Analyses of tomato peel and seed byproducts and their use as a source of carotenoids

Commercial tomato canning yields two different byproducts. One is the material that results from peeling tomatoes, while the other results from removing the seeds. The peel byproduct contained 100.8 g protein, 256.4 g ash and 299.4 g acid detergent fiber kg^?1. Ash content was high because the peel byproduct contained 83.8 g kg^?1 sodium as a result of using a sodium hydroxide solution to peel the tomatoes. The seed byproduct contained 202.3 g protein, 51.8 g ash, and 537.9 g acid detergent fiber kg^?1. An amino acid analysis of seeds indicated that approximately 60% of the protein results from amino acids. Both byproducts were analyzed for carotenoid content. The lycopene content of peel byproduct was 734 µg g^?1 of dry material. Significant amounts of lutein, β‐carotene, and cis‐β‐carotene were also present. Seed byproduct contained 130 µg lycopene kg^?1 of dry matter. The content of other carotenoids was approximately half of that present in the peels. Peel and seed byproducts were included at 75 g kg^?1 in hen diets to determine the transfer of carotenoids to the yolk. When fed at this concentration, the lycopene content of dry egg yolk was approximately 0.9 µg g^?1. Approximately 0.1% of the lycopene in peel byproduct and approximately 0.7% of the lycopene in the seed byproduct was transferred from the feed to the yolk. Lycopene appears more similar to carotene than to oxycarotenoids in its transfer to the yolk. Copyright © 2005 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。     

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.     

AN EXPERIMENTAL DRY CAUSTIC PEELER FOR CLING PEACHES AND OTHER FRUITS

SUMMARY– An experimental cling peach peeler was developed for continuous removal of alkaline peel as a solid rather than the dilute slurry of common industrial practice. The peeler consists of rows of soft rubber disks rotated in such a manner that peel material is gently wiped from the surface of fruit and flung into collectors. Cling peach halves were successfully peeled in a number of tests, with peeling losses comparable to those normally obtained commercially. Both mature and immature Bartlett pears were also successfully peeled. Dewaxing of immature pears with isopropy¹ alcohol was necessary to obtain adequate peeling. In single tests, whole apricots and freestone peaches were also successfully peeled.     

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.     

PEELING OF YAMS FOR PROCESSING

White yam (Dioscorea rotundata) lye or flame peeled were evaluated for quality characteristics and peeling loss in comparison to hand peeling. Lye concentration (15–20% at 98°C with a dipping time 3–5 min) effectively removed the histological peel as the flame method, (flame temperature was 857°C and exposure time was 9 min) with a peeling loss of 4% which was significantly lower than for hand peeling. Fresh yams were more readily peeled by these methods than stored yams. The yams peeled by lye or flame when cooked were quite acceptable as hand peeled yams. The adaptability of these methods for industrial scale up are examined.     

Essential Elements in Fresh and Canned Tomatoes

The content of 16 essential elements was determined in fresh and canned tomatoes by atomic absorption spectrophotometry. The elemental content of fresh tomatoes was compared with that of canned tomatoes. All data were analyzed statistically. There were significantly higher amounts of calcium, chloride, cobalt, copper, nickel, sodium, tin, and zinc in canned tomatoes than in fresh tomatoes. There were significantly lower amounts of magnesium, manganese, phosphorus, potassium, and silicon in canned tomatoes than in fresh tomatoes. No significant difference in iron was found between fresh and canned samples. Percentages of the established and estimated RDA's show that fresh and canned tomatoes are relatively good sources of potassium and relatively fair sources of iron. Canned tomatoes are a relatively good source of sodium. Element retention in the canned tomatoes was 77–7,651%.     

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.     

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.     

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.     

