Rice aroma was a comprehensive result of numerous volatiles and human sense. More than 300 volatiles were reported in rice. Rice aroma was widely researched by using sensory evaluation, gas ...chromatography (GC) method, and electronic nose (E-nose). Genetic factor was the main cause for rice aroma. However, the same rice variety might result in different aroma quality due to different planting, processing and storage.
The main purpose of this review is to elaborate the main volatiles contributing rice aroma, methods used for rice aroma evaluation and factors affecting rice aroma. Most volatiles with odor descriptions, odor thresholds and retention indices were summarized. Sensory evaluation, GC method, and E-nose were elaborated with respect to rice aroma analysis. The effects of gene, planting, processing and storage on rice sample were pointed out.
2-Acetyl-1-pyrroline (2-AP), aldehydes, heterocyclics, alcohols play important roles in rice aroma quality. GC-O-MS which combines the advantages of sensory descriptive analysis and GC-MS, can not only realize detailed sensory analysis of odor quality but also realize quantitative and qualitative detection of volatiles, playing an important role in exploring key aroma-active compounds. Besides of traditional electronic sensors, mass spectrometry and colorimetric sensors were used for E-nose, making it more novel and applicable. Water washing, high hydrostatic pressure, roasting and parboiling were thought as effective processing to improve rice flavor. Degree of milling and storage significantly affected rice flavor.
•The main volatiles contributing rice aroma were reviewed.•Volatiles with odor descriptions, thresholds and retention indices were summarized.•Methods used for rice aroma evaluation were elaborated.•Rice aroma was affected by gene, planting, processing and storage.
Summary
The study investigated the contribution of astaxanthin to the aroma characteristics and aroma‐active compounds (AACs) of dried shrimp (Litopenaeus vannamei) products. Three forms of ...astaxanthin (diester, monoester and free forms) were isolated from fresh shrimp. The astaxanthins were added to fresh shrimp and dried. The aroma characteristics and AACs of the dried shrimp samples were analysed using electronic nose (E‐nose), and sensory evaluation as well as gas chromatography–mass spectrometry (GC–MS). The potential correlation between sensory attributes and AACs was determined via partial‐least‐squares regression (PLSR) analysis. E‐nose and sensory evaluation of dried shrimp samples revealed a significant effect of astaxanthin on the aroma characteristics of dried shrimp, resulting in increased sensory scores of smoky, toasted, meaty and caramel aroma, while reducing fishy aroma. GC–MS analysis showed that astaxanthin had a significant effect on the concentration of AACs in shrimp products. The levels of 2,5‐dimethylpyrazine, 2‐ethyl‐3,6‐dimethylpyrazine and 2,3,5‐trimethylpyrazine, benzaldehyde, 3‐methylbutyraldehyde and 2‐nonanone were increased, while the concentration of trimethylamine was reduced. However, the effects of astaxanthin on the concentration of AACs depended on its form: the diester astaxanthin had the greatest effect, followed by monoester astaxanthin and free form. The PLSR results indicated a good correlation between most variables of sensory attributes and AACs.
Graphical of astaxanthin contribution to the aroma characteristics and aroma‐active compounds of hot‐air‐dried shrimp productsxxxx
•Interactions between oral mucosa, saliva and aroma compounds were studied in vitro.•Mucosal cells can metabolize several aroma compounds thereby generating new compounds.•Release kinetic patterns ...are different depending on aroma hydrophobicity.•Mucosal pellicle impacts early release, particularly for a less hydrophobic aroma.
The mechanism leading to aroma persistence during eating is not fully described. This study aims at better understanding the role of the oral mucosa in this phenomenon. Release of 14 volatile compounds from different chemical classes was studied after exposure to in vitro models of oral mucosa, at equilibrium by Gas-Chromatography-Flame Ionization Detection (GC-FID) and in dynamic conditions by Proton Transfer Reaction- Mass Spectrometry (PTR-MS). Measurements at equilibrium showed that mucosal hydration reduced the release of only two compounds, pentan-2-one and linalool (p < 0.05), and suggested that cells could metabolize aroma compounds from different chemical families (penta-2,3-dione, trans-2-hexen-1-al, ethyl hexanoate, nonan- and decan-2-one). Dynamic analyses for pentan-2-one and octan-2-one evidenced that the constituents of the mucosal pellicle influenced release kinetics differently depending on molecule hydrophobicity. This work suggests that mucosal cells can metabolize aroma compounds and that non-covalent interactions occur between aroma compounds and oral mucosa depending on aroma chemical structure.
The Persian silk tree (Albizia julibrissin) has delicate flowers with a pleasant aroma profile, displaying notes of hyacinth and rose with subtle nuances of citrus, coconut and spice. In this study, ...a total of 29 odorants were identified in the flowers from a single A. julibrissin selection by the application of a cold‐solvent extraction (CSE), followed by solvent‐assisted flavour evaporation (SAFE) and aroma extract dilution analysis (AEDA). Subsequently, nine odorants with flavour dilution (FD) factors ≥16 were quantitated by stable isotope dilution analysis (SIDA), and odour activity values (OAVs) were calculated. Odorants with OAV ≥1 included 2‐phenylacetaldehyde (OAV 3638), linalool (OAV 797), eugenol (OAV 231), geraniol (OAV 161), 1H‐indole (OAV 93), β‐ionone (OAV 31), 2‐phenylethanol (OAV 11) and γ‐octalactone (OAV 1). An aroma simulation model was prepared based on the quantitation data, and it closely matched the aroma of the flower isolate. Chiral chromatography was performed, and (S)‐(+)‐linalool was the only enantiomer detected. This study advances our understanding of A. julibrissin flower aroma chemistry and lays the groundwork for future investigations for the development of delicate floral aromas for flavour and fragrance applications.
