Effect of ultrasound processing on the bioaccessibility of phenolic compounds and antioxidant capacity of selected vegetables.

Ultrasound processing can result in cell wall disruption, facilitating the release of the cellular content. Therefore, we hypothesized that sonication of vegetables could be used as a pre-treatment to increase the bioaccessibility of phenolic and antioxidant compounds. Overall, sonication (40 kHz, 250 W, 4 °C, 20 min) did not affect the main physicochemical parameters of tomato, lettuce, zucchini, and green and red pepper (p < 0.05). The polyphenolic content and antioxidant activity of digestive enzymatic extracts was higher than that of water:methanol extracts (p < 0.05). In addition, sonication resulted in increased bioaccessibility of phenolic compounds in lettuce and green pepper (p < 0.05), while no effect was observed for tomato, red pepper, and zucchini samples suggesting a matrix-dependent effect. The amount of phenolic compounds and antioxidants released by vegetables during a simulated gastrointestinal digestion may be higher than the one that can be expected from measurements in usual aqueous-organic extracts.

Food matrix and processing influence on carotenoid bioaccessibility and lipophilic antioxidant activity of fruit juice-based beverages.

The biological activity of carotenoids depends on their bioaccessibility and solubilization in the gastrointestinal tract. These compounds are poorly dispersed in the aqueous media of the digestive tract due to their lipophilic nature. Thus, it is important to analyze the extent to which some factors, such as the food matrix and food processing, may improve their bioaccessibility. Beverages formulated with a blend of fruit juices and water (WB), milk (MB) or soymilk (SB) were treated by high-intensity pulsed electric fields (HIPEF) (35 kV cm(-1) with 4 µs bipolar pulses at 200 Hz for 1800 µs), high-pressure processing (HPP) (400 MPa at 40 °C for 5 min) or thermal treatment (TT) (90 °C for 1 min) in order to evaluate the influence of food matrix and processing on the bioaccessibility of carotenoids and on the lipophilic antioxidant activity (LAA). The bioaccessibility of these compounds diminished after applying any treatment (HIPEF, HPP and TT), with the exception of cis-violaxanthin + neoxanthin, which increased by 79% in HIPEF and HPP beverages. The lowest carotenoid bioaccessibility was always obtained in TT beverages (losses up to 63%). MB was the best food matrix for improving the bioaccessibility of carotenoids, as well as the LAA. The results demonstrate that treatment and food matrix modulated the bioaccessibility of carotenoids as well as the lipophilic antioxidant potential of beverages. Additionally, HIPEF and HPP could be considered as promising technologies to obtain highly nutritional and functional beverages.

Changes in vitamin C, phenolic, and carotenoid profiles throughout in vitro gastrointestinal digestion of a blended fruit juice.

The aim of this research was to evaluate the influence of an in vitro gastrointestinal digestion on the stability and bioaccessibility of vitamin C, phenolic compounds, and carotenoids, as well as the antioxidant activity in a blended fruit juice (BFJ) containing orange, pineapple, and kiwi. Vitamin C and most of the analyzed phenolic compounds were quite stable under gastric conditions (recovery > 75%), whereas carotenoids diminished significantly (to 64%). The concentration of all the evaluated compounds decreased during small intestinal digestion. The bioaccessibility of hydrophilic constituents was higher than that of lipophilic constituents. Flavonoids, vitamin C, and phenolic acids showed bioaccessibilities of 20.1, 15.0, and 12.7%, respectively. However, carotenes and xanthophylls were around 7.6 and 17.4% available for absorption. Despite the decrease in the concentration of these bioactive compounds after being subjected to an in vitro gastrointestinal digestion, results suggest that BFJ is an important source of bioaccessible constituents.

Soymilk phenolic compounds, isoflavones and antioxidant activity as affected by in vitro gastrointestinal digestion.

The aim of this research was to evaluate changes in the phenolic compounds, isoflavones and antioxidant activity of soymilk following in vitro gastrointestinal digestion (including dialysis). Gastric digestion significantly influenced the release of bioactive substances from the soymilk matrix, increasing the concentration of total phenolic components (35% as the sum of individuals and 14% by Folin-Ciocalteu [F-C] method), total isoflavone content (22%) and total antioxidant activity (76%). The concentration of all those compounds was reduced significantly in the duodenal fraction in comparison to gastric digestion and their lowest concentration was observed in the dialysed fraction, where phenolic acids were not detected. The bioaccessibility of soymilk phenolic compounds was 15% as the sum of individuals and 20% by F-C assay; isoflavones 36% and constituents with antioxidant activity 27%. Results suggest that most of these compounds were sufficiently available to be absorbed and could contribute health benefits.