Mature Green Tomato Research Articles

Predicting Color Development and Texture Changes in Tomatoes Treated With Hot Water and Exposed to High-Temperature Ethylene Using Support Vector Regression.

This study investigated the impacts of hot water treatment (HWT) at 50°C or 25°C for 5 min and high-temperature ethylene (HTE) exposure at varying temperatures (20°C, 30°C, or 35°C) and durations (24, 48, or 72 h) on the postharvest quality and antioxidant properties of mature green tomatoes (MG). Color changes, physicochemical characteristics, antioxidant compounds, and overall antioxidant ability were assessed. HWT increased β-carotene levels and oxygen radical absorbance capacity (ORAC) while preserving color metrics, despite later HTE exposure. Exposure to HTE delayed ripening, increased titratable acidity, and reduced dry matter content. The effects on antioxidant compounds varied depending on temperature and duration of exposure. A support vector regression (SVR) model predicted color parameters with high performance (R2 > 0.85) for lightness (L*), greenness-redness (a*), blueness-yellowness (b*), chroma, and hue values. The findings highlight the potential of HWT in postharvest quality management and underscore the complex interplay between HWT and HTE on tomato quality parameters.

Sustainable cooling solutions: Designing a zero-energy chamber with local materials in Eritrea

Tomatoes are one of the most widely consumed vegetables globally, yet they are also among the most perishable agricultural products, resulting in significant losses. In Eritrea, a low-income country, tomatoes hold great importance as a vital vegetable crop. To prolong the shelf life of tomatoes and other vegetables, controlled storage conditions, including temperature and humidity management, are essential. However, many small-scale farmers in Eritrea cannot afford expensive storage equipment for their harvested crops. This research aims to address this challenge by exploring the use of a zero-energy cooling chamber to extend the shelf life of raw tomatoes. The cooling achieved by this chamber also results in getting high relative humidity of the air in the cooling chamber from which the evaporation takes place relative to ambient air. A four side rectangular storage with total 0.175 cubic meter capacity, made of bricks; fine bed river sand, jute pad, PVC pipe having 16mm nominal diameter and it is reshaped in to square shape the edges connected by elbow connector placed at the upper center of cavity for keeping wet the sand with dimension of 78 x 78cm, a water tank with capacity of 20 litres connected to perforated PVC pipe for supplying water to the system. Results of the transient performance tests revealed that the zero energy cooling chamber storage temperature varied from ambient temperature by 17-20 oC. The environmental temperature at the period of test ranged over 25-32 oC. After construction of the structure, two stages (red and green mature) of sanmarzano variety tomato were tested. Data at 1, 5, 8,11,23,28 days was recorded and evaluated for firmness, color, general observation, and weight loss. As a result, those stored outside the chamber in ambient environment was in poor state and stayed only for 8 days in case of red tomatoes and 11 days in case of green mature tomato respectively, whereas tomato stored inside ZECC remained fresh at 23 and 28 days red ripe and green mature respectively.

As assessment of shelf life increasing competence of pectin (Zucchini) based edible coating on tomatoes

The most recent advancement in food packaging research involves improving the shelf life of perishable foods by utilising bio-based resources that are edible, eco-friendly, and biodegradable. The current study investigated the effect of edible pectin coating on mature green tomatoes to improve shelf life and storage properties. Zucchini pectin was used to make edible coating. The antimicrobial and antioxidant properties of extracted pectin were investigated. The findings indicated that the extracted pectin had antimicrobial (Staphylococcus aureus, Escherichia coli, and Aspergillus niger) and antioxidant (34.32% at 1 mg/mL) properties.Tomatoes were immersed in pectin solutions of varying concentrations, 1, 3, and 5% (w/v). Physiological evaluations of weight loss, total sugar content, titratable acidity pH, and ascorbic acid were performed on tomatoes during their maturing stages of mature green, light red, pure red, and breaking. Coating the tomatoes with pectin (5%) resulted in minimal weight loss while increasing the retention of total sugar, ascorbic acid, and titratable acidity. The shelf life of the pectin-coated tomatoes was extended to 11 days, while the uncoated control tomatoes lasted 9 days. Thus, a 5% edible pectin solution was found to be effective in coating tomatoes. The current study suggests that using 5% pectin as an edible coating on tomatoes can delay/slow the ripening/maturing process while also extending the shelf-life of tomatoes without affecting their physiochemical properties, which is scalable on a large scale for commercial purposes.

