Comprehensive study of volatile compounds and transcriptome data providing genes for grape aroma

Advances in Food Aroma Analysis: Extraction, Separation, and Quantification Techniques

Decoding the aroma composition plays a key role in designing and producing foods that consumers prefer. Due to the complex matrix and diverse aroma compounds of foods, isolation and quantitative analytical methods were systematically reviewed. Selecting suitable and complementary aroma extraction methods based on their characteristics can provide more complete aroma composition information. Multiple mass spectrometry detectors (MS, MS/MS, TOF-MS, IMS) and specialized detectors, including flame ionization detector (FID), electron capture detector (ECD), nitrogen-phosphorus detector (NPD), and flame photometric detector (FPD), are the most important qualitative technologies in aroma identification and quantification. Furthermore, the real-time monitoring of aroma release and perception is an important developing trend in the aroma perception of future food. A combination of artificial intelligence for chromatographic analysis and characteristic databases could significantly improve the qualitative analysis efficiency and accuracy of aroma analysis. External standard method and stable isotope dilution analysis were the most popular quantification methods among the four quantification methods. The combination with flavoromics enables the decoding of aroma profile contributions and the identification of characteristic marker aroma compounds. Aroma analysis has a wide range of applications in the fields of raw materials selection, food processing monitoring, and products quality control.

Transcriptomic profiling reveals a regulatory network governing volatile compound biosynthesis in Shine Muscat grapes (Vitis labruscana Baily × V. vinifera L.)

MAIN CONCLUSION

Winter berries accumulated more free volatile compounds than summer berries, and C6 volatile compounds were the main contributors to free volatile compounds. The volatile composition of grapes and wines is important in viticulture, since their aroma is one of the most important determinants of grape fruit quality. The aroma and general quality of grape fruit are influenced by the production of volatile compounds primarily influenced by crop management. In this study, the free and bound volatile compounds were determined using gas chromatography-mass spectrometry (GC-MS), along with the transcriptomic analysis using Shine Muscat grape (Vitis labruscana Baily × V. vinifera L.) of summer and winter berries under two-crop-a-year cultivation in Guangxi. The findings demonstrated that phenols, terpenoids, and alcohols were the main bound volatile compounds in fruits from both seasons, whereas aldehydes, terpenoids, and alcohols were the leading free volatile compounds. Free volatile compound concentrations were substantially higher in winter than summer berries, but bound volatile compound concentrations were much lower. Specifically, the concentrations/constitution of free C6 volatile compounds showed a significant difference between the two seasons and highly correlated with the transcription of three genes involved in the lipoxygenase (LOX) pathway. Winter berries had a higher concentration of aldehydes, which might be ascribed to the higher expression of VvLOXA (VIT_06s0004g01510) and VvHPL1 (VIT_12s0059g01060) genes, while the higher concentration of alcohols in summer berries might be due to the higher expression of alcohol dehydrogenase (VvADH1, VIT_18s0001g15410). Furthermore, two VvBGLU genes (VIT_05s0077g01150, VIT_01s0011g00760) were supposed to regulate the enzymatic hydrolysis of glycoside-bound compounds in grapes. Three transcription factors including MYB60, MYBA1, and GATA16 were highly correlated with VvADH1, and they might play an important role in grape C6 alcohol biosynthesis. The findings may help to reveal a transcriptional regulation network of volatile compounds biosynthetic in grapes and to develop efficient cultivation practices.

Comparative study of different commercial enzymes on release of glycosylated volatile compounds in white grapes using SPE/GC-MS

Glycosides represent a large source of potential flavor in grape must. Commercial preparations enzymes with glycosidase activity are commonly employed to enhance wine aroma. In this study, we conducted an evaluation of twelve commercial enzymes to assess their effectiveness in releasing volatile compounds from their conjugated forms in a white grape must under laboratory conditions by solid-liquid extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). In this laboratory-level experiment, regardless of the enzymes used, the total concentration of volatile compounds was not statistically affected by the treatments. While the total concentration of volatile compounds remained largely unchanged, four specific volatile groups were significantly affected by the enzyme treatments: acids, alcohols, C13-norisoprenoids, and terpenes. The results also revealed a significant effect of commercial enzymes on individual compounds, which led to a notable increase in the concentration of twenty-one aroma compounds, mainly terpenes. Rapidase Revelation Aroma and Enozym Extra Aroma emerged as the most powerful ones on the must's volatile composition with important ability to release higher concentrations of essential varietal aroma compounds, particularly terpenes and C13-norisoprenoids.

Chemical Profile and Potential Applications of Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro Kernel Oils: Analysis of Volatile Compounds and Fatty Acids

Sclerocarya birrea kernel volatile compounds and fatty acid methyl esters (FAMEs) from the Bubi district in Matabeleland North province of Zimbabwe were characterised by GC-MS. The volatile compounds of the oil include 65 different compounds from 24 distinct classes, dominated by 13 alcohols and 14 aldehydes (42%). Other classes include carboxylic acids, phenols, sesquiterpenes, lactones, pyridines, saturated fatty acids, ketones, and various hydrocarbons. The kernel oils revealed essential fatty acids such as polyunsaturated (α-linolenic and linoleic acids) and monounsaturated fatty acids (palmitic, palmitoleic, and oleic acids). Notably, oleic acid is the predominant fatty acid at 521.61 mg/g, constituting approximately 73% of the total fatty acids. Linoleic acid makes up 8%, and saturated fatty acids make up about 7%, including significant amounts of stearic (42.45 mg/g) and arachidic (3.46 mg/g) acids. These results validate the use of marula oils in food, pharmaceutical, and health industries, as well as in the multibillion USD cosmetics industry. Therefore, the potential applications of S. berria kernel oils are extensive, necessitating further research and exploration to fully unlock their capabilities.

Breeding new seedless table grapevines for a more sustainable viticulture in Mediterranean climate

The growing demand for sustainable and environmentally friendly viticulture is leading to a multiplication of breeding programs aimed at obtaining vines that are resistant to powdery mildew (PM) and downy mildew (DM), the two most damaging vine diseases. In Puglia, the most important Italian region for the production of table grapes, an extensive crossing program was launched in 2015 with 113 crosses, including elite table varieties, seedless varieties, and resistant varieties. The main seedling production parameters were measured for each cross. In particular, berries harvested as well as the number of seeds and seedlings obtained were considered. Approximately 103,119 seedlings were obtained and subjected to marker-assisted selection for seedlessness using the marker VvAGL11 and for resistance to PM and DM with appropriate markers. Approximately one third (32,638) of the progenies were selected as putative seedless and seventeen thousand five hundred-nine (17,509) were transferred to the field for phenotypic evaluation, including 527 seedless individuals putatively resistant, of which 208 confirmed to be resistant to DM, 22 resistant to PM, and 20 individuals that combined resistance and seedlessness traits. The work discusses the effects of parental combinations and other variables in obtaining surviving progeny and pyramiding genes in table grapes and provides useful information for selecting genotypes and increasing the efficiency of breeding programs for seedless disease-resistant grapes.

Analysis of Important Volatile Organic Compounds and Genes Produced by Aroma of Pepper Fruit by HS-SPME-GC/MS and RNA Sequencing

Pepper is an important condiment, and its aroma affects its commercial value. In this study, transcriptome sequencing and combined headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the differentially expressed genes and volatile organic compounds in spicy and non-spicy pepper fruits. Compared with non-spicy fruits, there were 27 up-regulated volatile organic compounds (VOCs) and 3353 up-regulated genes (Up-DEGs) in spicy fruits. The results of KEGG enrichment analysis of the Up-DEGs combined with differential VOCs analysis showed that fatty acid biosynthesis and terpenoid biosynthesis may be the main metabolic pathways for aroma differences between non-spicy and spicy pepper fruits. The expression levels of the fatty acid biosynthesis-related genes FAD, LOX1, LOX5, HPL, and ADH and the key terpene synthesis gene TPS in spicy pepper fruits were significantly higher than those in non-spicy pepper fruits. The differential expression of these genes may be the reason for the different aroma. The results can provide reference for the development and utilization of high-aroma pepper germplasm resources and the breeding of new varieties.