Treated Tomato Fruits Research Articles

Effect of delactosed whey permeate treatment on physico-chemical, sensorial, nutritional and microbial properties of whole tomatoes during postharvest storage

The objective of this study was to investigate the efficacy of delactosed whey permeate (DWP) treatment on the physico-chemical, microbial and antioxidant compounds of tomatoes stored at 15 °C for 21 days compared with traditional chlorine treatment. Fresh tomatoes were treated with 3 ml/100 ml DWP or 120 mg/l chlorine solutions and packed in perforated polypropylene bags. The results showed that DWP treatment significantly reduced the number of total aerobic counts (∼1.62 log cfu/g) and yeast and moulds (∼1.66 log cfu/g) of tomatoes compared to chlorine during storage. Moreover, the tomatoes treated by DWP remained firmer (22%) than the control fruits and maintained significantly (p < 0.05) higher levels of vitamin C (15%), total phenols (10%) and antioxidant activity (26%) at the end of storage. Sensory scores confirmed that the DWP treated tomato fruits retained a good appearance and overall quality compared to the chlorine treated samples. The aroma and texture attributes were maintained better in DWP treated tomatoes than chlorine treated tomatoes during storage. Therefore, DWP treatment could be used as a potential washing agent for fresh tomatoes to extend the shelf-life and maintain the nutritional quality during storage.

Effect of hyperbaric treatments on the quality attributes of tomato

Goyette, B., Vigneault, C., Charles, M. T. and Raghavan, V. G. S. 2012. Effect of hyperbaric treatments on the quality attributes of tomato. Can. J. Plant Sci. 92: 541–551. An experimental hyperbaric system was conceptualized, designed and built to explore the effect of hyperbaric treatment on the quality attributes of tomato. Tomato fruits at the early breaker stage were subjected to hyperbaric pressures of 1, 3, 5, 7 or 9 atmabsfor different durations (5, 10 or 15 d) at 13°C. The effect of hyperbaric treatment on postharvest quality of tomato fruit was evaluated with an emphasis on weight loss, firmness, color, titratable acidity (TA) and total soluble solids (TSS). Hyperbaric treated tomato fruit ripened more slowly and were characterized by lower respiration rate than fruits kept under ambient conditions. Significant differences in weight loss, color, lycopene concentration and firmness were found between hyperbaric treated and control tomato fruit. No significant difference was found in the sugar/acid ratio (TSS/TA).

Physiological basis of UV-C induced resistance to Botrytis cinerea in tomato fruit. V. Constitutive defence enzymes and inducible pathogenesis-related proteins

Changes in the protein content and profile of postharvest tomato fruit treated with the hormetic dose (3.7 kJ m −2) of ultraviolet light C (UV-C) at the mature green stage was investigated. In UV-C treated fruits, the total protein content increased until 10 d after treatment and decreased thereafter during a 30 d storage period; whereas in control fruit, protein content decreased constantly throughout the storage period. Using polyacrylamide gel electrophoresis (PAGE) it was shown that UV-C treatment affected the protein profile of tomato fruit in several manners: (1) UV-C repressed the expression of some proteins presumably associated with ripening; (2) it enhanced the expression of several constitutive proteins, of which one was an acidic β-1,3-glucanase, three acidic chitinases and three basic chitinases; and (3) it induced the synthesis of at least 5 new proteins of which four were basic proteins. Among the proteins induced by UV-C, three (a basic β-1,3-glucanase and two acidic chitinases) were apparently pathogenesis-related proteins as they were also induced by inoculation with Botrytis cinerea. The molecular mass (MM) of five of the UV-C induced proteins was determined using SDS-PAGE. Their molecular masses were 45, 39.4, 34.6, 10 and 8.9 kDa. The UV-C induced β-1,3-glucanase had a MM of 33.1 kDa. The MM of two constitutive chitinases were 48.3 and 30.5 kDa, and those of the two UV-C and pathogenesis-induced chitinases were 37.1 and 20.6 kDa. Furthermore, the glucanohydrolase activities induced by UV-C were maintained until the end of the storage period. It is likely that the PR-proteins with glucanohydrolase activities induced by UV-C are an integral part of the long-term resistance observed in UV-C treated tomato fruit.

