Production system influences volatile biomarkers in tomato

Dynamic changes in the water distribution and key aroma compounds of roasted chicken during roasting

The effects of roasting times (0, 2, 4, 6, 8, 10, 12, and 14 min) on the dynamic changes of the water distribution and key aroma compounds in roasted chicken during the electric roasting process were studied. In total, 36 volatile compounds were further determined by GC-MS and 11 compounds, including 1-octen-3-ol, 1-heptanol, hexanal, decanal, (E)-2-octenal, acetic acid hexyl ester, nonanal, 2-pentylfuran, heptanal, (E, E)-2,4-decadienal and octanal, were confirmed as key aroma compounds. The relaxation time of T22 and T23 was increased first and then decreased, while the M22 and M23 in roasted chicken were decreased and increased with increasing roasting time, respectively. The fluidity of the water in the chicken during the roasting process was decreased, and the water with a high degree of freedom migrated to the water with a low degree of freedom. In addition, the L*, a*, b*, M23 and all amino acids were positively correlated with all the key aroma compounds, while T22, M22 and moisture content were negatively correlated with all the key aroma compounds.

The Difference of Volatile Compounds in Female and Male Buds of Trichosanthes anguina L. Based on HS-SPME-GC-MS and Multivariate Statistical Analysis

Trichosanthes anguina L. (family Cucurbitaceae) is a monoecious and diclinous plant that can be consumed as a vegetable and has anti-inflammatory and antioxidant effects. The chemical composition and content of volatile compounds in female and male buds of T. anguina were explored by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) technology combined with multivariate statistical analysis. The results showed that the content of the volatile compounds was different between female and male buds. 2,2,6-trimethyl-6-vinyltetrahydro-2H-pyran-3-ol and 2,2,6-trimethyl-6-vinyldihydro-2H-pyran-3(4H)-one were the main volatile compounds in both female and male buds. Based on the multivariate statistical analysis of orthogonal projections to latent structures discriminant analysis (OPLS-DA) and t-test, the content of seven compounds was significantly different between female and male buds. The content of three compounds in male buds was higher than that in female, i.e., (E)-4,8-dimethyl-1,3,7-nonatriene, 1,5,9,9-tetramethyl-1,4,7-cycloundecatriene, and (E)-caryophyllene. Conversely, the content of (Z)-4-hexen-1-ol, (Z)-3-hexenyl benzoate, (Z)-3-hexenyl salicylate, and 2-hexen-1-ol in female buds was higher than that in male buds. This is the first report on the difference in the volatile compounds between female and male buds of T. anguina, which enriches the basic research on the monoecious and diclinous plant and provides a reference for the study of plant sex differentiation.

A cerumenolomic approach to bovine trypanosomosis diagnosis

INTRODUCTION

Trypanosomiasis caused by Trypanosoma vivax (T. vivax, subgenus Duttonella) is a burden disease in bovines that induces losses of billions of dollars in livestock activity worldwide. To control the disease, the first step is identifying the infected animals at early stages. However, convention tools for animal infection detection by T. vivax present some challenges, facilitating the spread of the pathogenesis.

OBJECTIVES

This work aims to develop a new procedure to identify infected bovines by T. vivax using cerumen (earwax) in a volatilomic approach, here named cerumenolomic, which is performed in an easy, quick, accurate, and non-invasive manner.

METHODS

Seventy-eight earwax samples from Brazilian Curraleiro Pé-Duro calves were collected in a longitudinal study protocol during health and inoculated stages. The samples were analyzed using Headspace/Gas Chromatography-Mass Spectrometry followed by multivariate analysis approaches.

RESULTS

The cerumen analyses lead to the identification of a broad spectrum of volatile organic metabolites (VOMs), of which 20 VOMs can discriminate between healthy and infected calves (AUC = 0.991, sensitivity = 0.967, specificity = 1.000). Furthermore, 13 VOMs can indicate a pattern of discrimination between the acute and chronic phases of the T. vivax infection in the animals (AUC = 0.989, sensitivity = 0.944, specificity = 1.000).

CONCLUSION

The cerumen volatile metabolites present alterations in their occurrence during the T.vivax infection, which may lead to identifying the infection in the first weeks of inoculation and discriminating between the acute and chronic phases of the illness. These results may be a breakthrough to avoid the T. vivax outbreak and provide a faster clinical approach to the animal.

