Evaluation of heat and oxidative damage during storage of processed tomato products. II. Study of oxidative damage indices

Tomato products (pulp, puree and paste) submitted to accelerated aging (30, 40 and 50 °C for 3 months) were studied to evaluate variations in the kinetics of the degradation of antioxidants and antioxidant activity. The carotenoids lycopene and β‐carotene, ascorbic acid, rutin and total phenolics were analysed. The antioxidant activity was measured using (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radicals and hydrogen peroxide, and (b) the linoleic acid/CuSO₄ system, which promotes lipid peroxidation. The ascorbic acid content decreased even at 30 °C, following pseudo‐first‐order kinetics, with an activation energy of 105 200 J mol^?1 for tomato pulp and 23 600 J mol^?1 for tomato paste. The lower the initial ascorbic acid content, the higher was the degradation rate. Variations in phenolic compounds occurred at 40 °C and higher, following pseudo‐zero order kinetics. The antioxidant activity of the hydrophilic fraction of the tomato products depended on both antioxidant degradation and the Maillard reaction and could not be described by a kinetic model. The β‐carotene content decreased even at 30 °C, whereas the lycopene content was stable in all samples. The antioxidant activity of the lipophilic fraction of the tomato products decreased following pseudo‐first order kinetics, with an activation energy of 22 200 J mol^?1 for tomato pulp and 20 200 J mol^?1 for tomato paste. It is concluded that significant ‘oxidative damage’ can occur in tomato products during their commercial shelf‐life. Copyright © 2003 Society of Chemical Industry     

High temperature-tolerant tomato lines: bioactive compounds

High global temperatures will be a great challenge for agricultural production in the near future. Therefore, adaptation of agricultural crops to the high temperatures or development of new heat-tolerant crops with known bioactive compounds is an important strategy for nutritional health and crop improvement programs. In this context, the bioactive compounds of newly developed high temperature-tolerant tomato lines were investigated in terms of lycopene, β-carotene, ascorbic acid and phenolic compounds to assist breeders for the selection of high temperature tolerant tomato varieties with high nutritional quality. Nineteen tomato lines, including control varieties from the “Turkey F1 Hybrid vegetable variety and quality line development” project and the GAP Agricultural Research Institute, were selected for the investigation. Line 11 was superior in lycopene and β-carotene content, while line 18 was superior in ascorbic acid content as compared to control varieties Cansun F1 and Alsancak RN F1. Urfa 2012 and line 28 were found to have the highest numbers of phenolic compounds. Chlorogenic acid, naringenin, trans-ferulic acid and rutin were key phenolic compounds detected in each of the tomato lines. These newly released tomato lines can be used as value-added germplasm or parent sources to develop new heat-tolerant cultivars in breeding programs or as commercial cultivars for their superior functional qualities.     

Phenolic compounds,lycopene and antioxidant activity in commercial varieties of tomato (Lycopersicum esculentum)

Nine commercial varieties of tomato (Rambo, Senior, Ramillete, Liso, Pera, Canario, Durina, Daniella and Remate) produced in Spain were analysed for their lycopene content, content of phenolic compounds and antioxidant capacity. The phenolic compounds were characterised as flavonoids (quercetin, kaempferol and naringenin) and hydroxycinnamic acids (caffeic, chlorogenic, ferulic and p‐coumaric acids). Antioxidant activity was measured using the DPPH and ABTS assays. The concentrations of lycopene and the various phenolic compounds as well as the antioxidant activity were significantly influenced by the tomato variety. Quercetin, the most abundant flavonoid, was found in concentrations ranging between 7.19 and 43.59 mg kg^?1 fresh weight, while naringenin levels were lower than 12.55 mg kg^?1. The most abundant hydroxycinnamic acid was chlorogenic acid, with values ranging from 14 to 32 mg kg^?1 fresh weight, followed by caffeic acid, while p‐coumaric and ferulic acids showed similar concentrations lower than 5 mg kg^?1. The highest content of lycopene was found in Ramillete, Pera and Durina (>50 mg kg^?1 fresh weight), while the concentration in the other varieties was between 50 and 30 mg kg^?1, with the exception of Liso (less than 20 mg kg^?1). The antioxidant activity of tomato extracts varied with the tomato variety and the assay method used. Individual compounds found to be significantly related to antioxidant capacity were lycopene and ferulic and caffeic acids, but not quercetin and chlorogenic acid. © 2002 Society of Chemical Industry     

