Relative Odor Activity Value Research Articles

Effect of different cooking times on the fat flavor compounds of pork belly

Fat has a great impact on the meat product flavor, which is influenced by cooking time. This study explored the effect of different steaming times on the fat flavor of pork belly. A total of 14 aldehydes, 11 ketones, 6 esters, 4 alcohols, and 1 acid volatile compounds were identified through gas chromatography ion mobility spectrometry (GC-IMS). The relative odor activity value (ROAV) combined with the principal component analysis (PCA) method showed that the aroma of pork belly fat was considerably different under different steaming times. The quantity of key volatile compounds with ROAV ≥ 1, namely, heptanal, ethyl hexanoate, 2-methylbutanal-m, 3-methylbutanal, ethyl acetate, and 2, 3-butanedione increased considerably in the fat after steaming. The fat gives rise to two key volatile compounds, hexanal-d and 1-heptanol, after steaming for 30 min. Similarly, ethyl formate and 3-hydroxy-2-butanone were obtained as the key volatile compounds after steaming for 180 min. PRACTICAL APPLICATIONS: Pork belly is the main ingredient of Chinese traditional dishes such as Dongpo's pork and braised pork in brown sauce. When heated for extended periods of time, the high fat content of pork belly gives rise to important precursors that influence the flavor characteristics of these dishes. However, studies comparing the diversities of volatile compounds in pork belly fat exposed to different heating times are sparse. To address this gap in literature, this study identified the flavor components of pork belly fat exposed to different heating times. The data from this study can act as a framework for further flavor research on pork belly products.

Insights into the Aroma Profile of Sauce-Flavor Baijiu by GC-IMS Combined with Multivariate Statistical Analysis.

Aroma is among the principal quality indicators for evaluating Baijiu. The aroma profiles of sauce-flavor Baijiu produced by 10 different manufacturers were determined by GC-IMS. The results showed that GC-IMS could effectively separate the volatile compounds in Baijiu, and a total of 80 consensus volatile compounds were rapidly detected from all samples, among which 29 volatile compounds were identified, including 5 alcohols, 14 esters, 2 acids, 2 ketones, 5 aldehydes, and 1 furan. According to the differences in aroma profile found by multivariate statistical analysis, these sauce-flavor Baijiu produced by 10 different manufacturers can be further divided into three types. The relative odor activity value of the identified volatile compounds indicated that seven volatile compounds contributed most to the aroma of sauce-flavor Baijiu in order of aroma contribution rate, and they were ethyl hexanoate, ethyl pentanoate, ethyl 2-methylbutanoate, ethyl octanoate (also known as octanoic acid ethyl ester), ethyl 3-methylbutanoate, ethyl butanoate, and ethyl isobutyrate. Correspondingly, the main aromas of these sauce-flavor Baijiu produced by 10 different manufacturers were sweet, fruity, alcoholic, etheral, cognac, rummy, and winey. On the one hand, this study proved that GC-IMS is well adapted to the detection of characteristic volatile aroma compounds and trace compounds in Baijiu, which is of positive significance for improving the aroma fingerprint and database of sauce-flavor Baijiu. On the other hand, it also enriched our knowledge of Baijiu and provided references for the evaluation and regulation of the flavor quality of sauce-flavor Baijiu.

Edible qualities, microbial compositions and volatile compounds in fresh fermented rice noodles fermented with different starter cultures

