Heating tomato puree in the presence of lipids and onion: The impact of onion on lycopene isomerization

A novel tomato pulp with high cis-lycopene content and bioaccessibility through plant-derived sulfur-containing compounds in a simulated food system

Cis (Z)-lycopene exhibits higher bioavailability and tissue accumulation efficiency compared with all-trans (E)-lycopene. A simulated food system was developed to convert all-E-lycopene to its Z-isomers during processing. This system consisted of an aqueous phase containing plant-derived sulfur-containing compounds and a medium-chain triglyceride (MCT) oil phase with dissolved all-E-lycopene. The study aimed to evaluate the effects of sulfur-containing compounds from different plant sources and heat treatments on lycopene isomerization and degradation. The results indicated that, compared with shiitake extract, leek extract, glucoraphanin, wasabi extract, and horseradish, allicin, alliin, and sulforaphane significantly promoted the Z-lycopene content under the optimal heat treatment conditions. The Z-lycopene content increased from 4.91 % to 77.1 %, 68.91 %, and 75.84 % in the allicin, alliin, and sulforaphane groups, respectively. Additionally, except for the shiitake extract group, the addition of other sulfur-containing compounds did not significantly affect lycopene degradation compared with thermal treatment alone (p > 0.05). For better quantitative analysis in food systems, alliin was used as a reference. The application of this method demonstrated that in screened alliin-rich garlic juice (21.20 mg/g) mixed with tomato pulp and MCT oil system, the percentage of total-Z-lycopene increased from 12.14 % to 59.57 %. The bioaccessibility of total-Z-lycopene significantly improved with the addition of garlic juice (p < 0.01). Among all isomers, the bioaccessibility of 9-Z-lycopene and 5-Z-lycopene showed the most significant increase (p < 0.01). This novel tomato pulp system enables the effective utilization of lycopene during processing.

Fate of Amadori compounds in processing and digestion of multi-ingredients tomato based sauces and their effect on other microconstituents

Amadori compounds (ACs), the first stable products of Maillard reaction, are detected in various products of fruits and vegetables, and show an antioxidant activity which can be related to beneficial effects in human health. In order to optimize the nutritional quality of a multi-ingredient tomato sauce (tomato puree - onion - olive oil - dried pepper), the fate of ACs during processing (drying, heating) and gastrointestinal digestion of a model meal was assessed as well as that of other microconstituents, i.e. carotenoids, phenolic compounds and capsaicinoids. The drying at 50 °C of fresh pepper induced the formation and accumulation of ACs after 6 days. During the heat treatment by microwave of multi-ingredient tomato sauce, Maillard reaction occurs in presence of dried pepper and the content in ACs in the tomato-based sauces increased (+33% to + 53%) depending of quantities of dried pepper added. The bioaccessibility of total ACs was 24-31% in duodenal phase and 18-22% in jejunal phase. Individual ACs have shown variable bioaccessibility, e.g. very high for Fru-Arg (50.8% to 71.3%), and very low for Fru-Met (1.8% to 2.2%). The kinetic monitoring of ACs in digestion medium showed that ACs are not stable (-46% in gastric phase, -49 % in intestinal phase) which indicated their potential degradation in the digestive tract. The presence of ACs in the multi-ingredients tomato sauces had no effect on the content of the other bioactive compounds monitored in the study and even promoted the bioaccessibility of total lycopene (+30%) but decreased the bioaccessibility of total phenolic compounds.

Lycopene in hydrophobic deep eutectic solvent with natural catalysts: A promising strategy to simultaneously promote lycopene Z-isomerization and extraction

Lycopene Z-isomerization and degradation in a series of hydrophobic natural deep eutectic solvents (HNDES) was firstly studied. The highest lycopene retention (about 84.6%) was found in HNDES composed of thymol and menthol (TM), and fatty acid-based HNDES promoted lycopene Z-isomerization (about 70% for total Z-isomers) and degradation. The addition of allyl isothiocyanate (AITC), diallyl disulfide (DADS) and capric acid into TM promoted Z-isomerization of lycopene (80% for total Z-isomers), especially 5Z-isomer (>30%), while lycopene remaining rate in TM/-capric acid was below 20%. During lycopene extraction from tomato power and watermelon juice by TM, the ratios of Z-isomer significantly (p < 0.05) increased especially with AITC and DADS (up to about 80%), and extraction yields increased even > 100% with capric acid. Lycopene in TM/-capric acid extracts showed low degradation with Z-isomers increasing during storage. TM with capric acid could simultaneously promote lycopene Z-isomerization and extraction.