A total of 29 odorants were identified in A. julibrissin flowers by the application of a cold solvent extraction (CSE), a versatile technique to capture delicate aromas, and aroma extract dilution analysis (AEDA). Additionally, 9 odorants were quantitated by stable isotope dilution analysis (SIDA). An aroma simulation model was prepared that closely matched the flower aroma isolate. Chiral chromatography was performed and (S)‐(+)‐linalool was the only enantiomer detected.
•31 aroma-active compounds are identified by molecular sensory science approaches.•18 volatiles with aroma activity in red raspberry are identified for the first time.•The dominant grassy and floral ...notes can be simulated using the aroma models.
The major aroma-active compounds in clear red raspberry juice were identified by molecular sensory science approaches. Thirty-one aroma-active compounds were identified using detection frequency analysis and aroma extract dilution analysis. Among them, 18 volatiles with aroma activity in red raspberry were identified for the first time, while 14 volatiles with odor activity values (OAVs) ≥ 1 were confirmed as the major aroma-active compounds. Three C6 aldehydes showed the highest detection frequencies of 8, and β-ionone exhibited the highest OAV of 9507 and flavor dilution factor of 512, which indicated that the floral and grassy note could be dominant in overall aroma. Quantitative descriptive analysis suggested that the grassy, floral, woody, and caramel-like notes can be simulated using aroma recombination model 1. Electronic nose analysis also demonstrated that model 1 had closer similarity to the original juice than others. The combination strategy used here would help improve the knowledge of red raspberry aroma.
Rougui Wuyi rock tea (WRT) with the premium aroma is a subcategory of oolong tea. Roasting is a unique process that provides a comprehensive aroma to WRT. The key aroma-active compounds of rough ...Rougui WRT (RR) and Rougui WRT with moderate fire (RM) were characterized by sensory-directed flavor analysis. A total of 80 aroma-active compounds were identified by gas chromatography-olfactometry-time-of-flight-mass spectrometry (GC-O-TOF-MS) and two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry (GC × GC-O-MS), and 42 of them revealing high flavor dilution (FD) factors (16-4096) during aroma extract dilution analysis were quantitated. Finally, the aroma recombination and omission experiments confirmed 26 odorants as key aroma-active compounds in Rougui WRT. Roasting enhanced the aroma of roasted, woody, burnt/smoky, and cinnamon-like odor impressions in RM evoked by 2- and 3-methylbutanal, furaneol, 3-methylbutanoic acid, propanoic acid, methional, β-myrcene, 2-pentylfuran, 5- and 6-methyl-2-ethylpyrazine, and furfural. In contrast, hexanal, linalool, (Z)-3-hexen-1-ol, (Z)-4-heptenal, (E)-2-heptenal, geraniol, pentanal, and β-nerolidol were responsible for the more intense floral, fruity, and grassy/fresh leaf-like aroma attributes in RR.
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•Thirty-one aroma-active areas of the four SMTs by SPME–GC–MS/O analysis.•No significant differences in aroma-active compounds among the four samples.•The laboratory simulation model ...can reflect the state of the real sample.•Twelve aroma-active compounds were key using aroma omission experiments.•Nonanal, (E)-2-octenal and (E,E)-2,4-decadienal made the greatest contribution.
Thyme (Thymus vulgaris L.) is widely used as a traditional spice in the cooking of goat meat (mutton) due to its distinctive flavor and the ability to weaken the “goaty flavor”. To investigate the aroma characteristics of stewed mutton with thyme (SMT), four SMT samples prepared using different cooking utensils were analyzed by gas chromatography–mass spectrometry/olfactometry (GC–MS/O). Totally, 26 aroma-active compounds (AACs) were determined by GC–MS/O and further quantified. Among these, 20 AACs exhibited odor activity values (OAV) greater than 1. However, no significant differences existed among the four SMTs, which indicated that different utensils had little effect on the aroma profile of SMTs. Aroma recombination and omission experiments results showed that nonanal, (E)-2-octenal, and (E,E)-2,4-decadienal had the greatest contribution to the aroma profile of SMTs. These three compounds, together with dimethyl trisulfide, 3-methyl-butanal, octanal, (E)-2-decenal, (E)-2-nonenal, methanethiol, hexanal, (E)-2-undecenal, and 1-octen-3-ol, were confirmed as the key aroma compounds in SMTs.
To determine the concentrations of aroma compounds involved in the fruity aroma of red wines, an analytical method was developed and optimized using liquid–liquid extraction and gas chromatography ...coupled to mass spectrometry (GC/MS). The aim was to reduce sample preparation and analysis time, with a single sample preparation and a single injection being needed to quantify 43 compounds. 19 esters, 13 monoterpenes, 5 C13-norisoprenoids, and 6 C6-aldehyde and alcohol compounds were quantified in 14 red wines made from different grape varieties grown in the Mediterranean basin. Samples were selected based on typical varietal aroma by a panel of experts, who produced 7 olfactory descriptors linked to desirable or non-desirable wine aromas. The instrumental analysis showed variations in concentrations of the quantified compounds among the wines. The wines described using positive fruity descriptors had higher mean total concentrations of esters, C6-alcohols, monoterpenes, and C13-norisoprenoids. Some non-ester compounds were positively correlated with the fruity descriptors. Sensory profile results obtained by a panel of 16 trained judges revealed that the addition of non-ester compounds (including 2 cyclic esters) to a red wine initially described as having cooked fruit aromas had a positive contribution to some fresh fruity notes. This study opens up new avenues for research on the potential involvement of non-ester compounds in the fruity expression of red wines.
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