beta-ionone and n-hexanal

Resistance to insect pests is an important self-defense characteristic of pepper plants. However, the resistance of different pepper cultivars to Spodoptera litura larvae, one of the main insect pest species on pepper, is not well understood.. Among seven pepper cultivars evaluated, cayenne pepper 'FXBX' showed the highest repellency to third instar S. litura larvae, Chao tian chili pepper 'BLTY2' showed the lowest repellency. Plant volatiles (1-hexene, hexanal, β-ionone, (E,E)-2,6-nonadienal, and methyl salicylate) affected host selection by S. litura. Among these, 1-hexene, hexanal, and β-ionone at concentrations naturally-released by pepper leaves were found to repel S. litura. Interestingly, S. litura larvae fed on the larva-attracting pepper cultivar, (BLTY2) had an extended developmental period, which was about 13 days longer than larvae fed on FXBX. Besides, the survival rate of larvae fed on BLTY2 was 22.5 ± 0.0%, indicating that the leaves of BLTY2 can kill S. litura larvae. Correlation analysis showed that larval survival rate, emergence rate, female adult longevity, and pupal weight were positively correlated with the vitamin C, amino acids, protein, cellulose, and soluble sugar contents, but were negatively correlated with wax and flavonoids contents.. We identified two different modes of direct defense exhibited by pepper cultivars against S. litura. One involves the release of repellent volatiles to avoid been fed on (FXBX cultivar). The other involves the inhibition of the growth and development or the direct killing of S. litura larvae which feeds on it (BLTY2 cultivar). © 2022 Society of Chemical Industry.

Topics: Aldehydes; Alkenes; Amino Acids; Animals; Ascorbic Acid; Cellulose; Flavonoids; Larva; Norisoprenoids; Spodoptera; Sugars

Roasting, an important process to refine Wuyi Rock tea, could impart different types of aroma to the final products. This study focuses on the differences in aroma characteristics among three kinds of refined teas, named light fire (LF), moderate fire (MF), and high fire (HF). A combination of solid phase microextraction (SPME) and a switchable system between GC-O-MS and GC × GC-O-MS was utilized to identify the odorants. In total, 97 aroma-active compounds could be smelled at the sniffing port, comprising alcohols, aldehydes, ketones, esters, heterocycles, and terpenes. However, only 52 obtained r-OAV >1. Significant differences were uncovered by the application of principal component analysis (PCA) and partial least squares regression (PLSR). Thereby, MF and HF had a more similar aroma profile, while in LF samples, alcohols, aliphatic aldehydes and some ketones were responsible for the aroma profile, such as (E,E)-2,4-hexadienal, octanal, hexanal, (E,Z)-2,6-nonadienal, (E)-β-ionone, 3-octen-2-one etc. Strecker aldehydes had a great impact on the aroma of MF, including 2-methylpropanal, 2-methylbutanal, 3-methylbutanal etc. Some N-heterocyclic compounds also affected the overall aroma, for instance, 6-methyl-2-ethylpyrazine. In HF, the majority of aroma compounds increased with increasing roasting temperature, especially N-heterocyclic compounds as well as furfural and 5-methyl-2-furancarboxaldehyde, which are all closely related to the Maillard reaction. Besides, 5-methyl-2-(1-methylethenyl)-4-hexen-1-ol, trans-linalooloxide and 2-nonanone also remarkably influenced the aroma of HF. In addition, it was supposed that most amino acids that participated in the Maillard reaction during roasting were decomposed from the compounds that combined with tea polyphenols and amino acids.

