Bioaccessibility of bioactive compounds after in vitro gastrointestinal digestion and probiotics fermentation of Brazilian fruits residues with antioxidant and antidiabetic potential

Differential Effects of In Vitro Simulated Digestion on Antioxidant Activity and Bioaccessibility of Phenolic Compounds in Purple Rice Bran Extracts

Pigmented rice varieties are abundant in phenolic compounds. Antioxidant activity and bioaccessibility of phenolic compounds are modified in the gastrointestinal tract. After in vitro simulated digestion, changes in antioxidant activity and bioaccessibility of phenolic compounds (phenolic acids, flavonoids, and anthocyanins) in purple rice brans (Hom Nil and Riceberry) were compared with undigested crude extracts. The digestion method was conducted following the INFOGEST protocol. Antioxidant activity was determined using the ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assays. The bioaccessibility index (BI) was calculated from the ratio of digested to undigested soluble phenolic content. Overall results showed that the in vitro simulated digested rice brans had lower antioxidant activity and lower total phenolic, flavonoid, and anthocyanin contents. However, the concentration of sinapic acid was stable, while other phenolic acids (gallic, protocatechuic, vanillic, ρ-coumaric, and ferulic acids) degraded after the oral, gastric, and intestinal phases. The BI of sinapic, gallic, vanillic, and ferulic acids remained stable, and the BI of quercetin was resistant to digestion. Conversely, anthocyanins degraded during the intestinal phase. In conclusion, selective phenolic compounds are lost along the gastrointestinal tract, suggesting that controlled food delivery is of further interest.

Nutritional Composition, Simulated Digestion and Biological Activities of Campomanesia xanthocarpa Fruit

Gabirobeira fruits are known for their rich nutrient content and bioactive phytochemical compounds that contribute to significant biological activities. Despite these attributes, the antioxidant potential and stability of phenolic compounds in gabiroba by-products after digestion have yet to be studied. The objective of this work was to evaluate the physical-chemical composition, antibacterial activity, α-amylase, and α-glucosidase inhibitory effects, as well as the in vitro digestibility of total phenolic compounds, total flavonoids, and antioxidant activity of powder and extract from gabiroba to valorize these byproducts. The gabiroba powder had low moisture, high carbohydrate and fiber content. The extraction using 80% ethanol demonstrated higher antioxidant, antibacterial, α-amylase, and α-glucosidase inhibition activities compared to the 12% ethanol and water extracts. Catechin and ferulic acid were the major phenolic compounds identified by HPLC-DAD. After digestion, both the powder and the gabiroba extract exhibited a bioaccessibility of more than 30% for total phenolic compounds and antioxidant activity during the gastric phase. However, the dry ethanol extract displayed higher total phenolic compounds after both the gastric and intestinal phases compared to the flour. Processing gabiroba into powder and extract is a promising approach to fully utilize this seasonal fruit, minimize waste, concentrate health-beneficial compounds, and valorize a by-product for use as a functional ingredient and raw material within the food and pharmaceutical industries.

Polyphenol Bioaccessibility and Antioxidant Activity of Pomegranate (Punica granatum) Peel Supplementation in Diet-Induced Obese Rats

Fruit by-products are a source of biocompounds with antioxidant properties and potential role in the obesity treatment. This study aimed to assess the effect of pomegranate (Punica granatum) peel (PP) supplementation on the total antioxidant capacity (TAC) in diet-induced obese rats. Thus, an in vitro gastrointestinal digestion was performed to evaluate the total phenolic content (TPC) and the antioxidant capacity of PP. Moreover, 15 male Wistar rats were randomized into three groups: control diet (CTL; 3.35 kcal/g), cafeteria (CAF) diet (3.72 kcal/g), and CAF diet supplemented with PP (CAF + PP; 200 mg/kg body weight; 3.72 kcal/g). Serum TAC was analyzed by ferric reducing antioxidant power and 2,2-Diphenil-1-picrylhydrazil assay. TPC in PP accounted for 8.82 ± 0.14 mg GAE/g in undigested samples. However, an in vitro digestion process was decreased by 94% the bioaccessibility of PP phenolic compounds in the intestinal phase, while PP supplementation increased serum TAC in diet-induced obese rats. Therefore, although PP phenolic compounds diminished after an in vitro digestion process, antioxidant effect was found in obese rats supplemented with PP.

