Processos de filtração por membranas aplicados na filtração de kombuchas

Abstract

Healthy eating is a growing trend among the population. As a healthy and functional drink, kombucha has great potential due to its many beneficial properties. Kombucha is prepared from the fermentation of add sugars in teas infusions, resulting in a carbonated, light and refreshing drink. Residues from the fermentation and production process of kombucha may not be visually pleasing to some consumers. In addition, residual microorganisms from fermentation continue to be in constant activity and result in microbiological instability in kombucha. An alternative to minimize these characteristics is the use of membranes separation processes. Membranes are barriers that act as filters, retaining particles and molecules larger than their pore size and allowing smaller particles and molecules to permeate. In this context, this study aimed to evaluate separation processes by membranes of microfiltration (MF) and ultrafiltration (UF) in kombuchas, in order to reduce turbidity, suspended solids concentration and the amount of residual microorganisms from fermentation. To achieve the proposed objective, the membranes were compacted and characterized in terms of hydraulic permeability and kombucha permeate flux. The hydraulic permeability of the MF membrane was 308.15 L·h-1·m-2·bar-1 and that of the UF membrane was 12.05 L·h-1·m-2·bar-1. For both membranes, the permeate kombucha flux reduced with time for each pressure evaluated individually, due to fouling. Two different batches of kombucha were used for the study: a batch of kombucha after the first fermentation process (K1) and a batch of finished and bottled kombucha (K2). The initials samples of kombuchas and the samples after the filtration processes were submitted to analysis of the parameters of turbidity, suspended and dissolved solids, microbial count, organic acids, pH, volatile acidity, alcohol content, sugars and organoleptic evaluation. The MF reduced the turbidity of K1 in 96.41 % and the turbidity of K2 in 95.93 %, and the UF reduced 99.97 % in K1 and 81.74 % in K2. Suspended solids were reduced by 66.40 % with MF and 93.06 % with UF for K1, and for K2 there was a reduction of 60.75 % with MF and 17.72 % with UF. Microorganisms showed reduction of 58.33 % with MF and 15.63 % with UF in K2. The kombuchas after MF and UF were visually clearer. The other parameters evaluated did not showed significant changes with the performance of the PSM. