Tomato Skin Research Articles

Tomato peeling by ohmic heating with lye-salt combinations: Effects of operational parameters on peeling time and skin diffusivity

Ohmic heating without lye has shown promise in tomato peeling; however the use of lye is known to yield high peeled-product quality. In this work, we studied the operational parameters of the ohmic peeling process, specifically, the influence of salt-lye concentration combinations and field strength on time for skin cracking during ohmic peeling. We further investigated the influence of electric fields on the lye diffusivity through tomato skin. The treatments of 0.01/0.5% NaCl/NaOH at 1610 V/m and 0.01/1.0% NaCl/NaOH at 1450 V/m were the conditions that required the shortest time for cracking. For NaCl/KOH mixtures, 0.01/0.5% NaCl/KOH at 2020 V/m and 0.01/1.0% NaCl/KOH at 1450 V/m required the shortest time for cracking. Studies on diffusion through the tomato skin showed that ohmic heating significantly improved lye diffusion (p < 0.05) at both 50 and 65 °C. After an initial period, diffusivities of lye peeling with ohmic heating were greater than those without ohmic heating at both 50 and 65 °C, confirming that the electric field enhances diffusion of NaOH through the tomato skin.

Naringenin ameliorates streptozotocin-induced diabetic rat renal impairment by downregulation of TGF-β1 and IL-1 via modulation of oxidative stress correlates with decreased apoptotic events

Context: Naringenin, a flavonone and a nutritive antioxidant which is mostly obtained from grapefruit, orange or tomato skin, has been extensively studied due to its radical scavenging activity.Objective: The present study investigates the protective effect of naringenin on rat kidney after streptozotocin-induced diabetes.Materials and methods: Sixty male Wistar rats were divided into six groups. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg/kg) in groups II, III and IV. Naringenin 5 mg/kg body weight was given to groups III and V, but 10 mg/kg was given to groups IV and VI, orally once a day for 10 weeks. After which all animals were sacrificed, and the biochemical, histopathological, immunohistochemical and apoptotic assays were conducted.Results: Naringenin treatment with 5 and 10 mg/kg significantly decreased (p < 0.05) the serum biochemical parameters, elevated tissue malondialdehyde levels and increased (p < 0.01) the reduced superoxide dismutase, catalase and reduced glutathione enzyme activities in the diabetic kidney. Diabetes-induced naringenin-treated groups showed an improved histology and revealed a significant reduction in apoptosis activity (7.2 ± 0.01 and 1.8 ± 0.05) and in expression of TGF-β1 (18.9 ± 3.4 and 10.2 ± 2.1) at a dose of 5 and 10 mg/kg, respectively. Similarly, in contrast to the diabetic group, a significant difference was observed in the IL-1 expression (15.68 ± 4.3) in 5 mg/kg and (9.85 ± 2.1) in 10 mg/kg naringenin-treated groups.Conclusion: Naringenin acts as a protective agent in diabetic renal impairment by altering oxidative stress, modulation of cytokines expression and apoptotic events.

Physical and Chemical Properties of Vacuum Belt Dried Tomato Powders

Vacuum belt drying (VBD) was used to produce powders (aw = 0.2–0.3) from tomato pulp and skin-rich fractions. Drying times ranged from 3 to 14 h for pulp slices, when conduction heaters were specified at 100 to 60 °C, and between 1 to 3 h for thin layers of tomato skins. Modeling of moisture isotherms showed that dried pulp had greater monolayer moisture than dried skins and at a given aw had greater associated moisture content. Hygroscopicity measurements at 86 % relative humidity showed that while the pulp powders pick up more moisture, they do so at a rate similar to the tomato skin powders. Both fractions produced flowable powders, but skin powders had greater flowability than pulp powders. In general, tomato skin powders were darker and redder than tomato pulp powders, presumably as the fresh skins had greater lycopene content (2674 μg/g d.w.) than the pulp (1997 μg/g d.w.). The least decrease in trans-lycopene occurred for pulp dried at 60 °C (3.7 % decrease) and for skins dried at 80 °C (1.7 % decrease).