Lycopene content and antioxidant activity of fresh and processed tomatoes and in vitro bioavailability of lycopene

BACKGROUND: Lycopene, a phytochemical, has attracted a great deal of interest over the past few years. This has triggered research on the biological properties of lycopene and on the numerous factors that control these properties. Therefore, the aim of the study was to investigate lycopene content and antioxidant activity of fresh, sun‐dried and canned tomatoes. In addition, in vitro bioavailability of lycopene was determined. RESULTS: Lycopene contents of fresh, sun‐dried and canned tomatoes were found to be 1.74, 5.51 and 3.55 mg 100 g^?1, respectively, on a fresh wet basis. The highest lycopene bioavailability was obtained for sun‐dried tomatoes (58.05%) and this was followed by fresh (28.67%) and canned tomatoes (21.83%). Fresh tomatoes showed the highest antioxidant activity against ABTS radical oxidation. This was followed by sun‐dried tomatoes and canned tomatoes. The inhibition effect of intestinal dialysates of the samples on ABTS radical oxidation was between 51.34% and 92.96%. CONCLUSION: Maintenance antioxidant activity and existence of lycopene following an in vitro digestion process were the main findings, which might contribute forthcoming studies in this scientific field. Copyright © 2007 Society of Chemical Industry     

Effects of Heat Treatment on the Carotenoid and Tocopherol Composition of Tomato

Abstract: The objective of this study was to determine the influence of thermal processing on the assessment of tocopherols and carotenoids, as well as their isomer formation in tomatoes. The sliced tomatoes were heated in an oven at 100, 130, and 160 °C for 5, 10, and 20 min, then freeze‐dried. Freeze‐dried samples were finely ground and the analysis was performed on lyophilized samples. The average concentrations of total lycopene, lutein, β‐carotene, α‐tocopherol, and γ‐tocopherol in fresh tomatoes (in 100 g dry weight) were 21.2, 1.1, 2.7, 8.0, and 2.5 mg, respectively. Oven baking of tomato at 160 °C for 20 min led to a significant increase in the apparent measurement of lycopene, β‐carotene, and α‐tocopherol content by 75%, 81%, and 32%, respectively. Heating induced isomerization of (all‐E) to various (Z) isomers of lycopene, and we found that the total (Z)‐lycopene proportion in the tomatoes increased with longer heating time. (All‐E)‐lycopene constituted 75.4% in fresh tomatoes and decreased to 52.5% in oven‐baked tomatoes (160 °C, 20 min), while (5Z)‐lycopene increased from 9.4% to 17.9% of total lycopene. However, β‐carotene release and isomerization was less influenced by the heat treatment than that of lycopene. These results suggested that thermal processes might break down cell walls and enhance the release of carotenoids and tocopherols from the matrix, as well as increase isomerization of lycopene and β‐carotene.     

Peel Removal by High Pressure Steam from Processing Tomatoes with Yellow Shoulder Disorder

Fruit of processing tomatoes were peeled using high pressure steam with lab and commercial equipment. Recovery ranged from 64.8% to 77.8% and quantity of adhering peel ranged from 385 to 1866 mg/kg fruit for nine genotypes steam peeled at 4.4 bar. Recovery decreased with increasing steam pressure and dwell time for VF 134 and Castlehy 1509. Quality of peeled Castlehy 1509 was superior to VF 134 fruit due to lack of yellow shoulder disorder (YSD) and consequent low quantities of adhering peel. Equations for prediction of % recovery and quantity of adhering peel as functions of steam pressure, dwell time, and % YSD were developed based on results of the lab scale experiment.     

Effects of freezing and canning of papaya slices on their carotenoid composition

An HPLC study of the carotenoid composition of fresh, frozen and canned papaya fruit slices was done. There were no qualitative differences between the carotenoid patterns of fresh and frozen papaya fruit slices (cultivar Sunrise). The major carotenoids found in papaya extracts were lycopene and carotenol fatty acid esters of-cryptoxanthin and-cryptoxanthin-5, 6-epoxide. Other xanthophylls detected were-crypto-xanthin,trans-zeaxanthin and cryptoflavin. It was possible to determine the quantitative losses of carotenoids in papaya slices as a result of the freezing process and frozen storage, since samples of these fruits were available before processing. The pigment pattern of the canned product showed lycopene as being a major pigment. Thermal treatment induced the degradation of carotenol fatty acid esters of xanthophylls. The freezing and canning processing of papaya slices led to significant decreases in the total carotenoids quantified by HPLC, with frozen female slices and canned samples showing lower amounts of pigments. Hunter colour values of frozen slices were similar to those of fresh papaya fruit slices.     

