Changes In Aroma Characteristics Research Articles

Changes in volatile flavor compounds of Kimchi cabbage (Brassica rapasubsp.pekinensis) during salting and fermentation.

A main ingredient of Kimchi is Kimchi cabbage, which is soaked in brine to reduce its crispness. Volatile profile of raw Kimchi cabbage (RC) is changed during salting; however, characteristic aroma-active compounds of salted Kimchi cabbage (SC) have not been investigated. The objective of this study was to evaluate changes in aroma characteristics of Kimchi cabbage during salting and fermentation. Sulfur-containing compounds, such as sulfides and isothiocyanates, increased markedly by salting. (Z)-3-Hexen-1-ol, (Z)-3-hexenal, and hexanal decreased by salting. Hexanal was the most intense in RC, followed by 3-(methylthio)butanal, (Z)-3-hexen-1-ol, and benzenepropanenitrile. Dimethyl trisulfide had the highest log3FD in SC. Methyl (methylthio)methyl disulfide, allyl methyl trisulfide, and dimethyl tetrasulfide were detected only in SC. Dimethyl trisulfide, dimethyl tetrasulfide, methyl (methylthio) methyl disulfide, and allyl methyl trisulfide, decreased greatly in SC during fermentation. Our results demonstrated that characteristic odor of Kimchi cabbage could be significantly changed by salting and fermentation.

Aromatic profiles and enantiomeric distributions of volatile compounds during the ripening of Dendropanax dentiger honey

Dendropanax dentiger honey (DDH) is a specialty herbal honey from China. Previous research on DDH has mostly focused on its composition and potential chemical markers, no studies have been conducted on the changes in aroma characteristics and chiral odorants during its maturation. Therefore, the present study aims to address the missing parts. The proportions and total concentrations of 185 volatile compounds identified in different classes varied with DDHs ripening. Fourteen common odor-active compounds were identified by odor activity values (OAVs) and GC-olfactometry (GC-O) analysis. The aroma profiles of DDHs were observed to vary at different ripening stages, although the dominant aroma characteristic was “fruity” aroma, which became more pronounced with increasing maturity. The enantiomeric contents and distributions of 7 volatile enantiomers were related to specific physicochemical indicators and the maturity of DDHs, among which the enantiomers of linalool oxide A may be a potential indicator to identify its maturity. Furthermore, precise quantification and OAVs calculation showed that the enantiomer (2S, 5S)-linalool oxide A presented the highest concentration (8.83–27.39 ng/mL) and only the enantiomer R-linalool (OAVs: 5.56–6.14) was an important contributor to the aroma profiles of DDHs at different stages of maturity. These results provided a new research idea for quality control and identification of DDHs at different maturity stages.

Identification of characteristic aroma and bacteria related to aroma evolution during long-term storage of compressed white tea.

Compressed white tea (CWT) is a reprocessed tea of white tea. Long-term storage has greatly changed its aroma characteristics, but the material basis and transformation mechanism of its unique aroma are still unclear. In this study, flavor wheel, headspace gas chromatography ion mobility spectroscopy, chemometrics, and microbiomics were applied to study the flavor evolution and important aroma components during long-term storage of CWT, and core functional bacteria were screened. During long-term storage, the aroma of CWT gradually changed from sweet, fruity and floral to stale flavor, woody and herbal. A total of 56 volatile organic compounds (VOCs) were identified, 54 of which were significantly differences during storage. The alcohols content was the highest during 1-5 years of storage, the esters content was the highest during 7-13 years of storage, and the aldehydes content was the highest during 16 years of storage. Twenty-nine VOCs were identified as important aroma components, which were significantly correlated with 6 aroma sub-attributes (P < 0.05). The functional prediction of bacterial community reminded that bacterial community could participate in the transformation of VOCs during storage of CWT. Twenty-four core functional bacteria were screened, which were significantly associated with 29 VOCs. Finally, 23 characteristic differential VOCs were excavated, which could be used to identify CWT in different storage years. Taken together, these findings provided new insights into the changes in aroma characteristics during storage of CWT and increased the understanding of the mechanism of characteristic aroma formation during storage.

Determination of Ortho‐ and Retronasal Detection Thresholds and Odor Impact of 2,5‐Dimethyl‐3‐Methoxypyrazine in Wine

2,5-Dimethyl-3-methoxypyrazine (DMMP) has been recently identified in both Coccinellidae-tainted (by either Coccinella septempunctata or Harmonia axyridis beetles) and untainted wines; however, little is known regarding its impact on wine aroma and flavor. The aims of this study were to obtain an accurate estimate of both the ortho- and retronasal detection thresholds of DMMP in red wine and to understand how DMMP contributes to the aroma profile of red wine. In the first study, thresholds were determined for 21 individuals using the ASTM E679 ascending forced choice method of limits. The orthonasal group best estimate threshold (BET) was 31 ng/L and the retronasal group BET was 70 ng/L. A moderate variation in individual thresholds was observed for the orthonasal modality (standard deviation (SD) = 19.8) and a larger variation was noted for retronasal thresholds (SD = 111.8). In the second study, a panel of 8 assessors performed descriptive sensory analysis on 3 red wines containing various concentrations of added DMMP (0, 50, and 120 ng/L). Results show significant changes in aroma characteristics in the 120 ng/L wine and smaller effects at the 50 ng/L level. Overall, wines spiked with DMMP generated lower intensity ratings for cherry and red berry descriptors and higher ratings for earthy/musty and green/vegetal descriptors. When considered with other recent results on DMMP concentrations found in wine, DMMP can be considered a hitherto undescribed impact odorant in some wine styles.

