Preservation of tomato juice under acid conditions

A technique for preserving tomato juice and crushed tomatoes under acid conditions has been developed. This eliminates the need for the usual processing time of 55 min in boiling water for 650 ml glass bottles, which would result in considerable savings in energy requirements by the tomato processing industry. The ketchup prepared from the acidified tomato juice and crushed tomatoes (after neutralisation) was rated by the panelists to be as good as a commercial tomato ketchup sample.     

Antioxidative capacity of tomato products

The antioxidative capacity of methanol/water and hexane extracts of five tomato juices, four canned tomatoes and four tomato pastes was measured using two test systems: with 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS⁺) and with linoleic acid emulsion. In both the ABTS assay and the linoleic acid system, most of the antioxidative capacity of analysed products was from the methanol-water fraction, which contained polyphenols and ascorbic acid. On the basis of the wet weight of the tomato products, tomato pastes had the highest activity towards ABTS⁺ (micromoles of Trolox equivalents per gram) followed by tomato juices, and canned tomatoes. The inhibition of formation of thiobarbituric acid-reactive substances in the linoleic acid emulsion was strongly dependent on antioxidant concentration. The results suggest that tomato products, in addition to fresh tomatoes, may also be important in supplying dietary antioxidant, especially polyphenols and carotenoids.     

Variability in the content of soluble sugars and cell wall polysaccharides in red‐ripe cherry and high‐pigment tomato cultivars

BACKGROUND: Soluble sugars and cell wall polysaccharides are well known for contributing to a range of ‘quality’ characteristics of fresh vegetables such as flavour, texture and healthy properties. Red‐ripe berries of 14 cultivars of cherry tomatoes and four cultivars of high‐pigment tomato hybrids, cultivated in the south of Italy, were analysed for their content of these important qualitative parameters. RESULTS: Sakura appeared to be the cultivar with the highest amount of soluble sugars (53 g kg^?1 fresh weight (f.w.)), mainly glucose and fructose, and, hence the ‘sweetest’ among cherry tomatoes. High‐pigment tomatoes, especially HLY02 and HLY13, showed a soluble sugar content much lower than cherry tomatoes, as expected for industrial, normal‐size tomatoes. Variations in the fructose/glucose ratio, of between 0.68 and 1.48, were evidenced among the different tomato cultivars. Cell wall polysaccharides isolated from whole fresh red‐ripe berries of each cultivar were analysed chemically. The amount of matrix polysaccharides (0.9–3.4 g kg^?1 f.w.) and cellulose (0.16–1.86 g kg^?1 f.w.), as well as their glycosidic composition, showed significant differences among the different cultivars. Cellulose to matrix polysaccharide ratio was highly variable and ranged between 0.06–1.44 and 0.17–0.77 in cherry and high‐pigment tomato cultivars, respectively. CONCLUSION: The differences evidenced in the total soluble sugar and cell wall polysaccharide composition, not only among different types of tomatoes but also different cultivars within the same typology, may play a fundamental role in the quality of tomatoes and deserve further investigations. Copyright © 2008 Society of Chemical Industry     

Contribution of some volatile tomato components and their mixtures to fresh tomato aroma

Some volatile components of fresh tomatoes and mixtures of these components were evaluated for their contribution to fresh tomato aroma. cis-Hex-3-enal was the only individual component evaluated which was rated moderately similar to the aroma of fresh tomatoes. A mixture of cis-hex-3-enal, 2-methylhept-2-en-6-one, eugenol and β-ionone significantly improved the aroma of tomato juice prepared from foam-mat-dried tomato powder. Since the individual components of the mixture did not give significant improvement, the desired effect probably occurred as a result of a complex interaction among the added components and juice.     