Effect of rotating tray drying on antioxidant components,color and rehydration ratio of tomato saladette slices

A rotating tray drier was built and controlled for drying of tomato slices at different temperatures (45, 50 and 60 °C) and air velocities (0.6 and 1.2 m s^?1) with and without tray rotation. Drying curves were fitted using the Page mathematical model. Effective diffusivities for the different drying conditions correlated well with the chemical composition variables; lycopene, ascorbic acid and total polyphenols (TPP). The effect of drying conditions over quality of dried tomato slices was evaluated by quantifying their contents of lycopene, ascorbic acid and TPP, and measuring their color and rehydration ratio. The best drying conditions were 60 °C drying temperature and 0.6 m s^?1 air velocity with the use of tray rotation. These conditions minimized the degradation of lycopene (2.9%), ascorbic acid (17.3%) and TPP (2.1%) during drying. Tray rotation has a contribution on the a* color value, as well as on the lycopene and ascorbic acid concentrations (5% significance level).     

Tomatoes and Tomato Products as Dietary Sources of Antioxidants

Tomatoes, as an agricultural product, represent an important commodity worldwide and comprise a significant part of the human diet. They are one of the most versatile and widely used fruits, being consumed in the raw state and used for the preparation of a wide range of products. Tomatoes and tomato products are rich in antioxidant compounds such as carotenoids (particularly lycopene), ascorbic acid and phenolic compounds. The regular consumption of tomatoes and tomato products has been correlated to a reduction in risk of contracting various types of cancer and cardiovascular diseases. This positive effect is attributed to the antioxidants present in tomatoes.     

Stability of nutritionally important compounds and shelf life prediction of tomato ketchup

Ketchup is an important source of tomato antioxidants in human nutrition, this ambient stable product is processed using several relatively important heat treatments and can be stored for one or more years at ambient temperature. Model storage experiments were carried out with two sets of commercial ketchup produced according to the Czech recipe: (a) hot-filled without subsequent pasteurization and (b) filled and pasteurized in the jar. The samples were stored at 25, 50, 75 and 90 °C, during the storage the content of total lycopene and ascorbic acid was observed as well as the colour parameters (a*, ΔE). The obtained data were processed using the pseudo first order (total lycopene, ascorbic acid and a*) and zero order kinetics (ΔE). The obtained results corresponded with the published data, but were not consistent between the both sets of the samples. The total lycopene and ascorbic acid degradation is more dependent on the conditions in the product, mainly on the previous history of heat treatment. The colour parameters, especially ΔE seemed to be more robust criterion, which could be used for the shelf life prediction estimation. The empirically set up shelf life by the producer was confirmed.     

The impact of thermal processing on bioactive compounds in Australian native food products (bush tomato and Kakadu plum)

This study was conducted to investigate the effect of food processing on the survival of bioactive compounds in Australian bush food products. The lycopene, beta carotene, and ascorbic acid were detected from bush tomato sauce, bush tomato ketchup and Kakadu plum chilli and ginger sauce. The finished product samples were collected during real food production line at three interval times; beginning, middle and the end of the real time manufacturing processes. The bioactive contents from the three products were stable throughout the heating process. In another experiment, bush tomato sauce (16% dried bush tomato content), Kakadu plum sauce (70% Kakadu plum filtrate) were prepared in the laboratory. Bioactive contents (lycopene and beta carotene) in lab formulated bush tomato sauce increased by 48 and 14% respectively. In contrast, ascorbic acid content in the Kakadu plum sauce lost by 16.9%. The experiment suggested that heat processing increased the level of lycopene and betacarotene but minimised ascorbic acid content in processed Australian Bush food products.     

