PEELABILITY AND YIELD OF PROCESSING TOMATOES BY STEAM OR LYE

Approximately 25% of the processed tomatoes grown in California are made into value‐added foods such as whole peeled and diced tomatoes. Peel removal is the first step in this process, and it must be optimized for both quality and yield. The effect of peeling conditions on tomato cultivars Halley 3155 and Heinz 8892 (H 8892) was evaluated. Considerable texture loss results from peeling; however, firmness was greater for cv. Halley 3155 than for cv. H 8892 regardless of peeling conditions utilized. Peeling under low steam pressures (12 psig) was insufficient to adequately peel either cultivar. While high pressure steam (18 psig) was more efficient at peel removal, increasing vacuum level from 20 in. to 24 in. did not improve peelability of either cultivar. Because cultivar affected peelability and yield, specific tomato cultivars should be evaluated and directed to either paste or whole peeled and diced tomatoes as appropriate.     

EVALUATION OF PROCESSING TOMATOES FROM TWO CONSECUTIVE GROWING SEASONS: QUALITY ATTRIBUTES, PEELABILITY AND YIELD

Peelability is an important quality parameter in the selection of tomato cultivars (cvs.) for whole peeled and dice processing. Six processing tomato cvs. were evaluated in two consecutive years to examine the effects of cv., maturity and physical attributes on peelability and yield. Physical attributes of the raw tomatoes (size, weight, pericarp wall thickness, color) and processed paste quality (pH, titratable acidity, soluble solids, Bostwick consistency, serum viscosity, color) were determined. Large variations in physical attributes and paste quality were observed in selected tomato cvs. and maturities. In general, most of the attributes indicative of paste quality were more desirable at the less mature (e.g., pink) stage and declined with maturity. Statistical analysis suggests that there were significant differences in percentage of peeled tomatoes, peel index, and yields of whole peeled and diced tomatoes between two consecutive growing years.     

CAN WE PREDICT PEELING PERFORMANCE OF PROCESSING TOMATOES?

Tomato processors are increasingly interested in being able to predict whether tomatoes will peel well, and therefore, yield high‐value processed tomatoes. We describe two statistical models for peeling applied to multiple years of data. One model is appropriate for perfect or defect‐free tomatoes, and the second model is valid for the normal population of tomatoes obtained following mechanical harvesting. The ability to peel perfect tomatoes was significantly affected by exposure of tomatoes to temperatures greater than 100F, by fruit weight and by pericarp wall thickness. The peelability of a normal population of tomatoes was influenced by tomato weight and width as well as degree‐days and exposure to temperatures greater than 90F. Thickness of the pericarp walls and red layer positively affected the peelability of normal tomatoes. The ability to predict tomato peelability using statistical models may improve the quality of processed tomatoes and may result in more efficient commercial peeling operations.     

Characterization of the Red Layer and Pericarp of Processing Tomato using Magnetic Resonance Imaging

Abstract: The characteristics of tomato pericarp are closely associated with peelabililty, an important quality attribute of processing tomatoes. Different types of tissue exist in the pericarp of tomato. The outermost region of the pericarp, the red layer, is removed with the skin during peeling. This study investigated the morphological features and tissue properties of red layer and pericarp for 3 processing tomato cultivars using magnetic resonance imaging (MRI). The red layer can be visualized in MR images with T₂ weighting, indicating the red layer has different properties compared to the rest of the pericarp region. Tomatoes were imaged with a set of MRI sequences with signal intensity dependent on different water proton properties. Principal component analysis (PCA) of the statistical features revealed clustering of fruit by cultivar. The spatial distribution of cultivars in the PCA score plot followed their rank of peeling performance. MRI demonstrated potential as a nondestructive method to characterize tomato pericarp and evaluate the peelability of processing tomatoes. Practical Application: Peelability of tomatoes affects the quality of value‐added whole peel and diced tomato products. The properties of the pericarp of tomato are directly related to the peelability of tomatoes. MRI provided a fast and nondestructive method to characterize the properties of tomato pericarp. The result of this work gives insight into the correlation between tomato pericarp characteristics and peelability.     