To shorten the fermentation time and reduce the heterozygous bacteria contamination during fresh fermented rice noodles (FFRNs) fermentation, four starter cultures that consist of Limosilactobacillus fermentum, Lactoplantibacillus plantarum and Saccharomyces cerevisiae were used to produce FFRN. The cooking qualities and texture profiles of FFRNs, the dynamics of microbial diversities and volatile compounds at different fermentation stages were explored. Results showed that the fermentation time of the adding starter culture groups required 12 h, while that the natural fermentation (NF) group required 36 h. Significant differences were observed in the texture profiles and cooking qualities of these five groups FFRNs (P ＜ 0.05). In addition, compared with NF group, the microbial diversity of four adding starter culture groups was significantly lower, which meant that the edible safety of FFRNs could be enhanced. Meanwhile, a total of 115 volatile compounds were detected by Gas chromatography-ion Mobility Spectrometry and Gas chromatography-mass spectrometry, the aldehydes, alcohols, acids and esters were increased while aldehydes were decreased in FFRNs during fermentation. Among these, the relative odor activity value of 50 volatile compounds was greater than 0.1, contributing unique flavors to FFRNs. Notably, the flavor of Lactoplantibacillus plantarum + Saccharomyces cerevisiae (L.p + S.c) and Lactoplantibacillus plantarum + Limosilactobacillus fermentum + Saccharomyces cerevisiae (L.pf + S.c) groups was richer than that of other groups.

Analyzing the Effect of Baking on the Flavor of Defatted Tiger Nut Flour by E-Tongue, E-Nose and HS-SPME-GC-MS.

In order to screen for a proper baking condition to improve flavor, in this experiment, we analyzed the effect of baking on the flavor of defatted tiger nut flour by electronic tongue (E-tongue), electronic nose (E-nose) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). According to E-tongue and E-nose radar plots and principal component analysis (PCA), baking can effectively change the taste and odor of defatted tiger nut flour, and the odors of samples with a baking time of >8 min were significantly different from the original odor of unbaked flour. Moreover, bitterness and astringency increased with longer baking times, and sweetness decreased. HS-SPME-GC-MS detected a total of 68 volatile organic compounds (VOCs) in defatted tiger nut flour at different baking levels, and most VOCs were detected at 8 min of baking. Combined with the relative odor activity value (ROAV) and heat map analysis, the types and contents of key flavor compounds were determined to be most abundant at 8 min of baking; 3-methyl butyraldehyde (fruity and sweet), valeraldehyde (almond), hexanal (grassy and fatty), and 1-dodecanol, were the key flavor compounds. 2,5-dimethyl pyrazine, and pyrazine, 2-ethylalkyl-3,5-dimethyl- added nutty aromas, and 1-nonanal, 2-heptanone, octanoic acid, bicyclo [3.1.1]hept-3-en-2-ol,4,6,6-trimethyl-, and 2-pentylfuran added special floral and fruity aromas.

Effect of different cooking methods on flavor compounds of Chinese traditional condiment Wuxiang powder

The Wuxiang powder is a Chinese traditional condiment with a strong aroma and flavor. Moreover, it is suitable for dishes prepared using several cooking methods. Gas chromatography-ion mobility spectrometry was used to analyze the changes in the flavor of the original Wuxiang powder, the air-fried Wuxiang powder and the stewed Wuxiang powder. A total of 49 volatile compounds were studied, including 17 aldehydes, 9 alkenes, 9 esters, 7 alcohols, 2 ethers, 2 furans, 1 acid, 1 ketone and 1 phenol. The contents of aldehydes, hydrocarbons, esters and alcohols were higher than others. The principal component analysis elucidated significant differences in the aroma among different cooking methods of the Wuxiang powder. According to the relative odor activity value, the major flavor compounds that contributed to the difference in the aroma among different cooking methods were (Z, Z)-2, 4-decadienal, anethole, decanal, 3-methylbutanal, β-caryophyllene, α-pinene, linalool, eugenol, octanal, heptanal, and hexanal.

