Solid-phase Microextraction Gas Chromatography Mass Research Articles

Characterization of stale odor in green tea formed during storage: Unraveling improvements arising from reprocessing by baking

Changes in key odorants and aroma profiles of three types of green tea during storage and after baking treatment were determined using headspace solid-phase microextraction–gas chromatography–mass spectrometry/olfactometry, odor activity value (OAV) and orthogonal partial least-squares discriminant analysis. As the stale odor developed during storage, the content of aldehydes decreased, whereas the contents of ketones and heterocycles (furans, pyrroles, etc.) increased. Key odorants, including (E,E)-2,4-heptadienal, α-terpineol, (E,E)-2,4-nonadienal and (E,E)-2,4-decadienal, appeared to be mainly responsible for the stale odor. After baking treatment, the stale odor was significantly improved, the contents of aldehydes and heterocycles were significantly increased and the content of alcohols was significantly decreased. Of these, 2-pentylfuran, hexanal, nonanal and limonene, which increased after baking, contribute the green, fruity and roasted aromas of green tea, because of their high OAVs, aroma intensities and variable importance in projection values. This study has improved understanding of the chemical changes resulting in stale odor development in green tea during storage and improvements arising from baking treatment, as well as providing a theoretical basis for the improvement of storage conditions and green tea flavor.

Analysis of the formation mechanism of volatile and non-volatile flavor substances in corn wine fermentation based on high-throughput sequencing and metabolomics

The purpose of this study was to reveal the relationship between core microorganisms and flavor substances in the fermentation process of corn wine. Microbial diversity, volatile and non-volatile flavor substances were detected by high-throughput sequencing (HTS), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME/GC–MS) and gas chromatography time of flight mass spectrometry (GC-TOF-MS). High performance liquid chromatography (HPLC) was used to detect organic acids in corn wine fermentation, and its physiochemical properties were tracked. The results showed that physiochemical factors changed obviously with fermentation time. Bacillus, Prevotella_9, Acinetobacter and Gluconobacter were the predominant bacterial. Rhizopus and Saccharomyces were the dominant fungi. Acetic acid and succinic acid were important organic acids in corn wine. According to variable importance of projection (VIP) > 1 and P < 0.05, 24 volatile flavor substances with significant difference were screened out from 52 volatile flavor substances. Similarly, 25 non-volatile flavor substances with significant differences were screened out from the 97 reliable metabolites identified by 223 chromatographic peaks. Eight key metabolic pathways were enriched from 25 non-volatile flavor substances according to path influence values > 0.1 and P < 0.05. Based on Two-way Orthogonal Partial Least Squares (O2PLS) model and Pearson correlation coefficient, Saccharomyces, Rhizopus, uncultured_bacterium, Aneurinibacillus, Wickerhamomyces and Gluconobacter may be the potential volatile flavor-contributing microorganism genus in corn wine. The Pearson correlation coefficient showed that Saccharomyces was significantly positively correlated with malic acid, oxalic acid, valine and isoleucine, and Rhizopus was positively correlated with glucose-1-phosphate and alanine. These findings enhanced our understanding of the formation mechanism of flavor substances in corn wine and provided the theoretical basis for stabilizing flavor quality of corn wine.

Differential characterization of volatile components and aroma sensory properties of different types of Hehong tea (Congou black tea)

AbstractTo explore the flavour characteristics and their different molecular mechanisms of different types of Hehong tea (Gongya, GY; Congou, CG and Laocong, LC) from the perspective of dry tea, we investigated their volatile compounds and sensory aroma sub‐attribute characteristics by headspace–solid phase microextraction–gas chromatography–mass spectrometry (HS‐SPME‐GC–MS), quantitative description analysis (QDA), and chemometrics. A total of 42 volatile compounds were identified in Hehong tea, of which alcohol content was the highest, the number of esters was the largest and pyrrole showed the largest differences. The volatile components of GY and LC differed, whereas those of CG and LC were more similar. There were 34 volatile components with a significant difference in the three types of Hehong tea. We established the aroma quantitative system of Hehong tea by using QDA. We found that sweety was probably the symbolic aroma sub‐attribute of Hehong tea, and woody was the characteristic sub‐attribute of LC, and there was a certain correlation among the aroma sub‐attributes. A total of 21 volatile components importantly contributed to the aroma sub‐attributes of Hehong tea. Furthermore, we screened out 18 marker volatile compounds that may be used as important indicators for distinguishing the three types of Hehong tea. Our findings add to our understanding of the flavour characteristics and aromas of the three types of Hehong tea and provide new strategies and thoughts for the evaluation of tea flavour using dry tea.

