Isoamyl Acetate Research Articles

Impact of fermentation through Wickerhamomyces anomalus and Saccharomyces cerevisiae on aroma and quality of mulberry wine

SummaryWickerhamomyces anomalus D1‐4, a non‐Saccharomyces yeast known for its aroma production, offers a novel approach to improving the aroma and quality of mulberry wine. We employed various inoculation methods for fermenting mulberry wine and assessed its physicochemical, bioactive compounds, antioxidant activities, colour and aroma components. The results revealed that the addition of Wickerhamomyces anomalus D1‐4 to the fermentation led to a significant increase in the levels of alcohols, terpenes, nitrogen oxides and methyl in mulberry wine, especially, produced the characteristic isobutyl acetate and isopentyl hexanoate, and greatly increased the relative content of isopentyl acetate, isopentyl alcohol and phenylethyl alcohol. The sequential inoculation of Saccharomyces cerevisiae for 24 h followed by Wickerhamomyces anomalus D1‐4 fermented for 9 days was the best fermentation method for mulberry wine. Regarding colour, bioactive compounds and antioxidant activities, the fermentation was superior to other fermentations, and it was also able to maximise the aroma of mulberry wine and give it a strong floral and fruity aroma, especially higher ethyl hexanoate and ethyl octanoate. These findings demonstrate the unique fermentation characteristics of non‐Saccharomyces yeasts in enhancing the flavour and quality of mulberry wine.

Multiomics reveals the formation pathway of volatile compounds in preserved egg yolk (PEY) induced by NaCl: Based on the model of PEY and salted egg yolk (SEY) treated with/without NaCl.

The models of preserved egg yolk (PEY) and salted egg yolk both treated with or without NaCl were performed to explore the effect of NaCl on the characteristic volatile compounds (VOCs) in PEY. 1-hexanol, 2-heptanone, isoamyl acetate, etc., compounds were confirmed as the characteristic VOCs in PEY mainly induced by NaCl and the formation of 1-octanol, 2-pentylfuran, ammonia, etc., characteristic VOCs induced by NaCl may depend on the combined effect of Cu2+ and OH-. Among them, 1-hexanol and 2-heptanone were formed from linoleic acid in PS(18:0_18:2) and oleic acid in PG(22:6_18:1), respectively, through multi-omics and correlation analysis. Meanwhile, 1-octanol may originated from β-oxidation of oleic acid in PS(18:1); 2-pentylfuran and ammonia maybe derived from the derivative of aspartate and the degradation of l-methionine, respectively. Moreover, this study provides a new insight to parse the influence of NaCl with/without other exogenous factors on the formation of VOCs in food products.

Optimization of a bio-based drilling fluid from waste Dacryodes Edulis (local pear) for oil exploration

This study focused on the development and optimization of a bio-based drilling fluid from local pear seed for oil exploration, which can help lessen the environmental impact of oil spills. Local pear seed being a biodegradable material was collected, prepared, its oil extracted, modified and optimized to obtain an eco-friendly and cost-effective drilling fluid. The selected materials used for this study was Local pear oil. The drilling fluid was characterized for proximate parameters and ultimate parameters. The prepared drilling fluid was optimized using response surface methodology (RSM) provided by Design-Expert software 13.0. Central composite design (CCD) was applied to study the variables affecting rheology of drilling fluid. The process factors which include pH (A), viscosity (B), mud density (c), temperature (D), rheology (E) interacted to produce the response (drilling fluid yield) for the studied sample. The optimized drilling fluid yield and the optimum values were obtained through iterations of one hundred (100) solutions and the best yield was selected at iteration number seven (95th solution), at a pH of 1, Viscosity of 119.783cP, mud density of 10.473kg/L, Temperature of 100°C, and Rheology of 76.809s-1, and the optimized drilling fluid yield value was 91.144%. The acidity and the alkalinity of the drilling fluid were measured by the concentration of the 9.5 ion in the fluid. Therefore, the biomaterial studied has demonstrated its optimal effectiveness and potential application as an additive for the development of drilling fluid for oil exploration.