Discrimination and characterization of the volatile profiles of five Fu brick teas from different manufacturing regions by using HS–SPME/GC–MS and HS–GC–IMS

Although aroma is one of the most essential factors determining the quality of Fu brick tea (FBT), the aroma profiles of FBTs from different manufacturing areas are rarely investigated. The aroma profiles of FBTs manufactured in five typical provinces of China were comprehensively analyzed on the basis of headspace gas chromatography–ion mobility spectrometry (HS–GC–IMS), headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS), sensory evaluation, odor activity value (OAV), and relative odor activity value (ROAV). HS–GC–IMS and HS–SPME–GC–MS identified 63 and 93 volatile organic compounds (VOCs), respectively. Multivariate statistical analysis indicated that the FBTs from different production regions had remarkably varied aromas. HS–SPME–GC–MS revealed that 27 VOCs (OAV >1) contributed to the overall aroma of the samples, of which 15 key differential compounds can effectively distinguish the aroma profiles of different FBTs. FBT from Shaanxi manifested a strong floral and fruity aroma; that from Hunan had a floral, grassy, and pine-woody aroma; that from Guizhou presented a grassy and herbal aroma; that from Guangxi exhibited a sweet, floral, and minty aroma; and that from Zhejiang possessed various fruit flavors and floral fragrance. OAV analysis identified the biomarkers responsible for the variation in the aroma characteristics of diverse FBTs. These biomarkers included linalool, 6-methyl-5-hepten-2-one, α-ionone, hexanal, and ethyl hexanoate. Sensory evaluation demonstrated that the infusion color and aroma of FBT samples from different provinces also greatly varied. Network correlation analysis revealed that Aspergillus and Eurotium were the crucial microorganisms for the metabolism and formation of VOCs. These findings provide new insight into the VOCs and fragrance features of FBTs produced in different regions of China.

Aroma effects of key volatile compounds in Keemun black tea at different grades: HS-SPME-GC-MS, sensory evaluation, and chemometrics

The present study aimed to explore the relationship between the grade and the characteristic aroma in Keemun black tea (KBT). Headspace solid-phase microextraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS), sensory evaluation, and chemometrics were employed to determine the changes in the flavor evolution of KBT at grade. The results showed that a total of 110 volatile components were identified. Linalool and linalool oxide were dominant. The orthogonal partial least squares discriminant analysis (OPLS-DA) combined with relative odor activity value (rOAV > 0.1) revealed that 11 volatile components were the key volatile compounds of KBT, such as benzeneacetaldehyde (rOAV: 3.43–5.96) and methyl salicylate (rOAV: 2.15 – 2.50). Furthermore, the partial least squares (PLS) model indicated that geraniol, linalool, and methyl salicylate benefited from the reservation of floral flavor of Keemun aroma characteristic of KBT. The findings presented in this thesis add to our understanding of KBT at different grades.

Effects of different cooking methods on volatile flavor compounds of chicken breast.

Chicken is one of the highest selling meats worldwide. Different cooking methods produce various flavor compounds in cooked chicken, which affect consumers' food choices. In this study, the volatile flavor components of Gushi chicken breast after stewing and air frying were detected using gas chromatography-ion mobility chromatography (GC-IMS) and principal component analysis (PCA), and the relative odor activity value (ROAV) was determined using PCA. A total of 43 volatile substances were identified. 3-(methylthio)propionaldehyde-M and benzene acetaldehyde can be used as characteristic flavor markers in the air-fried chicken breast.ethyl acetate, (E)-2-octenal-D, and 2-ethyl-1-hexanol-D can be used as characteristic flavor markers in the stewed chicken breast. Because these five substances have the most obvious contrast in the fingerprint. The following part describes the specific substances that have mainly contributed to the flavor system in the volatile system obtained by different cooking methods. Finally, the main flavor compounds of the stewed chicken breast were 3-methylbutanal-D, octanal-D, (E)-2-nonenal, and other 11 types of compounds (ROAV ≥1). Nine types of compounds (ROAV ≥1), including 3-methylbutanal-D, (E)-2-nonenal-M octanal-M, and hexanal-M, were the main compounds to characterize the air-fried chicken breast. PRACTICAL APPLICATIONS: GC-IMS technology combined with the principal component analysis of ROAV can be used to rapidly identify the main flavor substances and the flavor substances having an important role in modifying the overall taste of the sample. It plays a considerably important role in the aroma recombination of substances and can play a role in food processing.

