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Z‐isomers of lycopene exhibit higher bioavailability and antioxidant capacity than those of the all‐E‐isomer. Therefore, it is important to develop an efficient and environmentally friendly procedure for Z‐isomerization. The current methods for Z‐isomerization of (all‐E)‐lycopene use toxic chemicals such as organic solvents and catalysts. This study is aimed to develop a chemical‐free method for Z‐isomerization of (all‐E)‐lycopene in tomato powder by hot air and superheated steam heating. The Z‐isomerization reaction is promoted by heating above the melting point of lycopene. When heated with superheated steam, the thermal decomposition of lycopene is suppressed compared to that when heated with hot air. When tomato powder is heated at 240 °C for 5 min by superheated steam, the total Z‐isomer content and remaining lycopene are 69.0% and 90.7%, respectively, while with hot air heating, the total Z‐isomer content and remaining lycopene are 69.9% and 68.0%, respectively. These results indicate that the thermal Z‐isomerization of lycopene occurs in the molten state and heating in a low oxygen atmosphere suppresses the thermal decomposition of lycopene. Practical Applications: Tomato powder rich in lycopene Z‐isomers is an important ingredient for the food and animal feed industries. Since Z‐isomers of lycopene are more soluble in solvents including ethanol which is a low‐toxicity and environmentally friendly solvent, the efficiency of lycopene extraction with ethanol can be improved by using the Z‐isomer‐rich tomato powder as a raw material. The obtained Z‐isomer‐rich extract has a high added value because the Z‐isomers have higher bioavailability and antioxidant capacity than those of the all‐E‐isomer. In addition, since lycopene Z‐isomers exhibit higher accumulation efficiency and better color improvement in hen egg yolks than those of the all‐E‐isomer, Z‐isomer‐rich tomato powder is an effective animal feed. [ABSTRACT FROM AUTHOR]

The effect of microwave irradiation on Z‐isomerization of (all‐E)‐lycopene contained in tomato oleoresin is investigated, and the Z‐isomerization efficiency is compared to that of the conventional oil‐bath heating method. With a 4‐min microwave treatment at 2450 MHz frequency and 500 W power, the total Z‐isomer content of lycopene increased to approximately 70%, almost without decomposition, and the efficiency, at the same temperature, is higher than that with conventional heating. In both treatments, the (9Z)‐ and (13Z)‐isomers are mainly formed. Moreover, the effect of addition of vegetable oils to the oleoresin on the Z‐isomerization by microwave irradiation is examined. When roasted seed oils and garlic oil are added, the production of (5Z)‐lycopene, an isomer having higher functionality and storage stability among the Z‐isomers, is significantly increased. This work reveals that the promoting effect is probably caused by the presence of disulfide compounds existing commonly in the above oils: Thiyl radicals, produced from disulfide compounds by microwave irradiation, would act as a catalyst for the Z‐isomerization reaction. Practical Applications: Z‐Isomers of lycopene, which are the predominant forms in the human body, have higher bioavailability and antioxidant capacity than the all‐E‐isomer, which is the major configuration form in raw tomatoes. Thus, appropriate methods are required to achieve the efficient Z‐isomerization of (all‐E)‐lycopene. This study has developed an efficient production method for lycopene Z‐isomers by microwave irradiation of (all‐E)‐lycopene in edible vegetable oils containing disulfide compounds, in which neither organic solvents nor food additives are used. It would be practically feasible to utilize this procedure not only for food, drink, and dietary supplement manufacturing, but also for daily cooking. (all‐E)‐Lycopene in tomato oleoresin is efficiently isomerized to the Z‐isomers by microwave irradiation and the Z‐isomerization is accelerated by adding vegetable oils containing disulfide compounds. [ABSTRACT FROM AUTHOR]