Microarray analysis of gene expression profile induced by the biocontrol yeast Cryptococcus laurentii in cherry tomato fruit

To obtain an overall view on transcript modification during the cherry tomato fruit responding to biocontrol yeast Cryptococcus laurentii, we performed a microarrary analysis, using Affymetrix Tomato Genechip arrays, representing approximately 10,000 genes. The results showed that 194 and 312 genes were up- or down-regulated, respectively, more then ten time fold (log2 change ratio ≥ 2 or log2 change ratio ≤ − 2) in biocontrol yeast treated tomato fruit as compared with control fruits. Those up-regulated included genes involved in metabolism, signal transduction, and stress response. Conversely, genes related to energy metabolism and photosynthesis were generally down-regulated. Our results suggest that biocontrol yeast treatment induces fruit resistance response, suppresses energy metabolism and photosynthesis. A number of transcripts encoding proteins/enzymes which are known to be up-regulated under some biotic and abiotic stress are also up-regulated after the applying biological control yeast to cherry tomato fruit. The expression of these proteins might increase the fruit resistance towards postharvest pathogen infection and damage.

Delay of postharvest ripening and senescence of tomato fruit through virus-induced LeACS2 gene silencing

Plant virus-induced gene silencing (VIGS) is currently a powerful tool for the study of gene function in plants. Here we report the silencing of LeACS2 by vacuum-infiltration and the tobacco rattle virus (TRV)-based VIGS method, which leads to a significant delay of the postharvest ripening and senescence of tomato fruit. Harvested mature green tomato fruit were vacuum-infiltrated with Agrobacterium strain GV3101 containing pTRV1 and pTRV2- LeACS2. Because of the silencing of LeACS2, the ethylene climacteric and pigment changes were clearly delayed. The onset of fruit ripening and senescence was significantly postponed, and transcription of LeACS2 and ACC synthase activity were also suppressed in treated tomato fruit during storage. The silencing of LeACS2 by vacuum infiltration, however, did not alter the contents assayed at the end of storage. Our results indicate that vacuum infiltration is a highly efficient TRV-based VIGS method to silence LeACS2 in harvested tomato fruit. It can obviously delay ripening and senescence, and is a potential method for postharvest preservation of tomato fruit.

The possible involvement of peroxidase in resistance toBotrytis cinereain heat treated tomato fruit

Mature green tomatoes immediately after harvest were resistant to infection byBotrytis cinerea, although if held for 2 days at 20 °C they lost this resistance. Heat treatment (38 °C for 3 days) after inoculation preventedB. cinereadevelopment. If inoculated following the heat treatment lesions developed but more slowly than on control fruit. Only 60% of the heated fruit developed lesions if inoculated after 3 days at 38 °C and the average size was 1.6 cm, while 100% of the control fruit developed decay and the average decay diameter was 3.5 cm. A highly anionic peroxidase (TAP) mRNA was abundant in mature green tomatoes at harvest and decreased rapidly as the fruits were held at 20 °C. Holding fruit at 38 °C prevented the decrease in TAP mRNA, but once fruits were transferred to 20 °C the loss of mRNA was rapid. Soluble peroxidase activity decreased as harvested fruits were held at 20 °C, while during heat treatment activity was higher than at harvest. NaCl-extractable peroxidase activity was higher in fruits held at 20 °C or 38 °C than at harvest, but a greater increase was seen in heated fruits. Activity gels showed the appearance of new isoforms in heated tomatoes. We suggest that peroxidases may be involved in the resistance of heated tomatoes to pathogen infection.

Recovery of ethylene biosynthesis in diazocyclopentadiene (DACP)-treated tomato fruit

Diazocyclopentadiene (DACP), a competitive ethylene action inhibitor binds irreversibly to the ethylene receptor to reduce tissue responses to ethylene. Tomato fruit (Lycopersicon esculentum Mill cv lsquo;Rondellorsquo;) were treated with DACP at the mature green stage. Ethylene biosynthesis and respiration rate were depressed. Color changes from green to red were delayed. Compared to the control, ACC content increased and ACC oxidase activity in vivo decreased in DACP-treated fruit. Thus, decrease of ethylene production caused by DACP treatment was due to the reduction of ACC oxidase activity. The decline in ripening subsequently recovered after DACP treatment. Results from the Northern analysis for gene expression of ACC synthase and ACC oxidase, showed that expression of both genes declined in DACP-treated fruit, and then recovered. Therefore the recovery of ethylene production was due to the recovery in gene expression and activity of ACC oxidase. We conclude that the effects of DACP on ethylene biosynthesis are on expression of ACC synthase and ACC oxidase genes, and/or regulation of ACC oxidase activity.