SlZIP11 mediates zinc accumulation and sugar storage in tomato fruits.

Zinc (Zn) is a vital micronutrient essential for plant growth and development. Transporter proteins of the ZRT/IRT-like protein (ZIP) family play crucial roles in maintaining Zn homeostasis. Although the acquisition, translocation, and intracellular transport of Zn are well understood in plant roots and leaves, the genes that regulate these pathways in fruits remain largely unexplored. In this study, we aimed to investigate the function of SlZIP11 in regulating tomato fruit development. We used Solanum lycopersicum L. 'Micro-Tom' SlZIP11 (Solanum lycopersicum) is highly expressed in tomato fruit, particularly in mature green (MG) stages. For obtaining results, we employed reverse transcription-quantitative polymerase chain reaction (RT-qPCR), yeast two-hybrid assay, bimolecular fluorescent complementation, subcellular localization assay, virus-induced gene silencing (VIGS), SlZIP11 overexpression, determination of Zn content, sugar extraction and content determination, and statistical analysis. RT-qPCR analysis showed elevated SlZIP11 expression in MG tomato fruits. SlZIP11 expression was inhibited and induced by Zn deficiency and toxicity treatments, respectively. Silencing SlZIP11 via the VIGS technology resulted in a significant increase in the Zn content of tomato fruits. In contrast, overexpression of SlZIP11 led to reduced Zn content in MG fruits. Moreover, both silencing and overexpression of SlZIP11 caused alterations in the fructose and glucose contents of tomato fruits. Additionally, SlSWEEET7a interacted with SlZIP11. The heterodimerization between SlSWEET7a and SlZIP11 affected subcellular targeting, thereby increasing the amount of intracellularly localized oligomeric complexes. Overall, this study elucidates the role of SlZIP11 in mediating Zn accumulation and sugar transport during tomato fruit ripening. These findings underscore the significance of SlZIP11 in regulating Zn levels and sugar content, providing insights into its potential implications for plant physiology and agricultural practices.

Measures for Reducing Tomato Post-Harvest Losses at Farmer Level in the Lake Victoria Crescent Agro-Ecological Zone.

Globally, tomatoes (Solanum lycopersicum) are recognized as a significant vegetable crop with nutritional, health, and economic importance. In Uganda, small-scale tomato farmers, obtain low yields due to biotic and abiotic conditions of pests, diseases, lack of irrigation, and insufficient knowledge of sustainable farming practices. Post-harvest losses further hinder tomato production by limiting the amount of high-quality produce reaching the market. This study used a largely qualitative approach to understand the mechanisms tomato farmers in Wakiso and Luwero districts in Central Uganda use to reduce post-harvest losses at farm level. The study reveals that the Assila F1 Hybrid is the predominant variety—chosen for its firmness, extended shelf life, and resistance to pests and diseases. Farmers adopted staggered planting to manage post-harvest losses, harvesting mature green tomatoes in the morning and evening. However, a lack of technical expertise resulted in a deficiency of deliberate post-harvest treatments, and the absence of a mandatory body for produce inspection negatively impacted quality. Individual sales by farmers without standardized measurements also contributed to exploitation by middlemen. The study recommends farmers’ capacity building in appropriate post-harvest handling practices.

