Relative Contents Of Aldehydes Research Articles

Effect of microwave combined with ultrasonic pretreatment on the flavor of composite stewed soup‐stock

AbstractIn order to increase the content of flavoring components and nutrients in the stock, effects of microwave (MW) combined with ultrasonic pretreatment on water‐soluble proteins, flavor nucleotides, volatile gas constituents and sensory evaluation in the stewed stock were explored. The results showed that, compared with the control group (CK), MW, and ultrasonic (US) pretreatment could significantly promote the degradation of nucleotides and form a large number of 5′‐flavor nucleotides. The combined treatment of MW and US promoted protein hydrolysis and increased the content of water‐soluble protein. The microwave combined ultrasonication pretreated stew stock had the brightest color and the overall sensory score was better than that of the CK. In addition, GC–MS analysis showed that a total of 49 volatile substances were detected in the stock samples. After microwave combined ultrasonication pretreatment, the relative contents of aldehydes and alcohols in the stock increased significantly. The sensor response value of the electronic nose was the highest, indicating that the intensity of flavor characteristics increased. Therefore, MW combined with ultrasonic pretreatment can effectively promote the formation and dissolution of nutrients, and increase the content of flavorful nucleotides and volatile gases.Practical applicationThis study provides a novel processing method for traditional stewed stock. Ultrasonic combined with MW treatment can quickly degrade the protein in the raw material and dissolve it into the stock. At the same time, it promotes the formation of flavor nucleotides and accelerates the Maillard reaction to produce more flavor substances. The technology has the advantages of short processing time, environmental protection and safety. It can be used as a potential pretreatment technology to regulate the flavor of stock‐soup.

Optimizing Split-reduced drip fertigation schemes of Arabica coffee based on soil microcosms, bean yield, quality and flavor in dry-hot region of southwest China

As a characteristic cash crop in Yunnan Province, China, Arabica coffee ranks first in the country in terms of cultivation area and production, but has always suffered from poor soil nutrient management and a lack of scientific basis for fertilization. It is not clear how to improve the soil microecological environment using split-reduced drip fertigation at different reproductive stages of Arabica coffee to improve bean yield and quality. Therefore, a two-year (2020–2022) field experiment was conducted on 5-year-old Arabica coffee trees in a dry-hot region with five split-drip fertigation patterns, F450, F600, F750, F900 and F1050. Using the local conventional fertilization (Fertilizer of 900 kg ha−1 year−1 only in berry expansion, and no fertilization in early flowering and berry ripening) as the control (CK). The effects of different fertilization modes on soil microecological environment, bean yield, nutritional quality and characteristic flavor were studied, and a comprehensive benefit evaluation model to assess bean yield and nutritional quality under different fertilization modes was established. The results showed that F900 significantly increased soil nitrate nitrogen, available phosphorus, available potassium, microbial population and enzyme activities at early flowering and berry ripening stages compared to CK, while F900 reduced soil nitrate nitrogen, available phosphorus and available potassium but increased soil enzyme activity and microbial population at the berry expansion stage. Compared with CK, F450 decreased bean yield, caffeine and chlorogenic acid content by 31.83 %, 23.73 % and 13.48 %, respectively, while F750 increased two-year average yield, raw bean fat, caffeine and chlorogenic acid content by 20.52 %, 12.37 %, 5.48 % and 11.17 %, respectively. The two-year average yield of F600 showed less difference from CK. Marginal yield was positive and then negative with increasing fertilizer application. Dry bean yield decreased at a total fertilizer application of 900 kg ha−1 year−1. Correlation analyses showed a positive correlation between soil microbial environment and nutrient quality of coffee beans, while different correlations were found between nutrients and volatiles at dark and medium roasting levels. Cluster analysis revealed that the relative contents of aldehydes, alcohols, phenols, pyridines, and pyrroles were higher under dark roasted condition, while the relative contents of ketones, esters, acids, and pyrazines were higher under medium roasted condition. Based on the Entropy weight-TOPSIS method, F750 had the highest combined benefits in terms of yield increase and quality improvement, and the total fertilizer application decreased by 16.67 % compared to CK, thus F750 treatment was the most suitable split-drip fertigation strategy for Arabica coffee in the dry-hot region of Yunnan. This study provided a reference for drip fertigation systems of Arabica coffee in dry and hot regions.

