Estudo e caracterização de kefir de água a base de quinoa

Abstract

Quinoa is a plant species from the Chenopodiaceae family, rich in proteins, lipids and fiber, which gives it an interesting nutritional value. Despite being highly nutritious and having technological advantages, it is still little explored and known by consumers. Therefore, the objective of this work was to develop and characterize a drink, especially for the public with restrictions on the consumption of lactose, milk protein and/or vegan, based on water-soluble vegetable extract of quinoa (WVEQ) fermented with water kefir grains. Initially, an WVEQ was created, in which the effect of sucrose concentration (SC) (2; 6 and 10% (w/v)), inulin concentration (IC) (2.5; 3.0 and 3. 5% (w/v)) and xanthan gum concentration (XGC) (0, 0.08 and 0.16% (w/v)) through a central composite design (CCD) 23, containing 3 central points. The eleven formulations were subjected to fermentation with 5% (w/v) water kefir at 25±1°C for 12 hours and were subsequently characterized regarding: (i) cell growth of the grains, (ii) beverage yield, (iii) pH, (iv) soluble solids, (v) production of carbon dioxide (CO2), (vi) lactic acid and (vii) production of ethanol. The highest growth rates of kefir grains were obtained at maximum IC (3.5% (w/v)) and XGC (0.16% (w/v)), regardless of SC. Furthermore, it was possible to identify that the yield and concentration of lactic acid show opposite behavior, where the greater the production of lactic acid, there is a greater need for substrate consumption and a consecutive reduction in yield. After analyzing the dependent variables via regression analysis, no significant interactions were found (p ≤ 0.05) within a 95% confidence interval (α = 5%). Therefore, for the final stage, samples F1 (SC 2, IC 2.5 and XGC 0% (w/v)) and F8 (SC 10, IC 3.5 and XGC 0.16% (w/v)), because these are the extremes of the formulations, which are characterized in terms of proximate composition, microbiological composition of the kefir culture, analysis of organic compounds, sensory analysis and enzymatic and microbiological characterization before and after simulation of in vitro gastrointestinal digestion. In the centesimal characterization, fermentation increased the amount of proteins due to the high proteolytic activity of the microorganisms present in kefir, in addition to the increase in lipid content. The identification of microorganisms showed a prevalence of yeasts Saccharomyces sp., which explained the concentrations of ethanol identified in the composition of organic compounds through the metabolization of glucose, fructose and cellobiose. In the sensory analysis, the F8 formulation showed better results when compared to the F1 formulation. In vitro gastrointestinal digestion showed a reduction in lactic acid bacteria and yeast and an increase in acetic acid bacteria in the liquid phase for both formulations. As for the solid part, there was an increase in lactic acid bacteria and yeasts and acetic acid bacteria remained high. In the enzymatic profile, there was a reduction in all enzymes analyzed for both formulations, except for amylase in F1F, which went from 14.05 U/ mL to 39.41 U/mL. Therefore, it is concluded that the use of WVEQ as a substrate for the production of fermented beverages with water kefir culture appears to be a viable alternative for serving a specific market niche, with nutritional and technological advantages.