Aroma Intensity Research Articles

Effect of processing on aroma intensity and odor characteristic of Shuixian (Camellia sinensis) tea

Processing is extremely important for the formation of aroma characteristic of tea leaves. In this study, the effects of processing on the content of volatile compounds, aroma intensity and odor characteristic of Shuixian tea were analyzed. The results showed that the content of volatile compounds in Shuixian tea increased significantly after processing, among which terpenoids and esters were the highest. There were 18 key compounds constituting the aroma characteristics of Shuixian tea, among which geraniol and nerol were the most important compounds, which contributed 96.28% to the aroma of Shuixian tea. The odor characteristics of Shuixian tea were mainly floral and fruity and the contribution of floral mainly came from geraniol, while fruity mainly came from nerol. Geraniol and nerol compounds increased rapidly after the withering process of tea leaves. This study provided an important reference for the improvement of processing technology and quality enhancement of Shuixian tea.

Role of maturity status on the quality and volatile properties of mango fruits dried by infrared radiation

Drying characteristics and quality attributes are greatly dependent on the maturity status of fresh fruits. Hence, this work investigated the changes in quality and volatile properties of mangoes at ripening stages (from the lowest to highest degree—RS-1, RS-2, RS-3, RS-4) during infrared drying. Results showed that the total soluble solids/titratable acid, texture, nutrient composition (phenolic, vitamin C, β-carotenoid), and volatile compounds during drying were varied during drying. Moreover, fruits at RS-3 obtained the highest increase in total phenolic (8.72 mg/g), the most dramatic decrease in vitamin C (5.58 mg/g), and the lowest decrease in β-carotenoid contents (56.49 mg/100 g) during drying. After drying, the lower L* values, the higher a* and b* values were obtained for products with higher ripeness. Correspondingly, the color changed from light yellow to dark red-orange. The aroma intensity reduced after drying, and the aroma changed from tangerine and citrus to fruity, orange peel, and pineapple. According to the comprehensive quality evaluation model, the highest evaluation score at RS-3, which was 3.58%–42.90% higher than those of other stages.

Profiling of Volatile Organic Compounds (VOCs) of Wild Edible Durians from Sarawak, Borneo Associated with Its Aroma Properties

Volatile organic compounds determine the aroma properties of durian, and it is an important factor in durian acceptance by consumers. However, limited information is devoted to volatile organic compounds and aroma in wild edible durians. Therefore, the present study aims to characterize and compare the volatile organic compounds and aroma properties of the indigenous wild edible durians from Sarawak, Borneo. Seven genotypes, namely Durio dulcis, Durio graveolens (yellow-fleshed), Durio graveolens (orange-fleshed), Durio graveolens (red-fleshed), Durio kutejensis, Durio oxleyanus, and Durio zibethinus were characterized in this study. Solid phase microextraction combined with gas chromatography-mass spectrometry (SPME GC-MS) was used to detect the volatile organic compounds, while the quantitative descriptive analysis (QDA) method was used to characterize the aroma properties of wild edible durians. A total of 119 volatile organic compounds comprising alcohol, aldehyde, amine, ether, ester, ketone, nitrogen-containing, and sulfur-containing compounds were detected. Ester and alcohol compounds are the most predominant in the composition, especially D. graveolens (yellow- and orange-fleshed), and D. dulcis possessed three to nine times higher relative amount of ester compounds. PCA clearly classified the wild durians into different groups. Based on the QDA analysis, D. kutejensis has the mildest aroma among wild edible durians, while D. dulcis perceived a stronger sweet and grassy aroma. Partially Least Square (PLS) regression model analysis indicated a strong relationship between the volatile organic compounds and the aroma intensity perceived by the panelists. These findings could be the major component in the durian industry, paving the way for breeding efforts to create new cultivars that can improve consumers’ satisfaction.

