Effect of thermal processing on the degradation, isomerization, and bioaccessibility of lycopene in tomato pulp

Thermal processing affects the nutritional value of food products. The nutritional value is not only determined by the content but also by the bioaccessibility of nutrients. The present study was performed to gain detailed insight into the influence of thermal processing on the degradation, isomerization, and bioaccessibility of lycopene isomers in tomato pulp, without adding any other ingredient. The bioaccessibility, which is defined as the fraction of the nutrient that can be released from the food matrix, was measured using an in vitro method. The results demonstrated the rather high thermal stability of lycopene. Although a treatment at 140 °C induced isomerization, the contribution of cis-lycopene to the total lycopene content remained small. Results also confirmed that thermal processing as such can improve the in vitro bioaccessibility of lycopene in tomato pulp, but the improvement was only significant upon treatments at temperatures of 130 and 140 °C. At such intense process conditions, one should be aware of the negative effect on other quality and nutrient parameters. Possibilities of thermal processing as such to improve the nutritional value of tomato pulp (without the addition of other ingredients) thus looks rather limited.     

Effect of ultrasound treatments of tomato pulp on microstructure and lycopene in vitro bioaccessibility

The influence of ultrasound treatments of tomato pulp on microstructure and lycopene in vitro bioaccessibility was investigated. To this purpose, samples were subjected to ultrasound at a frequency and amplitude of 24 kHz and 100 μm, respectively, for increasing lengths of time. Results showed that ultrasound was responsible for loss of tomato cell integrity, as well as a decrease in the degree of pectin esterification. In contrast, rheological measurements showed that ultrasonically treated tomato pulp had greater gel-like properties than an untreated sample. It was inferred that ultrasound promoted the formation of a new network due to hydrogen bonding and hydrophobic interactions among the de-esterified pectin molecules. Such a reinforcement of the tomato pulp structure resulted in a decrease in lycopene in vitro bioaccessibility of the ultrasonically treated tomato pulp, probably due to the fact that the presence of a stronger network may make lycopene less available to the digestion process.     

The type and quantity of lipids present during digestion influence the in vitro bioaccessibility of lycopene from raw tomato pulp

This study elucidates the impact of the type and quantity of lipids, added upon digestion of raw tomato pulp, on the bioaccessibility of lycopene. Lycopene bioaccessibility was studied by measuring the micellarization during in vitro digestion. Coconut oil, palm oil, cocoa butter, olive oil, sunflower oil and fish oil were selected because of their distinctly different fatty acid composition. Upon adding 5% of lipid to raw tomato pulp, all tested lipids significantly improved the lycopene bioaccessibility. The largest increase in lycopene bioaccessibility was noticed after supplying 5% of sunflower oil, followed by olive oil and cocoa butter (not all differences were significant). A slightly smaller increase was observed when fish oil, coconut oil and palm oil were used. In addition, the effect of different quantities (0–10%) of coconut oil, olive oil and fish oil was examined. Over the entire concentration range, increasing the amount of coconut oil increased the lycopene bioaccessibility, while the highest bioaccessibility was found using 1 and 2% of respectively fish oil and olive oil. Moreover, depending on the amount of added lipid, the type of lipid resulting in the highest lycopene bioaccessibility differed. The results obtained clearly indicate that lycopene bioaccessibility depends both on the type and on the quantity of the lipid present during in vitro digestion of raw tomato pulp.     

Processing of tomato: impact on in vitro bioaccessibility of lycopene and textural properties

BACKGROUND: Human studies have demonstrated that processing of tomato can greatly increase lycopene bioavailability. However, the difference between processing methods is not widely investigated. In the current study different thermal treatments of tomato were evaluated with regard to their impact on in vitro bioaccessibility and retention of lycopene and β‐carotene as well as textural properties. Thermal treatments used were low (60 °C) and high (90 °C) temperature blanching followed by boiling. RESULTS: Lycopene was relatively stable during thermal treatment, whereas β‐carotene was significantly (P < 0.05) reduced by all heat treatments except for low temperature blanching. In vitro bioaccessibility of lycopene was significantly increased from 5.1 ± 0.2 to 9.2 ± 1.8 and 9.7 ± 0.6 mg kg^?1 for low and high temperature blanching, respectively. An additional boiling step after blanching did not further improve lycopene bioaccessibility for any treatment, but significantly reduced the consistency of low temperature treated samples. CONCLUSION: Choice and order of processing treatments can have a large impact on both lycopene bioavailability and texture of tomato products. Further investigations are needed, but this study provides one of the first steps towards tomato products tailored to optimise nutritional benefits. Copyright © 2010 Society of Chemical Industry     

Kinetics of temperature increase during tomato processing modulate the bioaccessibility of lycopene

The nutritional benefit of bioactive metabolites depends on their bioavailability, i.e. the proportion that leaves the food matrix, and crosses the enteral barrier to reach their cellular target. The present study focused on lycopene, the major and bioactive tomato carotenoid, the bioavailability of which is known to be enhanced in cooked products.     

