Lycopene: Isomerization Effects on Bioavailability and Bioactivity Properties

Lycopene cis-isomers have shown to be more bioavailable and bioactive than the naturally occurring all-trans-isomer. During food processing, lycopene undergoes geometrical isomerization, increasing the proportion of cis-isomers. However, lycopene tends to retro-isomerize during food storage. Because the stability, bioavailability, and distribution of lycopene isomers are physiochemical characteristics critical for health benefits, it is essential to preserve these properties in food products containing lycopene isomers.

The objective of this article is to review thermal and nonthermal technologies available for lycopene geometrical isomerization with a focus on the stability, bioavailability, and bioactivity of lycopene isomers.     

番茄红素在食品加工中的降解

番茄红素在食品中的降解方式主要有热氧化降解、化学氧化降解、光氧化降解和酶促降解等。影响番茄红素降解的主要因素包括氧气、食品添加物和水分活度。     

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.     

番茄红素热异构化机制及其影响因素研究进展

番茄红素是来自植物性食物中最重要的类胡萝卜素之一,它具有抗氧化、预防前列腺癌和心血管疾病的功 能。生鲜植物性食品中的番茄红素主要为全反式构型,但研究表明全反式番茄红素的生物活性和生物利用率不及其 顺式异构体。因此,利用食品加工技术（光照、加热、氧化、改变pH值、添加表面活性剂）促进食品中番茄红素 的异构化对提升产品营养品质具有重要意义,其中热处理是最方便、最经济的方式。本文在论述番茄红素热异构化 作用机制的基础上,分别对模拟体系和食物体系中的番茄红素热异构化的影响因素（溶剂种类、加热温度、加热时 间等）进行探讨,并得出溶剂种类和食物基质对番茄红素热异构化影响较大,提高温度或延长加热时间可促进番茄 红素异构化甚至使其发生降解的结论。最后提出了该领域研究中存在的问题及今后的研究方向。     

溶液pH对番茄红素稳定性及其降解动力学研究

番茄红素易受溶剂环境的影响造成损失。为揭示溶液环境对番茄红素稳定性的影响规律,本文基于紫外可见吸收光谱的变化研究了二甲基亚砜、四氢呋喃、丙酮等不同溶剂种类、比例及酸碱度对番茄红素紫外可见吸收光谱及其吸收强度的影响,并进行降解动力学研究。结果显示:番茄红素在四氢呋喃和二甲基亚砜溶剂中的特征吸收波长与其在丙酮溶剂相比红移,吸收峰3的波长由505 nm分别红移至511 nm和523 nm;番茄红素在有机溶剂水溶液体系中均呈H型聚集,光谱表现为吸收波长蓝移;番茄红素在有机溶剂中的降解均符合一级反应动力学,其在丙酮水溶剂中的半衰期为25.48 h;番茄红素在弱酸和弱碱性条件下更稳定。结果表明:弱酸性或弱碱性的丙酮和四氢呋喃水溶液可作为番茄红素的良好溶剂,本研究为番茄类食品的储藏、加工及开发应用奠定理论基础。     

红葡萄柚番茄红素和色泽热降解动力学及降解机制

对红葡萄柚中番茄红素和色泽进行热降解动力学研究。结果表明,不同温度条件下番茄红素和色泽降解均为一级降解动力学,确定红葡萄柚汁中番茄红素含量与色泽可用线性关系C/C_0=1.770 7(a~*/a_0~*)+0.801 2来表示;纯化后番茄红素含量与色泽在70、80、90℃条件下的线性关系分别为:70℃:C/C_0=1.856(a~*/a_0~*)-0.841 5;80℃:C/C_0=1.714(a~*/a_0~*)-0.711 8;90℃:C/C_0=1.492 1(a~*/a_0~*)-0.467 2。高效液相色谱-二极管阵列在线监测发现番茄红素热降解途径为:加热促使全反式番茄红素向单顺式异构体进行转变,继续加热导致全反式和单顺式异构体转变为双顺式异构体,而加热过程中双顺式异构体也可转变为单顺式异构体或发生降解,从而造成总番茄红素含量的下降。     