Use of GC-IMS and Stoichiometry to Characterize Flavor Volatiles in Different Parts of Lueyang Black Chicken during Slaughtering and Cutting.

Chilled and cut chicken is preferred by consumers for its safeness and readiness to cook. To evaluate the quality characteristics of various chilled chicken products, differences in volatile organic components (VOCs) of six different cut parts (breast, back, leg, heart, liver, and gizzard) of Lueyang black chicken were characterized through gas chromatography-ion mobility spectroscopy (GC-IMS) combined with stoichiometry. A total of 54 peaks in the signal of VOCs were detected by GC-IMS, and 43 VOCs were identified by qualitative analysis. There were 22 aldehydes (20.66-54.07%), 8 ketones (25.74-62.87%), 9 alcohols (4.17-14.69%), 1 ether (0.18-2.22%), 2 esters (0.43-1.54%), and 1 furan (0.13-0.52%), in which aldehydes, ketones, and alcohols were the main categories. Among the six cut parts, the relative content of aldehydes (54.07%) was the highest in the gizzard, and the relative content of ketones (62.87%) was the highest in the heart. Meanwhile, the relative content of alcohols (14.69%) was the highest in the liver. Based on a stable and reliable predictive model established by orthogonal partial least squares-discriminant analysis (OPLS-DA), 3-hydroxy-2-butanone (monomer and dimer), acetone, 2-butanone monomer, hexanal (monomer and dimer), isopentyl alcohol monomer, and n-hexanol monomer were picked out as characteristic VOCs based on variable importance in projection (VIP value > 1.0, p < 0.05). Principal component analysis (PCA) and the clustering heatmap indicated that the characteristic VOCs could effectively distinguish the six cut parts of Lueyang black chicken. The specific VOCs responsible for flavor differences among six different cut parts of Lueyang black chicken were hexanal (monomer and dimer) for the gizzard, 2-butanone monomer and hexanal dimer for the breast, hexanal monomer for the back, 3-hydroxy-2-butanone monomer for the leg, 3-hydroxy-2-butanone (monomer and dimer) for the heart, and acetone and isopentyl alcohol monomer for the liver. These findings could reveal references for quality assessment and development of chilled products related to different cut parts of Lueyang black chicken in the future.

Quality Assessment of Loquat under Different Preservation Methods Based on Physicochemical Indicators, GC–MS and Intelligent Senses

To explore the effects of different preservation methods on the quality of loquat after fresh-keeping treatment, various preservation techniques were employed. These included natural preservation (NP), vacuum freezing preservation (VFP), vacuum at room temperature preservation (VP) and freezing preservation (FP). The quality assessment involved analyzing the effects of these preservation methods using physicochemical indexes, a colorimeter, an electronic nose (E-nose), an electronic tongue (E-tongue) and gas chromatography–mass spectrometry (GC–MS). The results showed minor differences in loquat quality under different preservation methods, with sensory scores ranging from 55 to 78 and ΔE values ranging from 11.92 to 18.59. Significant variations were observed in moisture content (ranging from 53.20 g/100 g to 87.20 g/100 g), calorie content (ranging from 42.55 Kcal/100 g to 87.30 Kcal/100 g), adhesion (ranging from 0.92 to 1.84 mJ) and hardness (ranging from 2.97 to 4.19 N) (p &lt; 0.05). Additionally, the free amino acid content varied from 22.47 mg/g to 65.42 mg/g. GC–MS analysis identified a total of 47 volatile flavor substances in varieties of loquats, including 13 aldehydes, 9 esters, 6 ketones, 2 acids, 3 alcohols, 2 phenols, 3 pyrazines, 1 furan and 8 other substances. The relative content of aldehydes was significantly higher than that of other chemicals. The VFP and FP samples exhibited higher aldehyde content compared to the NP and VP samples. Moreover, Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) revealed 18 marked compounds that could differentiate between 5 loquat species. Analysis using E-nose and E-tongue indicated significant changes in the olfactory and gustatory senses of loquats following preservation. The VFP samples demonstrated the most effective preservation of loquat quality with minimal impact. This study provides some theoretical guidance for the home preservation of loquats.