Understanding Tomato Peelability

Approximately 75% of all tomatoes in the United States are consumed as processed and 25% as fresh. One of the first steps during processing involves removal of the peel and, unfortunately, more than 25% of the fruits (as measured by total weight) can be lost due to overpeeling. Additionally, conventional peeling applications have a negative environmental impact. Given the great potential economic benefits, many scientists have conducted research to attempt optimizing or predicting peeling performance when processing tomatoes. The literature regarding tomato peelability is contradictory in many cases; and several topics have been subject to ample debate over the years. Divergent conclusions are probably not due to faulty investigations, but rather to the extreme variability found among tomato cultivars, the effect of growing seasons, and maybe even the effect of climatic conditions on the day of harvest or during transportation to the processing plants. This review provides an in‐depth background needed for a better understanding of tomato physiology, maturation, and composition, as these could possibly influence the ease of peeling or “peelability.” The research studies directly involved with peeling tomatoes and predicting peelability are discussed in this paper as well. Different peeling methods, peeling grading scales, and fruit tagging procedures are presented, as well as experiments evaluating the effect that fruit defects, maturity, growing conditions, and other factors can have on the ease of peeling. Novel approaches for peelability prediction by means of spectroscopic and magnetic resonance technology are also discussed in this review.     

High-humidity hot air impingement blanching (HHAIB): An emerging technology for tomato peeling

Peeling is an essential operation for tomato processing. A new peeling method, high-humidity hot air impingement blanching (HHAIB) heating technology, was developed as an alternative to the conventional lye and hot-water peeling to eliminate the use of chemicals and the discharge of wastewater. The current work explored the feasibility of HHAIB for tomato peeling. The effects of heating temperature (100–120 °C), relative humidity (20%–40%) and heating time (0–180 s) on the peeling performance were investigated. The optimum treatment was found to be 110 °C heating temperature in combination with 40% of relative humidity and 75 s treatment time, which resulted in lower peeling loss, firmness loss and color deterioration compared with other HHAIB conditions that achieved 100% peelability. The comparative study of optimized HHAIB peeling with conventional lye and hot-water peeling showed that HHAIB peeled tomato obtained lower peeling loss and firmness loss, and higher preservation of phytochemicals, antioxidant capacity and color. In addition, compared with fresh tomatoes, HHAIB processing increased the antioxidant activity, lycopene, and total phenolic content in peeled tomatoes by 16.01%, 10.46%, 12.80%, respectively. The laser scanning confocal microscopy image of fresh tomato skin surface and the scanning electron microscope images of peels and flesh showed that HHAIB caused cracking of the epidermis and melting of the cuticular membrane while reduced the serious damage of flesh.Industrial practicePeeling is a necessary step in tomato processing, which impacts subsequent processing efficiency and product quality. At present, the most common used peeling methods in the industry are hot water or/and alkali peeling, but it induces the loss of water-soluble nutrients, chemical residues and waste liquid treatment. Therefore, the industry urgently needs an alternative peeling technology. The current work shows that HHAIB is a very promising peeling technology as it not only has an excellent peeling performance, but also enhances the preservation of phytochemicals, antioxidant capacity and quality attributes compared to conventional lye and hot-water peeling.     

The Choice of Canned Whole Peeled Tomatoes is Driven by Different Key Quality Attributes Perceived by Consumers Having Different Familiarity with the Product

Canned whole peeled tomatoes are a premium tomato product; however, no information is available about the key intrinsic and extrinsic quality attributes perceived by consumers when buying this product. This research considered consumers differing in the level of familiarity with peeled tomatoes, that is, knowledge, frequency of consumption, and availability of this product, on 3 markets: Chile (low), The Netherlands (medium), and Italy (high). The perceptions and preferences of each group were studied using first focus groups and subsequently conjoint analysis in order to identify the key quality attributes leading their preferences for this product. Focus groups identified 7 intrinsic attributes (color, packing medium, tomato consistency, acidity level, sweetness level, extra ingredients, and intensity of product taste), and 5 extrinsic attributes (packaging material, product type, country of origin, brand, and label design). Significant variations according to the familiarity were found. The conjoint analyses showed that color of tomatoes was the most important intrinsic quality attribute for all groups, while packaging material was the most important extrinsic quality attribute for Chileans and Dutch, being a glass container or a can with easy open the preferred packaging for respective groups. In contrast, country of origin was the most important parameter for Italians. We concluded that intrinsic and extrinsic attributes were strongly influenced by the degree of familiarity with canned whole peeled tomatoes.     