A strategy to maintain the organoleptic quality of flavor-β-cyclodextrin inclusion complexes: Characteristics aroma reconstruction of Osmanthus absolute

The proportion of odorants has a key effect on the odor/flavor profile of perfumes or food products. However, direct encapsulation changes the odorant release characteristics, resulting in corresponding variations in their organoleptic qualities. In this study, nine key odorants (KOs) of Osmanthus absolute (OA) were identified for the aroma reconstruction of OA. Inclusion complexes of β-cyclodextrin (β-CD) with KOs (KO-β-CDs) were obtained via co-precipitation, the loading of KOs in β-CD was varied from 34.86 to 108.88 mg/g. Based on the aroma release behavior analyses, main aroma characteristics of OA were reconstructed from the KO-β-CDs via replication of the headspace KO distributions of OA. Aroma profile evaluation validated the effectiveness of aroma reconstruction. Besides, the release characteristics of directly encapsulated OA (OA-β-CD) and OA were found to significantly differ. For example, linalool oxide furanoid contributed greater than 20% of the total KOs in the headspace of OA, contributed only 8.89% in the headspace of the OA-β-CD. Further, the aroma intensity of the five main descriptors was reduced to different degrees. The KO-β-CDs mixture resembles the odor profile of OA to a greater degree than OA-β-CD. Our methodology provides a route to maintain the organoleptic quality of flavors in β-CD inclusion complexes.

Comparison of Three Different Extraction Methods on Osmanthus Volatile Oil: Aroma and Biological Activity.

The osmanthus volatile oil was welcomed by consumers even if the high price since the unique and pleasant odor. Meanwhile, the low yield of osmanthus volatile oil restricts industrial production. In this work, an osmanthus volatile oil was obtained by means of a novel ultrasonic-assisted flash extraction method and was compared with the oil from hydrodistillation and supercritical fluid extraction on yield, aroma, and biological activities. The volatile oil obtained from the ultrasonic-assisted flash extraction was obtained with the petroleum ether and got a high yield at 3.51 % within a 40-min process, an increase of nearly 81 % from the single solvent extraction. This oil also showed a high aroma intensity and aroma compound concentration. Meanwhile, the oil also has the highest antioxidant ability but lower antibacterial activity against oil from hydrodistillation. It was considered that this work was helpful for the optimization of the extraction method of osmanthus volatile oil.

Influence of Prefermentative Cold Maceration on the Chemical and Sensory Properties of Red Wines Produced in Warm Climates

Red wines produced in warm climates generally possess a lower content of phenolic compounds and color structure than those produced in colder climates, which hinders bottle evolution. To improve these properties, cold maceration could be a useful procedure. To study the effect of this technique, Tempranillo, Merlot and Syrah grape varieties cultivated in the Jerez area (Southwest Spain) were cold macerated at 4 °C for ten days before alcoholic fermentation. Their composition and characteristics compared to the directly fermented control grapes were analyzed for phenolic content, color, volatile compounds, and sensory properties. It has been verified that phenolic content increased by around 10% during the treatment, which was maintained after the alcohol fermentation, along with an increase in color intensity and aromatic profile. This modification on the composition provided better scores for appearance, aroma intensity, and aroma quality in sensory analysis. The evolution of all studied parameters during 12 months of aging in the bottle is also studied, confirming the advantages of this technique in preserving the compositional and sensory characteristics throughout the period studied.

Digital evaluation of tea aroma intensity and odor characteristics changes during processing

AbstractBackgroundHuangjingui (Camellia sinensis)，a kind of oolong tea, is native to Anxi County, Fujian Province, China, and is a national tea tree species. Tea processing is the key link in the formation of its aroma characteristics, and it is important to analyze the influence of each processing process on the aroma intensity and odor characteristics of tea, in order to optimize the tea processing process and improve the quality of tea.ResultsThe processing process favored the accumulation of volatile compounds in oolong tea, as evidenced by the increase in their content from 9.793 to 123.052 μg/kg, of which the highest content was mainly in terpenoids, alcohols and esters substances. The aroma formation of oolong tea was mainly composed of 14 key compounds, among which the most critical compounds were four substances such as geraniol, α‐pinene, methyl salicylate and trans‐β‐ionone. The typical odor characteristics of oolong tea were floral and wood, among which the formation of floral odor mainly came from geraniol and methyl salicylate, and the formation of wood odor characteristics mainly came from α‐pinene and trans‐β‐ionone. Further analysis showed that the aroma quality of oolong tea could be improved by focusing on key processes such as fermentation and kneading during the processing of oolong tea.ConclusionThe processing was conducive to the accumulation of aroma compounds of oolong tea, improving the aroma intensity of tea leaves and forming the unique floral and wood odor characteristics of oolong tea.

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.