Bread enriched in lycopene and other bioactive compounds by addition of dry tomato waste.

The tomato processing industry generates high amounts of waste, mainly tomato skins and seeds, which create environmental problems. These residues are attractive sources of valuable bioactive components and pigments. A relatively simple recovery technology could consist of production of powders to be directly incorporated into foods. Tomato waste coming from a Romanian tomato processing unit were analyzed for the content of several bioactive compounds like ascorbic acid, β-carotene, lycopene, total phenolics, mineral and trace elements. In addition, its antioxidant capacity was assayed. Results revealed that tomato waste (skins and seeds) could be successfully utilized as functional ingredient for the formulation of antioxidant rich functional foods. Dry tomato processing waste were used to supplement wheat flour at 6 and 10% levels (w/w flour basis) and the effects on the bread's physicochemical, baking and sensorial characteristics were studied. The following changes were observed: increase in moisture content, titratable acidity and bread crumb elasticity, reduction in specific volume and bread crumb porosity. The addition of dry tomato waste at 6% resulted in bread with good sensory characteristics and overall acceptability but as the amount of dry tomato waste increased to 10%, bread was less acceptable.

A pilot scale electrical infrared dry-peeling system for tomatoes: Design and performance evaluation

A pilot scale infrared dry-peeling system for tomatoes was designed and constructed. The system consisted of three major sections including the IR heating, vacuum, and pinch roller sections. The peeling performance of the system was examined under different operational conditions using tomatoes with different cultivars and sizes. Three lines of tomatoes were heated and processed at the same time at a residence time of 125 s and achieved a percentage of fully peeled tomatoes of 85%, a peeling yield of 82%, and an average thickness of peeled tomato skin of 0.75 mm. When tomatoes were loaded as a single line, the required heating time was reduced to a range from 80 to 100 s, depending of tomato size, for achieving the same level of peeling percentage and yield. The presence of the vacuum section could achieve cracks in 100% of the tomatoes after IR heating. The peeled products from IR heating had high firmness and appealing surface integrity, which indicated desirable quality characteristics. Because the dry-peeling is a chemical- and water-free process, residuals of tomato skins after IR peeling could be easily utilised as value-added by-products.

Salinity induced fruit hypodermis thickening alters the texture of tomato (Solanum lycopersicum Mill) fruits

Irrigation of tomato (Solanum lycopersicum Mill) plants with brackish (including saline) water improves fruit taste and reduces yields. Salinity additionally leads to toughening of tomato fruit skin, the causative mechanism for which is unknown. The aim of this study is to characterize the effects of salinity on tomato fruit skin texture. Tomato (cherry and full size) plants were irrigated with fresh water (control, ED=1.01 dSm−1) and saline water (up to 12.61 dSm−1). Organoleptic assessment was compared to the force needed to puncture the cherry tomato fruit skin and to specific skin dry weight. The skin structure of cherry and full-size tomatoes was characterized by light microscopy. Chemical characterization of cell walls building the skin of cherry tomatoes was conducted by Raman micro-spectroscopy. Skin penetration force was found to be linearly correlated with its specific weight and with consumers' perceived thickness. Fruit histology revealed a linear correlation between thickness of the sub-epidermis and salinity of the irrigation water. The tougher tomato skin obtained under conditions of salinity is attributed to increased number of hypodermal cell layers rather than to changes in cell wall composition.

Mechanical Properties of Tomatoes Subjected to an Induced Compression during Storage