Characterization of key aroma compounds in Rice flavor baijiu from different rice raw materials by gas chromatography-ion mobility spectrometry and gas chromatography-olfactometry-quadrupole time of flight mass spectrometry

Rice flavor baijiu is one of the four traditional Chinese liquors, but the flavor difference caused by rice raw materials has received little attention. In this study, gas chromatography-ion mobility spectrometry (GC-IMS) combined with gas chromatography-olfactometry-quadrupole time of flight mass spectrometry (GC-O-QTOF/MS) were used to analyze five Rice flavor baijiu brewed from different rice raw materials. The results showed that there was a significant difference in the number and content of aroma compounds between the baijiu made from japonica rice and indica rice, and a total of 34 volatiles were characterized by the GC-IMS technique, which effectively constructed the fingerprint profile of the flavor differences of Rice flavor baijiu. GC-O-QTOF combined with aromatic extract dilution analysis (AEDA) tests identified 42 characteristic aroma active regions, 34 of which could be identified and quantified by the internal standard method. Sixteen aroma-active compounds in five baijiu samples showed high odor activity values (OAV). In addition, multivariate statistical analyses such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) effectively revealed the distribution patterns of the samples and their separation of relevant aroma activity markers. Six key aroma compounds, including isopentyl acetate, ethyl hexanoate, benzeneacetaldehyde, phenethyl acetate, undecane-2-one, and ethyl decanoate, were screened to have a greater effect on the flavor of Rice flavor baijiu.

Improving the aging aroma profiles of Italian Riesling and Petit Verdot Wines: Impact of spontaneous and inoculated fermentation processes

The study employed gas chromatography-ion mobility spectrometry to differentiate between wines undergoing spontaneous fermentation and inoculated fermentation, with aging periods of 3, 9, and 15 months. The results indicate that throughout the three aging periods, there was a notable increase in the levels of ethyl hexanoate (Monomer, M), 2-methyl butanal, ethyl octanoate (M), ethyl octanoate (Dimer, D), propyl acetate, and 3-methylbutanal in the spontaneous Italian Riesling wine (RS). Furthermore, the compounds isoamyl acetate (M), ethyl formate (D), 4-methyl-2-pentanone (M), and ethyl formate (M) demonstrated the highest concentrations at 15 months in RS, accordingly, these compounds displayed a consistent upward trend throughout the aging period. A total of 14 volatile compounds exhibited an upward trend from 3 to 15 months in the spontaneous fermentation of Petit Verdot Wine (VS). Subsequently, these compounds attained their maximum levels. Spontaneous fermentation effectively enhances the aromatic characteristics of wines, consequently improving their capacity for aging.

Single versus dual inoculation with indigenous Saccharomyces cerevisiae strains in winemaking.

Indigenous Saccharomyces cerevisiae strains and their combinations may be used to diversify wines and add complexity to sensory profiles. Here, two S. cerevisiae strains that represent regional genetic and phenotypic specificities for two major winegrowing areas of Greece were used in single- and mixed-culture fermentations. The kinetics and metabolic activities of the strains were analysed to evaluate the influence of each strain individually or in combination on wine quality. The two strains differentially affected the kinetics and the outcome of fermentation. They showed significant differences in the production of important metabolites that strongly affect the organoleptic profile of wines, such as volatile acidity, acetaldehyde, certain esters, and terpenes. Furthermore, the chemical and sensory profiles of wines produced by single cultures were different from those fermented by mixed culture inoculum. The concentration of certain metabolites was enhanced (e.g. isoamyl acetate, 1-heptanol), while others were suppressed (e.g. hexyl acetate, octyl acetate). Results highlight the potential worth of indigenous S. cerevisiae strains to differentiate local wines. The mixed culture S. cerevisiae inoculum was shown to generate novel wine characteristics, as compared to single cultures, thus offering alternatives to further diversify wines and increase their complexity.

Using abandoned unripe grape resources to solve the low-acid problem in the northwest wine region of China

Low acid is the main defect in the northwest wine region of China in recent years. The fermentation of unripe grape (UG) and wine grapes with low acid contents was carried out. Compared with control group (CK), the addition of UG addressed the core flaw that low acid grape bring to wine firstly, it significantly increased titratable acid, tartaric acid and malic acid while significantly decreasing alcohol and volatile acids in wine. Secondly, UG significantly improved wine color, the color parameters a*, b*, C* and L* were significantly increased to different degrees. At the same time, the addition of UG significantly improves other qualities of wine, including the phenolic substances and antioxidant capacity of wine. In addition, adding UGJ2% significantly improved the sensory quality, and pleasant volatile substances such as phenethyl alcohol, ethyl hexanoate, ethyl butyrate and isoamyl acetate were significantly increased, giving the wine more prominent floral and fruity aromas.

