Fermentation Kinetics of Rice Syrup, with High Content of Dextrose Equivalent, bySaccharomyces cerevisiaeand Characterization of Volatile Compounds from Wine

Abstract

Rice wine was made from broken rice (by‐product of rice processing), which was hydrolyzed by amylolytic enzymes, producing syrup with high content of dextrose equivalent (51.04% DE). The must presented 164 g/L of glucose (15 ºBx) and pH of 2.67 was fermented for 22 h at 25C by Saccharomyces cerevisiae. Fermented alcoholic (rice wine) reached yield value of 74.94% (Y1), 91.71% (Y2) and productivity (Pp) of 2.85 g/Lh in alcohol, with alcohol concentration of 62.8 g/L, 28.0 g/L of glucose, 2.5 °Bx and pH of 3.0. The kinetic parameters – Yp/s 27.75%, μN 0.008 h−1, gt 3.99 h, PN 0.13 logUFC/mLh – were determined. The wine contained a total of 11 volatile compounds identified by GC‐FID, 7 alcohols (methanol, ethanol, n‐propanol, n‐butanol, iso‐amylic alcohols, iso‐butanol and glycerol), 2 aldehydes (acetaldehyde and acetol), 1 ester (ethyl acetate) and 1 ketone (acetone). Practical Applications The product obtained showed potential features to be employed not only as alcoholic beverage, but also as a raw material in the production of other products such as vinegar, adding value to rice processing. Considering the production outlook and the amount of generated by‐product, it is a lower cost substrate for such application. The characterization of volatile flavor compounds might be made use not only for a better understanding of this new‐type product, but also for the further utilization in other wine or alcohol production.

Development of Blueberry and Carrot Juice Blend Fermented by Lactobacillus reuteri LR92

“…The specific growth rate (µ N ) and generation time (gt) were estimated at the time interval of the logarithmic phase. L. reuteri cell population gt was calculated as t/n, where (t) is the exponential growth time and the number of generations (n) was estimated from N = N 0 2 n , where N and N 0 are the final and initial number of cells, respectively [26].…”

Modeling and Kinetics of Bioconversion and Chemical Properties (Wine and Vinegar) from Banana Pulp By-Products

“…Lyophilized cells of S. cerevisiae ATCC 2345, were rehydrated in sterile distilled water, then they were transferred to Yeast Mannitol Broth (YMB -yeast extract 3.0 g/L, malt extract 3.0 g/L, bacto peptone 5.0 g/L, dextrose 10.0 g/L), and incubated in an orbital shaker with agitation and temperature control (CT-712 R, Cientec ® , Brazil), at 120 rpm, 30 °C for 24 h. The hydrolyzed banana was diluted with distilled water in aliquots of 4, 6, 8, 10, 12 and 14 °Bx, to which nutrients were added according to Spinosa et al [3]. After 24 h, 10% (v/v) of the YMB containing the S. cerevisiae were transferred to the hydrolyzed banana at 4 °Bx.…”

“…They were incubated in an orbital shaker at 120 rpm, 30 °C for 24 h. The previous sequence was repeated with the others hydrolyzed pulps (6, 8, 10, 12 and 14 °Bx) to obtain a sufficient amount of the inoculum (25% v/v of the total), containing 8 log viable cells/mL, and them transfered it to the hydrolyzed pulp at 15 °Bx. The counting of viable cells/mL was carried out in a Neubauer chamber [3] and the biomass was determined according to Alvarenga et al [2].…”

“…P, X and S represent ethanol or glycerol, biomass and sugar, respectively; the subscribed item 0 and f represent the initial and final concentration in g/L, respectively. The value of 0.511 was considered the stoichiometric yield in the conversion of sugar to ethanol and 0.088 was the stoichiometric yield the ethanol and glycerol [3]. Experimental data were adjusted and compared to the mathematical model (polynomial equation of third order) using the Matlab ® R2010a software.…”

“…Alcoholic fermentation involves an anaerobic reaction that converts fermentable sugars into alcohol, carbon dioxide, biomass and secondary products, such as organic acids, higher alcohols, aldehydes, esters, glycerol and methanol, which are responsible for the essential sensory attributes, such as aroma and flavor. Saccharomyces cerevisiae is the most commonly yeast used [3]. The fermentation efficiency and the final product quality are closely linked to the performance of yeast in the wort [2].…”