Postharvest Quality Evolution in Long Shelf-Life “Vesuviano” Tomato Landrace

“Vesuviano” or “piennolo” tomato is among the most famous Italian small tomato landraces and is cultivated on the slopes of Vesuvio volcano (Southern Italy). The “piennolo” tomato is an interesting case with regard to its potential sustainability, as it is traditionally grown in water-deficit conditions with a low fertilizer input. Fruits with a high firmness and a thick skin can be stored for 3–4 months at room temperature (“long shelf-life” or LSL tomato) without postharvest fungicide applications. The aim of this research was to study the retention, changes in quality, and nutritional traits of “Vesuviano” tomatoes over 120 days of “natural” storage. The dry matter, soluble sugar, organic acids, volatile compounds, and carotenoid contents were evaluated at harvesting and in fruits stored for 40, 80, and 120 days. Slight decreases in dry matter content, soluble sugars, and sweetness index were found, while the organic acids levels remained relatively stable. Moreover, interesting increases in the concentrations of certain flavor volatiles, alcohols, aldehydes, and terpenes were detected. Regarding carotenoids, the total lycopene levels exhibited a 1.5-fold increase from harvest to 120 days. The unchanged lycopene cis-isomer levels and the β-carotene/total lycopene ratio is characteristic of relatively stable isomerization activity and indicated an optimal ripening pattern up until the end of the “natural” storage period. These results, which demonstrate good overall quality retention of this LSL tomato, represent a well-grounded reason to enhance the cultivation and marketing of this genetic resource, the fruits of which can be appreciated by consumers during the winter–early spring, when high-quality fresh tomatoes are not available on the markets.

Profiling of 2-Acetyl-1-Pyrroline and Other Volatile Compounds in Raw and Cooked Rice of Traditional and Improved Varieties of India

Herein, optimized headspace solid phase microextraction with gas chromatography–tandem mass spectrometry (HS-SPME-GC-MS/MS) was used to estimate the 2-acetyl-1-pyrroline (2-AP) in raw and cooked rice samples of ten different traditional and improved varieties. Furthermore, HS-SPME-GC-MS-based volatile profiling was subjected to untargeted analyses to identify major odorants in raw and cooked rice samples, and to understand chemical proximities among volatile profiles. Results showed that 2-AP content was remarkably increased in cooked rice compared to raw. Among the varieties studied, Pusa-1652 (Improved Kala Namak) and Kala Namak-2 were superior in the 2-AP content than Basmati varieties. Additionally, Govind Bhog, Kala Jeera and Jeera-32 had 2-AP content equivalent to or superior to Basmati rice varieties. Altogether, 18 and 22 volatiles were identified in the raw and cooked rice samples studied, respectively. Of these, ethyl butyrate, ethyl 3-methylbutanoate, 2-undecanone, ethyl benzoate, ethyl benzeneacetate, 2-methylnaphthalene, and 1-methylnaphthalene were characteristically detected in the cooked rice. The high amount of 2-ethyl-1-hexanol was uniquely found in raw rice samples, which can be a marker compound for freshly milled rice. Along with 2-AP, butanoic acid and benzoic acid derivatives, phenylethyl alcohol, ethyl 3-hydroxybutyrate, and indole may be responsible for the overall perceived characteristic Basmati-like aroma in cooked rice.

Rapid Determination of 6-Methyl-5-hepten-2-one in Fruit with LLE-GC-MS

The volatile compound 6-methyl-5-hepten-2-one (MHO) is an important chemical intermediate and flavor component derived from carotenoid during fruit metabolism, which is important factor impacting consumer-liking. Fruit has complex matrix and is difficult to be purified during MHO analysis. A rapid liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS) method was developed for effective determination of MHO in fruit in this study. The calibration curves for MHO showed high linearity in the range of 100-2000 ng/ml with internal standard method. The limit of detection (LOD), limit of quantification (LOQ) were both <100 ng/ml. Real samples of tomato cultivar fruit were analyzed and RSD of biological replicates varied in the range of 2.01% to 12.59%. MHO showed varied content in different tomato fruit tissues of the selected cultivars, in addition to the variation between cultivars. Furthermore, the possible fragmentation patterns were proposed for the main characteristic ions of MHO and internal standard, based on isolation of the fragment ions after the precursor ion underwent splitting at the electron impact ion source. Compared with reported solid-phase microextraction (SPME)-GC-MS method, the validated method was more rapid, precise, accurate and low cost for MHO quantitation.