Evaluation of Loquat Jam Quality at Different Cooking Times Based on Physicochemical Parameters, GC-IMS and Intelligent Senses.

The study compared and analyzed the quality of loquat jam with different cooking times through physicochemical parameters, headspace-gas chromatography-ion migration spectroscopy (HS-GC-IMS) and intelligent senses. The results showed that with the prolongation of the cooking time, the color of loquat jam slowly deepened, the energy significantly increased, the adhesiveness, gumminess, hardness and chewiness enhanced, the free amino acid content increased from 22.40 to 65.18 mg/g. The organic acid content increased from 1.64 to 9.82 mg/g. Forty-seven volatile flavor compounds were identified in five types of loquat jam using HS-GC-IMS, among which the relative content of aldehydes was sharply higher than that of other chemical substances, playing an important role in the flavor formation of loquat jam. LJ0, LJ1 and LJ2 had higher aldehyde content, followed by LJ3 and LJ4 had the lowest aldehyde content. The orthogonal partial least squares-discriminant analysis (OPLS-DA) screened 15 marker compounds that could distinguish five types of loquat jam. The E-nose results showed a significant difference in olfactory sense between loquat jam cooked for 100 and 120 min. The E-tongue results corroborated the results of free amino acids (FAAs) and organic acids, indicating that the gustatory sense of loquat jam changed significantly when the cooking time reached 120 min. The results provided a basis for further research on the relationship between the cooking process and quality characteristics of loquat jam.

The volatile organic compounds emission mechanism of pretreated bamboo during heat treatment

Heat treatment can be used to improve bamboo product quality. Pretreatment of the bamboo material can reduce the energy consumption of heat treatment. However, large quantities of volatile organic compounds (VOCs) are released during the bamboo heat treatment process, causing potential problems for the environment and human health. In this study, the effects of pretreatment with sodium hydroxide and zinc chloride solutions on VOCs emissions during heat treatment were investigated. We also explored chemical and structural changes of heat-treated bamboo. The VOCs released by untreated bamboo during heat treatment were mainly aldehydes, alcohols, alkanes, and esters. Alcohol and alkane contents decreased as treatment temperature increased, accompanying the emergence of more complex chemicals. Compared with untreated bamboo, sodium hydroxide pretreatment destroyed the hemicellulose structure, released stable VOCs under heat treatment, and did not produce acidic compounds; ether compounds increased significantly with increase in temperature. The catalysis of zinc chloride pretreatment degraded hemicellulose during heat treatment. The relative contents of aldehydes and esters released from zinc chloride pretreated bamboo during heat treatment increased significantly with temperature. Up to 69.76 % of aldehyde compounds were released at 160 °C, among which the relative proportion of furfural reached 37.23 %. These results may provide theoretical support for controlling VOCs emissions from different pretreated bamboo materials during heat treatment, which is also conducive to the subsequent recycling of VOCs.

Electrophysiological and Behavioral Responses of Apis mellifera and Bombusterrestris to Melon Flower Volatiles.

