storage conditions can be used for freshness evaluation during storage.On the basis of PCA,it has been possible to classify the bayberry fruit into several different groups according to the different cultivars and storage phases.The volatile compounds associated with flavor differentiation were also observed.The volatiles(A6 and B9 for the 'Biqi' cultivar;D1 and E13 for the 'Dongkui' cultivar;El,E2,and E6 for the'Fenhongzhong' cultivar)could be of potential use for freshness evaluation.The spoiled bayberry was with higher levels of ethanol and acetic acid.6.The off-flavor difference of bayberry juice and intact fruit during storageTo gain a better understanding of the flavor deterioration in-bayberry over time,we also investigated the volatile changes and off-flavor formation in both fresh bayberry juice and intact bayberry fruits.Ethanol("alcoholic" note),ethyl acetate("fruity" note),and acetic acid("sour" note)were found to contribute to off-flavor accumulation,and large increases were detected in both the bayberry juice and fruit.Meanwhile,over the storage period,increased concentrations of 3-methyl-1-butanol(B2),1-nonanol(B9),ethyl hexanoate(C6),and hexanoic acid(E3)were found in the bayberry juice.In contrast,storage of the intact fruit resulted in increased concentrations of terpinen-4-ol(B10),methyl acetate(Cl),and y-terpinene(D3).It could be applied as a promising method for the quality control for food industries. 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