Exogenous dsRNA sequence based on miR1917 downregulates its target gene related to ethylene signaling in tomato seedlings and fruit

The recent developments in application of RNA interference present a novel strategy for combating plant diseases by targeting pathogen genes. This study aimed to design, synthesize, and administer a double-stranded RNA (dsRNA) in tomato (var. Microtom) plants, drawing inspiration from the interaction between miR1917 and its target, the negative regulator of ethylene perception, Constitutive Triple Response 4 splicing variant 3 (CTR4sv3). An assessment of the potential endogenous effects stemming from the application of RNA molecules onto plant tissues was conducted, with a particular focus on observing resultant phenotypic changes. For seedling development analysis, seeds were soaked in a dsRNA solution for analysis, and they showed triple response phenotypic traits: reduction in root and hypocotyl length by up to 81 % and 60 % respectively, coupled with the noticeable development of hook. Furthermore, an 81 % decrease in CTR4sv3 expression was recorded, along with a 17-fold increase in the ethylene biosynthesis gene ACO1. Conversely, green-mature tomato fruit were subjected to dsRNA injections, resulting in a 43 % reduction in CTR4sv3 levels, accompanied by a more than 3-fold increase in ACO1 levels. Altogether, it is reported that the utilization of dsRNA based on miR1917 downregulates CTR4sv3, and the concomitant increase in ACO1 in both seedlings and fruit. With these findings, we propose that miRNA and target interactions can serve as a basis for RNA interference design and its application in plants to inhibit the plant's own mRNA can modify biosynthetic pathways, addressing both scientific inquiries and technological objectives.

Sustainable Approaches to Prolonging Shelf Life in Green Mature Tomato Fruit

Green mature tomato fruits demonstrate better transportability compared to fully matured ones. This approach has the potential to play a significant role in diminishing postharvest losses and enhancing the accessibility of nutritionally rich fruit in developing countries. The instability of electricity and insufficient cold storage facilities is recognized for fading the shelf life of various fruits and vegetables. However, post-harvest interventions, including tomatoes, can extend perishable products' shelf life. Firstly, tomato fruits were harvested at the green mature stage and stored at 33℃ for 0, 10, 20, and 30 days, followed by a shift to 25℃. Subsequently, ten fruits were subjected to various treatments: A - control (25℃), B - 33℃ with 30-40% RH, C - 33℃ with 50-60% RH, and D - 33℃ with 80-90% RH. Different relative humidity (RH) levels were achieved using saturated salts, specifically MgCl2.6H2O, Mg (NO3)2.6H2O, and KCl+KNO3 for treatments B, C, and D, respectively. The evaluation encompassed parameters such as ethylene production, CO2 release, fruit firmness, weight loss, and color development. A higher temperature, such as 33℃, may be considered advantageous for the storage of green mature tomato fruit. Evidently, tomatoes were successfully stored for over 55 days at this temperature. Across all relative humidity (RH) conditions, there was more noticeable color development in fruits stored at 25°C compared to those stored at 33°C. Among the various RH conditions, fruits stored at 33°C with 80-90% RH experienced the least weight loss, although fruit firmness gradually declined over time. Storing green mature tomato fruit at 33°C with 30-40% RH resulted in the lowest ethylene production compared to 25°C and other RH conditions. Consequently, certain practical benefits of green mature tomato fruit under elevated temperatures and diverse relative humidity (RH) conditions are suggested. However, further detailed research may be necessary to explore potential metabolic changes.

Transcriptomic analysis in tomato fruit reveals divergences in genes involved in cold stress response and fruit ripening.