Contribution of beef base to aroma characteristics of beeflike process flavour assessed by descriptive sensory analysis and gas chromatography olfactometry and partial least squares regression

Descriptive sensory analysis and gas chromatography–mass spectrometry (GC–MS) analysis were conducted to investigate changes in aroma characteristics of beeflike process flavours (BPFs) prepared from enzymatically hydrolyzed beef (beef base) of different DH (degree of hydrolysis) with other ingredients. Five attributes (beefy, meaty, simulate, mouthful and roasted) were selected to assess BPFs. The results of descriptive sensory analysis confirmed that BPF2 from beef base of moderate DH 29.13% was strongest in beefy, meaty and simulate characteristics; BPF4 and BPF5 from beef base of higher DH (40.43% and 44.22%, respectively) were superior in mouthful and roasted attributes respectively; while BPF0 without beef base gave weaker odour for all attributes. Twenty six compounds from GC–MS were selected as specific compounds to represent beef odour based on their odour-active properties assessed by a detection frequency method of GC–O and correlation of their contents with sensory attributes intensity. Correlation analysis of molecular weight (MW) of peptides, odour-active compounds and sensory attributes through partial least squares regression (PLSR) further explained that beef base with DH of 29.13% was a desirable precursor for imparting aroma characteristics of beeflike process flavour.

Changes in aroma characteristics of simulated beef flavour by soy protein isolate assessed by descriptive sensory analysis and gas chromatography

Descriptive sensory analysis (DA) and gas chromatography (GC) analysis were conducted to investigate changes in aroma characteristics of simulated beef flavour (SBF) upon addition of soy protein isolate (SPI). Five attributes (beefy, roasted, yeasty, soymilk-like and cereal) were selected to assess various mixtures of SBF and SPI. The results of DA confirmed that “roasted”, “beefy” and “yeasty” notes were highly positively correlated with SBF concentration, and the beefy related notes were substantially suppressed by increasing SPI content. Fifteen peaks from GC analysis were selected as indicator peaks to represent beefy attribute based on their odour-active properties assessed by GC–olfactometry and correlation of their peak areas with beefy intensity in mixtures of SPI and SBF assessed by DA. The indicator peaks may form the basis of further research to explicate the nature of SPI–SBF interactions to explain the suppression of perceived intensity of beef flavour in soy protein products.

Changes in aroma characteristics during the preparation of red ginseng estimated by electronic nose, sensory evaluation and gas chromatography/mass spectrometry

The changes in aroma characteristics during the preparation of red ginseng were investigated by using an electronic nose equipped with metal oxide (MO) sensor arrays, sensory evaluation and gas chromatography. All the MO sensor responses for fresh ginseng were much higher than those of steamed ginseng and most MO sensor responses for red ginseng were also higher than those for steamed ginseng when analysed using the electronic nose. It was evaluated by sensory panels that fresh ginseng had strong fresh, earthy, herbaceous and floral flavour notes while steamed ginseng had only moderate earthy flavour note and red ginseng had strong fragrant, sweet and roast flavour notes. A characteristic fragrant and sweet aroma compound was isolated from red ginseng and it was identified 3-hydroxy-2-methyl-pyran-4-one. The amount level of the aroma component in Korean red ginseng headspace was significantly correlated with either the SY/LG sensor response or the SY/AA sensor response of electronic nose at 1% level. These results suggest that the electronic nose equipped with MO sensor arrays may be also available for the rapid monitoring the changes in aroma characteristics during the preparation of red ginseng.

Evaluation of the effect of drying on aroma of parsley by free choice profiling

Parsley has wide culinary usage in Spain and as a result of its characteristic colour, aroma and flavour is used in preparing food and drink to enhance taste and appearance. The effect of different drying treatments on the aroma characteristics of parsley (Petroselinum crispum L.) was studied using free choice profiling (FCP) analysis. Differences between samples were observed after applying generalised Procrustes analysis (GPA) to the FCP data. The highest differences were found between fresh parsley samples and dried samples obtained by air-drying at ambient temperature, oven-drying at 45 oC and freeze-drying. However, air-drying at ambient temperature produced less changes in aroma characteristics than the other drying methods and preserved the fresh and herbaceous notes.