Since Z-isomers of lycopene are more bioavailable and show a higher antioxidant capacity than the (all- E)-isomer, it is important to investigate foods containing high amount of the Z-isomer and develop practically feasible method for Z-isomerization of (all- E)-lycopene. First, we investigated the E/ Z isomer ratio of lycopene in raw and commercially available processed tomato products using an improved normal-phase HPLC method. The tomato products contained 4.6-33.4% of Z-isomers to the total lycopene, (5 Z)-lycopene being the most abundant Z-isomer. The oil-containing products like tomato sauce and tomato soup suffered heat processing contained a higher percentage of Z-isomers of lycopene (27.4-33.4%). Subsequently, the impact of the amount and types of oils added on thermal Z-isomerization of (all- E)-lycopene contained in tomato puree was investigated. Increased addition of olive oil to tomato puree increased the production of lycopene Z-isomers upon heating at 120°C. (all- E)-Lycopene contained in tomato puree was converted to Z-isomers in the range of 39.2-50.7%, when 5% of vegetable oil (linseed, soybean, corn, sesame, rapeseed, rice bran, safflower seed, olive, sunflower seed, or coconut oils) or animal fat (beef tallow and pork lard) was added before heating at 120°C for 30 min. When sesame oil was employed, the total Z-isomerization ratio and (5 Z)-lycopene content were significantly increased. Practical applications: The dietary intake of lycopene offers many health benefits such as decreased risk of cancer and arteriosclerosis. Lycopene has a large number of geometric isomers caused by E/ Z isomerization at arbitrary sites within the eleven conjugated double bonds, and the functionalities such as antioxidant capacity and bioavailability of the Z-isomers are higher than those of the all- E-isomer. This study clarified the foods richly containing Z-isomers of lycopene and demonstrated thermal Z-isomerization of (all- E)-lycopene contained in tomato puree with edible oils and fats. These findings will contribute to effective intake of lycopene and the development of facile isomerization of (all- E)-lycopene to Z-isomers in the fields of food, drink, and dietary supplement manufacturing, as well as for daily cooking at home. The Z-isomers of lycopene contents in processed tomato products and thermal isomerization of (all- E)-lycopene to the Z-isomers with edible oils and fats were investigated. The tomato products cooked with oils contained higher levels of the Z-isomers, and sesame oil had excellent promoting effect of thermal Z-isomerization of (all- E)-lycopene. [ABSTRACT FROM AUTHOR]

BACKGROUND Z-isomers of lycopene, which are abundantly present in processed tomato products, are more bioavailable than (all- E)-lycopene found predominantly in raw tomatoes. Despite extensive studies on the bioavailability and biological activities of Z-isomers of lycopene, detailed studies on their safety and toxicology are limited. RESULTS The geno-, acute and subacute toxicities of tomato oleoresin that contained high amounts of lycopene Z-isomers (10.9% lycopene with 66.3% Z-isomer content) and had been prepared with supercritical carbon dioxide were investigated. The oleoresin was non-mutagenic in the Ames test with and without metabolic activation ( S9 mix). The medial lethal dose ( LD50) of the oleoresin in rats, as determined by a single-dose oral test, was more than 5000 mg kg body weight−1 (bw) [361 mg ( Z)-lycopene kg bw−1]. In the 4-week repeated-dose oral toxicity test, rats were administered oleoresin at 4500 mg kg−1 day−1 [325 mg ( Z)-lycopene kg bw−1 day−1]. There were no clinically significant changes with respect to vital signs, physical examination outcomes and laboratory test values during the test period. CONCLUSION Based on our findings and as supported by its long history of consumption, tomato oleoresin that contains high amounts of Z-isomers of lycopene prepared with supercritical carbon dioxide can be considered as safe for human consumption. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study aims to improve the production efficiency of β-carotene suspensions using a naturally occurring Z-isomerization-accelerating catalyst, allyl isothiocyanate (AITC), via supercritical CO2 (SC-CO2). Namely, utilizing solubility improvement of β-carotene with the Z-isomerization by adding AITC in the SC-CO2-used dispersion process, the encapsulation efficiency of β-carotene was enhanced. The dispersion of β-carotene was conducted by ultrasonic treatment, and there was no involvement of organic solvents in the whole process. When 100 mg of AITC was added in the dispersion process, the encapsulation efficiency (β-carotene content in resulting suspension) was approximately 3.5 times higher than that without addition of the catalyst. Moreover, the Z-isomer ratio of β-carotene in the suspensions significantly improved, that is, it was approximately 12 times higher than the raw β-carotene material. Since Z-isomers of β-carotene are known to have higher antiatherosclerotic and antiatherogenic activities compared to the all-E-isomer, this one-step method not only efficiently produces β-carotene suspensions without organic solvents but also enhances the bioactivities of them. [ABSTRACT FROM AUTHOR]

