Tomatoes (Solanum lycopersicum) are of great significance in terms of the worldwide consumption of nutritional diets. More than half of the production is sold as fresh products, while the whole fruit is still typically processed into various products, including canned tomatoes, paste, juice, and puree. Tomatoes are rich in phenolic compounds, which are generally present as soluble and bound forms in nature. Large amounts of nutritional and bioactive compounds such as phenolics, flavonoids, carotenoids, vitamins, minerals and glycoalkaloids have drawn increasing interest in tomato fruits. However, there appears to be a certain anti-nutritional compound that negatively influences human health. As the role of antioxidants in human nutrition has gained increased interest, the bioavailability of tomato fruits is of great importance to be researched and studied, especially due to their associated health benefits for a number of chronic diseases, including certain types of cancer and cardiovascular disease. Nevertheless, the processing of tomatoes into various end products, including mechanical and heat treatments, is considered to be one of the most significant factors that are potentially affected by those nutritional properties, anti-nutritional compounds and causing changes in the bioavailability of antioxidants. In this review, the nutritional and anti-nutritional compounds, and related health and side effects were discussed. The review also focused on the effects of different food processing techniques on the in vivo and in vitro bioavailability of tomato antioxidants.

Roasting and digestion affect nut kernel phenolic compounds’ bioaccessibility and bioactivity. In this study, three types of raw and commercially roasted nut kernels (almonds, cashews, and walnuts) were treated by in vitro digestion and colonic fermentation. The objective was to analyze the effect of roasting on their phenolic content, associated antioxidant potential, bioaccessibility, and short chain fatty acid (SCFA) synthesis altering. Among these, raw and roasted walnuts performed best, with significantly higher total phenolic content (TPC), total flavonoid content (TFC), free radical scavenging (2,2′-diphenyl-1-picrylhydrazyl (DPPH) assay) values, and ferric reducing antioxidant power (FRAP) values after completing gastrointestinal digestion. With the exception of cashews, roasting had no significant effect on antioxidant capacity during digestion from oral to small intestinal phase. Almonds showed the highest DPPH values after 16-hour colonic fermentation, reaching above 7.60 mg TE per g. Roasting had a positive effect on the free radical savagery capacity of walnuts within 16–24 hours of fecal fermentation. Significant differences were found in the bioaccessibility of individual compounds in raw and roasted nuts. As for almond and walnut, roasting increases the release and breakdown of phenolic compounds during colonic fermentation and have a positive impact on the bioaccessibility of specific phenolic compounds. The colonic bioaccessibility of most phenolic compounds was the highest. Due to heat polysaccharide breakdown, the total SCFAs produced were limited up to 0.03 mM. Raw almonds produced the most SCFAs at 16-hour fermentation and illustrated more benefits to gut health.

Beans are widely consumed throughout the world, rich in non-nutrient phenolic compounds and other bioactive constituents, including alkaloids, lectins, and others. However, research about in vitro digestion impacts on the changes of bioactive compounds’ release and related antioxidant potential in different Vigna beans is limited. This research aimed to assess the modifications that occur in the content and bioaccessibility of phenolic compounds in four Vigna samples (adzuki bean, black urid whole, black eye bean, and mung bean), their antioxidant properties, and short chain fatty acids (SCFAs) production through static in vitro gastrointestinal digestion and colonic fermentation. Adzuki bean exhibited relatively higher total phenolic content (TPC; 4.76 mg GAE/g) and antioxidant activities after in vitro digestion. The black eye beans’ total flavonoid content (0.74 mg QE/g) and total condensed tannins (10.43 mg CE/g) displayed higher tendencies. For colonic fermentation, the greatest TPC value of entire samples was detected through a 2-h reaction. In most selected beans, phenolic compounds were comparably more bioaccessible during the oral phase. Acetic acid showed the highest level through SCFAs production, and the total SCFAs in adzuki beans was the greatest (0.021 mmol/L) after 16-h fermentation. Adzuki beans may be more beneficial to gut health and possess a stronger antioxidant potential after consumption.

The biochemistry underlying seed coat darkening of lentil due to extended storage is limited. This study investigated the relationship between seed coat darkening over time during storage and changes in concentration of phenolic compounds (total phenolic compounds, total condensed tannins, proanthocyanidins and anthocyanins) in two red lentil cultivars (PBA Hallmark and PBA Jumbo2), stored at two grain moisture contents (10 and 14%, w/w) and two temperatures (4 and 35 °C) for 360 days. Seed coat darkening was only significant (p = 0.05) at high temperatures (35 °C) but not at low temperatures (4 °C), irrespective of grain moisture content and cultivar. The concentration of all phenolic compounds tested in this study reduced significantly (p = 0.05) throughout the study period, regardless of temperature and grain moisture treatments. The changes in seed coat brightness and redness followed a linear pattern, except for yellowness, where phenolic compounds initially reduced linearly and then remained constant thereafter. Darkening of seedcoat was only associated with the reduction in phenolic compounds tested in this study at 35 °C, and not at 4 °C. This suggests that seed coat darkening due to extended storage may not be directly linked to broad reductions in the groups of phenolic compounds or individual compounds assessed in this study. This information prompts further research to identify the actual biochemical processes that cause the darkening of seed coats during storage and assist in developing cultivars with stable seed coat colour by selecting and modifying such processes.