Transcriptomic and metabolic analyses reveal differences in monoterpene profiles and the underlying molecular mechanisms in six grape varieties with different flavors

Monoterpenes are important compounds determining grape floral and fruity aromas. In this study, free and bound monoterpene contents and the transcriptome profiles of six grape varieties with different flavors were determined using HS-SPME/GC-MS and RNA-sequencing technologies. The different aroma types of grape varieties had significantly different free and bound monoterpene profiles. Linalool, trans-β-ocimene, β-cis-ocimene, geraniol, and β-myrcene were the main free monoterpenes in Muscat-type grapes. In contrast, trans-β-ocimene, γ-terpinene, and β-citronellol were the main free monoterpenes in strawberry-type grapes, while limonene and β-myrcene were the main free monoterpenes in neutral grapes. The total odor activity values (OAVs) of the free monoterpenes with OAVs >1 were more than 10-times higher in Muscat-type grapes than in strawberry-type and neutral grapes, which explains the high intensity of floral, rose and sweet aromas of Muscat-type grapes. A total of 21 genes related to monoterpene biosynthesis were detected in the three types of grape varieties, among which the expression of DXS, CMK, HDS, HDR, GPPS, HMGS, HMGR, MPDC, TPS14, and GT14 was positively correlated with monoterpene accumulation, indicating these genes may contribute to the differential accumulation of monoterpene compounds in analyzed grape varieties. These results clarify the monoterpene accumulation in grapes and underlying molecular mechanism.

Thermal stabilisation of cocoa fruit pulp — Effects on sensory properties, colour and microbiological stability

To improve cocoa pulp’s shelf-life, preservation processes are necessary while maintaining the quality of the pulp. We applied pasteurisation and UHT-treatment and investigated different quality parameters: dry matter content, water activity, total soluble solids, colour and peroxidase activity. Both technologies inactivated peroxidase successfully. The colour of the pasteurised pulp was similar to the fresh, while UHT-treated pulp was more brownish. The sensory properties were investigated in detail by descriptive analysis and the identification of aroma-active volatile organic compounds. Fresh pulp revealed the highest aroma intensity for attribute unripe banana-like, whereas UHT-treated pulp scored highest in the intensity of attribute tropical fruit-like. Pasteurised pulp showed strong similarities to the fresh pulp. Fresh cocoa pulp exhibited 74 aroma-active regions identified by GC-MS/O. UHT-treated and pasteurised pulp accounted for 66 and 60 aroma-active regions, respectively. Five identified substances were only found in the fresh and pasteurised pulp, namely: δ-carene, 1-pentanol, 3-(methylthio)propanol, phenol and δ-undecalactone. Similarly, fresh and UHT-treated pulp shared ten exclusive odorants, such as decanal, geraniol, and δ-nonalactone. The pasteurised and UHT-treated pulp shared two compounds, δ–decalactone and 5-(hydroxymethyl)furfural. Furthermore, the thermally treated pulps could be stored at 4 °C and 23 °C for 24 weeks without observing a significant growth of microorganisms. The rate of non-enzymatic browning was higher in samples stored at 23 °C compared to those stored at 4 °C, leading to higher browning indices. We demonstrated that pasteurisation and ultra-high temperature treatment are suitable technologies for the stabilisation of cocoa fruit pulp. These resulted in prolonged shelf-lifes and minimal changes in the sensory prorperties of the treated pulps, characterised by a reduction in the aroma diversities. This work provides important insights for the thermal stabilisation of further side-streams.

Serbian black truffle Tuber aestivum: Microbiota and effects of different freezing regimes on volatile aroma compounds during storage

The use of truffles in food is based mainly on the addition of artificial flavors, aiming to achieve an intense aroma in the products. As truffle is a natural product with nutritional and functional properties, it is important to find an optimal method for truffle storage. As the microbiota contribute to truffle aroma, the bacterial and yeast compositions in the rhizosphere and fruiting body of the truffle and the impact of different freezing methods on the volatile profile of the truffle Tuber aestivum during 90 days of the storage were determined. Bacteria and yeasts isolates were identified using 16s rRNA and 18s rRNA. The effect of freezing truffles at -20?C and -80?C with and without previous dipping in liquid N2 on the volatile compounds was observed using GC/MS. The results demonstrated that the isolated bacteria belonged to the phylum Proteobacteria, Firmicutes and Actinobacteria, and the identified species mainly belonged to Firmicutes, genus Bacillus sp. Isolated yeasts were identified as Cryptococcus sp., Debaromyces hanseinii, Candida fermentati and Rhodotorula mucilaginosa. The GC/MS analysis revealed that frozen truffle samples were richer in the compounds 2-butanone, 2-methyl-butanal, methanethiol and 2-butanol after freezing or during storage. The content of DMS, acetaldehyde, 3-octanone, ethanol, and 2-methyl-1-propanol significantly decreased immediately after freezing. Overall, the gained results indicated that freezing of truffles as a preservation method had profound effects on the volatile compounds, while previous dipping in liquid N2 showed no significant impact on the volatile profile of truffle Tuber aestivum.