Cold storage is widely used to extend the postharvest life of most horticultural crops, including tomatoes, but this practice triggers cold stress and leads to the development of undesirable chilling injury (CI) symptoms. The underlying mechanisms of cold stress response and CI development in fruits remain unclear as they are often intermingled with fruit ripening changes. To gain insight into cold responses in fruits, we examined the effect of the potent ethylene signaling inhibitor 1-methylcyclopropene (1-MCP) on fruit ripening, CI occurrence and gene expression in mature green tomatoes during storage at 20°C and 5°C. 1-MCP treatments effectively inhibited ethylene production and peel color changes during storage at 20°C. Storage at 5°C also inhibited both ethylene production and peel color change; during rewarming at 20°C, 1-MCP treatments inhibited peel color change but failed to inhibit ethylene production. Furthermore, fruits stored at 5°C for 14 d developed CI symptoms (surface pitting and decay) during the rewarming period at 20°C regardless of 1-MCP treatment. Subsequent RNA-Seq analysis revealed that cold stress triggers a large-scale transcriptomic adjustment, as noticeably more genes were differentially expressed at 5°C (8,406) than at 20°C (4,814). More importantly, we have found some important divergences among genes involved in fruit ripening (up- or down-regulated at 20°C; inhibited by 1-MCP treatment) and those involved in cold stress (up- or down-regulated at 5°C; unaffected by 1-MCP treatment). Transcriptomic adjustments unique to cold stress response were associated with ribosome biogenesis, NcRNA metabolism, DNA methylation, chromatin formation/remodeling, and alternative splicing events. These data should foster further research into cold stress response mechanisms in fruits with the ultimate aim of improving tolerance to low temperature and reduction of CI symptoms during cold storage.

Quantitative proteomic analysis of tomato fruit ripening behavior in response to exogenous abscisic acid.

To determine how abscisic acid (ABA) affects tomato fruit ripening at the protein level, mature green cherry tomato fruit were treated with ABA, nordihydroguaiaretic acid (NDGA), or sterile water (control, CK). The proteomes of treated fruit were analyzed and quantified using tandem mass tags (TMTs) at 7 d after treatment, and the gene transcription abundances of differently expressed proteins (DEPs) were validated with qRT-PCR. The postharvest tomato fruit underwent faster color transformation and ripening than the CK when treated with ABA. In total, 6310 proteins were identified among the CK and treatment groups, of which 5359 were quantified. Using a change threshold of 1.2 or 0.83 times, 1081 DEPs were identified. Among them, 127 were upregulated and 127 were downregulated in the ABA vs CK comparison group. According to KEGG and protein-protein interaction network analyses, the ABA-regulated DEPs were primarily concentrated in the photosynthesis system and sugar metabolism pathways, and 102 DEPs associated with phytohormones biosynthesis and signal transduction, pigment synthesis and metabolism, cell wall metabolism, photosynthesis, redox reactions, allergens, and defense responses were identified in the ABA vs CK and NDGA vs CK comparison groups. ABA affects tomato fruit ripening at the protein level to some extent. The results of this study provided comprehensive insights and datas for further research on the regulatory mechanism of ABA in tomato fruit ripening. This article is protected by copyright. All rights reserved.

The impact of alginate composites enriched with spent black tea, green tea, jasmine tea, and Oolong tea wastes on the shelf-life extension of fruits and vegetables

Bananas and tomatoes are of the most valuable staple foods in the world. They are widely cultivated in tropical countries. Freshly harvested green bananas and tomatoes are brought from the plantation field, packed and shipped to many countries such as the USA and European countries. However, being climacteric fruits, a major challenge for bananas and tomatoes supply stakeholders is the short post-harvest shelf-life due to rapid onset of ripening and undesirable ripening-associated changes, which result in their major losses. This work aimed to determine the impact of biocomposites based on spent tea waste (STW) and alginate on Cavendish banana (Musa acuminata) and tomatoes shelf-life. STW from black tea, green tea, jasmine tea, and Oolong tea were obtained through hot water extraction. The highest and lowest recoveries were recorded for green tea powder (96.0%) and Oolong tea leaf (88.33%), respectively. Composites were fabricated in sodium alginate cross-linked calcium chloride with or without STW. The STW-alginate composites were investigated for their effects on water absorptivity, gas absorptivity, and ripening of mature green bananas and tomatoes via monitoring of peel color changes visually and comparing to the standard color charts. The results indicated that the STW-alginate composites had variable effects on water absorptivity compared to the control. The spent green tea powder-alginate composite displayed the highest water absorptivity (212%). Moreover, the STW-alginate composites were able to prolong the ripening of both bananas and tomatoes stored in both plastic containers and modified atmosphere storage (MAP) bags at room temperature compared to the control. Composite enriched with spent green tea retained banana greenness for up to seven weeks compared to less than three weeks for the control. The results were consistent for follow-up study using MAP bags with banana and tomato. Specifically, compared to controlled group, green tea powder followed by Jasmine tea powder were the only two composites could extend to six weeks. Accordingly, STW-alginate composites hold potential as simple and novel bio-sorbents that can be applied in extending post-harvest banana shelf-life in a safe and sustainable manner.