Effect of Extrusion Temperature on Characteristic Flavor Compounds in Pea Flour

In order to explore the effects of extrusion processing on characteristic flavor compounds of pea flour and improve the flavor quality, in this study, electronic nose(E-nose) and gas chromatography-ion mobility spectrometry(GC-IMS) were used to investigate the effects of extrusion temperatures (120, 150, 180 ℃) on volatile flavor compounds of pea flour and compared with unextruded pea flour. The flavor differences between samples with different extrusion temperatures can be evaluated objectively by the electronic nose system. A total of 53 volatile substances in 8 compounds, including aldehydes, alcohols, ketones, acids, esters, pyrazines, furans and ethers were identified by GC-IMS. The relative content of alcohols, ketones, acids, esters, ethers decreased, the relative content of pyrazines and furans increased. The relative content of characteristic beany flavor compounds such as trans-2-octenal, hexanal, 1-octene-3 alcohol, n-hexanol, 1-pentanol, n-butanol and 2-pentylfuran decreased by 23.53%, 33.23%, 50.44%, 88.82%, 77.69%, 84.51%, 26.19%, respectively and the relative content of 2, 5-dimethylpyrazine, 2-methylpyrazine and 2-furanmethanol with roasted flavor increased by 16.16, 23.92, and 7.95 times, respectively at the extrusion temperature of 180 ℃. Relative odor activity value (ROAV) showed that n-nonanal, 3-methylbutanal, hexanal, n-octanal, 1-octen-3-ol, heptanal, ethyl acetate, n-butyraldehyde, trans-2-octenal, 2-pentylfuran, 2-ethylfuran and n-hexanol were the characteristic flavor compounds of raw pea flour. Principal component score determined that the flavor of the 180 ℃ extruded sample was the best.

The aroma profile and microbiota structure in oil furu, a Chinese fermented soybean curd

The aroma compounds and the microbial community of oil furu, a specific fermented soybean curd, during fermentation were investigated using HS-SPME-GC/MS and high-throughput sequencing, respectively, and their correlations and the predicted functional roles of the microbiota in oil furu were analyzed. Twenty two volatile flavor compounds (relative odor activity value ≥1) were identified that contributed to the aroma profile, which were mainly associated with the aroma attributes. Lactobacillales, Trichosporon and Mucor racemosus were the predominant genera during pre-fermentation, while Candida and Tetragenococcus were predominant during ripening. Correlation analysis showed significant correlation between the microbiota and aroma profiles, and Candida, Empedobacter, Lactobacillus, Pseudomonas, Stenotrophomonas, Trichosporon and Mucor racemosus were significantly and strongly correlated with the characteristic volatile aroma compounds of oil furu (P < 0.05, r > 0.6). Functional analysis showed that metabolic pathways showed higher activity in oil furu, which mainly included amino acid, lipid and carbohydrate metabolism. The results allowed identification of the important aroma compounds and understanding the contribution of the microbiota, and would be useful for designing starter cultures to produce oil furu with desirable aroma properties and understanding its aroma formation pathways.

Comparison of the microbial community and flavor compounds in fermented mandarin fish (Siniperca chuatsi): Three typical types of Chinese fermented mandarin fish products

Fermented mandarin fish have been receiving attention from consumers due to their nutritional value and specific flavor. Microbial diversity in fermented mandarin fish has an important impact on their flavor and quality. However, little is known about the microbiome and the differences among different products. In this study, the bacterial profiles and flavor compounds in three typical fermented mandarin fish products were investigated and compared, and a correlation network was used to explore the potential relationship between microorganisms and flavor. Bacterial community analysis demonstrated clear differences in microbiota among the HF-, MF-, and OF-fermented mandarin fish products. Psychrilyobacter, Fusobacterium, and Vibrio were the most dominant in the HF-, MF-, and OF-fermented products, respectively. In addition, 14, 12, and 4 flavor substances (relative odor activity value, ROAV ≥ 1) were detected in the muscles from the central dorsal and ventral sides of the three samples, respectively. Several bacteria correlated with the production of important flavor compounds, and three genera (Arcobacter, Psychrilyobacter, and Shewanella) were the primary microorganisms contributing to more than six characteristic flavor compounds in fermented mandarin fish products. Therefore, the study’s systematic method allows identificating important microbes and characteristic volatile flavor compounds in fermented mandarin fish and provides new insights into the relationship between microorganisms and flavor.