AbstractThe purpose of this work was to evaluate texture alterations due to compression load on tomatoes stored at 15 and 25C, which simulates transport in type “K” wooden boxes. The following mechanical properties were analyzed during storage: firmness, proportional deformity modulus, energy to deform the product, penetration force of the tomato skin and the energy required for penetration. Structural alterations were noticed solely by a puncture test. The mechanical property values significantly decreased during storage. The weight loss varied significantly among control and treatment tomatoes during storage, and the tomatoes stored at 25C obtained higher weight loss values. These results will aid in generating logistic procedures to prevent mechanical damage to tomatoes when they are transported in wooden boxes, thus increasing producer profitability. Furthermore, if damage to tomatoes does occur, professionals will be able to predict the shelf life of the tomatoes.Practical ApplicationsResults of this manuscript may aid and alert developers of packages to prevent quality loss due to compression loads throughout transport and/or storage. Furthermore, in order to analyze quickly the quality of tomatoes, puncture test can be used, in which its parameters were obtained. The manuscript states clearly that refrigeration is not efficient in order to prevent quality loss if the tomato fruits are submitted to compression loads. Thus, prior to storage temperature, compression of tomatoes stacked on top of one another must be avoided in order to maintain quality and increase shelf life of this product.

Olive oil enriched in lycopene from tomato by-product through a co-milling process

The aim of this investigation was to produce an olive oil (OO) naturally enriched with antioxidants, recovering carotenoids, in particular lycopene, using an industrial by-product of tomato seeds and skin. For this purpose, a technological process in a low-scale industrial plant to co-mill olives and tomato by-product in de-frosted or freeze-dried forms was applied and studied with respect to control samples. Preliminary results obtained from two different experiments were carried out by 40 kg of cultivar Correggiolo olives and 60 kg of olive blends from different cultivars. In both the experiments, the co-milling showed significant enrichment in carotenoids, especially in lycopene (mean values of 5.4 and 7.2 mg/kg oil from defrosted and freeze-dried by-products, respectively). The experimental results demonstrated the possibility to obtain a new functional food naturally enriched in antioxidant compounds, which might be marketed as “OO dressing enriched in lycopene” or “condiment produced using olives and tomato by-product”.

Insights into the mechanisms underlying the antitumor activity of an oxidovanadium(IV) compound with the antioxidant naringenin. Albumin binding studies

Naringenin, a natural antioxidant present in grapefruit, oranges and the skin of tomatoes showed low antioxidant properties among other flavonoids due to its structural characteristics. Since many flavonoids were shown to have cell-killing and antioxidant activities, naringenin was investigated herein. In parallel with its antioxidant activities the flavonoid showed very low cytotoxicity at concentrations up to 100μM against lung (A549) and breast (SKBr3 and MDAMB231) cancer cell lines. Furthermore, a newly-synthesized and characterized complex of naringenin and oxidovanadium(IV) ([VIVO(nar)2]·2H2O, VOnar, with weak ferromagnetic coupling) was also studied. As a result, VOnar acted as a better compound on cell-killing and antioxidant activities (in vitro) than naringenin. The anti-proliferative effect of VOnar was accompanied by reactive oxygen species (ROS) generation, cell membrane and DNA damages, cell cycle arrest, caspase 3/7 activation and mitochondrial potential reduction. The higher parameters observed for the MDAMB231 cell line have been related to its low glutathione (GSH) content. The assays of the interaction of bovine serum albumin (BSA) with the complex showed the affinity of protein toward it and that there is only one binding site on the BSA molecule. However, metal complexation decreased the binding affinity to BSA of naringenin probably due to a steric hindrance of the complex.

Coherences of instrumental and sensory characteristics: case study on cherry tomatoes.

The aim of this study was to investigate 6 cherry tomato varieties in terms of morphological, instrumental, and sensory attributes. Hungarian cherry tomato landraces have not been investigated in comparison with new commercial varieties for these traits. Parameters investigated were water-soluble antioxidant capacity (FRAP, DPPH, and TEAC), and total polyphenol, vitamin C, β-carotene, lycopene, total soluble solids, and acid contents. Colorimetric measurements as well as sensory analyses were conducted. It was concluded that varied antioxidant assays should be used in parallel to overcome the selectivity of any 1 method. Total phenolic content significantly contributed to results of antioxidant assays for the investigated varieties. The sensory profiles of the 6 cherry tomato varieties have been created. The differences between the products based on the 18 attributes were analyzed by Tukey post hoc test. The biplot of the principal component analysis showed that the sensory panel could discriminate the samples along the principal components. No correlation was found between colorimetric data a* and b* measured from pulp and lycopene, but a negative connection of β-carotene and hue was noted. Total polyphenol content showed correlations with colorimetric results, except for b*. The influence of tomato skin color on color perception is significant as in the present study instrumental data measured from pulp did not match that of the panelists evaluating intact fruit. Instrumental results of sugar content were supported by the ratings of the sensory panel.