Effects of industrial tomato paste processing on ascorbic acid, flavonoids and carotenoids and their stability over one-year storage

BACKGROUND : The effects of industrial tomato paste processing and long‐term (12 months) ambient storage on the content and stability of quercetin, kaempferol, ascorbic acid (AA), dehydroascorbic acid (DHAA), β‐carotene and lycopene were evaluated in a commercially produced tomato paste. RESULTS : The initial thermal treatment (hot break; 93 °C for 5 min) resulted in significant reductions in quercetin (54%), kaempferol (61%), AA (63%) and β‐carotene (30%), whereas subsequent processing steps (e.g. evaporation and sterilization) did not result in marked changes in these compounds. Lycopene was stable during hot break but decreased by 20% through evaporation and sterilization. The ratio of DHAA:vitamin C increased during hot break to 23%, whereas the ratio of DHAA:vitamin C remained relatively low in subsequent processing steps, indicating that AA was not oxidized. AA decreased with prolonged storage, with only 13% remaining at 12 months. The carotenoids and quercetin remained stable through 12 months of ambient storage. CONCLUSIONS : Tomato pomace contained significant amounts of carotenoids and flavonoids, indicating that it may be an underutilized processing byproduct. Copyright © 2011 Society of Chemical Industry     

Evaluation of the genotype, environment and their interaction on carotenoid and ascorbic acid accumulation in tomato germplasm

BACKGROUND: Tomatoes are an important source of antioxidants (carotenoids, vitamin C, etc.) owing to their high level of consumption. There is great interest in developing cultivars with increased levels of lycopene, β‐carotene or L ‐ascorbic acid. There is necessary to survey new sources of variation. In this study, the potential of improvement for each character in tomato breeding programmes, in a single or joint approach, and the nature of genotype (G), environment (E) and G × E interaction effects in the expression of these characters were investigated. RESULTS: The content of lycopene, β‐carotene and ascorbic acid determined was very high in some phenotypes (up to 281, 35 and 346 mg kg^?1 respectively). The important differences in the three environments studied (with some stressing conditions in several situations) had a remarkable influence in the phenotypic expression of the functional characters evaluated. Nevertheless, the major contribution came from the genotypic effect along with a considerable G × E interaction. CONCLUSION: The joint accumulation of lycopene and β‐carotene has a high genetic component. It is possible to select elite genotypes with high content of both carotenoids in tomato breeding programmes but multi‐environment trials are recommended. The improvement of ascorbic acid content is more difficult because the interference of uncontrolled factors mask the real genetic potential. Among the accessions evaluated, there are four accessions with an amazing genetic potential for functional properties that can be used as donor parents in tomato breeding programmes or for direct consumption in quality markets. Copyright © 2011 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     

Changes in the contents of antioxidant compounds in pepper fruits at different ripening stages,as affected by salinity

The interest in the consumption of pepper fruits (Capsicum annuum L.) is, to a large extent, due to its content of bioactive nutrients and their importance as dietary antioxidants. A greenhouse experiment was carried out to determine the effects of salinity and different ripening states of pepper fruits on several compounds with antioxidant properties. Fruits from plants grown under three saline treatments (0, 15, and 30 mM NaCl) were collected at three maturity states (green, turning, and red). Antioxidant activity in the hydrophilic (HAA) and lipophilic (LAA) fractions, lycopene, β-carotene, ascorbic acid, total phenolic compounds and reducing sugars were determined. From the nutritional point of view, the red state was the most appropriate state of maturation, since red peppers had the highest levels of lycopene, β-carotene, and sugars and the highest antioxidant activity for both hydrophilic and lipophilic fractions. The effect of salinity depended on the maturity state of the peppers: it had no effect on HAA, β-carotene or sugars, but decreased ascorbic acid and total phenolic compounds, and increased LAA and lycopene. The use of a moderately-saline water was beneficial when peppers were harvested in the red state, by increasing HAA and LAA in fruits, with no significant effects on other parameters.     

The anti-inflammatory effect of lycopene complements the antioxidant action of ascorbic acid and α-tocopherol

Tomato foods contain bioactive compounds, such as lycopene, ascorbic acid and α-tocopherol, which are assumed to show synergistic effects. The aim of the study was to investigate this presumed synergy. The effect on lipid peroxidation and inflammation was assessed. Lipid peroxidation was effectively inhibited by combinations of the compounds compared to the single compounds. Synergy between the combination of ascorbic acid and α-tocopherol was confirmed. Lycopene on its own effectively reduced inflammation by inhibiting the release of TNF-α and stimulating IL-10 production. The combination of lycopene, ascorbic acid and α-tocopherol tended to display a synergistic interaction on IL-10 production. Our observations highlight that lycopene mitigates inflammation, whereas ascorbic acid and α-tocopherol efficiently protect against lipid peroxidation. Both activities are complementary since they diminish the process of inflammation differently on different levels. In relation to health, this is an added value of fruit and vegetables such as tomato products that contain complementary bio-active compounds.     