Production system influences tomato phenolics and indoleamines in a cultivar-specific manner

Tomato (Solanum lycopersicum) fruit is a rich source of health-promoting compounds, and epidemiological studies show that tomato consumption may reduce the risk of chronic diseases. This study compared the effect of genotype, production system, and their interaction on eight tomato varieties grown in the open-field (OF) or net-house (NH), a structure completely covered with a 50-mesh screen to reduce pest and wind damage, in South Texas. The NH structure reduced solar radiation up to ~30% and decreased wind speed by 6.44 km/h compared with conditions measured in the OF. We simultaneously analyzed 16 phenolics and indoleamines using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight high-resolution mass spectrometry (UHPLC/ESI-HR-QTOFMS). The chemometric analysis showed a distinct difference between NH- and OF-grown tomatoes irrespective of the variety. The melatonin and serotonin contents showed a cultivar-specific effect of the production system. Likewise, the effect of cultivation systems on levels of phenolic acids and flavonoids varied based on tomato cultivar. Among the studied phenolic acids, significantly enhanced levels of sinapic acid were observed in OF-grown tomatoes. Similarly, we detected a considerable genotypic effect on gallic acid, p-coumaric acid, ferulic acid, sinapic acid, and naringin. The interaction of cultivar and production system substantially affected gallic acid, protocatechuic acid, sinapic acid, and apigenin. However, further studies need to be performed to explore the environment-specific effects on the total composition. In summary, our results indicate that the production system plays an important role in tomato composition beyond the natural genetic variation among cultivars.

Effect of Phosphorus Application on Arsenic Species Accumulation and Co-Deposition of Polyphenols in Rice Grain: Phyto and Food Safety Evaluation

The present study was aimed at exploring the effect of soil application of different concentrations of orthophosphate (P) (0, 10, 20, 30, and 40 mg kg-1) on rice agronomic and yield parameters, arsenic (As) species accumulation, and polyphenol levels in the grain of rice grown under As spiked soil (10 mg kg-1). The contents of As species (As(V), As (III), MMA and DMA) and polyphenols in rice grain samples were estimated using LC-ICP-MS and LC-MS/MS, respectively. P treatments significantly reduced the toxic effects of As on agronomic parameters such as root weight and length, shoot and spike length, straw, and grain yield. Among the treatments studied, only the treatment of 30 mg kg-1 P helps to decrease the elevated levels of As (V), As (III), and DMA in rice grains due to As application. The study revealed that 30 mg kg-1 was the optimal P application amount to minimize AS accumulation in rice grains and As-linked toxicity on agronomic parameters and chlorophyll biosynthesis. Furthermore, the levels of trans-ferulic acid, chlorogenic acid, caffeic acid, and apigenin-7-glucoside increased in response to accumulation of As in the rice grain. In conclusion, the precise use of phosphorus may help to mitigate arsenic linked phytotoxicity and enhance the food safety aspect of rice grain.

Effect of production system and inhibitory potential of aroma volatiles on polyphenol oxidase and peroxidase activity in tomatoes

BACKGROUND

Polyphenol oxidase (PPO) and peroxidase (POD) are key enzymes associated with shelf life and defense responses. Thus, the activity of PPO and POD enzymes is usually assessed to check the quality of food samples and to understand the physiological responses of plants to different stresses. However, the outcomes of PPO and POD activity assessment studies are highly dependent on assay conditions. Hence, in this study, we initially optimized PPO and POD extraction and high-throughput 96-well plates-based enzymatic activity assessment methods to evaluate the inhibitory potential of tomato volatile compounds. Later, we explored the effects of net-house and open-field growing on the PPO and POD activity in tomato fruits of eight cultivars.