Absolute quantification of protein NP24 in tomato fruit by liquid chromatography/tandem mass spectrometry using stable isotope-labelled tryptic peptide standard

Protein NP24 is a thaumatin-like protein contained in tomato (Lycopersicon esculentum Mill.). This protein is reported to be a putative tomato allergen and is listed as a food allergen in Structural Database of Allergenic Proteins (SDAP). In this research, we developed the quantitative analysis of NP24 by employing the protein absolute quantification (AQUA) technology composed of stable isotope-labelled internal standard (SIIS) peptide (GQTWVINAPR[13C6,15N4]) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). A linear relationship (r2>0.99) was found throughout the concentration range (2.0–500fmol/μL). The coefficients of variation (CVs) measured on each of the five days when NP24 contained in the tomato skin was analysed did not exceed 13%. Our developed assay of NP24 will contribute to the allergological examination of tomato and its derived products.

TOM-AUTOS Ford explores tomato waste for eco-friendly composite car parts

If all goes well, tomato-reinforced plastics could sprout up in cars over the next few years. Automaker Ford Motor Co. and ketchup giant H. J. Heinz Co. have revealed that they are exploring the use of tomato skins as a reinforcing component for plastic composite car parts such as wiring brackets and coin storage bins. At Heinz, researchers were looking for ways to repurpose peels, stems, and seeds from the more than 2 million tons of tomatoes the company uses annually to make ketchup. The unwanted materials are currently used as animal feed. Ford scientists, meanwhile, wanted to develop a lightweight material that “reduces our overall environmental impact,” says Ellen Lee, a plastics research specialist at the firm. So, two years ago Ford teamed up with Heinz to try fortifying polypropylene parts with a fiber made from cooked, extruded, and dried tomato skins. They found that the tomato fiber is ...

Development of multispectral imaging algorithm for detection of frass on mature red tomatoes

In this research, a multispectral fluorescence-based imaging algorithm was developed to detect frass contamination on mature Campari tomatoes. Tomato images were acquired using a hyperspectral fluorescence line-scan imaging system with violet LED excitation, then analyzed for wavelength selection. The fluorescence intensities at five wavelengths, 515nm, 640nm, 664nm, 690nm, and 724nm, were used to compute three simple ratio functions to detect frass contamination. The contamination spots were created on the tomato surfaces using four low-concentration frass dilutions. The algorithms detected over 99% of the 0.2kg/L and 0.1kg/L frass contamination spots and successfully differentiated these spots from tomato skin surfaces, stem scars, and stems. However, differentiation of the 0.05kg/L and 0.02kg/L frass contamination spots was more difficult. Adjusting the algorithm to successfully detect 95% of the 0.05kg/L spots also resulted in false-positive pixel detections occurring on 28% of the tomatoes. This study demonstrates that a simple multispectral fluorescence imaging algorithm based on violet LED excitation could be useful for rapid postharvest detection of frass contamination on tomatoes in processing lines.

Peeling mechanism of tomato under infrared heating: Peel loosening and cracking

Critical behaviors of peeling tomatoes using infrared radiation heating are thermally induced peel loosening and subsequent cracking. Fundamental understanding of the two critical behaviors, peel loosening and cracking, remains unclear. This study aimed at investigating the mechanisms of peel separation for tomatoes subjected to a newly developed infrared dry-peeling process. Microstructural changes in tomato epidermal tissues under infrared heating were compared with those of fresh, hot lye and steam treated samples. Theoretical stress analyses coupled with the experimentally measured failure stress of tomato skin were combined to interpret the occurrence of peel cracking within a framework of elastic thin shell theory. With the use of light microscopy and scanning electron microscopy, it was observed that peel loosening due to infrared heating appeared to result from reorganization of extracellular cuticles, thermal expansion of cell walls, and collapse of several cellular layers, differing from samples heated by hot lye and steam. Crack behaviors of tomato skin were attributed to the rapid rate of infrared surface heating which caused the pressure build-up under the skin and strength decrease of the skin. In order to achieve a sufficient skin separation for effective peeling using infrared, promoting rapid and uniform heating on the tomato surface is essential. The findings gained from this study provide new insights for developing the sustainable infrared dry-peeling technology.