As important pollinators, honeybees and bumblebees present a pollination behavior that is influenced by flower volatiles through the olfactory system. In this study, volatile compounds from melon flowers were isolated and identified by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS), and their effects on Apis mellifera and Bombus terrestris were investigated by electroantennogram (EAG) and behavior tests (Y-tube olfactometer). The results showed that 77 volatile compounds were detected in melon flowers, among which the relative content of aldehydes was the highest (61.34%; 82.09%). A. mellifera showed a strong EAG response to e-2-hexenal, e-2-octenal, and 1-nonanal. B. terrestris showed a strong EAG response to e-2-hexenal, e-2-octenal, 2,5-dimethyl-benzaldehyde, benzaldehyde and benzenepropanal. In behavior tests, the volatiles with the highest attractive rate to A. mellifera were e-2-hexenal (200 μg/μL, 33.33%) and e-2-octenal (300 μg/μL, 33.33%), and those to B. terrestris were e-2-hexenal (10 μg/μL, 53.33%) and 2,5-dimethyl-benzaldehyde (100 μg/μL, 43.33%). E-2-hexenal and e-2-octenal were more attractive to A. mellifera than B. terrestris, respectively (10 μg/μL, 10 μg/μL, 200 μg/μL). In conclusion, the volatiles of melon flowers in facilities have certain effects on the electrophysiology and behavior of bees, which is expected to provide theoretical and technical support for the pollination of A. mellifera and B. terrestris in facilities.

Effects of contact ultrasound &amp; far‐infrared radiation strengthening drying on water migration and quality characteristics of taro slices

This study explored the effects of contact ultrasound strengthening hot air drying (CU-HAD), far-infrared radiation drying (FIRD) and contact ultrasound strengthening far-infrared radiation drying (CU-FIRD) on the moisture state and distribution, microstructure, quality characteristics of taro. The results showed that the drying times of CU-HAD, FIRD and CU-FIRD were reduced by 26.32%, 47.37% and 63.16%, compared with single HAD, respectively. During the drying process, the free water was removed from the taro slices, the immobile water increased first and then decreased, and the T2 relaxation distribution curves shifted to the left; Moreover, with the progress of drying, the water content of taro slices continued to decline, and the signal of magnetic resonance imaging (MRI) decreased. As the change of water content was closely related to the internal structure of taro slices, the application of both CU and FIR produced looser tissue structure and larger micro-tunnels. And loose structure led to low hardness. Furthermore, compared with single HAD, the rehydration ratio, color difference, total phenolic content, DPPH radical scavenging activity and ABTS radical scavenging activity of CU-FIRD were significantly better than FIRD and CU-HAD. The relative contents of heterocyclics and esters in the taro slices dried by CU-FIRD method were similar to those of CU-HAD and more abundant than those of FIRD, and the relative contents of aldehydes and olefins were richer than those of the other two drying methods, which had a positive impact on the flavor. So CU-FIRD is suitable and promising for the production of dried taro products. Novelty impact statement Both CU and FIR applied in HAD could significantly accelerate water removal and improve product quality. CU-FIRD could affect the microstructure of both sides of taro slices, and achieve quicker moisture removal comparing with single application of CU or FIR. CU-FIRD could combine the advantages of CU and FIRD, and realize higher nutrient values and better antioxidant activities.

The Use of Electronic Nose in the Quality Evaluation and Adulteration Identification of Beijing-You Chicken.

The objective of this study was to reveal the secrets of the unique meat characteristics of Beijing-you chicken (BJY) and to compare the difference of quality and flavor with Luhua chicken (LH) and Arbor Acres broiler (AA) at their typical market ages. The results showed the meat of BJY was richer in essential amino acids, arachidonic acid contents, inosine monophosphate (IMP), and guanosine monophosphate (GMP). The total fatty acid and unsaturated fatty acid contents of BJY chicken and LH chicken were lower than that of AA broilers, whereas the ratios of unsaturated fatty acids/saturated fatty acids (2.31) and polyunsaturated fatty acids/monounsaturated fatty acids (1.52) of BJY chicken were the highest. The electronic nose and SPME-GC/MS analysis confirmed the significant differences among these three chickens, and the variety and relative content of aldehydes might contribute to a richer flavor of BJY chicken. The meat characteristics of BJY were fully investigated and showed that BJY chicken might be favored among these three chicken breeds with the best flavor properties and the highest nutritional value. This study also provides an alternative way to identify BJY chicken from other chickens.

Effects of Trichoderma asperellum 6S-2 on Apple Tree Growth and Replanted Soil Microbial Environment.