Anthocyanin Degradation in the Presence of Furfural and 5-Hydroxymethylfurfural

The influence of furfural (F) and 5-hydroxymethylfurfural (HMF) on degradation of cyanidin-3-glucoside (CG) was investigated in blackberry juice and in a citrate buffer model solution (pH 3,45) at 24°, 50° and 70°C. Presence of 0.012 M F or HMF accelerated pigment degradation. The acceleration was directly temperature-dependent, more pronounced in fruit juice, and considerably decreased in nitrogen. CG and HMF disappearance – but not the interaction between these compounds – followed the first-order reaction kinetics. The influence of formaldehyde (Fa) acetaldehyde (Aa) and benzaldehyde (Ba) on the stability of CG was investigated in blackberry juice. CG degradation effect of non-furane aldehydes (0.012 M) was Fa < Aa < Ba. CG and cyanidine (C) reactivities were studied by condensation with F and examination of molecular electrone properties (cyanidine, keto-pseudobase, anhydrobase, chalcone). Furfural did not react with CG but it did react with C. Electron charge distribution points to anhydrobase as the tautomeric form of C most reactive to F. Possible mechanisms of C decomposition in presence of F are proposed and discussed.     

热处理对不同颜色番茄中类胡萝卜素异构化和降解的影响

为综合利用彩色番茄资源,对比不同颜色番茄中类胡萝卜素的组成,研究类胡萝卜素热稳定性,阐述其异构化和降解的规律.利用高效液相色谱-二极管阵列检测器(HPLC-PDA)并配备YMC Carotenoid C30色谱柱分离类胡萝 卜素,并以光谱特征鉴定异构体,系统分析番茄中类胡萝卜素组成,并探究热处理温度和时间对其类胡萝卜素...     

Efficient Alkaline Isomerization of Lactose to Lactulose in the Presence of an Organogermanium Compound

Lactulose, a disaccharide widely used in pharmaceuticals and functional foods, is produced by lactose isomerization. Lactose and lactulose have an aldose–ketose relationship. Less than 25 % conversion of lactose into lactulose is achieved using the Lobry de Bruyn–Alberda van Ekenstein transformation with heating, whereas the conversion is increased to 80 % by the addition of an approximately equimolar concentration of the organogermanium compound 3-(trihydroxygermyl)propanoic acid (THGP) to the reaction mixture. To further understand this phenomenon, in this study, we analyzed the affinity between THGP and sugar isomers using ¹H nuclear magnetic resonance spectroscopy. For the dimethyl derivative of THGP with lactose and lactulose, the complex formation ratios at 0.1 M (1:1 mixing ratio) were 14 and 59 %, respectively, with complex formation constants of 1.8 and 43 M^–1, respectively. The complex formation capacity was approximately 24-fold higher for lactulose than for lactose. Moreover, THGP is considered to protect lactulose from alkaline degradation, resulting in high production yield of lactulose. Therefore, we concluded that high affinity for the isomerization product may promote isomerization and that promotion of sugar isomerization using an organogermanium compound is an effective method for converting lactose to lactulose.     

Thermal Isomerization and Degradation Behaviours of Carotenoids in Simulated Sweet Corn Juice

The thermal behaviour of carotenoids may affect the nutritional value and flavour quality of sweet corn juice. In this study, carotenoid compositions and volatile components in simulated sweet corn juice at elevated temperatures from 100 to 130 °C were identified and compared by C₃₀-HPLC-DAD-APCI-MS and HS-SPME-GC-MS methods. The result showed that with the increase of temperature, concentrations of total and trans carotenoids in sweet corn juice model decreased gradually, as compared with all-trans α-carotene and all-trans β-carotene, oxy carotenoids (such as all-trans lutein, all-trans zeaxanthin and all-trans β-cryptoxanthin degraded faster), especially for carotenoid epoxides (such as neoxanthin). Meanwhile, the concentration of total cis carotenoids was related with the formation of some oxidative products and volatile compounds. Levels of major volatile components derived from carotenoids in sweet corn juice model including 4-ethyltoluene, p-cymene, 2-ethyl-1, 4-dimethylbenzene, 1, 2, 3, 4-tetramethylbenzene, dodecane, BHT, 1,7-dimethyl naphthalene, hexanal, 2-nonenal, undecanal, benzaldehyde, geranyl acetone, etc. increased with temperature. Some new volatiles such as 1, 2, 4-trimethylbenzene, naphthalene, pentadecane, acetaldehyde, β-ionone, limonene, tridecanone, etc. were also formed under higher temperatures. It is suggested that the aromatic compounds containing benzene ring and alkane are produced by degradation of carotenoids, which affect the overall flavour of sweet corn juice.     

