Characterization and bioactivities of coffee husks extract encapsulated with polyvinylpyrrolidone.

Coffee processing generates large amounts of residues of which a portion still has bioactive properties due to their richness in phenolic compounds. This study aimed to obtain a coffee husks extract (CHE) and to encapsulate it (ECHE) with polyvinylpyrrolidone using a one-step procedure of solid dispersion. The extraction and encapsulation yields were 9.1% and 92%, respectively. Thermal analyses revealed that the encapsulation increased the thermal stability of CHE and dynamic light scattering analyses showed a bimodal distribution of size with 81% of the ECHE particles measuring approximately 711 nm. Trigonelline and caffeine were the main alkaloids and quercetin the main phenolic compound in CHE, and the encapsulation tripled quercetin extraction. The total phenolics content and the antioxidant activity of ECHE, assayed with three different procedures, were higher than those of CHE. The antioxidant activity and the bioaccessibility of the phenolic compounds of ECHE were also higher than those of CHE following simulated gastrointestinal digestion (SGID). Both CHE and ECHE were not toxic against Alliumcepa cells and showed similar capacities for inhibiting the pancreatic α-amylase in vitro. After SGID, however, ECHE became a 1.9-times stronger inhibitor of the α-amylase activity in vitro (IC50 = 8.5 mg/mL) when compared to CHE. Kinetic analysis revealed a non-competitive mechanism of inhibition and in silico docking simulation suggests that quercetin could be contributing significantly to the inhibitory action of both ECHE and CHE. In addition, ECHE (400 mg/kg) was able to delay by 50% the increases of blood glucose in vivo after oral administration of starch to rats. This finding shows that ECHE may be a candidate ingredient in dietary supplements used as an adjuvant for the treatment of diabetes.

Antioxidant Activity of Encapsulated Extracts and Bioactives from Natural Sources.

The low water solubility and low bioavailability of natural bioactive substances such as polyphenols and flavonoids, either in pure form or extracts, are a major concern in the pharmaceutical field and even on the food development sector. Although encapsulation has demonstrated success in addressing these drawbacks, it is important to evaluate the antioxidant activity of the encapsulated compounds. This article reviews the encapsulation of bioactive compounds from natural sources focusing their antioxidant activity after encapsulation. Attention is given to the methods and wall materials used, and the antioxidant activity methodologies (classical in vitro techniques such as DPPH, ORAC, FRAP and others, as well as in vivo/ex vivo tests to evaluate endogenous antioxidant enzymes or oxidative stress) applied to assess the antioxidant capacity are also comprehensively summarized.

Effect of drying method on mechanical, thermal and water absorption properties of enzymatically crosslinked gelatin hydrogels

ABSTRACT Enzymatically crossliked gelatin hydrogel was submitted to two different drying methods: air drying and freeze drying. The resulting polymeric tridimensional arrangement (compact or porous, respectively) led to different thermal and swelling properties. Significant differences (p < 0.05) on thermal and mechanical characteristics as well as swelling in non-enzymatic gastric and intestinal simulated fluids (37 ºC) were detected. Water absorption data in such media was modelled according to Higuchi, Korsmeyer-Peppas, and Peppas-Sahlin equations. Freeze dried hydrogel showed Fickian diffusion behavior while air dried hydrogels presented poor adjustment to Higuchi model suggesting the importance of the relaxation mechanism at the beginning of swelling process. It was possible to conclude that the same gelatin hydrogel may be suitable to different applications depending on the drying process used.

Development of dairy beverages functionalized with pure ergosterol and mycosterol extracts: an alternative to phytosterol-based beverages.

In the present work, Agaricus bisporus extracts obtained by ultrasound-assisted extraction (UAE), and ergosterol, were incorporated into dairy beverages at concentrations mimicking commercial phytosterol-added yogurts, to work as alternatives. The samples were analysed for nutritional and bioactive properties, and compared with controls (yogurts with no additives or phytosterols), at two storage times (right after incorporation (ST = 0) and after seven days at 4 °C (ST = 7)). The ones incorporated with the extract (YAb) and with ergosterol at the same concentration as in the extract (YPEAb) showed similar antioxidant properties as the ones with phytosterols (YPhy), but a higher cytotoxicity against tumor cells. YPEPhy, the sample with ergosterol at the same amount as phytosterols in YPhy, was the strongest in both bioactivities. For YAb, YPEAb and YPEPhy the antioxidant capacity increased from ST = 0 to ST = 7, meaning that the extract and ergosterol protected the yogurt from oxidation, improving the shelf life. Nutritional parameters were identical for all samples.