Trichoderma asperellum strain 6S-2 with biocontrol effects and potential growth-promoting properties was made into a fungal fertilizer for the prevention of apple replant disease (ARD). 6S-2 fertilizer not only promoted the growth of Malus hupehensis Rehd seedlings in greenhouse and pot experiments, but also increased the branch elongation growth of young apple trees. The soil microbial community structure changed significantly after the application of 6S-2 fertilizer: the relative abundance of Trichoderma increased significantly, the relative abundance of Fusarium (especially the gene copy numbers of four Fusarium species) and Cryptococcus decreased, and the relative abundance of Bacillus and Streptomyces increased. The bacteria/fungi and soil enzyme activities increased significantly after the application of 6S-2 fertilizer. The relative contents of alkenes, ethyl ethers, and citrullines increased in root exudates of M. hupehensis Rehd treated with 6S-2 fertilizer and were positively correlated with the abundance of Trichoderma. The relative contents of aldehydes, nitriles, and naphthalenes decreased, and they were positively correlated with the relative abundance of Fusarium. In addition, levels of ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), available phosphorus (AP), available potassium (AK), organic matter (SOM), and pH in rhizosphere soil were also significantly related to changes in the microbial community structure. In summary, the application of 6S-2 fertilizer was effective in alleviating some aspects of ARD by promoting plant growth and optimizing the soil microbial community structure.

Analysis of Volatile Flavor Substances and Fatty Acids in Different Parts of Small-Tailed Han Lambs

The purpose of this experiment was to study the differences of volatile flavor substances and fatty acid composition in different parts of Small-Tailed Han Lambs, and to preliminarily evaluate the nutritional value of fatty acids in four parts. The contents of fat, protein, volatile flavor substances and fatty acid in hind leg, tenderloin, upper brain and lamb chop of 4-month-old Small-Tailed Han Lambs were analyzed. The results showed that the main flavor compounds of Small-Tailed Han Lambs were octanal, nonanal, octanol, 1-octene-3-ol, caprylic acid and decanoic acid. The types and relative contents of aldehydes, alcohols and esters in the tenderloin were high, which played an important role in the formation of mutton flavor. The ratio of unsaturated fatty acids to saturated fatty acids in upper brain was significantly higher than that in other parts, the ratio of polyunsaturated fatty acids to saturated fatty acids was more than 0.4, and the contents of monounsaturated fatty acids and polyunsaturated fatty acids were both high. Therefore, the composition of fatty acids in the upper brain is more consistent with the nutritional value of fatty acids.

Influence of Frying Methods on Quality Characteristics and Volatile Flavor Compounds of Giant Salamander (Andrias davidianus) Meatballs

Effects of deep fat frying and hot air frying on texture, color difference, sensory score, yield, fat content, and volatile flavor compounds of giant salamander meatballs before and after frying were investigated. The results showed that, compared with the deep fat frying group, hot air-fried giant salamander meatballs had higher hardness, elasticity, and L ∗ ( p &lt; 0.05 ), but lower a ∗ , b ∗ value, fat content, and yield ( p &lt; 0.05 ). There was little distinction in sensory score, cohesiveness, and chewiness between the two frying methods ( p &gt; 0.05 ). Gas chromatography ion migration chromatography (GC-IMS) was used for flavor compound analysis, and 50 flavor compounds were analyzed, containing 22 aldehydes, 11 ketones, 6 olefins, 4 acids, 3 esters, 3 alcohols, and 1 phenol. Compared with the samples before frying, the relative contents of aldehydes and ketones of fried giant salamander meatballs increased significantly, while the relative contents of esters and alkenes decreased significantly. Principal component analysis showed that the GC-IMS spectra of volatile flavor compounds before and after deep fat frying and hot air frying varied greatly, and the cumulative contribution rate of the two principal components reached 86.1%, indicating that the GC-IMS technology might be used to distinguish giant salamander meatballs before and after frying, or with different frying methods. These results may offer a note for development and quality control of the precooked giant salamander meatballs in the future.

Optimization of fermentation conditions for fermented green jujube wine and its quality analysis during winemaking.