RESULTS

We found 150 mM of catechol and pH 7.0 were the optimal conditions for the maximum activity for the PPO assay. Conversely, 24 mM guaiacol with 12 mM H₂ O₂ and pH 6.0 was the best condition for the POD assay. Thermal inactivation studies confirmed that tomato POD is more resistant to heat than PPO. We found that the production systems had a considerable genotype-specific impact on tomato PPO and POD activity. Moreover, amongst the volatiles that were studied, β-damascenone and d-limonene showed 50% PPO inhibition at 40 and 80 mM, respectively.

CONCLUSION

The results of this study can be used to improve the shelf-life of fresh tomato fruit and its products. The findings also underscore the significance of PPO and POD enzymes as physiological trait markers in the tomato crop and fruit quality improvement programs. © 2020 Society of Chemical Industry.

Ethylene and Auxin: Hormonal Regulation of Volatile Compound Production During Tomato (Solanum lycopersicum L.) Fruit Ripening

As the auxin-ethylene interaction in climacteric fruit ripening has been highlighted, the hormonal regulation of aroma changes in climacteric fruits requires clarification. The influence of both phytohormones on the volatile organic compound (VOC) metabolism was evaluated during tomato (Solanum lycopersicum L.) fruit ripening. Tomato fruits cv. Micro-Tom and Sweet Grape at the mature green stage were randomly grouped according to treatment with ethylene (ETHY), auxin (IAA), or both (ETHY + IAA). At middle ripening, Micro-Tom ETHY + IAA fruits present VOC profiles similar to those of ETHY fruits, while Sweet Grape presents VOC profiles closer to those of IAA fruits. At full ripeness, Micro-Tom and Sweet Grape ETHY + IAA fruits show profiles closer to those of IAA fruits, suggesting that the auxin overlaps the ethylene effects. Aroma compounds positively correlated with consumer preferences (2-isobutylthiazole, 6-methyl-5-hepten-2-one, and others) are identified in both cultivars and have their contents affected by both hormone treatments. The transcription of genes related to the biosynthesis of important tomato VOCs that have fatty-acid and carotenoid precursors evidences their regulation by both plant hormones. Additionally, the results indicate that the observed effects on the VOC metabolism are not restricted to the Micro-Tom cultivar, as these are also observed in the Sweet Grape cultivar. In conclusion, ethylene and auxin directly regulate the metabolic pathways related to VOC formation, impacting tomato aroma formation during ripening since Micro-Tom fruits apparently at the same maturation stage have different aromas.

Analyses of short-chain fatty acids and exhaled breath volatiles in dietary intervention trials for metabolic diseases

As an alternative to pharmacological treatment to diseases, lifestyle interventions, such as dietary changes and physical activities, can help maintain healthy metabolic conditions. Recently, the emerging analyses of volatile organic compounds (VOCs) from breath and short-chain fatty acids (SCFAs) from plasma/feces have been considered as useful tools for the diagnosis and mechanistic understanding of metabolic diseases. Furthermore, diet-induced changes of SCFAs in individuals with diagnosed metabolic abnormalities have been correlated with the composition changes of the gut microbiome. More interestingly, the analysis of exhaled breath (breathomics) has gained attention as a useful technique to measure the human VOC profile altered as a result of dietary interventions. In this mini-review, we examined recent clinical trials that performed promising dietary interventions, SCFAs analysis in plasma/feces, and VOC profile analysis in exhaling breath to understand the relationship between dietary intervention and metabolic health.

Hormonal and metabolites responses in Fusarium wilt-susceptible and -resistant watermelon plants during plant-pathogen interactions

BACKGROUND

Fusarium oxysporum f. sp. niveum (FON) causes Fusarium wilt in watermelon. Several disease-resistant watermelon varieties have been developed to combat Fusarium wilt. However, the key metabolites that mount defense responses in these watermelon varieties are unknown. Herein, we analyzed hormones, melatonin, phenolic acids, and amino acid profiles in the leaf tissue of FON zero (0)-resistant (PI-296341, Calhoun Grey, and Charleston Grey) and -susceptible (Sugar Baby) watermelon varieties before and after infection.