番茄红素乳状液稳定性研究

研究了番茄红素溶于油脂后制备成乳状液的乳化稳定性。添加0.5%的阿拉伯胶能够显著抑制贮藏过程中乳状液粒径的增大,从而大大改善乳状液的乳化稳定性。VC和VE对乳状液体系的乳化稳定性有一定改善作用,其中VC对乳状液乳化稳定性的促进作用的贡献较大,二者按0.15%：0.001%比例复配加入后效果最好。     

番茄中番茄红素的提取纯化与稳定性的研究

微波法提取番茄红素的最佳提取工艺条件:微波360W,加热20s,固液比为1:0.9,浸提时间为5h。番茄中番茄红素的提取采用浸提法,以正己烷为重结晶的溶剂。结晶时间为30min,选择-5℃作为结晶纯化的温度。     

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.     

A study on thermal stability of lycopene in tomato in water and oil food systems using response surface methodology

Thermal processed tomato‐food products rich in Z‐lycopene isomers have demonstrated higher bioactivity compared to fresh products which contain mainly all‐E‐lycopene isomer. The objectives of this study were to optimise processing conditions for production of tomato products rich in Z‐lycopene isomers in water and oil systems. The results showed that the optimal conditions for water and oil systems were temperature 120 °C, heating time 2.14 h, and the percentage of Z‐lycopene isomers content was 51 ± 1% and 57 ± 2%, respectively. The ratio of tomato extract to oil/water had no influence on the Z‐lycopene formation. Therefore, from these results it can be concluded that the combination of high temperature and relatively short heat treatment time could improve formation of Z‐lycopene isomers or degradation of Z‐isomers is lower during tomato processing .These research results could be useful in assisting the industry to improve processing technology, nutritional value and health‐benefits of tomato‐based foods.     

Improved lycopene extraction from tomato peels using cell-wall degrading enzymes

Four commercial enzyme preparations with pectinolytic, cellulolytic and hemicellulolytic activities were tested for their ability to enhance lycopene extraction from tomato peels. Screening experiments were performed at 25 °C by subjecting the peels to a 4-h enzyme incubation followed by 1-h hexane extraction. Peclyve EP and LI were the most efficient, with an almost 20-fold increase in extraction yield. Peclyve LI was used to evaluate the influence of solvent type and enzyme incubation time on lycopene recovery. Hexane, ethyl acetate and the mixture hexane/acetone/ethanol 50:25:25 (v/v) were used as solvents. Under the best extraction conditions (1-h enzyme incubation followed by a 3-h solvent extraction at 40 °C) up to 440 mg of lycopene per 100 g of dry tomato peels were obtained. The percentage recoveries were in the range of 3–30%, for the untreated peels, and 77–98% for the enzymatically treated material.     

Beef hamburgers enriched in lycopene using dry tomato peel as an ingredient

The direct addition of dry tomato peel (DTP) to hamburgers may be useful both to obtain a new product enriched in lycopene and for providing a use for this by-product from the tomato industry. In this study, different amounts of DTP (0–6.0% w/w) were added to raw and cooked hamburgers, and the effects on the meat’s physico–chemical and sensorial characteristics were studied. The maximum DTP concentration compatible with good sensory acceptability and high lycopene content was determined. Addition of DTP increased the colour parameters a^∗ and b^∗ of raw and cooked hamburgers, and modified all textural properties probably because of the presence of fibre. The hardness values of cooked samples was significantly higher in the batch containing 6% DTP (67.6 N) than in a control batch (50.9 N, p < 0.05). The addition of DTP to 4.5% results in hamburgers with good overall acceptability and a lycopene content of 4.9 mg/100 g of cooked hamburger.     

Lycopene degradation, isomerization and in vitro bioaccessibility in high pressure homogenized tomato puree containing oil: Effect of additional thermal and high pressure processing

In the present study, the effect of equivalent thermal and high pressure processes at pasteurization and sterilization intensities on some health related properties of high pressure homogenized tomato puree containing oil were investigated. Total lycopene concentration, cis-lycopene content and in vitro lycopene bioaccessibility were examined as health related properties. Results showed that pasteurization hardly affected the health related properties of tomato puree. Only the formation of cis-lycopene during intense thermal pasteurization was observed. Sterilization processes on the other hand had a significant effect on the health related properties. A significant decrease in total lycopene concentration was found after the sterilization processes. Next to degradation, significant isomerization was also observed: all-trans-lycopene was mainly converted to 9-cis- and 13-cis-lycopene. High pressure sterilization limited the overall lycopene isomerization, when compared to the equivalent thermal sterilization processes. The formation of 5-cis-lycopene on the other hand seemed to be favoured by high pressure. The in vitro lycopene bioaccessibility of high pressure homogenized tomato puree containing oil was decreased during subsequent thermal or high pressure processing, whereby significant changes were observed for all the sterilization processes.     