The objective was to study the optimization of fermentation conditions for fermented green jujube wine and quality analysis. This study investigated the fermentation process conditions, the changes in physicochemical indexes, antioxidant capacity and volatile compounds measured from green jujube wine during winemaking. The optimized conditions (the initial sugar, yeast addition, fermentation time and SO2 treatments) for green jujube wine were 24%, 0.3%, 8d, 80mg/L, respectively. The results showed that the variation trend of different substances in green jujube wine in different fermentation periods were different. In the process of alcohol fermentation, the green jujube wine had a high 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging ability, 2,2'-amino-di (2-ethyl-benzothiazoline sulphonic acid-6) ammonium salt (ABTS) free radical scavenging ability and reducing power. Furthermore, a total of 50 volatile compounds were identified in green jujube wine, in which the relative content of aldehydes, ketones, heterocyclic and aromatic compounds were significantly reduced after fermentation.

红条茶加工中香气物质的动态变化

以桃源大叶种茶鲜叶为原料，按照经典红条茶加工工艺将其加工成红条茶，采用同时蒸馏萃取法(SDE)制备精油及GC-MS分析方法，研究其加工过程中香气物质的动态变化，以期为高香红条茶的加工提供参考。结果表明，加工成的红条茶共有110种香气组分，相对含量较高有22种，其中醇类9种，脂肪酸类3种，醛类5种，脂类3种，酮类2种；萎凋期间，醇类、脂类香气组分的相对含量逐渐增加，醛类、酮类、烃类、酸类香气组分的相对含量则逐渐下降；揉捻期间，醇类、酯类、醛类、酮类香气组分的相对含量递增，酸类、烃类香气组分的相对含量下降；发酵期间，醇类、醛类、酮类香气组分的相对含量持续增加，而酯类香气组分的相对含量先增后降，烃类和酸类香气组分的相对含量小幅下降；干燥期间，各类香气物质相对含量均下降。总体而言，从萎凋开始到发酵中后期，红条茶特征香气组分的相对含量呈逐渐增加趋势，而从发酵后期至干燥结束则呈逐渐降低趋势，在生产实际中，可通过适当延长萎凋时间、缩短发酵后期时间及干燥时间，有利于加工高香红条茶。 The black tea processed with traditional technology by Taoyuan leaves was used as the research object, and the aroma components were analyzed by simultaneous distillation and extraction (SDE) combining GC-MS technique, which provided reference for the processing of high-aroma black tea. The results show that the differences of aroma components of black tea were studied by chemical analysis. 110 species of aroma components were detected by GC-MS in totally, and 22 of them were high in content, including 9 types of alcohols, 3 types of fatty acids, 5 types of aldehydes, 3 types of lipids and 2 types of ketones. During the withering period, the relative content of alcohols and lipids increased gradually. The relative content of aldehydes, ketones, hydrocarbons and acids gradually decreased. The relative content of alcohols, lipids, aldehydes, and ketones showed an increasing trend during the period of rolling, and the relative content of acids and hydrocarbons decreased. During the fermentation period, the relative content of alcohols, aldehydes and ketones continued to increase, and the relative content of lipids was first increased and then decreased by the end of fermentation, and the relative content of hydrocarbons and acids decreased slightly. During the drying period, the relative content of all kinds of substances is decreased. As whole, from the beginning of the withering to the middle and late of fermentation, the relative content of characteristic aroma of black tea gradually increased, and then decreased from the later stage of fermentation to the end of drying. In the production, it is conducive to the processing of high-aroma black tea by moderately prolonging the withering time, shortening the time of late fermentation and drying.

Analysis of volatile compounds in L. edodes blanched by hot water and microwave

AbstractThe comprehensive flavour characterisation and volatile compounds of raw L. edodes, hot water blanching (HB) sample and microwave blanching (MB) sample were comparatively analysed by electronic nose technology and headspace solid‐phase micro‐extraction combined with gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS). Results indicated that volatile components in L. edodes markedly changed after HB and MB. Volatile compounds of raw L. edodes consisted mainly ketones, sulphide and alcohols, and 3‐octanone, as well as 1‐octen‐3‐one, were the major compounds. The content of ketones and sulphides in blanched samples markedly decreased, while the relative content of aldehydes, hydrocarbons and esters increased, which became the major volatile compounds of treatment samples. In addition, the percentage contents of esters, alcohols and sulphides in MB samples were significantly (P &lt; 0.05) higher than that in HB samples, especially 1‐octen‐3‐ol, which contributes more to mushroom flavour. Therefore, MB is a better pretreatment method of L. edodes processing and cooking according to the results of experiment.