RESULTS

We found that jasmonic acid-isoleucine (JA-Ile) and methyl jasmonate (MeJA) were selectively accumulated in one or more studied resistant varieties upon infection. However, indole-3-acetic acid (IAA) was only observed in the FON 0 inoculated plants of all varieties on the 16th day of post-inoculation. The melatonin content of PI-296341 decreased upon infection. Conversely, melatonin was only detected in the FON 0 inoculated plants of Sugar Baby and Charleston Grey varieties. On the 16th day of post-inoculation, the lysine content in resistant varieties was significantly reduced, whereas it was found to be elevated in the susceptible variety.

CONCLUSIONS

Taken together, Me-JA, JA-Ile, melatonin, and lysine may have crucial roles in developing defense responses against the FON 0 pathogen, and IAA can be a biomarker of FON 0 infection in watermelon plants.

Effects of genotype and production system on quality of tomato fruits and in vitro bile acids binding capacity

Tomato is an important source of health-promoting constituents, and researchers have focused on enhancing the content. In the present study, the influence of net-house (NH) and open-field (OF) growing conditions on physicochemical traits of tomatoes from eight different cultivars were evaluated. The tomato fruit qualities, such as color, total soluble solids (TSS), total acidity (TA), and pH were measured. Furthermore, ultra-performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) was used for identification and quantification of health-promoting compounds such as ascorbic acid, ß-carotene, lycopene, and its isomers. In addition, in vitro bile acid binding capacity of all tomato samples was analyzed along with soluble and insoluble dietary fiber analysis as biofunctional properties. The results suggest that production systems influenced tomato fruit quality and biofunctional characteristics in a variety-specific manner. Notably, TA and all-trans-ß-carotene values were considerably influenced by production systems, and their levels were higher in the NH- and OF-grown tomatoes, respectively. Our findings underline the importance of the rational choice of genotype and production system to obtain high-quality tomatoes with enhanced desired traits for breeders and consumers. PRACTICAL APPLICATION: Tomato is one of the nutritional high-valued horticultural crops. The present study aimed to assess the impact of production systems, such as net-house and open-field conditions, on physicochemical traits and biofunctional properties, in vitro bile acid binding capacity of eight tomato varieties. This study supplies a good reference for the rational selection of genotype and production system to obtain high-quality tomatoes with improved desired traits for breeders and consumers.

Tomato Metabolic Changes in Response to Tomato-Potato Psyllid (Bactericera cockerelli) and Its Vectored Pathogen Candidatus Liberibacter solanacearum

The bacterial pathogen ‘Candidatus Liberibacter solanacearum’ (Lso) is transmitted by the tomato potato psyllid (TPP), Bactericera cockerelli, to solanaceous crops. In the present study, the changes in metabolic profiles of insect-susceptible (cv CastleMart) and resistant (RIL LA3952) tomato plants in response to TPP vectoring Lso or not, were examined after 48 h post infestation. Non-volatile and volatile metabolites were identified and quantified using headspace solid-phase microextraction equipped with a gas chromatograph-mass spectrometry (HS-SPME/GC-MS) and ultra-high pressure liquid chromatography coupled to electrospray quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS), respectively. Partial least squares-discriminant analysis (PLS-DA) was used to define the major uncorrelated metabolite components assuming the treatments as the correlated predictors. Metabolic changes in various classes of metabolites, including volatiles, hormones, and phenolics, were observed in resistant and susceptible plants in response to the insects carrying the pathogen or not. The results suggest the involvement of differentially regulated and, in some cases, implicates antagonistic metabolites in plant defensive signaling. Upon validation, the identified metabolites could be used as markers to screen and select breeding lines with enhanced resistance to reduce economic losses due to the TPP-Lso vector-pathogen complex in Solanaceous crops.