Encapsulation Efficiency and Functional Stability of Cinnamon Essential Oil in Modified β-cyclodextrins: In Vitro and In Silico Evidence.

Essential oils (EOs) have good natural antioxidant and antimicrobial properties; however, their volatility, intense aroma, poor aqueous solubility, and chemical instability limit their applications in the food industry. The encapsulation of EOs in β-cyclodextrins (β-CDs) is a widely accepted strategy for enhancing EO applications. The complexation of cinnamon essential oil (CEO) with five types of β-CDs, containing different substituent groups (β-CD with primary hydroxyl, Mal-β-CD with maltosyl, CM-β-CD with carboxymethyl, HP-β-CD with hydroxypropyl, and DM-β-CD with methyl), inclusion process behaviors, volatile components, and antioxidant and antibacterial activities of the solid complexes were studied. The CEOs complexed with Mal-β-CD, CM-β-CD, and β-CD were less soluble than those complexed with DM-β-CD and HP-β-CD. Molecular docking confirmed the insertion of the cinnamaldehyde benzene ring into various β-CD cavities via hydrophobic interactions and hydrogen bonds. GC-MS analysis revealed that HP-β-CD had the greatest adaptability to cinnamaldehyde. The CEO encapsulated in β-, Mal-β-, and CM-β-CD showed lower solubility but better control-release characteristics than those encapsulated in DM- and HP-β-CD, thereby increasing their antioxidant and antibacterial activities. This study demonstrated that β-, Mal-β-, and CM-β-CD were suitable alternatives for the encapsulation of CEO to preserve its antioxidant and antibacterial activities for long-time use.

Carcass and meat quality of red-winged tinamou (Rhynchotus rufescens) selected for muscle growth

The aim of the present study was to evaluate the efficiency of selection for body growth and its association with carcass and meat quality traits in the red-winged tinamou. Two experimental groups were selected based on the selection index: selection group with a higher index (TinamouS) and commercial group with a lower index (TinamouC). Weight at 180 days and slaughter weight were significantly higher (p < 0.05) in the TinamouS group, as were hot carcass weight, skinless breast weight, wing weight, and thigh and drumstick weight. The meat quality traits or sensory attributes did not differ significantly (p > 0.05) between groups. A significant positive correlation (0.59; p < 0.05) was found between shear force and chewability and a significant negative correlation (- 0.59; p < 0.05) between aroma intensity and strange aroma. The present study suggests that the selection index promotes greater body growth and preserves meat quality and sensory traits in red-winged tinamou.

Sensory quality and consumer perception of high pressure processed orange juice and apple juice

High pressure processing (HPP) is an alternative to thermal pasteurization (TP) of beverages that can impart an extended shelf-life while delivering products with “fresh-like” sensory properties. However, studies documenting the sensory changes associated with HPP of fruit juices and their relation to consumer preferences are limited. In this paper, the effect of HPP on sensory quality and consumer perception of orange- and apple juice was investigated using a full experimental design with samples varying in treatment (HPP, TP), storage time (0, 3, 11 weeks for orange juice and 0, 4, 12 weeks for apple juice) and storage temperature (4 °C, 25 °C). Samples were first analyzed by descriptive analysis with a trained panel and subsequently submitted to a consumer liking test (N = 75). Treatment and storage conditions had a significant impact on sensory quality and on consumer perception. HPP could better maintain the sensory quality of both juices. Cold storage was effective in maintaining the product quality over the entire storage period. The main drivers of consumer liking were attributes associated with shorter storage times and/or cold storage (e.g., intensity of orange aroma and flavor in orange juice, apple flavor and aftertaste in apple juice), and to a lesser extent to treatment.

