Flavour and Fragrance Journal最新文献

Due to the disadvantages of low fragrance threshold and high volatility of pyrrole monomer under high-temperature process in tobacco or food, it cannot meet the market requirements. In order to develop pyrrole flavour precursors, 2,5-dimethyl-N-pyrroleacetic acid was synthesized by the Paal–Knorr reaction using 2,5-hexanedione and glycine as raw materials. Various pyrrole fragrance precursors such as 2-ethyl-4-oxo-4H-pyran-3-yl 2-(2,5-dimethyl-1H-pyrrol-1-yl)acetate (5a), 4-formyl-2-methoxyphenyl 2-(2,5-dimethyl-1H-pyrrol-1-yl)acetate (5b), pyridine-2-ylmethyl 2-(2,5-dimethyl-1H-pyrrol-1-yl)acetate (5c) and thiophen-2-ylmethyl 2-(2,5-dimethyl-1H-pyrrol-1-yl)acetate (5d) were synthesized by esterification from 2,5-dimethyl-N-pyrroleacetic acid with ethyl maltol, vanillin, 2-pyridinemethanol and 2-thiophenemethanol, respectively. As part of the study, IR, NMR and HRMS were used to characterize the target compounds. Using gas chromatography–mass spectrometry-olfactometer (GC–MS-O), the pyrrole esters obtained were evaluated for the characteristics of their aromas. The thermal stability was analysed using thermogravimetric analysis and pyrolysis gas chromatography/mass spectrometry. In addition, the pyrolysis mechanism was speculated. With TG-DTG results, the main mass loss phase of 5a occurred between 108°C and 450°C, with a dramatic mass loss reduction of 83.07%. At 118.60°C and 450°C, 5b showed a mass loss reduction of 60.80%. Furthermore, according to the Py-GC/MS analysis results, compounds 5a and 5b formed 8 and 7 pyrolysis products. The main pyrolysis products of 5a and 5b were 1-ethyl-2,5-dimethyl-1H-pyrrole, ethyl maltol, and vanillin, which are all aroma components used to blend cigarette smoke, can slow down the rate at which aromas are lost and mask unpleasant smoke. Study results provide a reference for the tobacco industry to further develop new high-temperature release aroma ingredients.

Many aldehydes are volatile compounds with distinct and characteristic olfactory properties. The aldehydic functional group is reactive and, as such, an invaluable chemical multi-tool to make all sorts of products. Owing to the reactivity, the selective synthesis of aldehydic is a challenging task. Nature has evolved a number of enzymatic reactions to produce aldehydes, and this review provides an overview of aldehyde-forming reactions in biological systems and beyond. Whereas some of these biotransformations are still in their infancy in terms of synthetic applicability, others are developed to an extent that allows their implementation as industrial biocatalysts.

A statistical approach was successfully applied to optimize the acylation of l-menthol 1 in the presence of natural kaolin as an eco-compatible catalyst. The influence of the main variation of the operating parameters, namely solvent volume, amount of the acyl donor, temperature and the catalytic rate of kaolin, was studied. A full factorial design (FFD) was used to search for the optimum of each parameter affecting the evolution of l-menthol 1 acylation. A quadratic polynomial regression model was applied to analyse the experimental data with a p-confidence level <.05 (95%). Statistical analysis of the data confirmed that temperature (T), acyl donor/acceptor ratio (Qa), kaolin mass (Qc) and solvent volume (V) were the significant factors affecting the l-menthol catalytic acylation process. The determination coefficient of the adopted model was in the order of 98%. A set of optimal reaction conditions was established, and experimental tests were performed to validate the optimal conditions; the threshold of 100% was reached. Monitoring the kinetic profile of the reaction by gas chromatography (GC) showed complete conversion after 30 min of reaction. An upgrade of this developed environmentally benign process was applied to some monoterpenic alcohols, and the corresponding acetates were yielding at 45%–90%.

Stewed mutton is popular for its nutritional and special flavour qualities. To determine the key aroma-active compounds of stewed mutton in different parts, six experimental groups (sheep fat, sheep bone, sheep brisket, sheep loin, sheep rib and sheep leg) were investigated by gas chromatography-olfactometry-mass spectrometry (GC-O-MS). Totally, 57 volatile compounds in mutton soup were identified. Of these, 22 aroma-active compounds were identified as key aroma compounds with odour activity values (OAVs) >1. The partial least squares regression (PLSR) results indicated that sheep fat (SF) was greatly related to most variables of sensory attributes, thus presented richer aroma. Among all samples, 3-hydroxy-2-butanone and (E)-2-nonenal were the major aromatic compounds they shared. There were 22 unique key aromatic compounds, including 3-methylthiopropana, (E)-2-decenal, γ-decalactone, (E)-2-octenal and hydroxyacetone, and the differences in these compounds contributed to the flavour profiles of mutton soup. Our research extends the knowledge into the flavour characteristics of different parts of mutton and provides powerful information for improving the flavour of mutton products.