The effect of the Z -isomer content on particle production of lycopene by the solution-enhanced dispersion by supercritical fluids (SEDS) process was evaluated. Using the thermal isomerization and filtering technique, lycopene containing a large amount of Z -isomers (65.3% and 97.8%) was prepared from (all- E )-lycopene. When (all- E )-lycopene was used as a raw material for SEDS precipitation, particles with an average size of 3.6 μm were obtained. On the other hand, when using lycopene containing a large amount of the Z -isomers, the lycopene particles became significantly finer compared with those obtained using (all- E )-lycopene. For example, when using lycopene containing 97.8% Z -isomers, uniformly sized particles with an average size of 75 nm were obtained. Interestingly, despite the Z -isomer content of the raw materials, the obtained lycopene particles were primarily in the thermodynamically stable all- E -isomer. Therefore, the Z -isomerization pre-treatment of lycopene is very effective to obtain uniform, stable, and fine particles using SEDS precipitation. [ABSTRACT FROM AUTHOR]

The effect of thermal Z -isomerization pre-treatment on lycopene extraction from dried tomato pulp by organic solvents and supercritical carbon dioxide (SC-CO 2 ) was evaluated. Although total Z -isomer content of lycopene in fresh tomato pulp was only 6.1%, it increased by thermal treatment at 120 and 150 °C for 1 h to 10.0% and 56.2%, respectively. Furthermore, by adding 1 g/100 g of olive oil to the pulp, the thermal Z -isomerization efficiencies of lycopene at 120 and 150 °C for 1 h improved significantly such that the total Z -isomer contents were 30.4% and 75.7%. After freeze-drying of the thermal treated tomato pulp, lycopene was extracted by ethanol, ethyl acetate, and SC-CO 2 . When any solvents were used for the extraction, lycopene recovery increased according to the Z -isomer content of dried tomato pulp, e.g. in the case that ethanol extraction was conducted from the pulp containing 6.1%, 30.4%, and 75.7% Z -isomer content of lycopene, lycopene recoveries were 4.3%, 28.1%, and 75.9%, respectively. These results strongly indicated that Z -isomers of lycopene are more soluble in solvents than the all- E -isomer. [ABSTRACT FROM AUTHOR]

The effect of Z -isomerization of (all- E )-lycopene on its solubility in organic solvents and physical properties was investigated. Lycopene samples containing different Z -isomer contents (23.8%, 46.9%, and 75.6% of total lycopene) were prepared from high-purity (all- E )-lycopene by thermal Z -isomerization in dichloromethane (CH 2 Cl 2 ). As the Z -isomer content increased, the relative solubility of lycopene significantly improved. Although (all- E )-lycopene barely dissolved in ethanol (0.6 mg/L), the solubilities of lycopene containing 23.8%, 46.9%, and 75.6% Z -isomers were 484.5, 914.7, and 2401.7 mg/L, respectively. Furthermore, differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses clearly indicated that (all- E )-lycopene was present in the crystal state, while Z -isomers of lycopene were present in amorphous states. A number of studies have suggested that Z -isomers of lycopene are better absorbed in the human body than the all- E -isomer. This may be due to the change in solubility and physical properties of lycopene by the Z -isomerization. [ABSTRACT FROM AUTHOR]