Degradation Kinetics of Lycopene and Visual Color in Tomato Peel Isolated from Pomace

Kinetics of lycopene and visual color degradation of tomato peel was studied at selected temperatures (50–100°C). Models based on lycopene and Hunter (a?×?b) values of fractional conversion were applied to determine the kinetic parameters. The degradation of lycopene and Hunter color values adequately followed first order reaction model with R²?>?0.97. The temperature dependence of the rate constants was adequately modeled by the Arrhenius equation. The activation energies of lycopene and color parameters were 18.27 and 29.07 kJ/mol, respectively, indicating greater temperature sensitivity of visual color parameters. Correlation of lycopene content and Hunter (a?×?b) values showed that they can be used interchangeably with good accuracy.     

Lycopene: Heterogeneous Catalytic E/Z Isomerization and In Vitro Bioaccessibility Assessment Using a Diffusion Model

Highly efficient heterogeneous catalytic E/Z isomerization of lycopene was achieved using an iodine‐doped titanium dioxide (I‐TiO₂) catalyst prepared by sol‐gel method. The effects of reaction temperature and reaction time were investigated in detail. The maximum total Z‐ratio of lycopene exceeded 78% after 2 h of refluxing at 75 °C in ethyl acetate. Moreover, lycopene samples with a series of total Z‐ratios were prepared and the bioaccessibility of these samples was estimated using a diffusion model, the results showed that the bioaccessibility of lycopene markedly increased conforming to a linear regression model with increasing of the total Z‐ratio of lycopene from 3.6% to 78.5%. Furthermore, the specific role of the microstructure and melting point of 3.6% and 78.5% total Z‐ratio of lycopene was also investigated to understand the probable mechanism for the enhanced bioaccessbility of (Z)‐lycopenes.     

Carotene Degradation and Isomerization during Thermal Processing: A Review on the Kinetic Aspects

Kinetic models are important tools for process design and optimization to balance desired and undesired reactions taking place in complex food systems during food processing and preservation. This review covers the state of the art on kinetic models available to describe heat-induced conversion of carotenoids, in particular lycopene and β-carotene. First, relevant properties of these carotenoids are discussed. Second, some general aspects of kinetic modeling are introduced, including both empirical single-response modeling and mechanism-based multi-response modeling. The merits of multi-response modeling to simultaneously describe carotene degradation and isomerization are demonstrated. The future challenge in this research field lies in the extension of the current multi-response models to better approach the real reaction pathway and in the integration of kinetic models with mass transfer models in case of reaction in multi-phase food systems.     

Kinetics of the Thermal Degradation of Patulin in the Presence of Ascorbic Acid

Degradation of the mycotoxin patulin between 25 and 85 °C without and with added ascorbic acid was studied, and the effectiveness of linear and nonlinear models for predicting reaction rates was compared. In agreement with previous reports, ascorbic acid significantly increased (P ≤ 0.05) the rate of patulin degradation at all temperatures studied. The data for patulin degradation in the absence of ascorbic acid were adequately modeled using a zero‐order linear kinetic model. However, the predictive abilities of zero and higher‐order linear models were not adequate to describe the more complex reactions that likely occurred when ascorbic acid was added. In contrast, the nonlinear Weibull model adequately described the patulin‐ascorbic acid reaction throughout the temperature range studied. Zero‐order rate constants and Weibull scale values for each of the respective reactions followed the Arrhenius law. Activation energies of 58.7 ± 3.9 and 29.6 ± 1.9 kJ mol^?1 for the reaction without and with ascorbic acid, respectively, confirmed decreased patulin stability in the presence of ascorbic acid and suggested that the mechanisms for the 2 degradation reactions were different.     

Kinetic Study of the Isomerization of Glucose into Fructose in the Presence of Anion‐modified Hydrotalcites

Isomerization of glucose to fructose was performed in a batch mode at 363 K in the presence of a commercial hydrotalcite catalyst, namely DHT‐4A2 from Kyowa, in its carbonate, hydroxide or mixed carbonate‐hydroxide form. Catalysts in their total or partial hydroxide form were found to be both more active and slightly more selective for fructose than in the carbonate form. However, in all cases, the high selectivity observed (≥90%) tends to drop relatively rapidly after 15% of glucose conversion. Nevertheless, in contrast to cation‐exchanged zeolites, no lixiviation phenomenon was observed. The recycled catalyst was as active as a fresh sample and the selectivity towards fructose was unchanged.     