Optimising emulsion stability during processing of model infant formulae using factorial statistical design

This study examined the effects of total solids (TS), preheat treatment temperature, and first‐ and second‐stage homogenisation pressures on the stability of model infant formula emulsions, using factorial statistical design. Oil droplet size decreased with increasing first‐ and second‐stage homogenisation pressures. The viscosity of emulsions after homogenisation was mainly affected by TS. Spray drying altered the protein profile of the interfacial layer around oil droplets compared to that posthomogenisation, but did not alter oil droplet size. This work made it possible to select optimum conditions to produce a stable infant formula emulsion, with the use of lower homogenisation pressures.     

不同条件下存放时番茄皮中番茄红素的降解动力学

光照、空气及温度等对番茄皮中番茄红素降解动力学参数的影响表明，温度对反应影响最为显著，番皮原料中番茄红素的含量变化遵从假一级反应规律，其ＬｎＫ－１／Ｔ关系为一条直线。作者计算出了番匣红素在光＋空气、光＋氮气、暗＋空气及暗＋氮气条件下降解反应的活化能分别为９．４５，１０．４６，９．７７及１４．５０ｋＪ／ｍｏｌ。     

番茄及其制品中番茄红素反相高效液相色谱法测定

建立了番茄及其制品中番茄红素高效液相色谱法测定方法.样品经丙酮加石油醚(2:1/V:V)(contain 0.1%BHT)提取,色谱柱采用(4.6×250 mm,i.d,5μm),流动相为甲醇-乙腈-二氯甲烷(体积比25:70:5),柱温为室温,检测波长为473 nm,番茄红素的保留时间为6 min.在3～24 mg/kg添加水平,回收率为87.8 %～99.9%,相对标准偏差为2.3%～5.8%.     

Dense phase carbon dioxide treatment of tomato juice: effect on physico-chemical properties,phenolic composition,lycopene isomerisation and in vitro bioaccessibility

The effect of dense phase carbon dioxide (DP-CO₂) technology on tomato juice qualities was investigated. Results showed that DP-CO₂ treatment induced a significant decrease in pH and an increase in titratable acid. Flavour profile and apparent viscosity were more close to the control (untreated) as compared to the heat-treated (95 °C for 20 min). Consumer acceptance test indicated that DP-CO₂ juices were more liked than the heat-treated in flavour, taste and overall acceptability. DP-CO₂ treatments at 30 MPa for 40 and 60 min had positive effects on the content of phenolic compounds, including myricinic acid, ferulic acid, naringin and chlorogenic acid. A significant increase in the relative content of sum cis-isomers was observed after DP-CO₂ treatment at 20 MPa. The in vitro lycopene bioaccessibility increased significantly after treatment at 20 MPa for 20, 40, 60 min as compared to the control and heat-treated.     

Cis-trans isomerisation of lycopene and colour stability of foam—mat dried tomato powder during storage

Tomato powder with ～3% moisture was obtained by foam-mat drying tomato paste (29% solids). Samples of powder were stored at various temperatures (?10° +2° +20° and +37°c), atmospheres (air, nitrogen) and humidities (with and without in-package desiccation), and colour changes were observed for periods of up to 1 year. The main cause of colour fading was the oxidation of lycopene. However, another phenomenon, trans—cis isomerisation of all-trans lycopene, can occur, with apparent loss of coloration, which is later restored by re-isomerisation. The existence of this mechanism was demonstrated by simultaneous measurements of total liposoluble colour at 420 nm and separations of carotenoid pigments by column chromatography on Al₂O₃. Neo-lycopene A (6-mono-cis-lycopene) and at least one other cis-lycopene isomer were found in fresh powder and in samples stored up to 5 months. cis-Isomers were more susceptible to oxidation. Colour changes depend upon the interplay of isomerisation and oxidation; in some cases, tomato powder was more intensively coloured after storage than when fresh. Storage at +20°c was more favourable for colour retention than storage at +2°c, or — 10°c. Excessive desiccation strongly promoted oxidation losses. Storage in an inert atmosphere improved colour retention. At +37°c non-enzymic browning, accompanied by formation of water, caused rapid darkening although carotenoid pigments were not lost to a great extent.