USE of ORGANIC SOLVENTS FOR IMPROVING PEELABILITY of TOMATOES

A prepeeling dip was used to demonstrate that removal or modification of the cuticular waxes from the tomato fruit could be used to improve the tomato peeling process. the tomatoes were dipped at various temperatures for I min prior to regular lye peeling. the optimum temperature was found to be 45C. Several organic solvents including chloroform, ethyl acetate, ketones, and alcohols were used. These tomatoes were compared to tomatoes peeled using the lye without the dip. the prepeeling dip reduced the thickness of the cuticular wax layer and produced cracks in the cutin surface. This facilitated good penetration of lye into the tomato resulting in more complete peeling. Peeling after pretreatment produced 86% well peeled tomatoes as compared to 33% well peeled in the control run.     

An Investigation of Some Important Storage Parameters in Acidified Bulk Storage of Tomatoes

Acidified bulk storage of tomatoes at a pH of approximately 1.3 was used to store whole tomatoes without spoilage for up to 4 months. Storage treatments of time and temperature lead to concurrent off flavor and brown color development which was presumed to be at least partially due to container oxygen permeability problems. Best quality in this study was found after storage at lowered temperatures. When unpeeled tomatoes were stored, they softened during storage and did not remain whole upon subsequent peeling. Heat peeled whole tomatoes stored in tomato juice gave the best storage quality of any treatment combinations used. The major problem experienced with this storage method was non-microbial chemical deterioration of product quality after storage.     

CHARACTERIZATION OF SURFACE AUXIN RESIDUE IN GREENHOUSE TOMATOES (LYCOPERSICON ESCULENTUM)

Greenhouse tomato samples (n = 20) was analyzed before and after peel removal in order to determine surface auxin residue. Mean 4‐CPA residue levels of greenhouse tomatoes with and without peels were 0.383 ± 0.123 mg kg^?1 and 0.241 ±0.085 mg kg^?1, respectively. This difference (36 ±13%) was statistically significant. The frequency distribution curve of tomatoes with peel had a peak point at 4‐CPA reside interval of 0.4‐ < 0.5 mg kg^?1 tomato, and shifted back to 4‐CPA residue interval of 0.2‐ < 0.3 mg kg^?1 for tomatoes without peel. Percentage of samples having 4‐CPA level lower than the critical concentration of 0.5 mg kg^?1 was 80% before peel removal, but increased to 100% upon being peeled. The mean 4‐CPA residue of peels was roughly estimated to be 3.449 mg kg^?1 peel based on peeled versus nonpeeled fruit residue.     

Evaluation of Lye and Steam Peeling Using Four Processing Tomato Cultivars

Fruit of four eastern tomato cultivars (cvs) were peeled using either high pressure steam or a lye bath under commercial conditions. Percent yield of whole fruit and finished product quality were determined. Yield of 5 sec steam-peeled fruit was 4.1% greater than lye-peeled fruit; no cvs differences were detected. Quantity of blossom-end peel was not affected by peel treatment, but differences among cvs were shown. Steam-peeled tomatoes averaged 6.2 cm² and lye-peeled < 1 cm² total peel/can. There were no differences among treatments or cvs in sensory color scores. Differences in surface bL/a values among cvs at the equator region of fruit were found. Although recovery was greater for steam-peeled than for lye-peeled fruit, canned product quality was better for lye-peeled fruit.     

Study of the volatile composition of tomato during storage by a combination sampling method coupled with gas chromatography/mass spectrometry

BACKGROUND: The volatile compositions of common tomato (Lycopersicon esculentum var. commune) and cherry tomato (Lycopersicon esculentum var. cerasiforme) during storage were studied by a combination sampling method, including headspace solid phase microextraction (HSSPME), simultaneous distillation extraction (SDE) and steam distillation (SD), coupled with gas chromatography/mass spectrometry (GC/MS) detection. RESULTS: Twenty‐one and 14 volatile compounds of fresh and stale common tomatoes and 27 and 17 volatile compounds of fresh and stale cherry tomatoes were identified with various degrees of certainty. The main identified volatile compounds of common and cherry tomatoes were C6 alcohols and aldehydes. During storage, saturated hexanal increased gradually whereas unsaturated (E)‐2‐hexenal decreased. Different volatile compositional characteristics at the fresh and stale storage phases obtained by HSSPME were specified by principal component analysis (PCA). Different metabolic pathways and enzyme catalyses resulted in the various volatile compositional characteristics during tomato storage. Five typical volatile compounds contributing greatly to the difference in volatile compositional characteristics of common and cherry tomatoes at the fresh and stale storage phases were distilled by a common model strategy. These compounds are potential biomarkers for tomato degradation, but further study is needed. CONCLUSION: The preliminary results suggest that the combination of HSSPME and conventional sampling methods would yield more representative information on changes in tomato volatile composition during storage. Copyright © 2007 Society of Chemical Industry     

不同去皮方法对番茄去皮效果和品质的影响

为优化现有番茄去皮工艺,开发新的去皮方法,以去皮难易程度和质量损失评价去皮效果,比较手工去皮、热水去皮、碱液去皮、功率超声去皮和超声与碱液联用去皮对去皮效果和产品质地、颜色、番茄红素提取率、p H值和可滴定酸含量等品质的影响,并结合扫描电子显微镜观察不同去皮方法果皮微观结构。结果表明,功率超声去皮较传统的热水去皮和碱液去皮,去皮难度小,质量损失少,且产品品质良好,番茄红素含量较高,而超声与碱液联用去皮较其他去皮方法虽去皮难度小,但质量损失过高。扫描电子显微镜观察结果表明,功率超声去皮较热水去皮、碱液去皮对果皮角质层的破坏力更大,可能是超声的空化效应使果皮与果肉更易分离,从而降低去皮损失。因此,功率超声去皮是一种潜在的新型环境友好型去皮方法。     

Enzyme aided extraction of lycopene from tomato tissues

Lycopene is a natural carotenoid pigment and a high value nutraceutical having wide use. The objective of the present work was to obtain a good yield of lycopene from tomato tissues, using cellulase and pectinase enzymes. Various parameters such as concentration of enzymes and time of incubation were optimised, to improve the yield of lycopene from tomatoes. Enzyme aided extraction of lycopene from whole tomatoes under optimised conditions resulted in an increase in the lycopene yield by 132 μg/g (198%) in cellulase treated sample and 108 μg/g (224%) in case of pectinase treated sample. Extraction from tomato peel under optimised conditions showed a remarkable increase in the yield of lycopene by 429 μg/g (107%) and 1104 μg/g (206%), for cellulase and pectinase treated samples, respectively. Likewise, the enzyme aided extraction of lycopene from fruit pulper waste and industrial waste of tomatoes was done to determine the potential for recovering the natural pigment from tomato waste.     

Effects of genotype and cultivation environment on lycopene content in red‐ripe tomatoes

Lycopene, a natural red pigment found in tomato, is correlated with reduced incidence of some cancers. Forty tomato varieties, including cluster F₁ hybrid tomatoes, round breeding line tomatoes (Lycopersicon esculentum Mill) and cherry tomato types (L esculentum var cerasiforme), grown under greenhouse and field conditions were evaluated for their lycopene content using high‐performance liquid chromatography (HPLC) and spectrophotometry. Lycopene content varied significantly among the tomato varieties, with cherry tomato types having the highest lycopene content. Greenhouse‐grown cluster and round tomatoes contained more lycopene (mean = 30.3 mg kg^?1) than field‐grown tomatoes (mean = 25.2 mg kg^?1), whereas cherry tomato types had a higher lycopene content in field‐grown (mean = 91.9 mg kg^?1) than in greenhouse‐grown (mean = 56.1 mg kg^?1) fruits. HPLC analysis of lycopene isomeric forms revealed a higher content of all‐trans isomers in all tomato genotypes examined. However, the cis isomeric form was exceptionally higher in the field‐ and greenhouse‐grown cherry tomato L esculentum var cerasiforme cv Gardener's Delight, which contained ～9.3 and 9.9 mg kg^?1 cis isomers respectively. Results indicate that genetics and choice of cultivation environment may have a strong influence on tomato lycopene content. Copyright © 2005 Society of Chemical Industry     

A multi-enzyme bioelectrode for the rapid determination of total lactate concentration in tomatoes,tomato juice and tomato paste

