The diversity of chili pepper volatile compounds and its relationship to insect pests

Selection activities in plant breeding can be carried out only if there is variation in the plant’s genetic materials. Plant volatile compounds are media for interaction between plants and insects, making them potential to be used as a selection parameter in resistant plant breeding programs against insect pests. This study aimed to determine the diversity of chili pepper (Capsicum spp.) volatile compounds and to explain its relationship to the main insect pests of chili pepper. The research was carried out at IVEGRI’s research station in Lembang, West Java, Indonesia from March to September 2020. The treatment involved 34 chili pepper varieties. The observation parameters included profiles of volatile compounds measured using GC-MS and incidence of main insect pests (thrips, worms, and fruit fly). The results showed that 87 volatile compounds detected, eight of them, i.e. 3,6-Nonadien-1-ol, (E, Z)-,β-Ocimene, trans-β-Ocimene, 3-Allylcyclohexene, 2,4,6-Octatriene, 3,4-dimethyl-, Neo-allo-ocimene, 1-Octanol and 2-Methylanisole showed a high level of diversity among the chili pepper varieties tested. The results of a simple correlation test showed positive and negative correlations between eight volatile compounds and pest incidence, with a range from -6.80 to 0.87. The relationship between these volatiles compounds and pest incidence will be subject to a further discussion.

The Effect of Antagonist Abiotic Stress on Bioactive Compounds from Basil (Ocimum basilicum)

Drought and flooding are some of the most common stressful conditions for plants. Due to the recent climate changes, they can occur one after another. This study is focused on the effect of antagonistic abiotic stress such as drought and flooding on the different metabolites from Ocimum basilicum leaves. Six-week-old plants of Ocimum basilicum were exposed to drought or flooding stress for 15 days, followed by antagonist stress for 14 days. The assimilation rates decrease drastically for plants under consecutive stresses from 18.9 to 0.25 µmol m−2 s−1 starting at day 3 of treatment. The stomatal conductance to water vapor gs was also reduced from 86 to 29 mmol m−2 s−1. The emission of green leaf volatiles compounds increases from 0.14 to 2.48 nmol m−2 s−1, and the emission of monoterpenes increased from 2.00 to 7.37 nmol m−2 s−1. The photosynthetic pigment concentration (chlorophyll a and b, and β-carotene), the flavonoid content, and total phenolic content decrease for all stressed plants. The results obtained in this study could indicate that the water status (drought and/or flooding) directly impacts basil plants’ physiological parameters and secondary metabolites.

Evolution of Carotenoid Content, Antioxidant Activity and Volatiles Compounds in Dried Mango Fruits (Mangifera Indica L.)

The aim of this research was to study the evolution of carotenoid compounds, antioxidant β-ctivity, volatiles and sensory quality in two mango cultivars dried at 50, 60 and 70 °C. Total carotenoids in fresh samples were about 12 and 6 mg/100 g (dry basis) in Keitt and Osteen samples, respectively. β-carotene was the main carotenoid, representing about 50% of total carotenoids. In both cultivars, carotenoids were more susceptible to drying at 60 °C. Total phenols and metal reduction activity were higher in Osteen than in Keitt, which had higher values in radical scavenging capacity. The antioxidant activities were best preserved with drying temperatures at 50 °C in Keitt and 60 °C in Osteen fruits. Fresh Osteen mango fruits had a volatile compound content of about 37.1, while Keitt of about 5.2 mg/kg (dry basis). All the compounds with odorous impact were significantly reduced after drying. As regards organoleptic characteristics through sensory analysis, Keitt dried mangoes were quite similar to the fresh product, compared to Osteen.

Characterization and Antioxidant Activity of Essential Oil of Four Sympatric Orchid Species

The volatile fractions from fresh inflorescences of naturally growing orchids Anacamptis coriophora (L.) R. M. Bateman, Pridgeon & M. W. Chase subsp. fragrans (Pollini), Anacamptis pyramidalis (L.) R. Ophrys holosericea (Burm.) Greuter and Serapias vomeracea (Burm. f.) B. were isolated by steam distillation and analyzed by GC/FID and GC/MS. Saturated hydrocarbons were quantified as the major constituents of the volatile fraction (47.87–81.57% of the total essential oil), of which long-chain monounsaturated hydrocarbons accounted from 9.20% to 32.04% of the total essential oil. Double bond position in linear alkenes was highlighted by dimethyl disulfide derivatization and MS fragmentation. Aldehydes (from 3.45 to 18.18% of the total essential oil), alcohols (from 0.19% to 13.48%), terpenes (from 0.98 to 2.50%) and acids (0.30 to 2.57%) were also detected. These volatiles compounds may represent a particular feature of these plant species, playing a critical role in the interaction with pollinators. DPPH assay evaluating the antioxidant activity of the essential oils was carried out, showing a dose-dependent antioxidant activity.