The effect of short-term storage temperature on the key headspace volatile compounds observed in Canadian faba bean flour.

The odour emitted from the high-tannin fab bean flour (Vicia faba var. minor), was characterized by headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC–MS). The relative odour activity value (ROAV) was used to monitor the changes in key volatile compounds in the flour during short-term storage at different temperature conditions. The key flavour compounds of freshly milled flour included hexanal, octanal, nonanal, decanal, 3-methylbutanal, phenyl acetaldehyde, (E)-2-nonenal, 1-hexanol, phenyl ethyl alcohol, 1-octen-3-ol, β-linalool, acetic acid, octanoic acid, and 3-methylbutyric acid; these are oxidative degradation products of unsaturated fatty acids and amino acids. Despite the low lipid content of faba beans, the abundances of aldehydes arising during room temperature storage greatly contributed to the flavour of the flour due to their very low odour thresholds. Two of the key volatiles responsible for beany flavour in flour (hexanal, nonanal) increased greatly after 2 weeks of storage at room temperature or under refrigerated conditions. These volatile oxidation products may arise as a result of enzymatic activity on unsaturated fatty acids, and was seen to be arrested by freezing the flour.

Effects of different preheat treatments on volatile compounds of camellia (Camellia oleifera Abel.) seed oil and formation mechanism of key aroma compounds.

In this study, volatile compounds of camellia seed oil (CSO) prepared by different preheat treatments (microwave, frying, roasting, and steaming) were identified by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS). A total of 107 volatile compounds were identified in CSO samples, including aldehydes (16), alcohols (6), ketones (3), heterocyclic compounds (26), esters (23), hydrocarbons (15), and others (17). Among them, untreated CSO is mainly hydrocarbons, roasting and steaming CSO are mainly aldehydes and alcohols, while microwave and roasting CSO are dominated by aldehydes and heterocyclic compounds. Fourteen volatile compounds with high relative odor activity value (ROAV≥1) were selected as key aroma compounds (KACs). Principal Component Analysis (PCA) and Cluster Analysis (CA) were performed on 14 KACs, which determined that there were 3, 3, 3, 7, and 6 characteristic aroma compounds (CACs) in untreated, microwaved, frying, roasting, and steaming CSO. Additionally, the potential formation pathways and mechanism of KACs were discussed. PRACTICAL APPLICATIONS: Flavor is an important factor for consumers to choose edible oils, and it is also one of the indicators of oil quality. Different flavors of CSO can cater to the needs of different consumers. CSO manufactories can choose different preheat treatments to produce CSO with various flavors to meet different customers' need. CSO with new flavor can extend its market share and increase its value.

Analysis of Volatile Components of Auricularia auricula from Different Origins by GC-MS Combined with Electronic Nose

Auricularia auricula is a kind of nutrient-rich edible fungus, which has the reputation of “king of vegetarians.” In this paper, the electronic nose combined with GC-MS technology was used to analyze the volatile components of A. auricula in Heilongjiang, Jilin, Shanghai, and Sichuan provinces to investigate the differences and characteristics of A. auricula in different origins. The results showed that the electronic nose could obviously distinguish the samples from Jilin and Shanghai with a high degree of discrimination, while it was inappropriate to distinguish the samples from Heilongjiang and Sichuan Province. GC-MS was used to further analyze the volatile compounds in A. auricula qualitatively and quantitatively. The results showed that 98 volatile components were detected and 23 of them were common components, including alcohols, aldehydes, acids, esters, hydrocarbons, and other volatile components. The relative content of acetic acid and diethyl azodicarboxylate in A. auricula from the four origins was relatively high. According to the relative odor activity value (ROAV), it was found that the key compounds that caused the aroma difference between different origins were 1-octene-3-ol, cis-3-nonene-1-ol, (E)-2-octenal, (E)-2-nonenal, (E,E)-2,4-nonadienal, and 3-methyl butanal.