Correlation between fungi and volatile compounds during different fermentation modes at the industrial scale of Merlot wines

Elucidation of the relationship between fungal community development and dynamic changes in volatile components during fermentation is of great significance in controlling wine production. However, such studies on an industrial scale are rarely reported. In this study, fungal community succession during spontaneous fermentation (SPF) and inoculation fermentation (INF) of Merlot wine was monitored by a research strategy combining culture-dependent and culture-independent methods. The volatile compounds were monitored during SPF and INF by headspace solid-phase micro-extraction coupled with gas chromatography-mass spectrometry technology. The Spearman correlation coefficient was also used to investigate the interplay between fungal communities and volatile compounds. We found that fungal community diversity in SPF decreased as fermentation progressed but was significantly higher than that of INF. Starmerella and Kazachstania were the dominant non-Saccharomyces genera in Merlot wine during SPF. However, the presence of commercial yeasts and sulphur dioxide led to a sharp decrease or the disappearance of non-Saccharomyces genera during INF. Spearman correlation analysis revealed that all major volatiles were positively correlated with most functional microbiotas except P. fermentans, S. bacillaris, E. necator, and D. exigua in INF. In SPF, most non-Saccharomyces were negatively correlated with core volatiles, whereas K. humilis, M. laxa, P. kluyveri, and A. japonicus were positively correlated with the major volatiles, especially some higher alcohols (isopentol, heptanol) and terpenes (linalool, citronellol). S. cerevisiae was positively correlated with most of the main volatile substances except ethyl isovalerate and isoamyl acetate. These findings provide a reference for comprehending the diverse fermentation methods employed in the wine industry and improving the quality of Merlot wines.

Strategies on aroma formation in Chardonnay sparkling base wine: Different Saccharomyces cerevisiae strains, co-inoculation with Torulaspora delbrueckii and utilization of bentonite.

The worldwide production of sparkling wines has been growing annually, driven by a market demand for high quality and more complex products. The present study aimed to evaluate the fermentation of Chardonnay must using two different Saccharomyces cerevisiae yeasts, either alone (from commercial brands A and B) or in combination with Torulaspora delbrueckii (ScA+Td and ScB+Td, respectively), as well as the addition of bentonite to the fermentation with ScA (ScA+Ben), to investigate their impact on aroma formation in sparkling base wine. Enological parameters, volatile composition, and sensory profile were evaluated. The results showed notable differences in total sulfur dioxide and volatile acidity among the S. cerevisiae strains. Moreover, the esters ethyl acetate, isoamyl acetate, hexyl acetate, and phenethyl acetate showed significant differences among treatments. Esters are recognized for their contribution to fruity and floral aromas, making them an essential part of the aromatic profile of wines. The descriptive analysis revealed that ScB+Td had the highest intensity of floral and tropical fruit notes, as well as aromatic clarity. The use of bentonite did not affect the aromatic composition or sensory profile of the wine. Therefore, the co-inoculation of S. cerevisiae with T. delbrueckii can lead to a base wine with a higher intensity of important volatile compounds and sensory attributes, providing an important alternative to produce winery products with a more complex aroma profile.

Exploring the Profile Contributions in Meyerozyma guilliermondii YB4 under Different NaCl Concentrations Using GC-MS Combined with GC-IMS and an Electronic Nose.