Influence of Cooking Methods on In Vitro Bioaccessibility of Phenolics, Flavonoids, and Antioxidant Activity of Red Cabbage

Red cabbage is rich in phytochemical compounds, and its consumption, either raw or cooked, has been linked to the prevention of several diseases. This work aimed to investigate the influence of cooking methods on in vitro bioaccessibility of phenolics and antioxidant activity of red cabbage. The vegetable was subjected to boiling, steaming, and microwaving for different times to evaluate color parameters, total phenolic (TPC), total flavonoid (TFC), anthocyanin content (AC), and antioxidant activity (FRAP, DPPH, and ABTS). The phytochemical bioaccessibility before and after cooking was also evaluated by in vitro simulated digestion. Steaming showed the most significant retention of the compounds after 20 and 25 min of cooking (72-86% for TPC, 72-77% for TFC, 75-79% for FRAP, 84-91% for DPPH, 70-83% for ABTS), followed by microwaving, which was more stable in 10 min. Microwaving decreased TFC and AC over time. Boiling did not show significant differences between the cooking times and showed more than 50% of losses of TPC, TFC, and AC and 30 to 60% of antioxidant activity. Steaming was the best cooking method, showing the most significant tendency to black coloration (< L*). In 10 min, it still showed the highest percentages of increase in TPC and the minor losses of TFC and AC in the gastric and intestinal phases. Steaming also increased the antioxidant after digestion when compared to uncooked red cabbage. These results are important to help consumers choose the most effective cooking method for red cabbage to retain its health-promoting components.

Ancient Wheat Varieties and Sourdough Fermentation as a Tool to Increase Bioaccessibility of Phenolics and Antioxidant Capacity of Bread

This study aimed to determine the impact of ancient wheat varieties (emmer, spelt and khorasan) and spontaneous sourdough fermentation on the bioaccessibility of total phenolic content (TPC) and the DPPH antioxidant capacity evolution during breadmaking and in vitro digestion. Sourdough and yeast-fermented modern wheat breads were used as controls. After 6 h of fermentation, the total titrable acidity of the sourdough increased from 139 to 167%. The wheat variety, type of fermentation and processing affected TPC, antioxidant activity and bioaccessibility. Antioxidant activity and TPC were reduced by dough mixing, increased after sourdough fermentation and slightly decreased or remained the same after baking. Although wheat flour had the highest TPC, the modeling of TPC kinetic revealed that emmer and spelt sourdough exhibited a higher bound phenolics release rate due to the higher acidity, which contributed to increased phenolics solubility. Although wheat bread, both before and after digestion, had the lowest TPC, especially the one prepared with yeast, high TPC bioaccessibilities and antioxidant activities after the digestion suggested that, except phenolics, digestion process improved the release of additional compounds with different bioaccessibility and biological activity. The results of this study proved that the application of sourdough fermentation can increase the potential of ancient wheats in the developing of functional bakery products.

An Integrative Review on the Main Flavonoids Found in Some Species of the Myrtaceae Family: Phytochemical Characterization, Health Benefits and Development of Products

This integrative review aims to identify the main flavonoids present in some species of the Myrtaceae family. Studies published between 2016 and 2022 were selected, specifically those which were fully available and written in Portuguese, English, or Spanish, and which were related to the fruits araçá (Psidium cattleianum), cambuí (Myrciaria floribunda), gabiroba (Campomanesia xanthocarpa), jabuticaba (Plinia cauliflora), and jambolan (Syzygium cumini). Scientific studies were gathered and selected in Google Scholar, Scielo, and Science Direct indexed databases, out of which 14 were about araçá, 7 concerned cambuí, 4 were about gabiroba, 29 were related to jabuticaba, and 33 concerned jambolan, when we observed the pre-established inclusion criteria. Results showed that the anthocyanins, such as cyanidin, petunidin, malvidin, and delphinidin, were the mostly identified class of flavonoids in plants of the Myrtaceae family, mainly relating to the purple/reddish color of the evaluated fruits. Other compounds, such as catechin, epicatechin, quercetin, and rutin were also identified in different constituent fractions, such as leaves, peel, pulp, seeds, and in developed products, such as jams, desserts, wines, teas, and other beverages. It is also worth noting the positive health effects verified in these studies, such as anti-inflammatory qualities for jambolan, antidiabetic qualities for gabiroba, antioxidant qualities for araçá, and cardioprotective actions for jabuticaba, which are related to the presence of these phytochemicals. Therefore, it is possible to point out that flavonoids are important compounds in the chemical constitution of the studied plants of the Myrtaceae family, with promising potential in the development of new products by the food, chemical, and pharmaceutical industries due to their bioactive properties.