Desenvolvimento de bebida fermentada com kefir de água em extrato vegetal hidrossolúvel de coco (cocos nucifera l.) com adição de inulina

Abstract

The use of water-soluble vegetables extracts (“plant-based”) has become a viable option of on-dairy substrate for the development of new food products, such as the production of fermented kefir beverages. In addition to not containing ingredients of animal origin, its help with physiological factors such as lactose intolerance and / or allergic to milk protein and is a food option for vegetarians and / or vegans. In this context, the objective of this study was the development of a vegan fermented beverage with water kefir grains on the substrate of water-soluble coconut extract (WSCE), with addition of inulin. The water kefir grains (5% w / w) were adapted to the WSCE substrate with different concentrations of inulin, xanthan gum and coconut sugar at a temperature of 25 ± 1 ° C. Formulations of fermented beverages were determined by means of a central composite design (CCD) 23, with 11 tests (F1 to F11). The CCD independent variables were concentrations of coconut sugar (2.0, 6.0 and 10.0%); inulin (2.0, 2.5 and 3.0%) and xanthan gum (0.0; 0.13 and 0.26%) and the dependent variables were cell growth of kefir grains, fermented beverage yield and production of lactic acid. Formulations were analyzed for pH values, soluble solids (SS) and CO2 production at 0, 24 and 48 hours of fermentation. Through the application of a principal component analysis (PCA) was observed that F3 and F6 were the formulations that inversely correlated with each other and in relation to the others, with acidity of 0.68 and 0.88g / 100mL lactic acid, pH between 4.5 and 4.8, CO2 production from 8.2 to 16.81% and SS of 6.69 and 7.40 ºBrix, in 24 hours of fermentation. Thus, these formulations were independently analyzed for physical-chemical characterization, sugar composition, organic compounds and enzymatic activity. As for the factorial design, the addition of coconut sugar, inulin and xanthan gum showed statistically significant results (p ≤ 0.05) when analyzed as independent variables or with interactions, in the fermented kefir beverages at WSCE. In addition, through the data of the Analysis of Variance (ANOVA), was observed that the regression model, for the cell growth of kefir grains, fermented beverage yield and production of lactic acid, was statistically significant at a level of 95% confidence, with determination coefficients (R2) of 98.46%, 91.68% and 83.00%, respectively. Cell growth rate of the grains was higher when the concentrations of inulin were close to 2.8 and 3.0% and with concentrations of approximate to 0.15% of xanthan gum, obtaining a growth rate of the 90%. Beverage yield and production of lactic acid were between 80 to 82.5% and 1.2 to 1.25%, respectively, when concentrations of xanthan gum and coconut sugar increased between 0,26% and 10,0%. Accordin to the microorganism’s identification, there was a higher prevalence of yeasts in relation to bacteria, this may have occurred due to the high concentrations of sugars available in the WSCE substrate and the addition of inulin. Regarding sugars concentrations and organic compounds, in F3 and F6, the metabolization of sugars was mainly directed towards the production of ethanol and acetic acid. In addition, was possible to observe greater enzymatic activity of amylase and peroxidase for F6 and inulinase for F3, due to the fact this formulation contains higher concentrations of inulin. Regarding centesimal composition, F3 and F6 fermented with kefir showed higher levels of lipids (2.84 and 3.26 g / 100g) and proteins (0.95 and 0.84 g / 100g) and lower energetic values (50.54 and 79.00 kcal), when compared to WSCE without fermentation, indicating that the fermentation process had a significant effect on nutritional values. All formulations evaluated showed high levels of moisture and low carbohydrates values. F3 and F6 fermented with kefir, and without fermenting, showed a yellowish grayish white color. Thus, was found that the water kefir grains showed a great potential for adaptation to the WSCE at 24 hours of fermentation. Therefore, it favored the development of a non-dairy fermented beverage that may become an alternative food product for people with lactose intolerance, allergic to dairy products and vegans.