An Efficient Solid-Phase Microextraction–Gas Chromatography–Mass Spectrometry Method for the Analysis of Methyl Farnesoate Released in Growth Medium by Daphnia pulex

Methyl farnesoate (MF), a juvenile hormone, can influence phenotypic traits and stimulates male production in daphnids. MF is produced endogenously in response to stressful conditions, but it is not known whether this hormone can also be released into the environment to mediate stress signaling. In the present study, for the first time, a reliable solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method was developed and validated for the ultra-trace analysis of MF released in growth medium by Daphnia pulex maintained in presence of crowding w/o MK801, a putative upstream inhibitor of MF endogenous production. Two different clonal lineages, I and S clones, which differ in the sensitivity to the stimuli leading to male production, were also compared. A detection limit of 1.3 ng/L was achieved, along with good precision and trueness, thus enabling the quantitation of MF at ultra-trace level. The achieved results demonstrated the release of MF by both clones at the 20 ng/L level in control conditions, whereas a significant decrease in the presence of crowding was assessed. As expected, a further reduction was obtained in the presence of MK801. These findings strengthen the link between environmental stimuli and the MF signaling pathway. Daphnia pulex, by releasing the juvenile hormone MF in the medium, could regulate population dynamics by means of an autoregulatory feedback loop that controls the intra- and extra-individual-level release of MF produced by endogenous biosynthesis.

Evaluation of Rosa germplasm resources and analysis of floral fragrance components in R. rugosa.

Rosa rugosa (Rosaceae) is an important functional plant used in food products, tea, and aromatherapy. Characteristics of R. rugosa varieties based on the biological traits and floral fragrant components were studied by applying an analytic hierarchy process, headspace solid-phase microextraction gas chromatography–mass spectrometry, and metabolomic analysis. The 77 Rosa accessions (comprising 27 R. rugosa varieties, 43 scented R. hybrida cultivars, and seven fragrant R. species) were grouped into nine classes based on 17 morphological characters and 16 targeted fragrant substances by cluster analysis. Three R. rugosa cultivars differing in fragrance type were selected for volatile metabolomics analysis at four stages of flower development. In total, 156 differential volatile organic compounds (VOC) were detected and the VOC content patterns were further investigated in two important metabolic pathways (the monoterpenoid biosynthetic pathway, and the phenylalanine, tyrosine, and tryptophan biosynthesis pathway). The results provide a foundation for efficient use of Rosa germplasm and insights into the utilization of R. rugosa as a functional flower.

Volatile metabolomics and chemometric study provide insight into the formation of the characteristic cultivar aroma of Hemerocallis

Due to its ornamental, edible, and medicinal value, Hemerocallis has been historically loved and used in China. However, the current understanding of the aromatic profiles of this flower is rather limited. This work aimed to evaluate and classify the aromatic profiles of Hemerocallis flowers from 10 cultivars, the volatiles of which were analyzed using solid-phase microextraction–gas chromatography–mass spectrometry. Sensory evaluation, odor activity value and relative odor activity value calculations, and chemometric analysis were also performed, the result showed that a total of 81 volatile components were identified. Linalool, 3-furanmethanol, indole, phenylacetonitrile, nerolidol, benzaldehyde, nonanal, geranial, (E)-β-ocimene, and volatile components specific to the different types were found to have an essential role in identifying these 10 varieties. The findings presented in this thesis add to our understanding of Hemerocallis.

Sexual Differences in Eurya loquaiana Dunn Floral Scent and How Pollinators Respond.

