Desenvolvimento de aerogéis de amido de trigo germinado e não germinado incorporados com extrato de casca de uva obtida do resíduo da fermentação vinária

Abstract

This study aimed to produce water-absorbing bioactive aerogels from biodegradable raw materials (starch and PEO) and agroindustrial residue from wine fermentation (grape skin). The work is divided into two studies. Study 1 is entitled ―Physically cross-linked aerogels based on germinated and non-germinated wheat starch and PEO for application as water absorbers for food packaging‖. In this study, aerogels were produced using germinated (GWS) and non-germinated (NGWS) wheat starch with and without poly(ethylene oxide) (PEO). Aerogels were produced by gelatinizing starch (10%, w/v, in distilled water), followed by freeze/thaw cycles. A 6% PEO solution (0.6 g PEO/10 mL distilled water) was added to the dispersion for the aerogel produced with starch and PEO. The thermal properties, FT-IR absorption profile, relative crystallinity, morphology, water absorption properties and texture profile of the aerogels were evaluated. All aerogels showed high degradation temperature, water absorption capacity, and physical integrity after immersion in water. However, those produced with GWS were visually more structurally sound compared to the aerogels produced with NGWS. Wheat germination had no impact on the texture parameters of aerogels. However, adding PEO increased the water absorption capacity and reduced the hardness and cohesion of the resulting aerogels. Due to the high water absorption potential, the aerogel produced in this study can serve as an absorbent matrix in food packaging. In study 2, entitled ―Extraction of bioactive compounds from grape residues and their use in absorbent bioactive aerogels‖, aerogels were produced using GWS, with and without PEO, and incorporated with the extract obtained from grape skin (GSE) at concentrations of 5 and 10% (w/w). The GSE was evaluated for total phenolic compounds and anthocyanins. The aerogels were characterized by morphology, density, porosity, water absorption capacity, FT-IR absorption profile, relative crystallinity, total phenolic compounds, antioxidant activity, and in vitro release profile of phenolic compounds in a food simulant medium. The total phenolic compounds in the ECU was 226.25 ± 0.01 mggallic acid/gGSE. All aerogels showed low density and high porosity. All aerogels showed high water absorption capacity (581.4 to 997.5%). The antioxidant activity of the aerogels increased with the increase in the GSE concentration and with the addition of PEO in the formulation. The aerogels were able to gradually release GSE for up to 120 days in the hydrophilic simulating medium and 240 h for the hydrophobic medium. However, complete GSE release occurred only in the hydrophilic medium. Starch-based aerogels showed potential to be used in developing active packaging for food. They may act as a natural antioxidant by releasing GSE compounds into the food or absorbing exudates released by food.