Evaluation of overhead spray-applied sanitizers for the reduction of Salmonella on tomato surfaces

Abstract: Efficacy of sanitizers in an overhead spray and brush roller system was examined for reducing Salmonella on unwaxed, mature green tomatoes. Surface inoculated tomatoes were treated in the overhead spray system for 5, 15, 30, and 60 s. A sodium hypochlorite (NaOCl) study tested NaOCl (25, 50, and 100 mg/L) against a water control. A sanitizer study examined NaOCl (100 mg/L), chlorine dioxide (ClO₂; 5 mg/L), peroxyacetic acid (PAA; 80 mg/L), and water. The overhead spray system was also compared to a scale‐model flume. All NaOCl concentrations were significantly more effective at removing Salmonella than water and achieved at least a 3‐log₁₀ CFU/mL reduction at different treatment times (P < 0.05). NaOCl (100 mg/L) achieved a 4 ± 1.8 log₁₀ CFU/mL reduction at 15 s. In the sanitizer study, NaOCl, ClO₂, and PAA achieved at least a 3‐log₁₀ CFU/mL reduction at 15 s and between 3.9 and 5.5 log₁₀ CFU/mL reductions at 30 to 60 s. NaOCl (100 mg/L) in the overhead spray system significantly reduced more Salmonella than in the flume at 15 to 60 s. NaOCl flume treatment only reached a 1.3 ± 1.1 log₁₀ CFU/mL reduction at 15 s. Results of this study demonstrate the ability of sanitizers in the laboratory model overhead spray system to reduce Salmonella on tomato surfaces. An overhead spray system could be implemented instead of flumes to achieve higher pathogen reduction with less water and sanitizer use, thereby lowering packing costs. Practical Application: The use of a non‐recirculating, overhead spray brush roller system could offer a cost effective and efficacious way of washing tomatoes. The use large communal dump tanks in tomato processing has been suspected as a source of contamination in the tomato processing process. If effective, the brush roller system could augment or possible replace currently used dump tanks.     

Use of alginate or zein as edible coatings to delay postharvest ripening process and to maintain tomato (Solanum lycopersicon Mill) quality

BACKGROUND: Edible coatings could be effective tools for delaying the ripening process of fruits. Alginate or zein as edible coatings were assayed in tomato in order to maintain parameters related to quality during postharvest storage. RESULTS: Coated tomatoes showed lower respiration rate and ethylene production than control ones, with a twofold lower concentration of ethylene precursor. In addition, the evolution of parameters related to tomato quality losses, such as softening, colour evolution and weight loss, was significantly delayed (4–6 days on average) in coated tomatoes as compared to controls. Thereafter, sugars, organic acids (and especially ascorbic acid) and scores from sensory analysis remained at much higher levels at the end of storage in treated than in control tomatoes. CONCLUSIONS: Coatings based on alginate or zein could be effective tools for delaying the tomato‐ripening process during postharvest storage, and in turn maintaining tomato quality and its acceptability by consumers. Copyright © 2008 Society of Chemical Industry     

Flavor of tomato and tomato products

Abstract

The characteristic sweet‐sour taste of tomato and its overall flavor intensity are due to the following components: reducing sugars (fructose and glucose), free acids (mainly citric’ acid), their ratio, as well as some volatile substances, not identified so far, and the interplay between the above‐mentioned groups of compounds. Of the minerals, potassium (by influencing the free acid content) and phosphate (due to its buffering capacity) indirectly affect the taste. The effect of the free amino acids (glutamic acid, glutamine, gamma‐aminobutyric acid, and aspartic acid) is not unambiguously proven.

The characteristic tomatolike flavor is predominantly determined by volatile substances. Volatile substances develop partly during ripening, partly during the comminution of the ripe fruit, as an effect of the enzymes activated. Volatile substances characterizing fresh tomato flavor are derived mainly from fatty acids and amino acids. Differences between the flavors of different varieties, the less characteristic, weaker flavor of hothouse‐grown tomatoes or artificially ripened ones, are explained by the different quantitative proportions of the volatile substances. So far no key substance playing a decisive role in the flavor of tomato has been detected. Of the approximately 400 volatile compounds so far identified, several were found, however, which have an important role in the flavor of fresh tomato (cis‐3‐hexenal, trans‐2‐hexenal, 2‐isobutylthiazole, hex‐anal, cis‐3‐hexen‐1‐ol, 2E,4E‐decadienal, 6‐methyl‐5‐hepten‐2‐one, etc.).