Impact of the Closure Oxygen Transfer Rate on Volatile Compound Composition and Oxidation Aroma Intensity of Merlot and Cabernet Sauvignon Blend: A 10 Year Study

This study evaluated the impact of closure type on unoaked 100 %-Merlot, oak-aged 70%-Merlot/30%-Cabernet Sauvignon, and 30%-Merlot/70%-Cabernet Sauvignon during a 10 year period. Closures were microagglomerate corks, screw caps, and synthetics with the known oxygen transfer rate (OTR), ranging from 0.1 to 4.6 mg/y, including natural corks. Oxidation intensity perception, dissolved oxygen, sulfite, and 3-methyl-2,4-nonanedione (MND) were monitored on a regular basis. After 10 years of aging, additional aroma impact markers were evaluated (3-sulfanylhexan-1-ol, H2S, DMS, methional, and phenylacetaldehyde). Low OTR levels (≤0.3 mg/y) delayed the oxidation of red wines in this long-term experiment. In addition, our results led us to hypothesize that the MND concentration in young wines might be linked with their ability to produce it during bottle aging that is with their aging potential. Finally, we found that the kinetic accumulation of MND in wines was first strongly impacted by its intrinsic composition and thereafter by the OTRT0 of the stopper.

Incorporation of nisin and oregano essential oil in cow’s milk to improve the quality of fresh cheese

Firstly, this study aimed to determine the effect of adding nisin (0, 250 and 500 IU mL-1) and oregano essential oil (OEO) (0, 0.025% and 0.05%), alone or in combination, on Staphylococcus aureus load in cow’s milk. Next, it was evaluated the sensory, physicochemical and microbiological quality of fresh cheese (FC) manufactured with milk added of nisin + OEO (C1) or nisin alone (C2) compared to a control cheese (C0, milk without the addition of nisin or OEO). Results showed that adding nisin effectively reduced the S. aureus count in milk in a similar manner to adding way the combination of nisin + OEO compared to the control. FC quality evaluation results revealed that C1 and C2 did not alter the physicochemical quality of FC (pH, fat and total solids content) during storage (0-8 days) compared to the control. Furthermore, C1 and C2 reduced in a similar manner aerobic mesophilic bacteria and Enterobacteriaceae count in FC compared to the control during storage. Sensory evaluation showed that consumers did not value FC added of nisin + OEO (C1) due to its intense aroma of oregano, rating it with the lowest global quality.

Unraveling the impact of the capsule material on the aroma of brewed coffee by headspace analysis using a HiSorb probe followed by reverse fill/flush flow modulation GC×GC-MS.

The present paper discusses the use of a high-concentration-capacity tool, HiSorb, to investigate the impact of capsule material on the aroma profile of espresso-brewed coffee. The specific high-concentration-capacity probe used is characterized by a sorbent volume (63 μL) intermediate between the solid-phase microextraction (SPME) fiber (0.6 μL) and the stir-bar sorptive extraction rod (126 μL). The extraction performance of the HiSorb was compared, in terms of both absolute signal and compound coverage, with both an equivalent sorbent (polydimethylsiloxane) and a divinylbenzene/carboxen/polydimethylsiloxane SPME fiber using both targeted and untargeted approaches. The HiSorb showed superior extraction compared with the SPME fibers. The HiSorb was then optimized in terms of extraction time and temperature and used to investigate the volatile profile of 23 espresso-brewed coffees prepared with capsules made of different materials-aluminum, compostable, and aluminum multilayer pack-prepared using a refillable capsule. Comprehensive two-dimensional gas chromatography equipped with a reverse fill/flush flow modulator and coupled to mass spectrometry was used to obtain a chromatographic fingerprint of the volatile profile of the brewed coffee. The data were aligned and compared using a tile-based approach, and the results were obtained by performing raw data mining within the same software platform. The data mining enabled the extraction of informative features responsible for the differentiation between the different capsule materials, showing a significant depletion in aroma intensity in the compostable capsule.