Using Meyerozyma guilliermondii YB4, which was isolated and screened from southern Sichuan pickles in the laboratory, as the experimental group, we investigated the changes in growth, total ester content, and volatile flavor substances of M. guilliermondii YB4 under different NaCl concentrations. The growth of M. guilliermondii YB4 was found to be inhibited by NaCl, and the degree of inhibition increased at higher NaCl concentrations. Additionally, the total ester content of the control group (CK) was significantly lower compared to the other groups (p < 0.05). The application of NaCl also resulted in distinct changes in the volatile profile of YB4, as evidenced by E-nose results. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS) were employed to analyze the volatile compounds. A total of 148 and 86 volatiles were detected and identified using GC-MS and GC-IMS, respectively. Differential volatiles among the various NaCl concentrations in YB4 were determined by a variable importance in projection (VIP) analysis in partial least squares-discriminant analysis (PLS-DA). These differentially expressed volatiles were further confirmed by their relative odor activity value (ROAV) and odor description. Ten key contributing volatiles were identified, including ethanol, 1-pentanol, nonanal, octanal, isoamyl acetate, palmitic acid ethyl ester, acrolein, ethyl isobutanoate, prop-1-ene-3,3'-thiobis, and 2-acetylpyrazine. This study provides insights into the specificities and contributions of volatiles in YB4 under different NaCl concentrations. These findings offer valuable information for the development of aroma-producing yeast agents and the subsequent enhancement in the flavor of southern Sichuan pickles.

Amyl Acetate and Isoamyl Acetate.

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 1988, along with updated information regarding product types and concentrations of use, and confirmed that Amyl Acetate and Isoamyl Acetate are safe as cosmetic ingredients in the practices of use and concentration as described in this report.

Volatile Organic Compounds of Scheffersomyces spartinae W9 Have Antifungal Effect against Botrytis cinerea on Strawberry Fruit.

This study aims to evaluate the antifungal effects of volatile organic compounds (VOCs) produced by a marine biocontrol yeast, Scheffersomyces spartinae W9. The results showed that the VOCs from the yeast inhibited the growth of Botrytis cinerea mycelium and spore germination by 77.8% and 58.3%, respectively. Additionally, it reduced the disease incidence and lesion diameter of gray mold on the strawberry fruit surface by 20.7% and 67.4%, respectively. Electronic micrographs showed that VOCs caused damage to the morphology and ultrastructure of the hyphae. Based on headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS), S. spartinae W9 emitted 18 main VOCs, and the pure substance of VOCs, such as 3-methyl-1-butanol, 2-methyl-1-butanol, 2-phenylethanol, and isoamyl acetate, showed antifungal effects against B. cinerea mycelium growth. Among them, 2-phenylethanol exhibited the strongest antifungal activity. It has been concluded that VOCs are the key antifungal mechanism of S. spartinae W9, and a promising strategy for controlling gray mold on strawberry fruit.

Characterization of Key Compounds of Organic Acids and Aroma Volatiles in Fruits of Different Actinidia argute Resources Based on High-Performance Liquid Chromatography (HPLC) and Headspace Gas Chromatography-Ion Mobility Spectrometry (HS-GC-IMS).

Actinidia arguta, known for its distinctive flavor and high nutritional value, has seen an increase in cultivation and variety identification. However, the characterization of its volatile aroma compounds remains limited. This study aimed to understand the flavor quality and key volatile aroma compounds of different A. arguta fruits. We examined 35 A. arguta resource fruits for soluble sugars, titratable acids, and sugar-acid ratios. Their organic acids and volatile aroma compounds were analyzed using high-performance liquid chromatography (HPLC) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). The study found that among the 35 samples tested, S12 had a higher sugar-acid ratio due to its higher sugar content despite having a high titratable acid content, making its fruit flavor superior to other sources. The A. arguta resource fruits can be classified into two types: those dominated by citric acid and those dominated by quinic acid. The analysis identified a total of 76 volatile aroma substances in 35 A. arguta resource fruits. These included 18 esters, 14 alcohols, 16 ketones, 12 aldehydes, seven terpenes, three pyrazines, two furans, two acids, and two other compounds. Aldehydes had the highest relative content of total volatile compounds. Using the orthogonal partial least squares discriminant method (OPLS-DA) analysis, with the 76 volatile aroma substances as dependent variables and different soft date kiwifruit resources as independent variables, 33 volatile aroma substances with variable importance in projection (VIP) greater than 1 were identified as the main aroma substances of A. arguta resource fruits. The volatile aroma compounds with VIP values greater than 1 were analyzed for odor activity value (OAV). The OAV values of isoamyl acetate, 3-methyl-1-butanol, 1-hexanol, and butanal were significantly higher than those of the other compounds. This suggests that these four volatile compounds contribute more to the overall aroma of A. arguta. This study is significant for understanding the differences between the fruit aromas of different A. arguta resources and for scientifically recognizing the characteristic compounds of the fruit aromas of different A. arguta resources.

