Effect of sea water on biochemical properties of fruit of tomato (Lycopersicon esculentum Mill.) genotypes differing for ethylene production

BACKGROUND: Three near‐isogenic lines of cv. Gimar differing in ethylene production were used to evaluate the influence of salinity on fruit quality. Plants were grown in rockwool culture and were irrigated with nutrient solution with electrical conductivities (ECs) of 3 and 8 mS cm^?1, which corresponded to 0 and 10% of sea water. For fruits picked at ‘red‐turning’ and ‘red‐ripe’ stages physico‐chemical parameters, ethylene, ascorbate and organic acid content, and cell reductive power were analysed. RESULTS: The same response was observed in all genotypes: the higher salinity growth solution increased dry matter content, total soluble solids (TSS) and titratable acidity but reduced crop yield. Ascorbic acid and also organic acid contents showed a greater accumulation with ripening in the mutant genotypes: this might be due to a slowing of ripening. Our data confirm the lack of any relationship between the larger accumulation of TSS and ethylene production in the fruits of salt‐treated plants. CONCLUSION: These findings suggest that although salinity (10% sea water) reduces fruit yield, it does not have a negative effect on quality. So, it seems possible that controlled use of diluted sea water, combined with suitable tomato genotypes might represent a valid alternative to fresh irrigation water. Copyright © 2007 Society of Chemical Industry     

Comparison of physicochemical,microscopic and sensory characteristics of ecologically and conventionally grown crops of two cultivars of tomato (Lycopersicon esculentum Mill.)

BACKGROUND: Numerous studies have compared ecologically produced foods with conventionally produced competitors, with contradictory results. In this work we investigated the physicochemical, microscopic and sensory properties of two tomato cultivars (Lladó and Antillas), which were grown both ecologically and conventionally. RESULTS: The physicochemical variables size, weight, firmness, total acidity, pH, total solids content, lycopene content and CIELab a*, b*, a*/b*, C* and h* were all significantly influenced by cultivar, as were the sensory variables external colour, internal colour, external aroma intensity and flavour persistence. Compared with conventionally grown tomatoes, ecologically grown tomatoes had larger total solids contents and larger values of the CIELab colour parameters b*, C* and h*, but smaller sizes and weights and smaller values of the CIELab parameter ratio a*/b*; however, these physicochemical differences were insufficient for growing method to have a significant influence on any of the sensory attributes that were evaluated. Microscopy showed the influence of cultivar on lycopene content, but no other structural differences were observed between the two cultivars or between tomatoes grown by different methods. CONCLUSIONS: The statistically significant differences found in this study were mainly between cultivars rather than between tomatoes grown using different management practices. Copyright © 2009 Society of Chemical Industry     

Review of flavonoids and other phenolics from fruits of different tomato (Lycopersicon esculentum Mill.) cultivars

BACKGROUND: Tomato, one of the most important vegetables worldwide, contains a range of flavonoids and phenolic acids in addition to lycopene, which are regarded as potentially useful compounds with respect to health benefits. Composition data in fresh tomatoes vary due to genetic and environmental factors and cultural practices. Breeding programs aim to produce tomatoes with enhanced levels of flavonoids and other phenolics. RESULTS: The present paper gives an overview of flavonoids, stilbenoids and other phenolics reported to occur in tomato fruits. Contents are reported for a wide range of cultivars and types. Metabolism of phenolics during fruit maturation and tissue location are described, and an overview of measured contents is given. Effects of environmental conditions and cultural practices are estimated using available literature. Recent literature on transgenic tomatoes is included, and possibilities for regulating phenolic contents in tomatoes are discussed. CONCLUSION: The literature review clearly discloses a rapidly growing interest in flavonoids and other phenolics in tomato fruits and products made thereof. This is particularly connected to the antioxidant properties of these compounds as well as other possible health effects. Choice of cultivar and effects of environment and agronomic practices are important factors with respect to phenolic qualities and quantities of tomatoes. Copyright © 2009 Society of Chemical Industry     

Organically grown tomato (Lycopersicon esculentum Mill.): bioactive compounds in the fruit and infection with Phytophthora infestans