Effects of different thawing methods on flavor compounds and sensory characteristics of raspberry

AbstractIn order to identify more suitable thawing method to preserve aroma, taste, and other sensory quality of raspberry, five thawing methods were used to treat frozen raspberry, namely water bath thawing, microwave thawing, ultrasonic thawing, room temperature thawing, and refrigeration thawing. Gas chromatography‐mass spectrometry was employed to study the quantitative and qualitative analysis of the volatile compounds, and the characteristic flavor components of raspberry were compared by relative odor activity value (ROAV). Electronic tongue technique and fuzzy comprehensive evaluation were used to ensure the changes in sensory qualities of raspberry. The results showed that the time of microwave thawing was 0.57 minutes, and drip loss was 4.40%. Both of them were the lowest among the five thawing methods. The volatile components of raspberry included aldehydes, esters, ketones, alcohols, fatty acids, terpenes, and other compounds. Among them, there were 19 kinds of volatile components in quick‐frozen raspberries, 18 volatile components in raspberries after treated by microwave thawing and refrigeration thawing, 16 volatile components after room temperature thawing, 12 volatile components after ultrasonic thawing, and 10 volatile components after water bath thawing. The characteristic flavor compounds of raspberry were identified as acetaldehyde, alpha‐ionone, beta‐ionone, raspberry ketone, alpha‐terpene, and alpha‐pinene. Microwave thawing was the most suitable way to preserve the characteristic flavor components of raspberry, but water bath thawing could destroy the most of compounds. After microwave thawing, raspberry tasted best and was most acceptable to consumers. Therefore, microwave thawing was the most appropriate method to preserve raspberry flavor and sensory quality among the five thawing methods.

Use of relative odor activity value (ROAV) to link aroma profiles to volatile compounds: application to fresh and dried eel (Muraenesox cinereus)

ABSTRACT Volatile compounds in fresh and dried eels were investigated. Electronic nose (E-nose), headspace solid-phase microextraction combined with gas chromatography–mass spectrometry (HS–SPME–GC–MS), and relative odor activity value (ROAV) were applied to distinguish odors between fresh and dried eels. Results showed that E-nose could effectively distinguish the aroma among fresh eels, eels dried under 35°C and 12°C, and different drying methods had a significant influence on nitrogen oxides and methane in volatile compounds of dried eels. Total 37 and 28 volatile compounds detected in dried and fresh eel, respectively, were remarkably different. Relative odor activity values (ROAV) identified hexanal, nonanal, benzaldehyde, octanal, and 1-octen-3-ol as key flavor compounds in both fresh and dried eels. However, a serial of compounds, including 2-ethylfuran, 2,3-octanedione, (E, Z)-2,6-nonadienal, D-limonene, and 2-Zn-pentylfuran, added the sweet and meaty flavor of dried eel and neutralized the original strong grassy and fishy taste of fresh eel, primarily led to the difference in their odors.

Sensory characteristics of low sodium dry-cured beef and their relation to odor intensity and electronic nose signals

ABSTRACT In this study, the influence of Na content in dry-cured beef by partial replacement with KCl, L-lysine, and L-histidine was investigated. Dry-cured beef aged over 57 days, compared to the control groups (100% NaCl), salt-substituted groups (SS, 39.7% of NaCl, 51.3% of KCl and a blend of 7% L-lysine and 2% L-histidine) had a significant impact on the taste thresholds, relative odor activity value (ROAV), electronic nose (E-nose), and sensory evaluation. This study revealed that the salt substitute process modified the sensory profile by intensifying the “aroma” and differentiating the control group from SS group. The results represented salt substitute analysis of dry-cured beef and may be used by food companies and other stakeholders to understand the changes in sensory characteristics of dry-cured beef due to 100% NaCl process. Salt substitute was developed successfully, presenting a good performance.