This work presents a new multi-enzyme bioelectrode for the combined determination of d(−)-l(+)-lactic acid in samples of whole tomatoes, chopped tomatoes, tomato paste and tomato juice. The principle of the biosensor is based on the catalytic activity of the enzymes l(+)-lactic acid oxidase (LOD), d(−)-lactic acid dehydrogenase (D-LDH) and horseradish peroxidase (HPO). The three enzymes are immobilized on the tip of an amperometric oxygen selective electrode. The total concentration of d(−)-l(+)-lactic acid is proportional to the amount of O₂ consumed. The biosensor has been tested for standard solutions of d(−)-l(+)-lactic acid, as well as for real samples. The latter set of experiments has been carried out in three different laboratories, indicating a good repeatability and reproducibility of the obtained results. The main characteristics of the lactate biosensor on real samples (whole tomatoes, chopped tomatoes, tomato paste and tomato juice) have been compared, in terms of both analytical and practical features, with those of a traditionally employed enzymatic-spectrometric technique, based on the oxidation of d-l-lactic acid, catalysed by d-lactate dehydrogenase and l-lactate dehydrogenase, with production of pyruvate and NADH, and on the subsequent spectrometric determination, at λ= 340 nm, of the NADH formed.     

Proximate composition, minerals and vitamins in selected canned vegetables

The proximate composition, and mineral and vitamin contents of canned white asparagus, whole peeled tomatoes, mushrooms and lentils were studied. The composition of the canned products did not vary during the harvest season, but calcium, sodium and potassium contents depended on the hardness of the water, added sodium chloride, and, in the case of lentils and mushrooms, the use of potassium metabisulfite or sulfur dioxide during soaking. After the canning process, the studied vegetables retained at least 89% protein, 65% carbohydrate and between 47% and 95% of the vitamins B₁, B₂, B₆ and C (dry weight basis, DW) versus the respective raw materials. The canned mushrooms and lentils did not lose crude fiber and whole peeled tomatoes and white asparagus retained 73% (DW) crude fiber.     

Metabiotic Association of Fusarium, Alternaria, and Rhizoctonia with Clostridium botulinum in Fresh Tomatoes

Clostridium sporogenes and C. botulinum grew, and toxin was produced by C. botulinum in a metabiotic relationship with fungi in fresh tomatoes. Fungi of the genera Alternaria, Rhizoctonia and Fusarium were studied. Infection of tomatoes with the fungi increased the pH of tomato tissues as high as pH 8.0. A gradient in pH across the tomato tissue was observed with pH in healthy tissue at approximately normal values (pH 4.3 to pH 4.5). Macerates from tomatoes inoculated with C. botulinum and Alternaria or Fusarium were toxic to mice but Rhizoctonia infected tomatoes did not tend to support toxin production by C. botulinum even though the pH of infected tomatoes was pH 5.3 to 7.6.     

EFFECT OF TOMATO DECAY PROPORTION ON ERGOSTEROL LEVEL AND SOME TOMATO PULP PROPERTIES

There is a need to develop a chemical method to determine the amount of decayed tomatoes used to produce tomato products. Tomato pulp samples produced from surface decayed tomatoes as sound, 30, 60 and 100% were tested for pH, brix, titrable acidity, Hunter L, a and b, Howard Mold Count (HMC) and ergosterol values. Tomato pomace for each decay portion was tested for HMC and ergosterol. Ergosterol analysis was carried out by high‐pressure liquid chromatography (HPLC). Decay proportion was linearly correlated with HMC (r = 0.97) and ergosterol (r = 0.96) in pulp samples but not to pH and acidity. Only ergosterol measurement was applicable in tomato pomace and correlated well (r = 0.95) with the decay proportions. In general, the color values of the samples produced from 100% decayed tomatoes were high compared with the others. The measurement of ergosterol has the potential to be used for the quality assessment of tomato products made from Red Top tomatoes.     

Tomatine,chlorophyll, β‐carotene and lycopene content in tomatoes during growth and maturation

Tomato (Lycopersicon esculentum) plants synthesise nutrients, pigments and secondary metabolites. These include the green pigment chlorophyll, the yellow pigment β‐carotene, the red pigment lycopene and the colourless glycoalkaloid α‐tomatine. The levels of these compounds are strongly influenced by the maturity of the tomatoes. Widely consumed Japanese tomato varieties Momotaro, Momotaro‐T93 and First Memory at five different stages of ripeness, each harvested at 10, 20, 30, 40 and 50 days after flowering of the plants, were analysed for the contents of these compounds. Additionally, tomato clusters from different locations along the vine on the same plant were also evaluated. The results show that chlorophyll and tomatine concentrations decrease rapidly during the growth of the tomatoes. By contrast, β‐carotene and lycopene levels are low in immature and high in mature tomatoes. The location of the tomato clusters and tomato variety did not significantly affect these results. The possible usefulness of these results to optimise health‐promoting effects of tomatoes is discussed. © 2003 Society of Chemical Industry