BACKGROUND: Tomato fruits are characterized by a good nutritional profile, including different bioactive compounds such as carotenoids, phenolic compounds and ascorbic acid. The objective of this study was to analyze the content of bioactive compounds in the fruit and the infection by Phytophthora infestans of 28 tomato genotypes from organic outdoor production. The relationship between bioactive compounds in the fruit and infection with P. infestans was estimated. Field experiments were carried out in 2004 and 2005 at two locations in central Germany. RESULTS: Significant variation among genotypes, locations and years was observed for the content of lycopene, ascorbic acid, total phenolic compounds, antioxidant capacity and the infection level of P. infestans. Antioxidant capacity seemed to be influenced mainly by the phenolics and was highest in small fruits, which were less infected with P. infestans. CONCLUSION: The large genetic variation among tomato genotypes for the content of bioactive compounds in their fruit allows for selection gains. None of the investigated bioactive compounds can be recommended for the indirect selection for increased field resistance against P. infestans. Copyright © 2011 Society of Chemical Industry     

Optical properties and appearance characteristics of tomato fruit (Lycopersicon esculentum)

Characterisation of the optical properties of the internal structures of tomatoes enhances assessment of the composite appearance. Reflectance colorimetry and the Kubelka-Munk analysis to distinguish three distinct maturity groups of tomatoes were tested. Differences in the scatter, absorption and internal transmittance were found amongst the component structures of the intact tomato. Tomato fruit was also pulped and a range of dilutions prepared. The decrease in scatter, absorption and increase in internal transmittance with increased dilution suggests the importance of optical properties with changes in concentration.     

Development of chilling injury symptoms in stored tomato fruit (Lycopersicon esculentum Mill)

Mature-green tomato fruit cv Calypso were stored at 5, 7,12 or 19^oC for 0, 3, 9, 12 or 21 days, ripened at 19^oC for 3 or 6 days and analysed for surface colour (a_L/b_L ratio), firmness, and tissue disorganisation in chill-damaged (pitted) and adjacent unpitted tissues. Manifestation of cell disorganisation and death was evident in pitted tissues. Alternaria spp, Stemphylium spp, Penicillium spp and Aureobasidium spp were isolated from pitted tissues. Fruit stored for either 9 or 12 days at 5 or 7°C subsequently ripened to an acceptable colour, but longer storage times inhibited satisfactory colour development. After storage at 12 or 19°C, fruit surface colour improved progressively with time. Loss of fruit firmness was highest at 19°C but decreased with increasing temperature from 5 to 12°C, showing biphasic maxima firmness loss on days 9 and 21. Surface pits occurred at the stem end and in the equatorial region of the fruit. Fruits were also stored at 7, 12 or 19°C for 10 or 20 days and then ripened at 19°C for 10 days before evaluation of visible defects; these were greatest at 7°C followed by 19°C and were lowest at 12°C.     

Variation of the chemical composition of tomato cultivars (Lycopersicon esculentum Mill.) according to resistance against the tomato yellow leaf curl virus (TYLCV)

BACKGROUND: Tomato producers are looking for alternatives to protect their crops against the tomato yellow leaf curl virus (TYLCV), including replacement of cultivars with other more resistant ones. Major chemical components, sugars, mineral composition, organic acids, lycopene, total phenols and hydroxycinnamic acids were determined in six tomato cultivars, three of them (Boludo, Dorothy and Tyna) resistant, and the other three (Daniela, Dominique and Thomas), non‐resistant against TYLCV. RESULTS: The Daniela cultivar showed the greatest difference with respect to the others, mostly due to the higher content of soluble solids. The major significant differences between the mean values according to the cultivar and resistance against the TYLCV were observed for total soluble solids, pH, ascorbic acid, total phenols and hydroxycinnamic acids. High coefficients of correlation were found between glucose and fructose, and among ferulic, caffeic and p‐coumaric acids. CONCLUSION: Linear discriminant analysis made it possible to differentiate tomato samples according to the cultivar. A clear varietal influence on the chemical composition was observed; however, resistance or non‐resistance against TYLCV does not seem to influence the chemical composition. Copyright © 2008 Society of Chemical Industry     