In the course of tomato processing the flavor substances undergo substantial qualitative and quantitative change, which may or may not be favorable. Depending on the extent of heat treatment and its duration, the reducing sugar and amino acid content decreases while the acid content (by the formation of pyrrolidone carboxylic acid) increases. A part of the volatile substances (mainly those providing “green” smell) evaporates and at the same time—traceable back to the breakdown of sugars and carotenoids—new components, among them those which characterize the “cooked” smell of tomato products, are formed (e.g., dimethyl sulphide, acetaldehyde). Although our knowledge as to the qualitative and quantitative composition of tomato flavor, the factors affecting it, and the effect of certain compounds on it has substantially increased, we are still not in the position to consciously develop the flavor during cultivation and processing. To achieve this further systematic research work is necessary.     

Evidence of antiplatelet aggregation effects from the consumption of tomato products,according to EFSA health claim requirements

Abstract

The beneficial effect of fresh tomatoes or processed tomato products on platelet aggregation depends on the presence of bioactive compounds in these products, in sufficient quantities, to produce a relevant physiological effect, when consumed as part of a normal diet. This work is focused on reviewing the development on tomato products bioactive compounds, particularly with reference to its potential biological activity with beneficial effect on the prevention of platelet aggregation.

The most relevant studies found show that all bioactive compounds found in Water-soluble tomato concentrate are in tomato fruit and other tomato products, and there is enough evidence of their beneficial effects. According to the European Food Safety Authority requirements, further intervention studies (human clinical trials) using valid markers should be performed in order to demonstrate the beneficial effects of tomato products as consumer products (paste, puree, sauce or juice) on platelet aggregation. Our PubMed review results support the development of promising nutritional strategies involving tomatoes and tomato products to tackle cardiovascular disease as antiplatelet aggregation.     

Distribution behaviour of acaricide cyflumetofen in tomato during home canning

The distribution behaviour of cyflumetofen in tomatoes during home canning was studied. The targeted compound cyflumetofen was determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after each process step, which included washing, peeling, homogenisation, simmering and sterilisation. Results indicated that more cyflumetofen was removed by washing with detergent solution compared with tap water, 2% NaCl solution and 2% CH₃COOH solution. Peeling resulted in 90.2% loss of cyflumetofen and was the most effective step at removing pesticide residues from tomatoes. The processing factors (PFs) of tomato samples after each step were generally less than 1; in particular, the PF of the peeling process for cyflumetofen was 0.28.     

Evaluation of in-line absorption photometry to predict consistency of concentrated tomato products

This study evaluated the correlation between optical density as measured by absorption photometry, water-insoluble solids (WIS) and consistency as measured by the Bostwick consistometer for a variety of concentrated tomato products. Linear regression analysis indicated a linear correlation (R²=0.97) between optical density and WIS content in diluted tomato paste, a linear correlation (R²⩾0.92) between optical density and consistency in various commercial tomato products and a linear correlation (R²=0.93) between optical density and consistency during commercial production of tomato puree made from ripe tomatoes. The optical density appeared to be unaffected by product temperature and flow rate. Potential limitations of in-line absorption photometry to monitor and control tomato product consistency are briefly discussed.     

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.     

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.     

Glass transitions for freeze-dried and air-dried tomato

Glass transition temperatures of freeze-dried tomato conditioned at various water activities at 25 °C were determined by differential scanning calorimetry (DSC). Air-dried tomato with and without osmotic pre-treatment in sucrose/NaCl solutions was also analyzed. Thermograms corresponding to the low water activity domain (0.11 ⩽ a_w ⩽ 0.75) revealed the existence of two glass transitions, which were attributed to separated phases formed by sugars and water and other natural macromolecules present in the vegetable. Both transitions were plasticized by water and experimental data could be well correlated by the Gordon-Taylor equation in the low-temperature domain, and by the Kwei model in the high-temperature domain. For higher water activities, the low-temperature glass transition curve exhibited a discontinuity, with suddenly increased glass transition temperatures approaching a constant value that corresponds to the T_g of the maximally freeze-concentrated amorphous matrix. The unfreezable water content was determined through the melting enthalpy dependence on the moisture content.     