Salmonella transfer potential between tomatoes and cartons used for distribution

Corrugated fiberboard boxes (cartons) can be reused during fresh market tomato packing and repacking. The fate of Salmonella on the new, used, and dirty tomato packaging cartons, and Salmonella transfer between tomatoes and new, used, and dirty packaging cartons was assessed. Mature green tomatoes or blank cartons were spot inoculated with cocktail of rifampicin-resistant Salmonella strains before touching cartons/tomatoes at 0, 1, or 24 h postinoculation. Tomatoes were placed on new, used, and dirty carton squares (5 by 5 cm) for 0, 1, and 7 days of contact at 12°C and 25°C with a relative humidity value of 85%. Transfer coefficients (TCs) were calculated for all conditions. Salmonella populations decreased following inoculation by 2–3 log units during 24 h drying regardless of storage temperature; the presence of debris enhanced survival at 12°C. In general, the highest transfer rates occurred with wet inoculum. The highest Salmonella transfer was calculated for wet inoculated tomatoes with 7 days of contact time at 25°C (TC = 14.7). Increasing contact time decreased TCs for new cartons, but increased TCs for used and dirty cartons. Regardless of carton condition or storage temperature, a greater population of Salmonella was transferred from tomatoes to cartons than from cartons to tomatoes. Salmonella transfer between tomatoes and cartons is highly dependent on moisture, with increased levels of moisture increasing transfer, highlighting the importance of harvesting and packing dry tomatoes.

THE EFFICACY OF POSTHARVEST BIOCONTROL TREATMENTS IN CONTROLLING SPOILAGE OF TOMATO FRUIT IN SOUTH AFRICAN COMMERCIAL SUPPLY CHAINS

In this study, the effectiveness of postharvest biocontrol treatments using B-13 yeast isolate in controlling spoilage of tomato fruit was evaluated in selected commercial supply chains in South Africa. Mature green tomatoes were harvested from three commercial farms in Limpopo (Musina, Mooketsi and Pont drift) during summer and transported through the three supply routes to Pietermaritzburg, where four postharvest treatments were applied to the fruit, then stored in ambient and cold storage (11oC) conditions. The fruit was sampled over a 30-day storage period and its firmness, colour, weight loss, marketability and incidences of decay assessed. Fruit stored under ambient conditions had higher incidences decay, diseases and physiological disorders compared to samples stored in cold storage, with these incidences varying widely with pre-storage treatments applied on the fruit. The supply chain route significantly (p≤0.05) influenced the physicochemical and subjective quality of tomato fruit. Biocontrol treatment reduced mass loss of fruit and had comparable physicochemical and subjective attributes to chlorine treated fruit. Biocontrol treatment was also effective in maintaining fruit firmness and colour for the first eight days of storage. Biocontrol treated fruit had 7.9% and 7.7% lower mass loss compared to control and chlorine fruit treated fruit, respectively. Although, biocontrol treatment showed promising prospects in controlling tomato spoilage and improving its shelf life, integrating it with other treatments should be further tested to improve its efficacy.

