Extração de carboidratos do farelo de trigo e avaliação do potencial efeito prebiótico

Abstract

As food production increases, so does the generation of agro-industry waste from processing. Wheat is the most consumed food in the world and, of the product resulting from it’s milling, 25% is bran with a carbohydrate content of around 60 to 75%. In this fraction, 9.1 to 38.9% is starch and 55 to 60% is non-starch carbohydrates (dry basis), mainly arabinoxylans (AX). Studies have shown that AXs can be hydrolyzed, leading to the formation of arabinoxylooligosaccharides (AXOS). These oligosaccharides have prebiotic effects that promote health by stimulating the activity of beneficial bacteria in the colon. The main method of extraction is enzymatic; however, it is necessary to look for simpler and less expensive methods of extracting AXs. The aim of this study was to evaluate the process of extracting carbohydrates from wheat bran by ultrasonic and hydrothermal treatment, followed by a study of their prebiotic activity. The wheat bran was characterized in terms of its centesimais composition and physicochemical properties; subsequently, the conditions for extracting the carbohydrates by ultrasonic and hydrothermal treatment were determined, using experimental design strategies. The carbohydrates extracted by the treatment with the highest yield were precipitated, freeze-dried and characterized by High Performance Liquid Chromatography (HPLC) and the functional groups were evaluated by FTIR. The digestibility of the CFTs was assessed by simulating the conditions of the digestive tract in vitro. The prebiotic activity was assessed by the effect of the CFTs on the growth of the probiotic microorganisms Lactobacillus acidophilus, Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus and Bifidobacterium lactis when cultivated in broths containing 15 and 30 g L-1 of the CFTs, glucose, inulin and oligofructose for 48 hours; The prebiotic activity score (PAS) and pH evolution, organic acid production and sugar consumption were also evaluated in the trials with the different carbohydrate sources. Extraction by ultrasonic treatment had a yield of 43.47%, while hydrothermal treatment extracted 72.36% and was therefore chosen for the other analyses. The digestibility of CFT was 0.86% and 2.04% at concentrations of 15 g L-1 and 30 g L-1, respectively, which was better than inulin (3.16% and 2.39%) and oligofructose (22.25% and 18.53%) (control prebiotics). The viability of L. acidophilus, when compared to the other probiotics tested, performed better when inoculated with CFT. Sugar consumption and acid production indicated intense bacterial cell activity of the probiotics tested. The low PAS value of CFT compared to inulin and oligofructose prevented the extracted carbohydrates from being considered as prebiotic ingredients.