Kinetic and thermodynamic investigation of mancozeb degradation in tomato homogenate during thermal processing

BACKGROUND: The kinetic and thermodynamic parameters of mancozeb degradation in tomato homogenates under the conditions prevailing in the manufacture of tomato products (at 60–100 °C for 0–60 min) were investigated. A gas chromatography–mass spectrometry method was used to analyse residual mancozeb in tomato homogenate. Ethylenethiourea (ETU), the main toxic degradation product of mancozeb, was measured by high‐performance liquid chromatography (HPLC)–with photodiode array detector (PDA). RESULTS: The degradation of mancozeb and the formation of ETU in tomato homogenates were adequately described as first‐order kinetics. Dependence of the rate constant followed the Arrhenius relationship. Apparent activation energies, temperature coefficients, half time and time to reduce to 90% of the initial value of mancozeb were calculated as kinetic parameters. The thermodynamic parameters of mancozeb were also described as Δg^d = ? 2.440 and 7.074 kJ mol^?1; Δh^d = ? 32.555 and ? 42.767 kJ mol^?1; Δs^d = ? 0.090 and ? 0.150 kJ mol^?1 K^?1; K_e = 0.414 and 9.797 L g^?1 for 333 and 373 K respectively. CONCLUSION: Current findings may shed light on the reduction of mancozeb residue and its toxic degradation product during thermal processing of tomatoes and may also be valuable in awareness and prevention of potential risks from dietary exposure. Copyright © 2011 Society of Chemical Industry     

Quality of fresh‐cut tomatoes as affected by salt content in irrigation water and post‐processing ultraviolet‐C treatment

BACKGROUND: There is little information available concerning the effect of sanitizing agents, including ultraviolet (UV‐C) light, on nutritional composition of fresh‐cut produce. In this study, the influence of UV‐C light irradiation (3.2–19.2 kJ m^?2) on the nutritional quality of fresh‐cut tomato cv. Durinta grown under either low (2.4/2.8 dS m^?1) or high (4.9/7.7 dS m^?1) electrical conductivity (EC) of the hydroponic nutrient influx/efflux solution was investigated. RESULTS: When grown under low EC UV‐C light treatment reduced development of microbial population of fresh‐cut tomato, increased phenolic content and delayed degradation of vitamin C after 7 days of storage at 4–6 °C. UV‐C light irradiation had no significant effect on appearance, color or lycopene content of fresh‐cut tomato. In recently harvested intact tomatoes, the lycopene and vitamin C contents were 30% higher in tomatoes irrigated with high EC, whereas the phenolic content was unaffected by the salt treatment. After fresh‐cut processing, phenolic and vitamin C contents of fresh cuts produced from tomatoes treated with high EC decreased by > 10%. This decline was initially accelerated in tomato treated with UV‐C light irradiation. CONCLUSIONS: Our results revealed that fresh‐cut tomatoes are affected dissimilarly by UV‐C treatments, depending on the degree of salt stress undergone by plants before harvest. We determined the impact of a sanitizing procedure on nutritional composition, an effect often overlooked but with great significance to ensure overall quality of fresh produce. Our findings revealed the need for more nutritional studies addressing the effect of multiple stress factors from pre‐harvest to post‐processing stages. Copyright © 2008 Society of Chemical Industry     

Optimisation of biological and physical parameters for lycopene supercritical CO2 extraction from ordinary and high‐pigment tomato cultivars

BACKGROUND: Lycopene is used for several industrial applications. Supercritical CO₂ (SC‐CO₂) extraction from red‐ripe tomato fruits is an excellent technique to replace the use of harmful solvents. In this study, starting from red‐ripe tomatoes of ordinary and high‐lycopene cultivars, the effect of different agronomical and technical aspects on lycopene content, stability and yield was evaluated throughout the production process from fresh tomatoes to the final SC‐CO₂‐extracted oleoresin containing lycopene. RESULTS: Red‐ripe tomato cultivars differed in their lycopene content. Irrigation excess or deficit caused an increase in the amount of lycopene in the fruits. Fresh tomatoes were processed into a lyophilised matrix suitable for SC‐CO₂ extraction, which could be stored for more than 6 months at ? 20 °C without lycopene loss. Under the optimal extraction conditions, efficiencies of up to 80% were achieved, but the recovery of lycopene in the extracted oleoresin was very low (～24%). Co‐extraction of the tomato matrix mixed with a lipid co‐matrix allowed the recovery of ～90% of lycopene in the oleoresin. Using the high‐lycopene cultivars, the yield of total extracted lycopene increased by ～60% with respect to the ordinary cultivars. Lipids and other biologically active molecules were present in the oleoresin. CONCLUSION: A method for extracting, from a tomato matrix, a natural and solvent‐free oleoresin containing lycopene dissolved in a highly unsaturated vegetable oil has been described. The oleoresin represents an excellent product for testing on cancer and cardiovascular disease prevention. Copyright © 2010 Society of Chemical Industry     