SRE处理对采后番茄贮藏效果的影响

研究乙醇的新型固体缓释剂(slow-release ethanol,SRE)对采后番茄贮藏效果的影响。以番茄‘粉太郎’为试材,破色期采收,在20℃、相对湿度85%的条件下贮藏,用SRE处理,以不做任何处理为对照,测定番茄贮藏期间品质特性、乙烯释放量及多聚半乳糖醛酸酶(polygalacturonase,PG)和纤维素酶活性。结果表明:SRE处理可以提高果实亮度,延缓果实质量损失率降低,减少可溶性固形物含量损失,保持一定硬度,同时提高了果实贮藏后期糖酸比,比对照果实延缓变红6 d。SRE处理显著降低乙烯释放量和PG、纤维素酶活性。综上,SRE处理可以延缓采后番茄果实成熟衰老,从而延长货架期,使番茄更长久保持风味品质。     

Formation of protein-bound residues of the fungicide chlorothalonil in tomatoes (Lycopersicon esculentum Mill.)

Adding the fungicide chlorothalonil to homogenized tomatoes leads to formation of bound residues in a pH dependent reaction. Recoveries of the fungicide ranged from 84% in pulps with natural pH (4.2) to 7% in pulps with alkaline pH (10.0). Incubation experiments with different model constituents, e.g. carbohydrates, organic acids, and proteins, showed that only the latter were responsible for the very low recoveries of the fungicide. Accordingly, in spiked protein solutions and in spiked tomato pulp, protein-bound residues of chlorothalonil were detected by a dot-blot immunoassay as a structure-specific method.     

Expression of carotenoid biosynthetic pathway genes and changes in carotenoids during ripening in tomato (Lycopersicon esculentum)

To study the expression pattern of carotenoid biosynthetic pathway genes, changes in their expression at different stages of maturity in tomato fruit (cv. Arka Ahuti) were investigated. The genes regulating carotenoid production were quantified by a dot blot method using a DIG (dioxigenin) labelling and detection kit. The results revealed that there was an increase in the levels of upstream genes of the carotenoid biosynthetic pathway such as 1-deoxy-d-xylulose-5-phosphate reductoisomerase (DXR), 4-hydroxy-3-methyl-but-2-enyl diphosphate reductase (Lyt B), phytoene synthase (PSY), phytoene desaturase (PDS) and ζ-carotene desaturase (ZDS) by 2-4 fold at the breaker stage as compared to leaf. The lycopene and β-carotene content was analyzed by HPLC at different stages of maturity. The lycopene (15.33 ± 0.24 mg per 100 g) and β-carotene (10.37 ± 0.46 mg per 100 g) content were found to be highest at 5 days post-breaker and 10 days post-breaker stage, respectively. The lycopene accumulation pattern also coincided with the color values at different stages of maturity. These studies may provide insight into devising gene-based strategies for enhancing carotenoid accumulation in tomato fruits.     

Methyl jasmonate coupled with modified atmosphere packaging to extend shelf life of tomato (Lycopersicon esculentum Mill.) during cold storage

The effects of methyl jasmonate coupled with modified atmosphere packaging (MJ+MAP) on the quality and shelf life of mature green tomato ( Lycopersicon esculentum Mill.) were investigated during cold storage at 5 °C. Tomatoes were treated with 10⁻⁴  m MJ and packaged under 5%O₂/5%CO₂/90%N₂ in a plastic bag. The effects of MJ+MAP were compared with control as well as heat treated (HT) samples. Control samples were tomatoes packaged under atmospheric air. HT samples were prepared by dipping tomatoes in hot water at 50 °C for 3 min and packaged under atmospheric air. The results showed that MJ+MAP and HT could delay ethylene production during tomato ripening and consequently slowed down the softening rate. MJ+MAP tomatoes showed better quality and less chilling injury (CI) symptoms than HT and control samples. Based on a nine-point score, shelf life criteria assumed that rejection would occur when the sensory attributes declined below 5. Control and HT overall acceptance scores were shown to fall below 5 scores after 3 and 6 weeks storage, while MJ+MAP had overall acceptance scores above 5 for up to 9 weeks. Control and HT samples could be stored for about 4 and 6 weeks, respectively, while MJ+MAP tomatoes could be stored for up to 9 weeks.     