Isothiocyanate-functionalized silica as an efficient heterogeneous catalyst for carotenoid isomerization

Daily consumption of carotenoids is associated with multiple health benefits, but their bioavailability is generally extremely low. In this context, the Z-isomerization is receiving attention as a method for increasing carotenoid bioavailability because this approach is superior to conventional physical approaches. Here we investigated the feasibility of using isothiocyanate-functionalized silica (Si-NCS) as a heterogeneous catalyst for carotenoid isomerization. We found that this catalyst promoted Z-isomerization of (all-E)-carotenoids with high efficiency, e.g., when lycopene and astaxanthin solutions were incubated at 50 °C with 10 mg/mL Si-NCS, their total Z-isomer ratios increased by approximately 80 and 50 %, respectively. Furthermore, the Z-isomerization was successfully performed continuously by introducing carotenoid solution into a column packed with Si-NCS. Materials rich in carotenoid Z-isomers have not been used in practical applications due to high production cost and quality limitations (e.g., low Z-isomer ratio). The use of Si-NCS has sufficient potential to solve both these issues.

Effect of food processing on antioxidants, their bioavailability and potential relevance to human health

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Processing alters the amount, matrix interaction, and structure of antioxidants.

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It is not easy to dissociate processing effects from food matrix effects.

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It is still difficult to make general statements on the effects of processing on bioavailability.

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Facilitated release by heat, pressure, etc. contributes to increased bioaccessibility.

It has long been recognized that the antioxidants present in fresh plant materials may be very different to those we ingest via our foods. This is often due to the use of food processing strategies involving thermal/non-thermal treatments. Current research mostly focuses on determining what is present in vegetative starting materials; how this is altered during processing; how this influences activity in the gut and following uptake into bloodstream; and which in vivo physiological effects this may have on human body. Having a better understanding of these different steps and their importance in a health-and-nutrition-context will place us in a better position to breed for improved crop varieties and to advise the food industry on how to optimize processing strategies to enhance biochemical composition of processed foods. This review provides an overview of what is currently known about the influence which food processing treatments can have on antioxidants and gives some pointers as to their potential relevance.

Sulfur-Containing Compounds: Natural Potential Catalyst for the Isomerization of Phytofluene, Phytoene and Lycopene in Tomato Pulp

The effects of some sulfur-containing compounds on the isomerization and degradation of lycopene, phytofluene, and phytoene under different thermal treatment conditions were studied in detail. Isothiocyanates such as allyl isothiocyanate (AITC) and polysulfides like dimethyl trisulfide (DMTS) had the effect on the configuration of PTF (phytofluene), PT (phytoene), and lycopene. The proportion of their naturally occurring Z-isomers (Z1,2-PTF and 15-Z-PT) decreased and transformed into other isomers including all-trans configuration, while Z-lycopene increased significantly after thermal treatment, especially for 5-Z-lycopene. The results showed that increase in heating temperature, time, and the concentration of DMTS and AITC could promote the isomerization reaction effectively to some extent. In addition, 15-Z-PT and the newly formed Z4-PTF were the predominant isomers in tomato at the equilibrium. Unlike the lycopene, which degraded significantly during heat treatment, the isomers of PTF and PT were stable enough to resist decomposition. Moreover, the isomerization of three carotenoids was enhanced, and the bioaccessibility of lycopene increased significantly with the addition of shii-take mushroom containing sulfur compounds, while there was no positive effect observed in that of PTF and PT.