Use of ultrafiltration for preparing improved tomato pulp

The characteristics of high-quality tomato pulp (commercial def.: crushed or diced tomatoes with about 30% tomato juice as packing medium) canned with tomato juice pulp enriched by ultrafiltration as packing medium were compared with those covered with conventional vacuum-concentrated juice.
Both hot- and cold-break products were prepared and those containing 20% serum-reduced packing juice proved to be the best, showing no signs of syneresis on storage and with improvements in sensory properties, colour and non-enzymatic browning; some volatile components were reduced.     

Effect of calcium and calmodulin antagonists on ethylene biosynthesis in tomato fruits

The aim of this work was to elucidate the mode of action of calcium in calcium-inhibited ethylene biosynthesis. In one experiment, mature green tomatoes were treated with 1·5% (w/v) CaCl₂+60 μM N-6(aminohexyl)-1-naphthalenesulphonamide (W5). 1·5% (w/v) CaCl₂+60 μM N-6(aminohexyl)-5-chloro-1-naphthalenesulphonamide (W7), 1·5% (w/v) CaCl₂ alone or distilled water (control). The control and the W7 treatment had much higher ethylene production than either the CaCl₂ treatment alone or the CaCl₂+W5 treatment. In another experiment, similar tomatoes were treated with 1·5% (w/v) CaCl₂+15 μM trifluoperazine (TFP). 1·5% (w/v) CaCl₂ only, or distilled water (control). The treatment with 1·5% CaCl₂+15 μM TFP gave higher ethylene production than 1·5% (w/v) CaCl₂ without TFP, and nearly the same level as the control towards the end of the experimental period. For enzyme and intermediate metabolite assays, mature green tomatoes were treated with 1·5% (w/v) CaCl₂ plus either W5 or W7. W5 treatment had a lower ethylene forming enzyme (EFE) activity, higher 1-aminocyclopropane-1-carboxylic acid (ACC) concentration, similar levels of ACC synthase activity and 1-(malonylamino)-cyclopropane-1-carboxylic acid concentration, compared to the control and W7 treatment. As W7 is a more potent calmodulin antagonist than W5, these results suggest a calcium-calmodulin inactivation of EFE activity. © 1998 SCI.     

樱桃番茄生物保鲜技术研究

本文利用生物涂膜技术对番茄进行涂膜保鲜。涂膜剂的主要成分为壳聚糖、木立芦荟等配制成酸性溶液在番茄表面涂膜。研究结果表明,涂膜液中含2%的壳聚糖、50%的木立芦荟抑菌剂,pH 5.4为最佳涂膜液酸度,能够使番茄中的总酸、总糖、维生素C以及水分的含量与新鲜番茄最接近,果实坚硬,失水少,具有最好的保鲜效果。     

毛细管气相色谱法测定番茄中的非挥发性有机酸、高级脂肪酸和低分子量糖类

本文提出了应用毛细管气相色谱法(CGC)对番茄内的非挥发性有机酸、高级脂肪酸和低分子量糖类进行测定的方法。番茄样品经匀浆后用水在超声波振荡下提取,减压干燥后, 用羟胺吡啶(2.5mg/ml)先将糖转化为肟,再用硅烷化试剂(BSTFA+1%TMCS)衍生化,然后进行毛细管气相色谱分析。有机酸的测定采取将番茄样品加入H2SO4-CH3OH(10%) 30ml衍生化2h,经萃取、干燥后再进行毛细管气相色谱分析。针对方法的前处理条件、重现性及回收率均进行了探讨。结果显示番茄中糖类主要含有葡萄糖、果糖,酸类主要包括柠檬酸、苹果酸、棕榈酸。此外, 对比不同品种的番茄样品中糖及有机酸含量成分进行了营养对比实验。