番茄红素及其制品稳定性研究进展

番茄红素是一种功能性食用色素,具有优越的生理功能。但是它不稳定,容易被氯化而影响其保健作用的发挥,文中就番茄红素及其制品的稳定性做一综述。     

番茄红素脂质体生物利用率的比较研究

番茄红素的理化性质极大地限制了其生理活性功能的发挥,脂质体作为一种常见药物载体,考虑将其作为番茄红素的产品剂型,提高番茄红素的生物利用率。选取薄膜- 超声法制备番茄红素脂质体,经体外实验及体内实验研究可知：油溶番茄红素在人工胃液和无胆酸盐的人工肠液中无释放,但在添加胆酸盐的人工肠液中释放率达91%;番茄红素脂质体和番茄红素微胶囊在人工胃液中释放率低于22%,在添加胆酸盐和无胆酸盐的人工肠液中24h 释放率均达80%～90%。以油溶番茄红素为参照剂型,自制番茄红素脂质体与市售番茄红素微胶囊均具有较长的体内滞后时间和较低的清除率,延长了有效作用时间;自制番茄红素脂质体相对生物利用率为154.42%,大大优于油溶番茄红素,接近市售番茄红素微胶囊(205.03%)。     

Effects of Extraction and Purification Methods on Degradation Kinetics and Stability of Lycopene from Watermelon under Storage Conditions

Lycopene was extraction, isolation and purification using recrystallization, column chromatography, and preparative thin layer chromatography (TLC) methods as well as degradation kinetics of lycopene were studied at refrigerated temperature and room temperature for 3 wk from watermelon. Higher lycopene degradation was observed at refrigerated temperature as compared to ambient temperature throughout the storage periods. The highest amount of lycopene retained in recrystallization (101.69 μg/g) followed by column chromatography (18.20 μg/g) and preparative TLC (15.57 μg/g). Color parameters, half‐life time (t_1/2), and color retention (%R) were dependent on extraction, isolation, and purification methods and storage life. Recrystallization and preparative TLC were followed by first order reaction model. Preparative TLC exhibited higher activation energy than did the recrystallization and column chromatography. Therefore, the result shows that recrystallization method could apply to extract and purify lycopene from watermelon that would also be used as a natural colorant as well as value‐added product.     

Degradation of Lycopene, α-Carotene, and β-Carotene During Lipid Peroxidation

The stability and antioxidant effectiveness of lycopene, a-carotene, and b-carotene were compared during oxidation of methyl linoleate at 37 and 60 °C. Two carotene concentrations, 80 or 160 mg/g of methyl linoleate, were used to determine a concentration effect. At 37 °C, the degradation rates were: lycopene > β-carotene > α-carotene. Lycopene and α-carotene inhibited hydroperoxide formation, lycopene being the more effective antioxidant. β-Carotene inhibited hydroperoxide formation at the lower concentration but did not show an antioxidant effect at the higher concentration. At 60 °C, the carotenes degraded 6 to 8 times faster than at 37 °C and did not show an antioxidant effect. BHT or α-tocopherol effectively suppressed the hydroperoxide formation and degradation of the carotenes.     

秋橄榄果实中番茄红素有机溶剂的萃取及其稳定性研究

利用有机溶剂萃取秋橄榄中的番茄红素,对影响萃取的诸因素,如萃取剂的种类、料液比、萃取温度和萃取时间等进行研究,并用响应面法优化提取工艺条件;另外,还研究了温度、光照、金属离子对秋橄榄番茄红素稳定性的影响。结果表明:用丙酮作萃取剂时,秋橄榄果实中番茄红素的提取效果最佳,优化后的萃取温度为52℃,萃取时间为2.1 h,料液比为1:21(g:mL)。验证实验发现,萃取量为(218.03±9.10)μg/g鲜重,与预测值较接近。秋橄榄果实中的番茄红素在高温、阳光直照、Fe3+存在的条件下十分不稳定。