The use of brick-walled evaporative cooler for storage of tomato

A cost-effective alternative to cold storage is the brick-walled evaporative cooler (BEC). The effects of BEC on mature green and breaker ‘Diamante Max’ tomatoes were assessed. Two trials were carried out at ambient conditions with (i) 27.13±0.78 °C and 80.89±4.47%RH; (ii) 26.93±0.87 °C and 80.05±5.20% RH and with BEC (i) 25.49±0.58 °C and 99.90±0.10% RH; (ii) 25.42±0.90 °C and 97.75±3.25% RH. BEC-stored tomatoes showed 10.36% lesser weight loss, lesser decay incidence, redder color and better visual quality compared to control fruit. The higher L* and hue of around 90 in ambient-stored tomatoes indicated a lighter color as fruit turned to yellow compared to a lower L* and hue in BEC indicating a darker red color. An increased chroma was recorded as fruit turned from green or breaker to yellow, orange, or light red while the values of a* became negative. The BEC maintained the firmness and total soluble solids, especially in mature green tomatoes. After 49 days of storage, 61.8% of the fruit stored in the BEC were marketable compared to 23.3% in ambient conditions. The BEC system showed 27.16% higher annual benefit over cost than the ambient storage conditions. Thus, the BEC system can potentially maintain the quality of ‘Diamante Max’ tomatoes.

Modeling the metachronous ripening pattern of mature green tomato as affected by cultivar and storage temperature

Nutritional benefits and organoleptic characteristics, including visual, textural, taste, and flavor, are the critical characteristics of economically important fruit. Ripening is a crucial phenomenon in the formation of these quality characteristics in fruits. Therefore, controlling the ripening phenomenon is extremely important not only to maximize the benefits of the fruit but also to avoid food losses caused by over-ripening. Tomato is an important model plant, especially for research on fruit ripening. The metachronous model of tomato ripening is presented in this report. This model predicts the postharvest ripening time of tomato fruit in terms of red color development based on the storage period. A modified sigmoid-type function model was used to develop the prediction model. The observations and analyses were conducted at different storage temperatures and in different tomato cultivars. The result exhibits that the integration of the proposed model and time lag was successfully showing the postharvest ripening time history of tomato fruit at the full range ripening process, from onset to fully ripe. This study provides critical information on postharvest quality control research and supply chain development in eliminating food loss and waste, which leads to the realization of sustainable development goals.

Chitosan oligosaccharide treatment improves quality attributes of tomato fruit stored under room temperature

Effect of chitosan oligosaccharide (COS), a natural product of low-cost and non-toxic with high biological activities, on quality attributes of tomato during post-harvest storage was investigated. Mature green tomato fruit were treated with 0.5 g L−1 COS and stored under room temperature. The results showed that COS was effective in improving fruit quality as revealed by redder color skin, higher content of nutrients such as carotenoids (lycopene and β-carotene) and vitamin C, and increased emissionb of flavor-associated volatiles (1-penten-3-one, heptanal, (E)-2-heptenal, 2-phenylacetaldehyde, 2-phenylethanol, 2-isobutylthiazole and β-ionone). The increased content of carotenoids upon COS treatment was correlated with the elevated expression levels of carotenogenic genes such as SlDXS, SlGGPS, SlPSY1, SlPDS, SlZDS, and SlLCY-B2. Moreover, COS-treated fruit exhibited accelerated occurrence of climacteric ethylene peak, enhanced ethylene production, and elevated expression of genes involved in ethylene biosynthesis (SlACS2, SlACS4, and SlACO1), perception (SlETR3), and response (E4 and E8), implying that COS might regulate fruit ripening and quality by enhancing ethylene biosynthesis and signaling. These findings help to extend our understanding of the function of COS in fruit ripening and provide a new strategy to improve tomato fruit quality during room temperature storage.

Maintenance shelf-life quality of cocktail tomatoes by using UV-C illumination and Arabic gum coating.