Eurya plants are usually dioecious or subdioecious with small fragrant flowers. Here, we investigate the floral scent components of the subdioecious species Eurya loquaiana Dunn and how floral scent affects pollinators. Headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) was used to compare the floral scents of male, female, and hermaphrodite flowers. We also test whether differences in floral scent affect the foraging behaviors of pollinators and describe the flower morphological traits of the three sexes. Twenty-eight floral scent compounds were tentatively identified, and four monoterpenoids were tentatively identified as the most abundant compounds: linalool oxide (pyranoid), linalool, lilac aldehyde, and linalool oxide (furanoid). There were floral scent differences among the sex types, and male flowers were more attractive to pollinators in the wild, even when visual factors were excluded, indicating that pollinators likely distinguish sexual differences by floral scent. In the competition for pollinators, the advantage that male flowers have over female and hermaphrodite flowers can likely be accounted for the differences in floral scent and display size.

An enzymatic tandem reaction to produce odor-active fatty aldehydes

Aldehydes represent a versatile and favored class of flavoring substances. A biocatalytic access to odor-active aldehydes was developed by conversion of fatty acids with two enzymes of the α-dioxygenase pathway. The recombinant enzymes α-dioxygenase (α-DOX) originating from Crocosphaera subtropica and fatty aldehyde dehydrogenase (FALDH) from Vibrio harveyi were heterologously expressed in E. coli, purified, and applied in a coupled (tandem) repetitive reaction. The concept was optimized in terms of number of reaction cycles and production yields. Up to five cycles and aldehyde yields of up to 26% were achieved. Afterward, the approach was applied to sea buckthorn pulp oil as raw material for the enzyme catalyzed production of flavoring/fragrance ingredients based on complex aldehyde mixtures. The most abundant fatty acids in sea buckthorn pulp oil, namely palmitic, palmitoleic, oleic, and linoleic acid, were used as substrates for further biotransformation experiments. Various aldehydes were identified, semi-quantified, and sensorially characterized by means of headspace–solid phase microextraction–gas chromatography–mass spectrometry–olfactometry (HS–SPME–GC–MS–O). Structural validation of unsaturated aldehydes in terms of double-bond positions was performed by multidimensional high-resolution mass spectrometry experiments of their Paternò–Büchi (PB) photoproducts. Retention indices and odor impressions of inter alia (Z,Z)-5,8-tetradecadienal (Z,Z)-6,9-pentadecadienal, (Z)-8-pentadecenal, (Z)-4-tridecenal, (Z)-6-pentadecenal, and (Z)-8-heptadecenal were determined for the first time.Key points• Coupled reaction of Csα-DOX and VhFALDH yields chain-shortened fatty aldehydes.• Odors of several Z-unsaturated fatty aldehydes are described for the first time.• Potential for industrial production of aldehyde-based odorants from natural sources.Graphical abstract

Characterization of volatile composition, aroma-active compounds and phenolic profile of Qingxin oolong tea with different roasting degrees

Due to the premium flavor, Qingxin oolong tea (QOT), which is grown and produced in Taiwan, is widely appreciated. Roasting is a crucial process for shaping its flavor. However, the effect of roasting on the aroma and taste of QOT was not fully understood. In this study, the volatile composition, aroma-active compounds and phenolic profile of QOT with different roasting degrees, including the unroasted (UR), the medium roasted (MR) and the heavy roasted (HR) were analyzed. As revealed by headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and multivariate statistical analyses, UR and MR demonstrated similar volatile profiles, while heavy roasting changed the volatile composition greatly. Multiple nitrogen-containing compounds, such as 3,5-diethyl-2-methylpyrazine and 2-ethyl-3,5-dimethylpyrazine, were uniquely found in heavy roasted samples, which can be ascribed to the extensive Maillard reaction. Moreover, eight compounds were identified and verified as key aroma-active compounds by using gas chromatography-olfactometry-mass spectrometry (GC-O-MS), aroma recombination and omission experiments. The aldehydes and alcohols, such as linalool, benzeneacetaldehyde and α-farnesene, with a floral scent were the dominant aroma-active compounds in UR and MR, while 2-ethyl-3,5-dimethylpyrazine and 3,5-diethyl-2-methylpyrazine with a roasted scent were the main aroma-active compounds in HR. Furthermore, as revealed by ultra-high performance liquid chromatography and Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap-MS), flavanols and phenolic acids were significantly lower in abundance in UR and MR as compared to those in HR, whereas flavonols were less affected by roasting. These findings provide useful information for understanding the flavor characteristics of this popular oolong tea for the first time.