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.     

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.     

荔枝冻结规律探讨及速冻加工技术

果皮褐变、裂果和汁液流失多是目前荔枝速冻生产的难题。本文通过测定荔枝在不同冻结温度下的冻结曲线及其结冰率和汁液流失率等情况 ,探讨荔枝冻结规律 ,为提高速冻荔枝商品质量提供参考。试验结果表明 :荔枝冻结过程 3个阶段不明显 ;冻结点约为 -3 0℃ ;最大冰晶生成带约在 - 3～ - 15℃。建议荔枝速冻采用去皮速冻工艺 ,这样既可避免果皮褐变问题 ,又可解决速冻与裂果的矛盾 ,减少汁液流失 ,提高速冻荔枝的商品价值 ,同时方便食用或加工其它制品     

Mechanical and Thermal Pretreatments of Crushed Tomatoes: Effects on Consistency and In Vitro Accessibility of Lycopene

ABSTRACT:  The effects of mechanical and thermal treatments on the consistency and  in vitro  lycopene accessibility of crushed tomatoes were evaluated. Different crushing intensities and a subsequent heat treatment carried out as a heat shock (95 °C for 8 min) or a boiling step (100 °C for 20 min) were examined. Additional homogenization was compared with milder crushing regarding the effect on lycopene content and  in vitro  accessibility. Textural properties, polygalacturonase and pectinmethylesterase activity, pectin degree of methoxylation, lycopene content, and  in vitro  lycopene accessibility were evaluated. Microstructure was studied using both light and transmission electron microscopy. Crushing and subsequent heating affected the pectin degree of methoxylation and the consistency of the crushed tomatoes. The mechanical and thermal treatments did not affect the lycopene content to any great extent; however,  in vitro  accessibility seemed to improve with extensive crushing followed by heating. Crushing or homogenization in itself was not enough to increase  in vitro  lycopene accessibility.     

DEFECTS AND PEELABILITY OF PROCESSING TOMATOES

Peeling is one of the first operations in the manufacture of whole peeled and diced tomatoes, and the peelability of processing tomatoes is significantly affected by the presence of various tomato defects, in particular yellow eye and blossom‐end rot. Tomato maturity also impacts both the percentage of peeled fruit and yield. Immature fruits are typically undercolored and small in size. Sunburned regions on the tomato surface are difficult to peel as well. In this study, we determined the impact of 24 selected tomato defects on tomato peelability and yield of whole peeled tomatoes. There are potential advantages to sorting to remove selected tomato defects early in the process.     

Thermal Stability and Isomerization of Lycopene in Tomato Oleoresins from Different Varieties

ABSTRACT: Lycopene, a tomato carotenoid, has been associated with the inhibition of certain chronic diseases including prostate cancer. Tomato oleoresin is a lipid-rich material resulting from successive solvent extraction of the tomato fruit. Thermal stability and isomerization of lycopene in oleoresins prepared from 3 different tomato varieties, Roma, High Lycopene, and Tangerine, and tomato peel waste, were studied at 25 °C, 50 °C, 75 °C, and 100 °C in the dark. Thermally degraded lycopene compounds and isomers of lycopene were analyzed by a combination of C₃₀ reversed-phase high-performance liquid chromatograph with a photodiode array detector, UV-visible spectrometer, or mass spectrometer. Effects of antioxidants on lycopene were also studied at 50 °C. As the storage temperature increased from 25 °C to 100 °C, the degradation of total lycopene in oleoresin from all samples increased significantly ( P <0.05). Lycopene at 25 °C and 50 °C may degrade mainly through oxidation without isomerization. Isomerization of lycopene in tomato oleoresins increased at 75 °C and 100 °C. Tetra- cis lycopene in Tangerine tomato varieties followed different degradation and isomerization pathways compared with all -trans lycopene in other tomato varieties. Addition of α-tocopherol or butylated hydroxytoluene slowed the rate of degradation of lycopene in oleoresin.