A comparison of dynamic mechanical properties of processing-tomato peel as affected by hot lye and infrared radiation heating for peeling

This study investigated the viscoelastic characteristics of tomato skins subjected to conventional hot lye peeling and emerging infrared-dry peeling by using dynamic mechanical analysis (DMA). Three DMA testing modes, including temperature ramp, frequency sweep, and creep behavior test, were conducted to evaluate the transition temperatures and dynamic moduli of tomato peels heated by infrared radiation and hot lye at four heating durations (30, 45, 60, and 75s). Fresh tomato peels were used as a control. Results showed that dynamic moduli of tomato peels were sensitive to temperature ramp and frequency sweep tests. Over a temperature range from 20°C to 100°C, transition temperatures of infrared treated peels (63–72°C) and lye treated peels (43–75°C) were significantly lower than those of fresh control (∼88°C). Values of both storage and loss moduli of infrared heated peels were considerably higher than those of the fresh control, whereas values of the storage and loss moduli from the lye peeled samples were lower than those of fresh peels. DMA tests effectively differentiated the viscoelastic behaviors of tomato peels and indicated mechanistic differences between the lye peeling and infrared dry-peeling.

Accumulation of anthocyanins in tomato skin extends shelf life

Shelf life is one of the most important traits for the tomato (Solanum lycopersicum) industry. Two key factors, post-harvest over-ripening and susceptibility to post-harvest pathogen infection, determine tomato shelf life. Anthocyanins accumulate in the skin of Aft/Aft atv/atv tomatoes, the result of introgressing alleles affecting anthocyanin biosynthesis in fruit from two wild relatives of tomato, which results in extended fruit shelf life. Compared with ordinary, anthocyanin-less tomatoes, the fruits of Aft/Aft atv/atv keep longer during storage and are less susceptible to Botrytis cinerea, a major tomato pathogen, post-harvest. Using genetically modified tomatoes over-producing anthocyanins, we confirmed that skin-specific accumulation of anthocyanins in tomato is sufficient to reduce the susceptibility of fruit to Botrytis cinerea. Our data indicate that accumulation of anthocyanins in tomato fruit, achieved either by traditional breeding or genetic engineering can be an effective way to extend tomato shelf life.

A new method for modelling biological variation using quantile functions

We describe a general method for modelling biological variability as a function of time using fruit populations as examples. The method can incorporate variations in the biological age or maturity of fruit or other produce, as well as variations in the biological property being measured. Key developments are the use of quantile functions to describe the stochastic elements of the model, the assignment of probabilities to individual measurements based on their rank order within a sample, the use of individual measurements rather than means in the fitting process, and the fact that a single model equation with a single set of parameters describes the distribution of measurements across an entire population as a function of time. Using a representative fruit sample taken at a specific time and generalised model parameters, the technique allows the prediction of future fruit population distributions and the prediction of the date when a defined percentage of the fruit population meet a particular specification.The model development process demonstrates how to account for both biological age variability and measure (hue) variability simultaneously, the latter including components of measurement uncertainty and variability not related to biological age. Using quantile functions as the stochastic elements provides a wide range of distributional options.The method is described in detail using, as examples, a Complementary Log–Log sigmoid to model changes in ‘Hort16A’ kiwifruit hue angle preharvest, and a Logistic sigmoid to model changes in ‘Tradiro’ tomato skin hue data postharvest.The kiwifruit data comprised ten samples of 90 destructive hue angle measurements taken across the growing season from each of eight maturity areas (MAs). Allowing MA-specific parameter sets, the entire data set was modelled with an adjusted rsd of 0.46°. Further exploration of the sensitivity of model parameters showed that the model parameter tm, which defines the timing of the ‘maturity’ of each MA, needed to be MA-specific.The tomato colour data comprised 120 fruit measured non-destructively on seven occasions postharvest. Initial model fits using a Normal distribution for the biological age component gave an rsd of 1.05°. The rsd was reduced to 0.61° using a four-parameter generalised lambda quantile function to describe the biological age variability and 0.63° when using a truncated Normal, suggesting that the underlying distribution was not Normal.The models are readily fitted using any statistical or computational package that offers non-linear optimisation including Microsoft Excel with Solver. The technique can be used as effectively with destructive as with non-destructive measurement data, in preharvest and postharvest situations, and can provide visualisation as well as computational tools. It can be applied to any populations that vary with time and where the units of the populations exhibit variability. These modelling techniques have formed the basis for decision support tools that have been operating commercially since 2007.