Profiling of Volatile Organic Compounds from Four Plant Growth-Promoting Rhizobacteria by SPME-GC-MS: A Metabolomics Study.

The rhizosphere microbiome is a major determinant of plant health. Plant-beneficial or plant growth-promoting rhizobacteria (PGPR) influence plant growth, plant development and adaptive responses, such as induced resistance/priming. These new eco-friendly choices have highlighted volatile organic compounds (biogenic VOCs) as a potentially inexpensive, effective and efficient substitute for the use of agrochemicals. Secreted bacterial VOCs are low molecular weight lipophilic compounds with a low boiling point and high vapor pressures. As such, they can act as short- or long-distance signals in the rhizosphere, affecting competing microorganisms and impacting plant health. In this study, secreted VOCs from four PGPR strains (Pseudomonas koreensis (N19), Ps. fluorescens (N04), Lysinibacillus sphaericus (T19) and Paenibacillus alvei (T22)) were profiled by solid-phase micro-extraction gas chromatography mass spectrometry (SPME–GC–MS) combined with a multivariate data analysis. Metabolomic profiling with chemometric analyses revealed novel data on the composition of the secreted VOC blends of the four PGPR strains. Of the 121 annotated metabolites, most are known as bioactives which are able to affect metabolism in plant hosts. These VOCs belong to the following classes: alcohols, aldehydes, ketones, alkanes, alkenes, acids, amines, salicylic acid derivatives, pyrazines, furans, sulfides and terpenoids. The results further demonstrated the presence of species-specific and strain-specific VOCs, characterized by either the absence or presence of specific VOCs in the different strains. These molecules could be further investigated as biomarkers for the classification of an organism as a PGPR and selection for agricultural use.

Association of Refreshing Perception with Volatile Aroma Compounds, Organic Acids, and Soluble Solids in Freshly Consumed Cucumber Fruit

Refreshing is a multidimensional concept for the response to a food consumption experience, especially for drinks. The consumer has daily needs for refreshing; however, the perception of refreshing and the associated food sensory quality and molecule composition are underexplored. This study aimed to (1) use a consumer study to evaluate the refreshing perception of eight cucumber varieties, (2) identify volatile aroma and nonvolatile taste compounds in cucumber with instrumental analysis, and (3) explore the potential correlation between refreshing perception and aroma- and taste-related compounds using statistical analysis. The cucumber consumer study (n = 103) showed that cucumbers were perceived as refreshing in general (intensities 3.3–5.4, 0–10 line scale). The analysis of volatiles with solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) identified 155 volatiles. Aldehydes and alcohols were the most dominant, accounting for 25.5%–77.9% and 15.0%–58.1%, respectively. Soluble solids and three organic acids were quantified in the eight cucumber varieties using a refractometer and high-performance liquid chromatography (HPLC), respectively. Cucumber variety differences in these variables (volatiles, organic acids, and soluble solids) were significant (p ≤ 0.05). Compounds associated with refreshing perception were investigated using partial least-squares (PLS) regression, and refreshing perception was highly correlated with aldehydes (mainly C6 and C9 aldehydes), organic acid, and soluble solids. The findings would bring in a new potential use of cucumber, especially when the food industry is interested in developing products perceived as refreshing with natural flavorings.

Effect of High Hydrostatic Pressure Combined with Sous-Vide Treatment on the Quality of Largemouth Bass during Storage.