Comprehensive analysis of volatile compounds in cold-pressed safflower seed oil from Xinjiang, China.

Three varieties of safflower seed oil (SSO) from Xinjiang Autonomous Region, China, were analyzed by headspace solid‐phase micro‐extraction gas chromatography coupled with mass spectrometry (HS‐SPME‐GC‐MS) to reveal volatile components. Overall, 67 volatile components were determined and four compounds including isoamyl alcohol, caproic acid, n‐pentanal, and heptanal were newly identified in SSO as aroma‐active components. Meanwhile, 16 compounds were selected by relative odor activity value (ROAV) to evaluate contributions of single compounds to the overall odor (ROAV > 1), in which nonanal, (Z)‐6‐nonenal, and (E)‐2,4‐decadienal were the top three contributed substances (ROAV > 70). The sensory panel was described as eight definition terms (grassy, fruity, almond, mushroom, fatty, sweet, paddy, and overall fragrance). Principal component analysis (PCA) revealed a significant separation of three cultivars with the first principal component (PC‐1) and the second principal component (PC‐2) expressing 73.9% and 23.1%, respectively. Both PCA and ROAV allowed identifying the compounds positively correlated to sensory evaluation.

Assessment of chemical composition and sensorial properties of ciders fermented with different non-Saccharomyces yeasts in pure and mixed fermentations

This work presents the attempt to enhance the flavor complexity of cider fermented by different non-Saccharomyces species. Pichia kluyveri and Hanseniaspora vineae pure cultures were used as reference ciders. Mixed cultures between all 4 species gave 5 fermentations, where Hanseniaspora uvarum or Torulaspora quercuum were included for apple juice fermentation. Chemical composition and sensorial properties of all ciders were studied. The results indicated that the growth of P. kluyveri and H. vineae were interreacted and also affected by H. uvarum and T. quercuum. H. vineae was more capable of consuming sugar than P. kluyveri. Ciders from the single culture fermentation with P. kluyveri (Pk), as well as from mixed fermentation with P. kluyveri and H. uvarum (Pk-Hu), had high residual sugar, sugar/acid ratio, and glucose-fructose consumption ratio. Large shifts in the consumption and production of organic acids and polyphenols among all ciders were observed. The calculation of the relative odor activity value (rOAV) showed that 17 volatile compounds had an rOAV >1 in at least one sample, and acetate esters and ethyl esters were the groups with the highest number of volatile compounds of importance to the cider aroma. Among these 17 compounds, 3-methylbutyl acetate, 2-methylbutyl acetate, ethyl hexanoate, ethyl octanoate, and β-damascenone exhibited high rOAVs in some ciders and might contribute fruity, floral, and sweet features to the cider aroma. Besides, the tropical fruity aroma from 3-methylbutyl acetate was only perceived in Pk and Pk-Hu. The partial least squares regression (PLSR) analysis revealed that acetate esters contributed positively to the roasted and cooked odor of all ciders. This is the first study evaluating simultaneous fermentation of two non-Saccharomyces yeasts to produce cider, which provides new insights into cider production.

Characterization and screening of non-Saccharomyces yeasts used to produce fragrant cider

The objective of this work is to characterize and screen non-Saccharomyces yeast strains for the production of ciders. A total of 199 volatiles were observed in the ciders that were generated from 163 non-Saccharomyces yeasts. Candida zemplinina, Hanseniaspora vineae and Torulaspora delbrueckii were found to produce relatively more volatile compounds than other species. There were 29 volatiles with a relative Odor Activity Value (rOAV) > 1. Based on analysis of aroma content, aroma complexity and aroma impact, 35 samples were further selected for Principal Component Analysis and sensory analysis. The results revealed that two groups of ciders were differentiated by the presence of decanal or β-damascenone, while the remaining samples contained 2-methylbutyl acetate. Additionally, partial least-squares regression showed that tropical fruit, kernel fruit, stone fruit and floral aroma notes had the greatest impact on the overall aroma of these ciders.