The aim of the study was to investigate the effects of Arabic gum (AG) coating, UV-C illumination and its combinations on postharvest quality parameters of cocktail tomatoes (Solanum lycopersicum L. cv. Ipekce F1 ). After harvest, mature green tomatoes were treated with 10% Arabic gum (AG10), 20% AG (AG20), 3.6kJ m-2 ultraviolet-C (UV-C) illumination, 3.6kJ m-2 UV-C+AG10 and 3.6kJ m-2 UV-C+AG20, and stored at 20 °C for 20 days. The highest titratable acidity (TA), total soluble solids (TSS) and the lowest weight loss were obtained in AG20 treatments. Maximum fruit firmness and L* value were in AG20 and UV-C+AG20 treatment. The greatest h° values were recorded in AG20, UV-C+AG20 and control group. The highest vitamin C content were obtained from AG20, UV-C+AG10 and UV-C+AG20 treated tomatoes. Minimum lycopene content was determined from AG10, AG20, UV-C+AG10 and UV-C+AG20 treatments. Maximum chlorophyll content was determined from UV-C+AG20-treated tomatoes. AG10, AG20, UV-C+AG10 and UV-C+AG20 treatments resulted in lower ethylene emissions as compared to control and UV-C-treated tomatoes. AG20, UV-C+AG10 and UV-C+AG20 treatments generally had lower values than control and UV-C in term of respiration rates. It is concluded that AG20 treatment effectively maintained the postharvest quality and biochemical properties of cocktail tomatoes as compared to other tested treatments. © 2021 Society of Chemical Industry.

Additional Blue LED during Cultivation Induces Cold Tolerance in Tomato Fruit but Only to an Optimum.

Simple SummaryLED lighting is increasingly applied to increase yield and quality of greenhouse produced crops, especially tomatoes. Tomatoes cannot be stored at cold temperatures due to chilling injury that manifests as quick quality deterioration during shelf life. The aim of this study is to investigate whether additional blue LED lighting can mitigate the negative effects of cold storage for ‘Foundation’ tomatoes. We applied three treatments, 0, 12 or 24% additional blue light during cultivation, and investigated quality attributes at harvest, after cold storage and subsequent shelf-life. We observed that red harvested tomatoes cultivated with 12% additional blue light acquired cold tolerance. Interestingly, these tomatoes were slightly less red colored at harvest and showed a faster loss of red color during cold storage. The measured red color is closely related to the lycopene concentration. We hypothesize that lycopene, a known antioxidant, present in 12% additional blue cultivated tomatoes mitigates chilling injury. Other antioxidants present in tomatoes were only affected by the ripeness at harvest and were therefore not involved in the acquired cold tolerance. The cultivation of tomatoes using additional blue LED is an attractive way to produce tomatoes that can withstand long transport at cold temperatures at the expense of a slightly less red tomato at the consumer.Tomato is a chilling-sensitive fruit. The aim of this study is to examine the role of preharvest blue LED lighting (BL) to induce cold tolerance in ‘Foundation’ tomatoes. Blue and red supplemental LED light was applied to achieve either 0, 12 or 24% additional BL (0B, 12B and 24B). Mature green (MG) or red (R) tomatoes were harvested and cold stored at 4 °C for 0, 5, 10, 15 and 20 d, and then stored for 20 d at 20 °C (shelf life). Chilling injury (CI) indices, color and firmness, hydrogen peroxide, malondialdehyde, ascorbic acid and catalase activity were characterized. At harvest, R tomatoes cultivated at 12B were firmer and showed less coloration compared to fruit of other treatments. These fruits also showed higher loss of red color during cold storage and lower CI symptoms during shelf-life. MG tomatoes cultivated at 12B showed delayed coloring (non-chilled) and decreased weight loss (long cold stored) during shelf life compared to fruit in the other treatments. No effects of light treatments, both for MG and R tomatoes, were observed for the selected antioxidant capacity indicators. Improved cold tolerance for R tomatoes cultivated at 12B points to lycopene having higher scavenging activity at lower concentrations to mitigate chilling injury.

Metabolic changes associated with chilling injury tolerance in tomato fruit with hot water pretreatment.