In order to estimate the effects of high hydrostatic pressure treatment at 400 MPa for 0 min and 10 min (HHP-0, HHP-10) and high hydrostatic pressure in combination with sous-vide treatment (HHP-0+SV, HHP-10+SV) on the quality of largemouth bass stored at 4 °C for 30 days, the physicochemical changes were evaluated by microbiological determinations, pH, sensory evaluation and texture analysis, and the flavour changes were analysed by solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) and amino acid automatic analyser. The results show that HHP-0+SV and HHP-10+SV treatment effectively inhibited microbiological growth and attenuated physiochemical changes (pH, sensory evaluation, flesh and texture) of largemouth bass fillets. HHP+SV treatment prolonged the storage period of largemouth bass fillets for 24 days. The content of total free amino acids in control (CK) samples was high, but HHP+SV treatment caused the loss of free amino acid content. Especially when stored for 30 days, the total free amino acid content of HHP-0+SV and HHP-10+SV was only 14.67 mg/100 g and 18.98 mg/100 g, respectively. In addition, a total of 43 volatile compounds were detected and elucidated, among which hexanal, heptaldehyde, octanal and nonanal showed a decreasing tendency in HHP groups and an increasing trend in HHP+SV groups throughout the storage.

Preliminary Evaluation of the Use of Thermally-Dried Immobilized Kefir Cells in Low Alcohol Winemaking

Low alcohol wines (≤10.5% vol) are novel products that have gradually been gaining the consumers’ and market’s interest over the last decade. Taking into account the technological properties of immobilized cell systems alongside with the commercial need for dry cultures, the aim of the present study was to assess the suitability of thermally-dried immobilized kefir cells on DCM, apples pieces, and grape skins in low alcohol wine production. Storage of thermally-dried kefir culture in various temperatures (−18, 5, and 20 °C) resulted in high viability rates for immobilized cells (up to 93% for yeasts/molds immobilized on grape skins and stored at −18 °C for 6 months). Fermentation activity was maintained after storage in all cases, while high operational stability was confirmed in repeated batch fermentations for a period of 6 months. Principal Component Analysis (PCA) revealed that the fermentation temperature rather than the state of kefir culture affected significantly volatiles detected by Head Space Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry analysis. Notably, all new products were of high quality and approved by the sensory panel.

Comparative Analysis of Volatile Compounds in Tieguanyin with Different Types Based on HS-SPME-GC-MS.

Tieguanyin (TGY) is one kind of oolong tea that is widely appreciated for its aroma and taste. To study the difference of volatile compounds among different types of TGY and other oolong teas, solid-phase microextraction–gas chromatography–mass spectrometry and chemometrics analysis were conducted in this experiment. Based on variable importance in projection > 1 and aroma character impact > 1, the contents of heptanal (1.60–2.79 μg/L), (E,E)-2,4-heptadienal (34.15–70.68 μg/L), (E)-2-octenal (1.57–2.94 μg/L), indole (48.44–122.21 μg/L), and (E)-nerolidol (32.64–96.63 μg/L) in TGY were higher than in other varieties. With the increase in tea fermentation, the total content of volatile compounds decreased slightly, mainly losing floral compounds. Heavily fermented tea contained a higher content of monoterpenoids, whereas low-fermentation tea contained higher contents of sesquiterpenes and indole, which could well distinguish the degree of TGY fermentation. Besides, the volatiles analysis of different grades of TGY showed that the special-grade tea contained more aroma compounds, mainly alcohols (28%). (E,E)-2,4-Heptadienal, (E)-2-octenal, benzeneacetaldehyde, and (E)-nerolidol were the key volatile compounds to distinguish different grades of TGY. The results obtained in this study could help enrich the theoretical basis of aroma substances in TGY.