Optimizing Secondary Electrospray Ionization High-Resolution Mass Spectrometry (SESI-HRMS) for the Analysis of Volatile Fatty Acids from Gut Microbiome

Gut microbiota plays essential roles in maintaining gut homeostasis. The composition of gut microbes and their metabolites are altered in response to diet and remedial agents such as antibiotics. However, little is known about the effect of antibiotics on the gut microbiota and their volatile metabolites. In this study, we evaluated the impact of a moderate level of ampicillin treatment on volatile fatty acids (VFAs) of gut microbial cultures using an optimized real-time secondary electrospray ionization coupled with high-resolution mass spectrometry (SESI-HRMS). To evaluate the ionization efficiency, different types of electrospray solvents and concentrations of formic acid as an additive (0.01, 0.05, and 0.1%, v/v) were tested using VFAs standard mixture (C2-C7). As a result, the maximum SESI-HRMS signals of all studied m/z values were observed from water with 0.01% formic acid than those from the aqueous methanolic solutions. Optimal temperatures of sample inlet and ion chamber were set at 130 °C and 85 °C, respectively. SESI spray pressure at 0.5 bar generated the maximum intensity than other tested values. The optimized SESI-HRMS was then used for the analysis of VFAs in gut microbial cultures. We detected that the significantly elevated C4 and C7 VFAs in the headspace of gut microbial cultures six hours after ampicillin treatment (1 mg/L). In conclusion, our results suggested that the optimized SESI-HRMS method can be suitable for the analysis of VFAs from gut microbes in a rapid, sensitive, and non-invasive manner.

Ethylene and Benzaldehyde Emitted from Postharvest Tomatoes Inhibit Botrytis cinerea via Binding to G-Protein Coupled Receptors and Transmitting with cAMP-Signal Pathway of the Fungus

Tomato storage conditions are difficult largely due to Botrytis cinerea infection which causes gray mold disease. However, the effects of the volatile organic compounds (VOCs) emitted by postharvest tomatoes on this fungus remain unclear. We analyzed the effects of tomato-emitted VOCs on B. cinerea pathogenicity, germination, and hyphal growth with bioassay, predicted the causative active compounds by principle component analysis, identified G-protein-coupled receptors (GPCRs) which captured chemical signals in the B. cinerea genome by stimulating molecular docking, tested the binding affinities of these receptors for the active compounds by fluorescence binding competition assay, and identified an associated signaling pathway by RNA interfere. The VOCs emitted by postharvest tomatoes inhibited B. cinerea; ethylene and benzaldehyde were the active compounds causing this effect. One of the identified GPCRs in B. cinerea, BcGPR3, bound tightly to both active compounds. Two genes associated with the cAMP signaling pathway (BcRcn1 and BcCnA) were downregulated in wild-type B. cinerea exposed to the active compounds, as well as in the ΔBcgpr3 B. cinerea mutant. Exposure to postharvest tomato VOCs reduces B. cinerea pathogenicity due to ethylene and benzaldehyde volatiles. The BcGPR3 protein is inactivated by the active compounds, and thus fails to transmit signals to the cAMP pathway, thereby inhibiting B. cinerea.

Aroma patterns of Beijing rice vinegar and their potential biomarker for traditional Chinese cereal vinegars

Beijing rice vinegar is a typically traditional Chinese cereal vinegar and prevalent in the northern part of China. In this study, the volatile aroma analysis of different fermentation stages of Beijing rice vinegar was carried out by headspace-solid phase micro-extraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS). The aroma could be classified into acids, alcohols, esters, aldehydes, ketones, polyphenols and heterocyclic compounds. The aroma constituents varied at each fermentation stage. Principle component analysis (PCA) was employed to distinguish the specific aroma compounds. At the alcoholization stage, alcohols were mainly ethanol (1993.10 μg/100 mL, 70%), and phenyl-ethyl alcohol (588.64 μg/100 mL, 20%). The ethyl ester meanwhile started to be produced and was the most prevalent ester. The high contents of ethanol, 3-methyl-butanol and phenyl-ethyl alcohol could be the potential aroma biomarker for the alcoholization stage. At the vinegarization stage, ethanol was largely consumed, as well as i-butanol and i-amyl alcohol. The concentration of volatile acids was 1948.01 μg/100 mL with acetic acid the most dominant one (> 90%). Acetic acid and 3-hydroxy-2-butanone were representative compounds for vinegarization stage and could be the potential biomarkers. Furthermore, the aroma comparison of 7 kinds of classic cereal vinegars was carried out. PCA results indicated that the specification of aroma biomarkers for each type of vinegar was practical, serving as the indicators or predictors for both the vinegar fermentation stage identification, vinegar sensory evaluation, and offering a potential for vinegar identification and quality improvement. The assessment strategy was also used to compare the typical Chinese and other important western vinegars.