Enriched (Z)-lycopene in Tomato Extract via Co-Extraction of Tomatoes and Foodstuffs Containing Z-isomerization-accelerating Compounds

The aim of this study was to promote the Z-isomerization of lycopene in its extraction process from tomato pulp by adding foodstuffs containing Z-isomerization-accelerating compounds. The addition of onion, broccoli, mustard, makonbu (Saccharina japonica), or shiitake mushroom (Lentinus edodes) to the ethyl acetate extraction process significantly accelerated the Z-isomerization of lycopene. For example, when lycopene was extracted from tomato pulp at 70 °C without foodstuffs, the total Z-isomer ratio of lycopene in the extract was 38.4 ± 0.5%, whereas when onion, broccoli, mustard, makonbu, and shiitake mushroom were added to the process and the extraction was performed using the same procedure, the total Z-isomer ratios significantly increased to 53.6 ± 0.4, 47.9 ± 0.3, 48.2 ± 0.1, 41.5 ± 0.9, and 42.0 ± 1.2%, respectively. Since the above foodstuffs contain large amounts of carotenoid Z-isomerization-accelerating catalysts, i.e., polysulfides, isothiocyanates, or iodine, those components would promote Z-isomerization of lycopene in the extraction process. Since lycopene Z-isomers potentially have higher bioavailability and biological effects than the all-E-isomer, lycopene extraction with foodstuffs having a Z-isomerization-promoting effect in ethyl acetate should enhance the health benefits of tomato extracts.

The Nutraceutical Properties of "Pizza Napoletana Marinara TSG" a Traditional Food Rich in Bioaccessible Antioxidants

Italian gastronomy experiences have ever-enhancing fame around the world. It is due to the linkage between taste and salubriousness commonly related to Mediterranean foods. The market proposes many types of pizza to suit all palates. The antioxidant potential of the “Pizza Napoletana marinara” included in the register of traditional specialties guaranteed (TSG) was determined in this work. ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) method evaluated the antioxidant activity of the pizza homogenized. In vitro digestion models estimated the intestinal and gastric bioaccessibility of the main antioxidant compounds (lycopene and phenolics). To our knowledge, this is the first study to provide the content, antioxidant potential, and bioaccessibility of the antioxidants (polyphenols and lycopene) contained in the traditional pizza “marinara TSG”. Our results showed that the “Pizza Napoletana marinara” had polyphenols concentration, lycopene level, antioxidant activity, and bioaccessibility of phenolic compounds and lycopene better than other similar pizzas. They confirmed the nutritional importance of traditional preparations and established the nutraceutical potential of “pizza marinara TSG” as a food rich in bio-accessible antioxidants.

Synergistic Effects of Food Ingredients and Vegetable Oils on Thermal Isomerization of Lycopene

Recent investigations have demonstrated that some food ingredients and vegetable oils, such as onion, garlic, and sesame oil, enhanced thermal Z-isomerization of (all-E)-lycopene in tomatoes. However, the synergistic effects of these ingredients and oils have not yet been investigated. This study aims at clarifying how the combined use of lycopene Z-isomerization-promoting food ingredients and vegetable oils impacts thermal Z-isomerization of (all-E)-lycopene in tomato puree. Apart from a few exceptions, when olive oil was used as a reaction medium, the combined use of garlic, cabbage, broccoli, shiitake mushroom, and makonbu improved the total Z-isomer ratio of lycopene after heating compared to the separate use of the tested ingredients. However, when onion was used together with the other ingredients, the Z-isomer ratio significantly decreased compared to its individual use. Moreover, when garlic, cabbage, broccoli, shiitake mushroom, and makonbu were used with sesame and mustard oils, that exhibit higher Z-isomerizationpromoting effect than that of olive oil, the lycopene Z-isomerization reaction was further enhanced. However, when onion was combined with these oils, the Z-isomer ratio decreased compared to that measured upon the combined use of onion with olive oil. Our results on these synergistic effects are not only important for the food and drink manufacturing industries but also for daily home cooking.