The physico-chemical characteristics of extruded snacks enriched with tomato lycopene

Adding tomato derivatives to traditional starchy extruded snacks can improve their nutritional properties by adding lycopene and fibre; however the physico-chemical properties of these products must also be considered. Ingredients and extrusion parameters, including temperature, alter these properties, but their effect on lycopene content is not known. In this study, crisp low density extruded snacks were manufactured from corn, wheat and rice, with or without dried tomato skin or paste powder extruded at temperatures of 140, 160 or 180 °C. Lycopene content and the physico-chemical properties (expansion, density, hardness, colour parameters and percentage of moisture loss) of the extruded products were measured. Lycopene retention was higher in products containing tomato skin powder and significantly lower when wheat flour was used to make the snacks. Increases in the processing temperature improved the physico-chemical characteristics of the snacks but had no significant effect on lycopene retention (P > 0.05).     

Carotenoid and phenolic profile of tomato juices processed by high intensity pulsed electric fields compared with conventional thermal treatments

The effect of high intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1500 μs of overall treatment time with bipolar pulses of 4-μs at 100 Hz) and heat pasteurisation (90 °C for 30 s or 60 s) on carotenoids and phenolic compounds as well as on some quality attributes (pH, soluble solids and colour parameters) of tomato juice was evaluated and compared, having the untreated juice as a reference. Processing enhanced some carotenoids (lycopene, β-carotene and phytofluene) and the red colour of juices, whereas no significant changes in phenolic compounds, pH and soluble solids were observed between treated and untreated juices. A slight decrease in overall health-related compounds was observed over time, with the exception of some carotenoids (β-carotene and phytoene) and caffeic acid. However, HIPEF-processed tomato juices maintained higher content of carotenoids (lycopene, neurosporene and γ-carotene) and quercetin through the storage time than thermally and untreated juices. Hence, the application of HIPEF may be appropriate to achieve not only safe but also nutritious and fresh like tomato juice.     

Bio-preservation of fresh-cut tomatoes using natural antimicrobials

Effects of several natural volatile compounds such as methyl jasmonate (MJ), ethanol (ETOH), their combination (MJ–ETOH), tea tree oil (TTO) and garlic oil (GO) were evaluated on fresh-cut tomato storage at 5 °C for 15 days. Microbial growth, in-packaged atmosphere, quality attributes (firmness and color) and bioactive compounds (lycopene content, ascorbic acid and phenolic compounds) of fresh-cut tomatoes were determined. The shelf-life based on microbial growth was longer on fresh-cut tomatoes treated with natural volatile compounds than in control fresh-cut tomatoes. Treatment with ETOH combined with MJ was more effective in suppressing microbial proliferation than the individual treatments with each natural volatile compound. The lowest in-packaged atmosphere modification was detected in fresh-cut tomatoes treated by ETOH. In addition, this treatment better maintained firmness and color attributes than those treated with the other antimicrobial compounds. Related to the bioactive compounds, the use of MJ let keep higher content of lycopene, ascorbic acid and phenolic compounds than the other treatments. Thus, the shelf-life of fresh-cut tomatoes could be prolonged by the use of natural antimicrobials, which do not have significant negative effects on health-related compounds.     

Extraction of Lycopene from Tomato Paste by Ursodeoxycholic Acid Using the Selective Inclusion Complex Method

Lycopene, a precursor of β‐carotene with well‐known antioxidant activity and powerful health properties, can be found in many natural products such as tomato (Lycopersicon esculentum), watermelon, red pepper, and papaya. Many separation methods have been reported for extracting lycopene from its sources. The inclusion complex is an effective method for extraction and purification of organic chemicals. This procedure has 2 main components: host and guest molecules. In this study, lycopene (guest) was extracted from tomato paste by ursodeoxycholic acid, the inclusive agent (host). The molecular structure of the extracted lycopene was then confirmed by ¹HNMR and its purity was evaluated using high‐performance liquid chromatography and UV‐Vis spectrophotometry methods, in comparison with a standard product. The results indicated that the proposed separation method was very promising and could be used for the extraction and purification of lycopene from tomato paste.     