Topics: Alcohols; Aldehydes; Gas Chromatography-Mass Spectrometry; Norisoprenoids; Odorants; Plant Leaves; Polyphenols; Smell; Solid Phase Microextraction; Tea; Temperature; Volatile Organic Compounds

Dee are a unique and rapidly growing part of the global snack food market and are recognised as having distinct sensory properties (taste and texture). In this study, the development of important volatile aroma compounds over storage was evaluated and their chemical origin explained. Sweet potatoes were batch fried in high oleic sunflower oil (HOSO) and subjected to accelerated shelf life testing. Headspace volatiles were analysed using SPME GC-MS and correlated with sensory perception. All the components (sweet potatoes, oil and β-carotene) showed significant degradation after 3 weeks of storage at accelerated conditions (equivalent to 12 weeks in real-time at 25 °C). Marker volatiles associated with lipid oxidation such as hexanal, octanal, pentanal were identified, in addition to norisoprenoids from β-carotene degradation such as β-ionon, 5,6-epoxy-β-ionone, dihydroactinidiolide (DHA) and β-cyclocitral. The most prominent marker of lipid oxidation (hexanal) rapidly increased at week 1, whereas the carotene degradation makers did not rapidly increase until week 3 suggesting a delayed response. The frying temperature during the batch frying process of SPC was also shown to play a significant role in the sensory perception of the product over the shelf life. Overall, the results suggest that tight control of process variables and raw material design may enable extended shelf life and potentially enhanced health credentials for the product. These findings are unique to SPC, but also of value to the wider food industry.

Topics: Aldehydes; Benzofurans; beta Carotene; Cooking; Diterpenes; Food Industry; Gas Chromatography-Mass Spectrometry; Hot Temperature; Ipomoea batatas; Lipid Metabolism; Lipids; Norisoprenoids; Odorants; Oxidation-Reduction; Sensation; Sunflower Oil; Taste; Volatile Organic Compounds

The objective of this study was to characterize the flavor of a premium Florida tomato variety that has significant potential for producing a high quality processed juice product. A high-quality Florida plum tomato variety (Garden Gem), and a typical grocery-store plum tomato variety (Roma) were thermally processed into tomato juices without any additives. The 2 pilot products and a popular commercially available tomato juice (low sodium with sugar and flavor added) were compared using sensory evaluation and instrumental analysis. Flavor compounds in these products were identified using dynamic headspace purge and trap-gas chromatography-mass spectrometry (PT-GC-MS) by MS library match and retention index and were semi-quantitated using internal standards. Color, uniformity, overall liking, tomato flavor, sweetness and texture were rated using a hedonic scale. Analysis of variance, correlation and principal component analysis were used to analyze both sensory and flavor data. Among the 3 products, Garden Gem juice was rated significantly (P < 0.05) higher for overall liking, tomato flavor, and sweetness by the 119 consumer panelists in both seasons. Garden Gem juice was found to contain higher levels of 3 sweet/fruity related aroma compounds: 6-methyl-5-hepten-2-one, linalool, and β-ionone. The commercial tomato juice contained a high level of the Maillard reaction-related notes furfural, dimethyl sulfide, and the least amount of green-related notes (hexanal, E-2-hexenal and Z-2-heptenal). The flavor profile of the Roma tomato juice was similar to Garden Gem juice except it contained substantially lower amounts of hexanal and 2-isobutylthiazole. The compound β-ionone (fruity note) was not detected in either the commercial or Roma juice.. This proof of concept study demonstrates that high flavor quality tomatoes can be used to create better tasting processed tomato products. The study also demonstrates how sensory preference can confer a potential market advantage over existing commercial products. The Garden Gem variety has potential to add desirable flavor attributes to processed tomato products. This research may also provide insights for product developers to which flavor volatiles best reflect sensory observations for different aspects of tomato flavor.

Topics: Adolescent; Adult; Aged; Aldehydes; Color; Consumer Behavior; Female; Florida; Fruit; Fruit and Vegetable Juices; Gas Chromatography-Mass Spectrometry; Humans; Ketones; Male; Middle Aged; Norisoprenoids; Pilot Projects; Principal Component Analysis; Solanum lycopersicum; Taste; Volatile Organic Compounds; Young Adult