Nitric oxide reapplication during controlled atmosphere storage impacts on oxidative stress and volatiles production in 'Cripps Pink' apples

The aim of this study was to evaluate the effect of different concentrations of nitric oxide (NO) reapplied during controlled atmosphere (CA) storage on oxidative stress defense mechanisms and on profile of volatile compounds of 'Cripps Pink' apples. Fruit were treated with NO at 0, 1, 2, 5, or 10 μL L−1 every seven days during CA storage (0.8 kPa of O2, <0.5 kPa of CO2, at temperature of 1.5 ± 0.2 °C, and 94 ± 2% RH). Fruit were evaluated after 8 months of CA storage, followed by seven days of shelf life. In general, linear and quadratic models adjusted to quantitative levels of NO showed increased contents of total phenolic compounds (in the pulp and peel tissues), increased activity of catalase, reduced activity of lipoxygenase, reduced content of H2O2, reduced lipid peroxidation and ethylene production in the fruit with the increase of NO concentrations. NO treatment had no effect in the total antioxidant activity and in the activity of the enzymes superoxide dismutase and peroxidase in the fruit. The increase of NO concentrations reduced the volatile compounds butyl acetate, hexyl acetate, 2-methylbutyl acetate, ethyl butanoate, til 2-methylbutanoate, and 1-butanol in the pulp of the fruit. The results show that weekly application of NO at ∼6 μL L−1 during CA storage of 'Cripps Pink' apples improved the mechanisms to protect the fruit from oxidative stress, but it might impair the production of the main esters associated with aroma.

Selection of Salt-Tolerance and Ester-Producing Mutant Saccharomyces cerevisiae to Improve Flavour Formation of Soy Sauce during Co-Fermentation with Torulopsis globosa.

Soy sauce, as a traditional seasoning, is widely favoured by Chinese and other Asian people for its unique colour, smell, and taste. In this study, a salt-tolerance Saccharomyces cerevisiae strain HF-130 was obtained via three rounds of ARTP (Atmospheric and Room Temperature Plasma) mutagenesis and high-salt based screening. The ethanol production of mutant HF-130 was increased by 98.8% in very high gravity fermentation. Furthermore, ATF1 gene was overexpressed in strain HF-130, generating ester-producing strain HF-130-ATF1. The ethyl acetate concentration of strain HF-130-ATF1 was increased by 130% compared to the strain HF-130. Finally, the soy sauce fermentation performance of Torulopsis globosa and HF-130-ATF1 was compared with T. globosa, HF-130, HF-130-ATF1, and Torulopsis and HF-130. Results showed ethyl acetate and isoamyl acetate concentrations in co-fermentation of T. globosa and HF-130-ATF1 were increased by 2.8-fold and 3.3-fold, respectively. In addition, the concentrations of ethyl propionate, ethyl caprylate, phenylethyl acetate, ethyl caprate, isobutyl acetate, isoamyl alcohol, phenylethyl alcohol, and phenylacetaldehyde were also improved. Notably, other three important flavour components, trimethylsilyl decyl ester, 2-methylbutanol, and octanoic acid were also detected in the co-fermentation of T. globosa and HF-130-ATF1, but not detected in the control strain T. globosa. This work is of great significance for improving the traditional soy sauce fermentation mode, and thus improving the flavour formation of soy sauce.

Lachancea quebecensis a Novel Isolate for the Production of Craft Beer.