Effects of microbial community structure and its co-occurrence on the dynamic changes of physicochemical properties and free amino acids in the Cantonese soy sauce fermentation process

The soy sauce produced by Cantonese fermentation has a unique flavor, among which brine fermentation plays an important role. In this fermentation process, 61 volatile compounds, including 19 esters, 10 aldehydes, 9 alcohols, 5 phenols, and 18 others, were identified by headspace solid-phase microextraction–gas chromatography–mass spectrometry. Seventeen kinds of free amino acids were detected by high-performance liquid chromatography. Results showed that Touyou, which comprised 1.5 g/100 g total nitrogen, 1.0 g/100 mL amino acid nitrogen, 3.66 g/100 g reducing sugar, 1.44 g/100 mL total acid, 17.04 g/100 mL salt content, and 27.3% umami free amino acids, had excellent quality. High-throughput sequencing was used to identify microorganisms. The top 3 of bacteria were Weissella, Staphylococcus, and Lactobacillus, and the top 3 fungi were Aspergillus, Zygosaccharomyces, and Candida. The co-occurrence network analysis of microorganisms showed that the top-ranked microorganisms were Plectosphaerella, Aureobasidium, unidentified_Mortierellales_sp, Glutinomyces, Faecalibacterium, and Cladophialophora. Then, eight microorganisms (VIP[pred] > 1) were obtained by two-way orthogonal partial least squares model, namely, Staphylococcus, Candida, Weissella, Aspergillus, Zygosaccharomyces, Lactobacillus, Monilinia, and Clavispora. Correlation analysis showed that these microorganisms were strongly related to flavor metabolites. This study explored the dynamics of traditional Cantonese fermentation, which has positive implications for optimizing this traditional fermentation process.

Effect of Natural Antioxidants from Marigolds (Tagetes erecta L.) on the Oxidative Stability of Soybean Oil.

In recent years, synthetic antioxidants that are widely used in foods have been shown to cause detrimental health effects, and there has been growing interest in antioxidants realised from natural plant extracts. In this study, we investigate the potential effects of natural antioxidant components extracted from the forage plant marigold on the oxidative stability of soybean oil. First, HPLC-Q-TOF-MS/MS was used with 1,1-diphenyl-2-picrylhydrazyl (DPPH) to screen and identify potential antioxidant components in marigold. Four main antioxidant components were identified, including quercetagetin-7-O-glucoside (1), quercetagetin (2), quercetin (3) and patuletin (4). Among them, quercetagetin (QG) exhibited the highest content and the strongest DPPH radical scavenging activity and effectively inhibited the production of oxidation products in soybean oil during accelerated oxidation, as indicated by reductions in the peroxide value (PV) and acid value (AV). Then, the fatty acids and volatile compounds of soybean oil were determined with gas chromatography–mass spectrometry (GC-MS) and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). A total of 108 volatile components, including 16 alcohols, 23 aldehydes, 25 ketones, 4 acids, 15 esters, 18 hydrocarbons, and 7 other compounds, were identified. QG significantly reduced the content and number of aldehydes and ketones, whereas the formation of acids and hydrocarbons was completely prevented. In addition, the fatty acid analysis demonstrated that QG significantly inhibited oxidation of unsaturated fatty acids. Consequently, QG was identified as a potential, new natural antioxidant that is believed to be safe, effective and economical, and it may have potential for use in plant extracts feed additives.

Comparative analysis of floral scent profiles between two Chimonanthus praecox plants under different rhythms and blooming stages

Chimonanthus praecox is an economically important ornamental plant species native to China. It is known for its winter-season flowering times and strong fragrances. Floral fragrances vary with different circadian rhythms. Despite many studies examining the circadian-rhythm-based changes in floral fragrance, limited information is available about the floral fragrance of C. praecox with circadian rhythms. In this study, headspace solid-phase microextraction gas chromatography—mass spectrometry was used to identify the floral scent compounds in var. grandiflorus and var. intermedius from Yunnan, China. In total, 69 volatile compounds, which were largely acids, alcohols, esters, aromatic compounds, terpenes, aldehydes, and ketones, were identified and the most predominant compounds were alcohols. Compounds m-xylene, p-xylene, 2-norbornanemethanol, o-xylene, cyclohepta-1,3,5-triene, germacrene D, ethylbenzene and 3,4-dimethoxycinnamic acid contributed to the floral scent of C. praecox. While var. grandiflorus and var. intermedius flowers contained about the same number of floral scent compounds (53 and 52, respectively), their compositions varied greatly. Furthermore, hierarchical cluster analysis based on the main compounds in var. grandiflorus and var. intermedius with different circadian rhythms indicated that opened flowers had similar compounds while unopened flowers had different ones. In addition, the amounts and contents of floral scent compounds between the two C. praecox varieties were affected differently by temperature, humidity and light intensity. Our findings will contribute to the exploration of the biosynthesis and emission mechanisms of floral scent compounds in C. praecox.