Colour of post-harvest ripened and vine ripened tomatoes (Lycopersicon esculentum Mill.) as related to total antioxidant capacity and chemical composition

Greenhouse grown tomatoes (cvs ‘Durinta’, ‘Favorita’ and ‘Liberto’) were harvested green and vine ripe. Colour measurements and chemical analyses were performed on green, post‐harvest red and vine‐ripe fruits. Partial least square (PLS) regression was applied to predict the ferric reducing ability of plasma (FRAP) by means of colour measurements (L*, a* and b*). The PLS showed that 78% of the variation in colour were able to predict 74% of the variation in FRAP value. Chemical variables and colour variables together were able to predict 88% of the variation in FRAP by means of PLS regression. Linear regression showed a high negative correlation between high values of L*, b* and FRAP, and a high positive correlation between titratable acidity, a*, hue, a*/b*, soluble solids, vitamin C, dry matter and FRAP values. Thus, colour measurements of intact tomatoes can be used as a non‐destructive method to assess total antioxidant capacity of tomatoes.     

Inhibition of tomato (Licopersicon esculentum Mill.) pectin methylesterase by pulsed electric fields

High intensity pulsed electric fields were utilized for inhibition of pectin methylesterase (PME) from tomato and a 93.8% reduction of the initial activity was achieved with 400 pulses of 0.02-ms pulse-width at 24 kV/cm. The classical exponential decay model as well as Hülsheger’s and Fermi’s empirical models adequately described the enzymatic inhibition. Hülsheger’s equation yielded parameter values of 0.7 kV/cm, 0.48 ms, and 39 kV/cm, for critical electric field intensity, critical treatment time, and the independent constant factor, respectively. For Fermi’s equation, the critical electric field and steepness parameters ranged from 10.8 to 28 kV/cm and 5.7 to 11 kV/cm, respectively. The residual PME activity reduction as a function of the energy supplied per volume unit was described by an exponential decay model with the constant equal to 0.068 (m³/GJ).     

Effect of different packaging systems on the quality of tomato (Lycopersicon esculentum var. Rio Grande) fruits during storage

A packaging system is designed in our laboratory and evaluated for its suitability to extend storage life and improve the quality of tomato (var. Rio Grande) fruits at ambient temperature (Patent App. No. 484/2005). Freshly harvested mature green tomatoes were packed in polyethylene packaging with or without treating with calcium chloride, boric acid and potassium permanganate. The fruits were then evaluated for changes in quality parameters within the different stages of ripening. The treatments improved the storage life up to 96 days when compared with that of control (32 days). The results showed that within each ripening stage, the treated fruits remained better than that of control and all the ripening stages and treatments are significantly different ( P  < 0.05) from each other. It can also be deduced that treated fruits showed lower weight loss (%), total soluble solids (TSS) contents, acidity and spoilage incidence while ascorbic acid contents, sugar to acid ratio, flavour, texture, colour and overall acceptability were higher in treated fruits when compared with control at the red stage of ripening. Total sugars (%) were low in fruits treated with calcium chloride and boric acid with or without potassium permanganate.     

Fast determination of bioactive compounds from Lycopersicon esculentum Mill. leaves

Lycopersicon esculentum leaves, usually considered as a by-product of tomato production, present several bioactive compounds of interest for industries like food, pharmaceutical and cosmetics. Nevertheless, before industrial application, suitable methods to identify and quantify those metabolites should be developed. In this study agitation with aqueous methanol was used for phenolic compounds extraction. Solid-phase extraction (SPE) was performed as the purification step before alkaloids analysis. Among the SPE sorbents tested, sulphonic acid bonded silica with H(+) counterion (SCX) proved to be the most efficient one for removing interfering components. Fifteen phenolics and four steroidic alkaloids were identified in 35 and 20 min analysis, respectively. The optimised methods were validated, revealing to be accurate, fast, simple and sensitive. Thus, these methods represent an easy and fast analytical approach, using equipment available in almost laboratory, which render them to be appropriate for routine analysis.