Yeasts are ubiquitously present in different natural sources. Some of these yeasts have interesting characteristics for the production of fermented food products. This study characterized Lachancea thermotolerans and L. quebecensis isolated from insects to determine their brewing potential. The yeasts were evaluated according to their fermentative potential in glucose and maltose-defined media and their resistance to ethanol and hop. Finally, craft beer was elaborated at a laboratory scale (10 L). The yeasts utilized glucose as the only carbon source and produced 3.25 ± 1.77, and 4.25 ± 1.06% (v/v), of ethanol for L. thermotolerans and quebecensis, respectively. While in the maltose-defined medium, ethanol content reached 3.25 ± 0.45, and 3.92 ± 0.36, respectively. The presence of alpha acids and ethanol affected the growth of L. quebecensis, which showed lower growth at 90 IBU and 8 ethanol% (v/v) mixtures. The craft beer brewed with L. quebecensis in monoculture experiments showed fruity flavors associated with ethyl acetate and isoamyl acetate. The ethanol content reached 3.50 ± 0.46% (v/v). The beer pH was 4.06 ± 0.20, with a lactic acid concentration of 1.21 ± 0.05 g/L. The sensory panel identified the beer as "fruity", "floral", "hoppy", "sweet", and "sour". To our knowledge, this is the first time L. quebecensis was reported as a potential candidate for sour beer production with reduced ethanol content.

Antifungal effect of volatile organic compounds (VOCs) release from Antarctic bacteria under postharvest conditions

The generation of biological control agents for postharvest fungal control has prompted the search for different natural sources due to studies indicating adverse effects that may be related to the use of conventional fungicides (e.g., SO2). Some bacteria that have the ability to generate volatile organic compounds (VOCs) with antifungal activity stand out in this regard. Thus, the Antarctic bacterium Pseudomonas sp. AN3A02, which can grow in very cold environments with low nutrient availability, has shown a fungistatic effect on Botrytis cinerea in dual culture. In this study, in vitro assays were performed to evaluate its effect and activity on strains of B. cinerea isolated from blueberries using dual-plate assays. An antifungal assay (in vivo) was performed by artificial wounding on blueberries inoculated with B. cinerea (1 ×106 conidia/mL) and stored at 0 °C for 20 d plus 3 d at 20 °C. The results obtained showed that in the presence of the bacteria, the severity of gray mold on blueberries was reduced by 71.38 %. In addition, this bacterium released a diversity of VOCs, including alcohols (1-octanol, 10.3 %), aldehydes (paraldehyde, 2.1 %), esters (ethyl butyrate, 4 %; isoamyl acetate, 2 %), ketones (2-nonanone, 1.4 %), terpenes (linalool, 1.9 %; D-limonene, 0.7 %), phenolic derivatives (2,4-di-tert-butylphenol, 2.5 %) and other groups, which were identified by GC–MS. The release of VOCs affects and modifies the hyphae and germ tube of B. cinerea, influencing its growth. Therefore, a new and environmentally friendly alternative for postharvest pathogen control could be generated based on this Antarctic microorganism.

VOCs from fungi-infected apples attract and increase the oviposition of yellow peach moth Conogethes punctiferalis.

Plant volatile organic compounds (VOCs) modified by plant-associated microbes can attract or repel the oviposition of herbivores. Here, we explored the effects of three different fungi on apples' VOCs and the cascading impacts on the oviposition preference of yellow peach moth [YPM, Conogethes punctiferalis (Guenée)]. Among Penicillium crustosum-infected apples (PCA), Rhizopus oryzae-infected apples (ROA), Colletotrichum gloeosporioides-infected apples (CGA) and healthy apples (HA), mated YPM females preferred to oviposit eggs on ROA and CGA, and showed significant attractiveness to VOCs from PCA, ROA, and CGA under laboratory conditions. The VOCs analyses showed that there were significant differences between fungi-infected apples (ROA, CGA) and control treatments (mechanically damaged apples (MDA), HA) in terms of the relative contents of 13 VOCs. The relative contents of ethyl 2-methylbutyrate, ethyl caprylate, estragole, ethyl hexanoate in ROA and CGA were higher than those in MDA. The relative content of isopropyl 2-methylbutyrate in ROA was significantly higher than those in HA and CGA. The relative contents of 2-methylbutyl acetate, butyl 2-methylbutyrate, hexyl 2-methylbutyrate, amyl hexanoate, hexyl hexanoate, (E, E)-α-farnesene in ROA and CGA were lower than those in HA. The relative content of hexyl acetate in ROA and CGA was significantly higher than that in MDA, but lower than that in HA. Additionally, 10 fungi-induced VOCs were detected in ROA and/or CGA. When 20 VOCs from ROA and/or CGA were tested as individuals or mixed blends in Y-tube olfactometer assays, mated YPM females preferred amyl 2-methylbutyrate, isoamyl 2-methylbutyrate, isopropyl 2-methylbutyrate, hexyl propionate (common VOCs in ROA, CGA, and HA), and heptacosane (a fungi-induced VOC in ROA), but no significant preferences were observed between individual compounds and mixed blends, except for hexyl propionate. Different fungi infection increased the relative contents of common VOCs from healthy and fungi-infected apples, which ultimately resulted in the significant attractiveness for the oviposition of mated YPM females. This study clarified why fungi-infected apples were more attractive to YPMs than healthy apples and screened out the crucial VOCs for YPM oviposition. © 2023 Society of Chemical Industry.