Impact of onions in tomato-based sauces on isomerization and bioaccessibility of colorless carotenes: phytoene and phytofluene

Onions as an interesting ingredient have been proved to promote Z-isomerization of lycopene and increase bioaccessibility of total-lycopene. Phytoene (PT) and phytofluene (PTF), the precursors of lycopene, are colorless carotenes, which are attracting much attention and are also abundant in tomatoes. Therefore, onions might also affect the distribution and bioaccessibility of PT and PTF isomers during heating tomato (hot-break and cold-break purees)-onion-extra virgin olive oil (EVOO) sauces. The addition of onions (or diallyl disulfide present in onions) into tomato purees did not cause degradation of PT or PTF; however it favored E/Z-isomerization of PT and PTF by reducing the proportions of their natural Z-isomers (Z-15-PT and Z2,3-PTF) and decreased the bioaccessibility of total-PT and total-PTF. Simultaneously, a complex picture was obtained for the effect of onions on the bioaccessibility of individual PT and PTF isomers, depending on the precise isomer. Bioaccessibility of PT and PTF isomers in tomato-based sauces decreased in the order: 15-Z-PT > all-E-PT; Z2,3-PTF > all-E-PTF > Z4 or Z5-PTF; total-PT > total-PTF. E-isomerization of PT and PTF enhanced by onions during heating tomato-onion purees decreased their bioaccessibility.

Chemical Stability of Lycopene in Processed Products: A Review of the Effects of Processing Methods and Modern Preservation Strategies

Lycopene, one of the most dominant carotenoids in a person's diet, is a well-known natural compound that has protective effects against chronic diseases. Industrial and domestic processing and storage conditions significantly influence retention and isomerization of lycopene; thus, in recent years, great attention has been given for their preservative effects of lycopene. This review highlights recent strategies that have been developed to preserve lycopene in processed products, especially in tomato pulp, puree, paste, and juice. The key factors influencing lycopene degradation and isomerization, such as ingredients and intensity of thermal treatments, are also discussed. Special attention was paid to the crystalline structures of lycopene which facilitate its resistance to degradation and isomerization. Emerging non-thermal processing methods, such as ultrasound and high-pressure processing (HPP), are critically evaluated for their preservation of thermo-labile compounds. Novel trends to improve lycopene stability by micro- and nanoencapsulation and addition of antioxidants are also included to examine their efficacy to protect against light, heat, oxygen, and other oxidative processes. Finally, recommended processing and storage conditions are discussed to provide strategies to retain the highest possible amount of bioactive lycopene until consumption.

Improved Carotenoid Processing with Sustainable Solvents Utilizing Z-Isomerization-Induced Alteration in Physicochemical Properties: A Review and Future Directions

Carotenoids—natural fat-soluble pigments—have attracted considerable attention because of their potential to prevent of various diseases, such as cancer and arteriosclerosis, and their strong antioxidant capacity. They have many geometric isomers due to the presence of numerous conjugated double bonds in the molecule. However, in plants, most carotenoids are present in the all-E-configuration. (all-E)-Carotenoids are characterized by high crystallinity as well as low solubility in safe and sustainable solvents, such as ethanol and supercritical CO₂ (SC-CO₂). Thus, these properties result in the decreased efficiency of carotenoid processing, such as extraction and emulsification, using such sustainable solvents. On the other hand, Z-isomerization of carotenoids induces alteration in physicochemical properties, i.e., the solubility of carotenoids dramatically improves and they change from a “crystalline state” to an “oily (amorphous) state”. For example, the solubility in ethanol of lycopene Z-isomers is more than 4000 times higher than the all-E-isomer. Recently, improvement of carotenoid processing efficiency utilizing these changes has attracted attention. Namely, it is possible to markedly improve carotenoid processing using safe and sustainable solvents, which had previously been difficult to put into practical use due to the low efficiency. The objective of this paper is to review the effect of Z-isomerization on the physicochemical properties of carotenoids and its application to carotenoid processing, such as extraction, micronization, and emulsification, using sustainable solvents. Moreover, aspects of Z-isomerization methods for carotenoids and functional difference, such as bioavailability and antioxidant capacity, between isomers are also included in this review.