Floral Scent Composition and Emission Patterns of Three Symplocos Species

The main floral scent compounds and the dynamic changes in the flower opening process of Symplocos decora, S. botryantha, and S. paniculata were analyzed by SPME and GC-MS techniques. The results showed that terpenes and alcohols are the main floral scent compounds in S. decora with purple color, whereas in S. decora with white color, there is considerable relative content of aldehydes and ketones except terpenes and alcohols. Aldehydes and alcohols are the main floral scent compounds in S. botryantha and S. paniculata. Among the major compounds, l-verbenone is the specific volatile compound in S. decora, while 2-ethylbutanal is the specific volatile compound in S. botryantha. Generally speaking, the varieties of floral scent compounds are increasing with the development of flower stages and attain the largest numbers at fullopening stage. The differences in the kinds of main floral scent compounds and the relative content of them may be the main reason for the fragrance difference among these three species.

Antisense suppression of alcohol acetyltransferase gene in ripening melon fruit alters volatile composition

Volatile esters are characteristic aroma components of melon (Cucumis melo L.) fruit. Alcohol acetyltransferase (AAT) (EC2.3.1.84) catalyzes the reactions of aliphatic and aromatic alcohols to their esters in the presence of acyl CoA in fruit and flowers. In this study, melon plants were transformed with a gene construct containing a melon AAT cDNA (AAT2) in an antisense orientation, driven by the constructive cauliflower mosaic virus 35S promoter, by ovary-injection transformation method. The transformed plants displayed a range of decreased AAT activities in the ripening fruit. The relative content of volatile esters was reduced, and the average relative content in the transgenic fruit was 78% of the wild-type fruit. However, the relative contents of aldehydes and alcohols increased; the average relative contents were 3.2 times and 2.4 times of those in the wild-type fruit, respectively. Apart from the difference in the volatile compounds, no other phenotypic alterations were noted, including other quality indices, such as the sugar, vitamin C and carotenoid contents. Our study indicates that AAT plays the key role in volatile ester formation in melon fruit.

Aroma Volatile Compound Analysis of SPME Headspace and Extract Samples from Crabapple ( Malus sp.) Fruit Using GC-MS

Volatile compounds from the ripened crabapple fruit of six varieties (Red Splendor, Strawberry Parfait, Pink Spire, Radiant, Sparkler, and Flame) were analyzed by the use of the SPME/GC/MS method. The changes in the volatiles between the ripened and upon full maturity fruit states were studied in Red Splendor and Strawberry Parfait. An effort was made to summarize an effective method for searching and identifying new idioplasms containing a particular fruit aroma within Malus. A total of 37 compounds were identified from the sample. The main aroma volatiles of the six varieties of fruit were comprised of 2-hexenal, 3-hexenal, hexanal, 2,4-hexadienal, benzaldehyde, diethyl phthalate. The main volatile compound of the crabapple fruit was 2-hexenal, but the relative content percentages were different (45.37, 21.98, 33.56, 32.21, 38.60, and 45.88%). The aroma components accumulated differently as the fruits ripened. The relative content of aldehydes and esters decreased as alcohols increased after the Red Splendor and Strawberry Parfait fruit ripened. For Red Splendor, the main volatile was still 2-hexenal, but the relative content decreased to 42.89%, and the relative content of alcohols increased by 13.86% as aldehydes and esters declined by 12.16 and 7.18%, respectively. For Strawberry Parfait, the main volatile was changed to cyclohexanol, and the relative content increased to 46.43%, while the relative content of alcohols increased by 49.03% as aldehydes and esters declined by 23.74 and 9.34%, respectively.