Sensory lexicon and aroma volatiles analysis of brewing malt

Malt is an important raw material in brewing beer. With the increasing development of craft beer, brewing malt has contributed diverse colours and abundant flavours to beer. While “malty” and “worty” were commonly used to describe the malt flavour of beer, they are still inadequate. This study focused on developing of a sensory lexicon and a sensory wheel for brewing malt. Here, a total of 22 samples were used for sensory evaluation. The panels identified 53 attributes to form the lexicon of brewing malt, including appearance, flavour, taste, and mouthfeel. After consulting with the experts from the brewing industry, 46 attributes were selected from the lexicon list to construct the sensory wheel. Based on the lexicon, rate-all-that-apply analysis was used to discriminate between six samples of different malt types. The principal component analysis results showed that malt types were significantly correlated with sensory features. To further understand the chemical origin of sensory attributes, partial least squares regression analysis was used to determine the association between the aroma compounds and sensory attributes. According to the colour range and malt types, 18 samples were used for sensory descriptive analysis and volatile compounds identification. Seven main flavours were selected from the brewing malt sensory wheel. 34 aroma compounds were identified by headspace solid phase microextraction gas chromatography-mass spectrometry-olfactometry. According to the partial least squares regression results, the aroma compounds were highly correlated with the sensory attributes of the brewing malt. This approach may have practical applications in the sensory studies of other products.

Effect of Lentinan on Lipid Oxidation and Quality Change in Goose Meatballs during Cold Storage.

The effects of different concentrations of lentinan (LNT) (0, 0.5, 1, 2 and 4%) on the oxidation characteristics and physicochemical properties of goose meatballs were investigated during different cold storage (4 °C) stages (3, 7 and 12 days). After adding LNT, the thiobarbituric acid reactive substances (TBARS) and total volatile base nitrogen (TVB-N) of goose meatballs significantly decreased compared to the LNT-free sample during cold storage, which indicated that LNT can inhibit the fat oxidation and the release of nitrogenous substances. Meanwhile, the presence of LNT makes microstructure of the goose meatball samples become denser during the whole storage time. The headspace solid phase microextraction gas chromatography-mass spectrometry (SPME-GC-MC) results showed that the proportion of aldehydes in the 4% LNT group reached 0 during storage, suggesting that high LNT concentration inhibits the formation of oxidized products in meat products. The sensory evaluation showed that the addition of LNT improved the color, appearance, flavor, and overall acceptance of goose meatballs, and the 2% LNT group had the highest score in overall acceptance. In summary, the addition of LNT could delay lipid oxidation and improve the quality of goose meatballs during cold storage.

Aroma Profile and Phenolic Content of Honey Wine Produced from Wild Rose Fruit

In this study, two chromatographic techniques were applied to determine the aroma profile and phenolic compounds of “Honey wine” produced by addition of Wild Rose Fruits ( Rosa odorata -Andrews-Sweet). In addition, another control wine was produced with sucrose and rose fruits in order to differentiate compounds produced by yeast fermentation from those originated from honey and rose fruits. After maturation aroma components, phenolic compounds and sugar composition of wines were identified. Aroma components were determined by headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME/GC-MS) techniques in wine samples. The dominant aroma components in both wines were ethanol, ethyl acetate, isobutyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl caprylate, ethyl decanoate, capronate ethyl. Some minor differences in the percentage of major aroma components were determined between two wine samples. Phenolic and sugar compositions were identified by high performance liquid chromatographic (HPLC) method in fruit extract and wine samples. While the total amount of phenolic compounds were 3604.9 mg/l in fruit juice, 74.3 mg/l in control wine and 111.8 mg/l in honey wine, the most abundant phenolics in both wines were catechin, epicatechin and routine .