Optimization of the production of roasted-nutty aroma by a newly isolated fungus Tolypocladium inflatum SRH81 and impact of encapsulation on its quality

BackgroundPyrazines are used in food industry to impart the foods nutty-roasted flavor. However, their extraction from natural sources is difficult and expensive. At the same time, there is awareness against the chemical food additives. Microorganisms are approved as natural producers of flavors. The aim of the present study was to assess the ability of the newly isolated fungus Tolypocladium inflatum SRH81 to produce pyrazines and studying the effect of encapsulation in gum Arabic on the quality of the biogenerated volatiles. The parameters affecting the biogeneration of pyrazines were optimized. The headspace volatiles of each culture were isolated and identified by solid phase microextraction (HS-SPME) and gas chromatography coupled with mass spectrometry (GC-MS). The volatiles showed the highest pyrazines content and best nutty-roasty flavor was subjected to encapsulation. ResultsThe selected fungus was identified as Tolypocladium inflatum SRH81. A high correlation was found between the consumed sugar and dry matter content of each culture. Incubation of the fungus culture enriched with 0.5 g amino acids/50 mL medium for 12 days at pH 8 showed the highest generation of pyrazines and best odor sensory quality. Nine pyrazines were identified among them 2-methylpyrazine was the major compound after incubation for 12 days. A positive correlation was found between the total pyrazines and intensity of roasty-nutty aroma. Encapsulation gave rise to a significant decrease in the total volatiles, while the odor intensity showed insignificant decrease. ConclusionsThe results of the present study revealed the potential ability of Tolypocladium inflatum SRH81, that was isolated from Egyptian soil, to produce pyrazines having roasted- nutty aroma.

The Effects of Pepper (Zanthoxylum bungeanum) from Different Production Areas on the Volatile Flavor Compounds of Fried Pepper Oils Based on HS-SPME-GC-MS and Multivariate Statistical Method.

Fried pepper oil retains the overall flavor outline of pepper, and its unique rich and spicy flavor is deeply loved by consumers. In order to study the effect of different production areas of pepper on the flavor compounds of fried pepper oil, taking dried pepper from seven different production areas as raw materials, and taking rapeseed oil as a carrier oil as well as a constant frying temperature to prepare pepper oil, the present study analyzed the volatile flavor components of pepper oil qualitatively and quantitatively by employing headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The principal component analysis (PCA) method was used to construct the correlation analysis model of volatile flavor substances among different samples of pepper oil. Applying the hierarchical cluster analysis (HCA), the main volatile substances causing the flavor differences of pepper oil from different production areas were identified. The results showed that a total of 81 chemical components were identified, including 15 alcohols, 10 aldehydes, 5 ketones, 34 hydrocarbons, 11 esters, 6 acids, and others. Terpinen-4-ol, linalool, 2,4-decadienal, trans-2-heptenal, sabinene, linalyl acetate, bornyl acetate, myrcene, 1-caryophyllene, trans-α-ocimene, and limonene were selected as the main substances leading to the flavor differences among the pepper oil samples. These 11 chemical components played a decisive role in the construction of the overall aroma of the pepper oil. Using a descriptive sensory analysis, it was concluded that pepper oil from different production areas holds different aroma intensities. Compared with the other six samples, S4 Hanyuan Pepper Oil (HYPO) shows a relatively strong trend toward a spicy fragrance, fresh grassy fragrance, floral and fruity fragrance, fresh sweet fragrance, and fatty aroma.

Characterization of aroma compounds and effects of amino acids on the release of esters in Laimao baijiu.

Laimao baijiu is a typical soy-sauce aroma-type baijiu in China. Amino acids are non-volatile compounds in baijiu and are beneficial to human health. Aroma is one of the important indicators that are used to evaluate the quality of baijiu. The interaction between aroma-active compounds and non-volatile compounds can also affect the release of aroma compounds. In this study, we identified the active-aroma compounds and amino acids in Laimao baijiu by stir bar sorptive extraction (SBSE), gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS), and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The interaction between amino acids and key esters was investigated by sensory analysis and partition coefficients. A total of 63 aroma compounds and 21 amino acids were identified. Twenty-one esters were identified from them as major aroma-active ester compounds with odor activity values ≥ 1. Finally, sensory analysis revealed that l-alanine had a significant effect on the strength of the aromas of esters, suggesting that low concentrations of amino acids were more likely to promote the release of esters and high concentrations were more likely to inhibit this. The partition coefficient can be a good explanation for this phenomenon. l-Alanine can significantly affect the aroma intensity of key ester aroma compounds in Laimao baijiu, and the effects of different concentrations of amino acids are different. This work shows that amino acids, as non-volatile compounds, have a regulatory effect on the release of aroma compounds in alcoholic beverages, which may provide new technical support for the aroma modulation of alcoholic beverages. © 2022 Society of Chemical Industry.