Hot water treatment (HWT) of tomato (Solanum lycopersicum L.) fruit reduces the symptoms of chilling injury (CI). The aim of this study was to identify metabolites associated with HWT-induced CI tolerance in tomato fruit cv. Imperial. Mature green tomatoes with HWT (42°C/5min) and control were stored under chilling conditions (5°C/20days) and then ripened (21°C/7days). Methanol extracts from pericarp were analyzed for total phenolics (TP), antioxidant activity (AoxA), and metabolic profiling by UPLC-DAD-MS and GC-MS. After cold storage and ripening, HWT fruit showed less CI, higher TP, and AoxA than control. It also showed an increased accumulation of phenolics, sugars, and some alkaloids that may be mediated by azelaic acid, glutamine, and tryptophan. The levels of N-feruloyl putrescine, esculeoside AII, and hydroxy-α-tomatine II were reduced. The better metabolic performance of HWT fruit under cold storage was associated with a higher accumulation of several metabolites (e.g., antioxidants and osmolytes) in ripening fruit. PRACTICAL APPLICATION: The identification of metabolites associated with the reduction of chilling injury (CI) symptoms in HWT tomato fruit extends the understanding of the mechanisms involved in CI tolerance. This information provides targets that could be used to develop strategies for preventing CI (e.g., genetic improvement of tomato, direct application of key metabolites). The application of such strategies will increase the economic value and decrease postharvest losses.

Mass Spectrometry Imaging Analysis of Metabolic Changes in Green and Red Tomato Fruits Exposed to Drought Stress

Plant metabolism is altered in response to various environmental changes. In vegetable crops such as tomato (Solanum lycopersicum), the metabolic composition of fruits varies depending on the variety or cultivar as well as the cultivation method used. Few studies have examined the metabolic fluctuations in fruits under stress conditions, such as drought. We previously examined the metabolomes of mature green tomato fruits, which undergo drastic changes in chemical composition during ripening, and mature red fruits in response to drought stress. We detected or predicted fluctuations in the levels of fatty acids and phospholipid constituents, such as inositol and ethanolamine. In this study, we determined the localizations of these metabolites in fruits using mass spectrometry imaging. The accumulation patterns of stearic acid and palmitic acid were similar, but unlike these fatty acids, oleic acid accumulated to high levels in the placenta. Inositol is involved in various physiological processes; under drought conditions, this metabolite is synthesized by a different pathway compared to under normal conditions. The biosynthesis of pectin, a component of the gel surrounding the seeds, was suppressed under drought stress but increased in seeds. We propose that under drought conditions, a shift to phospholipid biosynthesis occurs that protects seeds from dehydration.

Assessment of Contamination Risk from Fecal Matter Presence on Fruit and Mulch in the tomato fields based on generic Escherichia coli population

The purpose of this study was to evaluate the fate of generic Escherichia coli in fecal pats under different field conditions and to predict Salmonella and Shiga toxin-producing E. coli (STEC) survival dynamics based on developed models. Eight trials were conducted during spring and fall in both North and Central Florida. Fresh cattle feces (1g) was placed on mature green round tomatoes located inside (TIP) and outside (TOP) of the plant canopy. Fecal pats (10 g) were placed under (MUP) and distant (MDP) to tomato plants on plastic mulch. Pathogen populations were predicted based on developed models. Declines in generic E. coli populations over 7 days (Log CFU/g) in fecal pats were between 0.9 and 2.7 on TIP, 1.2 and 3.0 on TOP, 0.2 and 1.2 on MUP, and 0.4 and 1.5 on MDP in the Central Florida fall and spring trials, respectively. E. coli populations remained stable at ≤4.2 and ≤ 6.5 Log CFU/g during all North Florida trials. The concentration changes in predicted Salmonella and STEC population were less than 2.1 Log CFU/g in fecal pats for all conditions. Developed models predicted similar pathogen survival trends to generic E. coli with no dramatical impact under the field conditions.