Nutrition Quality Parameters of Almonds as Affected by Deficit Irrigation Strategies

The influence of full irrigation, double-regulated (RDI) and sustained deficit irrigation (SDI) treatments on almond quality was assessed by analyzing different parameters: sugars, organic acids, antioxidant activity, total phenolic content (TPC), and volatile compounds. Almond quality studies for plants submitted to water stress are scarce, and it is essential to understand the biochemical responses of plants to water stress in maintaining fruit yield and quality. Citric acid, sucrose, antioxidant activity, and TPC were not affected by the application of studied deficit irrigation strategies (DI). An increase in malic acid and a decrease in glucose was observed for stressed samples (T3 and T4), while a higher number of total volatiles compounds was found for moderate RDI (T2). Using deficit irrigation strategies, the almond yield and quality was not changed, and in fact, some parameters, such as glucose and key volatile compounds, slightly increased under moderate RDI. This finding might encourage farmers to implement these strategies and contribute to sustainable agriculture.

Assessment of the conditions of the thermoplastic extrusion process in the bioactive and mechanical properties of flexible films based on starch and Brazilian pepper

The objective of this work was to produce, through the thermoplastic extrusion process followed by blowing, manioc starch-based flexible films added with Brazilian pepper oil as an antioxidant and plasticizer agent, and verify if the bioactive compounds contained in the fresh pepper oil are present after the drying step of the thermoplastic extrusion. After analysis by gas chromatography-mass spectrometry volatiles compounds were identified in the films. Pepper oil also influenced the mechanichal properties of the films.These results suggest that the temperatures used in the process, kept some of the existing compounds in the Brazilian pepper essential oil adhered to the packages. Keywords: Termoplastic extrusion, temperature, bioactivs compounds

Quality Parameters, Volatile Composition, and Sensory Profiles of Highly Endangered Spanish Citrus Fruits

There is very little information available on the chemical composition and the quality attributes of the citrus species studied which are truly endangered in Spain. None of the fruits studied is available for commercial purposes, which is the main interest and novelty of this study. The aim of this work was to fully describe the morphology, volatile composition, and sensory profile of traditional citrus fruits: sour lime (SoLi), sweet lime (SwLi), and sweet lemon (SwLe), to have the information to convince farmers and growers to cultivate these fruits again. The predominant sugar was fructose while citric acid prevails in SoLi and SwLe. Regarding volatiles compounds, monoterpenes, monoterpenoids, and esters predominated in the juices, and these three families plus sesquiterpenes in the peels. The juice of SoLi presented the highest content of esters (14.8%), SwLi juice presented similar values of both monoterpenes and monoterpenoids (46.1 and 46.0%, resp.), and SwLe juice had the highest content of monoterpenes (72.2%). The results demonstrated the high potential of these citrus materials for the agrofood industry. Therefore, it will be possible to recover these vegetal materials at risk of disappearing for potential uses by the food industry and simultaneously help maintaining the biodiversity.

Wine yeast phenomics: a standardized fermentation method for assessing quantitative traits ofSaccharomyces cerevisiaestrains in enological conditions

This work describes the set up of a small scale fermentation methodology for measuring quantitative traits of hundreds of samples in an enological context. By using standardized screw cap vessels, the alcoholic fermentation kinetics ofSaccharomyces cerevisiaestrains were measured by following the weight loss over time. Preliminary results showed that the kinetic parameters measured are in agreement with those observed in larger scale vats. The small volume used did not impair any analysis of the strain performance. Indeed, this fermentation system was coupled with robotized enzymatic assays and 8 end-point metabolites of enological interest were measured accurately. Moreover, the vessel used offers the possibility to assay 32 volatiles compounds using a headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry approach. Data presented demonstrates that the shaking conditions significantly impacted the mean and the variance of kinetic parameters, primary metabolites, and the production of volatile compounds. This effect was likely due to an enhanced transfer of dissolved oxygen during the first hours of the alcoholic fermentation. To test the efficiency of this experimental design, the phenotypic response of 35 wine industrial starters was measured in five grape juices from the Bordeaux area. A multivariate analysis illustrated that strains were better discriminated by some grape must, than others. The technological performances as well as the phenotypic robustness of these strains was measured and discussed. The optimized methodology developed allows investigating multiple fermentation traits for numerous yeast strains and conditions and greatly contributes in achieving quantitative genetics studies as well as yeast selection programs.