Comparative Study of the Solvent Extraction and Characterization of Oil from the Seeds of Avocado, Bush Pear and Cashew

Due to their many purposes and functions for mankind, oils from fruits and seeds are given a lot of importance today. As a result, there is a higher demand for cashew, avocado, and bush pear oils. The Soxhlet extractor and petroleum ether as the extracting solvent are used in this work to extract and characterize the oils from the seeds of Cashew, Avocado, and Bush pear. Physical and chemical studies of the extracted oil were performed alongside with the identification of any trace metals. The findings assessed the yield, color, relative density, refractive index, acid value, peroxide value, iodine value, and saponification value free fatty acid for Bush pear, Avocado pear, and Cashew seeds. The yield (%) of the oil produced from the various seeds of cashew, avocado, and bush pear oils is of specific significance. This finding reveals highest oil yield of 38.2% in Avocado pear oil, compared to 34.4% and 27.4% oil yield in Bush pear seed, and Cashew seed, respectively. In addition to being edible, Bush pear and Cashew oil's low acid value of 6.4 mg KOH/g and 7.7 mg KOH/g, respectively compared to Avocado oil's low acid value of 14.6 mg KOH/g avocado suggests that Bush pear and Cashew oils finds good applications in the paint industry. The study also showed that potassium had the highest concentration of any metal, with 45.8 mg/100g in avocado oil, compared 24.9 mg/100g and 1.68 mg/100g for Cashew seed oil and Bush pear, respectively. Zinc had the lowest concentration, with a value of 0.38 mg/100g observed in Cashew compared with 1.32 mg/100g and 2.06 mg/100g for Bush pear and Avocado, respectively. Hence, this reveals that Oils extracted from Cashew finds good applications in the production of hydraulic oil with exceptional lubrication properties. The FTIR study shows that functional groups including alkanes, alkenes, carbonyls, etc. are present in the seed oils of Bush pear, Avocado pear, and Cashew seeds.

Metabolomics and metatranscriptomics reveal the influence mechanism of endogenous microbe (Staphylococcus succinus) inoculation on the flavor of fermented chili pepper

This study integrated metabolomic and metatranscriptomic techniques to examine how the endogenous microbe, Staphylococcus succinus, influenced the essential flavor of fermented chili peppers. The mechanisms governing spontaneous fermentation and S. succinus-inoculated fermentation were also elucidated. Esters (e.g., ethyl undecanoate, isoamyl acetate, and methyl salicylate), terpenes (e.g., terpinen-4-ol), and alcohols (e.g., α-terpineol, linalool, and 4-methyl-3-heptanol) were found to be the key aroma-active compounds, aspartic acid (Asp) and glutamic acid (Glu) were identified as primary flavoring free amino acids. Notably, during the early stages of S. succinus-inoculated fermentation, the production of these essential metabolites was abundant, while their gradual increase over time was observed in the case of spontaneous fermentation. Metatranscriptomic analysis revealed that S. succinus inoculation could up-regulate genes related to glycolysis, amino acid metabolism, and aroma compound synthesis. These changes sequentially boosted the production of sweet and umami free amino acids, enhanced organic acid levels, increased unique aroma compound generation, and further improved the flavor and quality of the fermented chili peppers. Therefore, S. succinus inoculation can augment the sensory quality of fermented chili peppers, making this strain a promising candidate for Sichuan pickle fermentation starters.