The majority of people have a bitter taster phenotype, they perceive substances such as phenylthiocarbamide (PTC). This could be associated with a lower preference for bitter foods. The ability to detect bitter taste is due to TAS2R28 receptor. The aim of this study was to determine the preferences for basic flavours, taste combinations and bitter taste-related foods in a sample of Chilean university students and to relate it to their PTC taster phenotype and genotype. A 5-point Likert-type online survey on taste and food preferences was applied to 149 Chilean university students (19.2 years; 69.8% women; 29.5% men and 0.7% prefer-not-to-say). It classified students as strong taster (ST), intermediate taster (IT) or non-taster (NT) through a PTC taste test. To assess the relationship between phenotype or genotype and students' preferences, we analysed frequency tables using Fisher's exact test. To genotype determination, it extracted DNA from buccal mucosal cells of 25 students (18.9 years; 72% female and 28% male). A fragment of TAS2R38 gene amplified (PCR) and digested (HaeIII). Our results show that 85.9% of students had a PTC taster phenotype (37.6% ST, 48.3% IT vs. 14.1% NT). Sweet taste was the most preferred, while bitter taste was the least. There was no association between taste and food preferences with student's phenotype or genotype. ST students presented homozygous taster genotype (55.6%); IT students, heterozygous taster genotype (75%); and NT students, homozygous non-taster genotype (50%). Both the PTC taster phenotype and genotype associated are not related to a lower preference for bitter taste and foods studied. Our results will allow us to generate promotion and education strategies for healthy eating, through the inclusion of bitter foods.

Volatile compounds can reach olfactory epithelium though the nose (orthonasal olfaction) or the mouth (retronasal olfaction). Although differences have been found between these two pathways in terms of odour sensitivity and identification, few studies have examined ortho- and retronasal differences taking into consideration the three main dimensions of olfactory perception (i.e. hedonicity, intensity and familiarity). Olfactory perception, and particularly odour hedonic perception, is influenced by several factors such as sex or age. Another variability factor worth considering, especially regarding food-related odours, is the ability to experience pleasure simulated by smell or taste, which can be measured with the Chemosensory Pleasure Scale (CPS). Thus, the aims of this study were (1) to compare odour sensory ratings in response to ortho- and retronasal presentation and (2) to examine the relationship between CPS scores and odour sensory ratings in ortho- and retronasal pathways. Participants rated ten food odours in ortho- and retronasal conditions using visual analogue scales and were divided into two subgroups based on the median CPS score (CPS+ and CPS− groups). Results revealed similar sensory responses to food odours between ortho- and retronasal pathways for the three main dimensions of olfactory perception. Interestingly, when CPS scores were considered, clear differences in odour familiarity and hedonicity were shown, particularly for the retronasal pathway (i.e. odours were perceived as more pleasant and more familiar in CPS+ group than in CPS− group). Overall, these findings suggest that differences in odour perception between ortho-and retronasal pathways may be related to specific individual characteristics such as chemosensory hedonic capacity.

Compared with peppermint oil, natural peppermint has more ingredients, a layered fragrance, and a green colour. It has been widely used as a nutritional additive, herbal tea, food flavouring or colouring. In this work, the retention of volatile flavour compounds of peppermint powders was enhanced by propylene glycol, a reagent that enhances hydrogen bonds and moisture absorption. The levels of influence of propylene glycol content on the retention of different volatile flavour compounds, moisture absorption and water distribution were evaluated by GC–MS, dynamic water absorption instrument (DVS), and low-field nuclear magnetic resonance (LF-NMR), respectively. GC–MS analysis showed that the volatile substances of peppermint powders (PMs) without propylene glycol were reduced to 22 kinds after storage for 90 days, and the total amount of volatile substances remained at 40.94%; PG2 with 2% propylene glycol had the best flavour retention. After 90 days of storage, the residual percentage of volatile flavour compounds of PG2 was approximately 72.56%, which was significantly increased compared with that of PM. The DVS results suggested that all the peppermint powders adopted a type III moisture absorption isotherm, and they all had multilayer adsorbed water. PG2 had the best moisture retention capacity and the highest hygroscopic hysteresis, while PG4 with a high propylene glycol content had a relatively poor moisture retention capacity. Similarly, LF-NMR analysis showed that PG2 had a higher proportion of bound water and lower relaxation times T₂₁ and T₂₂ under different humidity conditions, indicating that it had the strongest water binding capacity. The correlation analysis showed that there was a significant positive correlation between the residual volatile compounds of peppermint powders and the peak area of bound water A₂₁. The higher the proportion of strongly bound water in peppermint particles was, the more residual volatile substances were identified in peppermint particles. These results show that peppermint particles supplemented with propylene glycol can significantly improve the flavour retention ability of peppermint powders. In short, the results could be applied to the storage stability and quality control of peppermint products.

The essential oils of Lavender (Lavandula angustifolia) and Tropical Basil (Ocimum basilicum) are characteristically high in both linalool and linalyl acetate esters, key constituents determining essential oil (EO) quality and activity. The enrichment of these products in linalyl acetate has a great interest in the industry. Herein, we report the production of linalyl acetate using the free lipase PPL as a catalyst in a solvent-free medium. Parametric studies referring response surface methodology (RSM) were applied to optimize the conversion. The optimal experimental condition for (R)-linalool acylation (temperature at 60°C, catalyst amount at 150 mg, volume of acetic anhydride at 1 mL, and reaction time at 5 days) was obtained from an experimental design analysis. Under these conditions, the enzymatic acylation was carried out for both pure linalool, Lavandula angustifolia and O. basilicum essential oils as substrates. 24.94% conversion of pure linalool to linalyl acetate was obtained; however, essential oils gave lower conversions (conv = 13%).

8-methyldecanal is a characteristic ingredient of Australian finger lime (Citrus australasica), and has found important applications in flavour and fragrance industry. A novel and practical preparation method of 8-methyldecanal is presented. Starting from cheap and readily available 6-chloro-1-hexanol, 8-methyldecanal was prepared in five steps with an overall yield of 50.7%.