Performance evaluation of a novel food packaging material based on clay/polyvinyl alcohol nanocomposite

The effectiveness of a novel, laminated clay/polyvinyl alcohol nanocomposite food-packaging film was examined by barrier analysis and food shelf-life monitoring. The effect of storage conditions on the film's oxygen permeability was studied and compared to commercial LLDPE/PET film as control. Additionally, pouches of 14 cm × 10.5 cm prepared from both films were filled with tomato paste as the food model, and stored at different temperatures (20–50 °C) and humidities (20–85% RH) for 10 days. Incorporating a coating layer containing 30 wt% (d.b.) of clay into polymer was found to improve its barrier properties, with drastic reduction of oxygen transmission rates (OTR) up to 99%, especially at 20% RH. While surrounding humidity affected the OTR of composite film significantly more than that of control film, the OTR of composite film was lower and less susceptible to temperature changes. The changes of food physical-chemical properties with time showed that the pouches of composite film significantly decreased ascorbic acid and lycopene oxidation of tomato paste by up to 88 and 37%, respectively. Furthermore, no discolouration occurred to the samples packaged by the nanocomposite film as compared to the control.Industrial relevanceA novel clay/polyvinyl alcohol nanocomposite film was developed with excellent barrier properties against oxygen. Evaluation of the performance of this food-packaging film indicated that incorporation of montmorillonite enhanced food preservation as suggested by decreased ascorbic acid and lycopene oxidation, and no discolouration of tomato paste. This new approach could be adopted by the food industry to assist commercial producers and retailers for preserving and extending the shelf-life of a variety of food products.     

Effect of illumination and chlorophylls on stability of tomato carotenoids

Lipidic extract from tomato peels, or tomato peels plus stalks, dissolved in ethanol were submitted to illumination. Lycopene, β-carotene, phytoene and phytofluene isomerisation and degradation, during storage at room temperature for 28 days, were studied. Degradation of chlorophylls a and b were analysed in lipidic extracts from stalks. Total lycopene and all-E-lycopene degradation was found to fit to a first-order model. The degradation rate constant was lower in extracts from peels −0.0137 (all-E-lycopene) and −0.0737 (total lycopene), than in those from peel plus stalk −0.0415 (all-E-lycopene) and −0.0854 (total lycopene). Z-lycopene isomers showed an inconsistence change during storage, in all analysed samples. Concentration of β-carotene from extracts of tomato peels plus stalks decreased slightly during storage. Phytoene and phytofluene degradation were not significantly affected by both storage conditions and chlorophylls. The obtained results showed that some compounds from stalks, such as chlorophylls, could favour lycopene and β-carotene degradation during storage under illumination.     

Effect of Fruit Ripening Stage on Physico-Chemical Properties, Nutritional Composition and Antioxidant Components of Tomato (Lycopersicum esculentum) Cultivars

In this study, we investigated the effects of fruit ripening stage on the physico-chemical properties and nutritional contents of three greenhouse grown tomato cultivars (‘Monika’, ‘Isabella’ and ‘Cherry’). Significant changes (p?≤?0.05) occurred in fruit colour, total soluble solids, protein, fibre, ascorbic acid (vitamin C) and lycopene content at different stages of ripening. ‘Cherry’ tomato contained significantly (p?≤?0.05) higher total soluble sugar and several nutrients including fibre. However, the plum-type tomato cultivars (‘Monika’ and ‘Isabella’) contained higher vitamin C and lycopene than ‘Cherry’ tomato. In all tomato cultivars, it was found that up to 50% of final lycopene content occurred during the final phase (from red to deep red colour) of fruit ripening.     

Improving the stability of lycopene Z-isomers in isomerised tomato extracts

Tomato-based foods rich in Z-lycopene are potentially more bioavailable and have greater bioefficacy compared to natural tomato products which mainly contain all-E-lycopene. To prepare a stable tomato extract with a high level of Z-lycopene, geometrical isomerisation of lycopene was studied in organic solvents either alone or in the presence of a tomato extract. Interconversion between the isomers was observed in all systems with 13Z-lycopene being the least stable. Heating a tomato extract containing mainly the all-E-isomer in ethyl acetate produced successively 13Z-, 9Z- and 5Z-lycopene. An isomerised tomato oleoresin with a minimal content of the most unstable 13Z-lycopene could be obtained by refluxing tomato oleoresin in ethyl acetate for 1 week. In this isomerised tomato oleoresin, total lycopene and lycopene isomer profiles were shown to remain constant for 1 year at room temperature. Accordingly, this product is a valid source of stable and potentially highly bioavailable lycopene.