Influence of Heat Treatments on Carotenoid Content of Cherry Tomatoes.

Tomatoes and tomato products are rich sources of carotenoids—principally lycopene, followed by β-carotene and lutein. The aim of this work was to study the effect of heat treatment on carotenoid content in cherry tomatoes. Raw and canned products were sampled and analysed; furthermore whole, skin and pulp fractions of cherry tomatoes were analysed when raw and home-processed, in order to better understand heat treatment effects. Lycopene content in canned tomatoes was two-fold higher than in raw tomatoes (11.60 mg/100 g versus 5.12 mg/100 g). Lutein and β-carotene were respectively 0.15 mg/100 g and 0.75 mg/100 g in canned tomatoes versus 0.11 mg/100 g and 1.00 mg/100 g in raw tomatoes. For home-processed tomatoes, β-carotene and lutein showed a content decrease in all thermally treated products. This decrease was more evident for β-carotene in the skin fraction (−17%), while for lutein it was greater in the pulp fraction (−25%). Lycopene presented a different pattern: after heat treatment its concentration increased both in the whole and in pulp fractions, while in the skin fraction it decreased dramatically (−36%). The analysis of the isomers formed during the thermal treatment suggests that lycopene is rather stable inside the tomato matrix.

Discrimination and Simultaneous Determination of 6-BA and KT by Polarized Synchronous Light Scattering and Synchronous Light Scattering Spectrum

In pH=5.70 B-R buffer solution, Na2WO4 and rhodamine 6G（R6G） could react with natural cytokinins of 6-benzylaminourine (6-BA) and kinetin (KT) and resulted in a great enhacement of synchronous light scattering (SLS) signals. This article first established the degree of polarized synchronous light scattering (P) based on the measurements of the polarized synchronous light scattering signals to distinguish two natural cytokinins of 6-BA and KT. Simultaneously based on the synchronous scattering spectrum and the double standard curve method, a novel method for simultaneous determination of 6-BA and KT was developed by SLS spectralmethod. The method was applied to simultaneous determination of 6-BA and KT in balsam pear skin and tomato skin with satisfactory results.

Effect of tomato post-harvest treatment and storage conditions on the biological activity of benomyl and methylthiophanate residues in fruits and their processed products

The biological activity of benomyl and methylthiophanate residues in tomatoes and their processed products was examined. Fungicide residues were most active in concentrated pulp of tomatoes, less in pulp and the least in fresh fruits. The fungicide residues activity was very high after 90 days of storage of processed products. The pulp and concentrated pulp of tomatoes treated and stored for 14 days at 15°C, also contained very active fungicide residues. The translocation of benomyl from treated tomato skin into the tissue begun slowly. This process was faster in green or yellow fruits, but it was the fastest in small green fruits. The influence of storage conditions on the activity of fungicide residues depended on the storage length. The residues were the least active in fruits stored under low pressure of 38 mm Hg for 14 days, but this activity increased during the storage period and the residues were very active after 34 days of tomato storage.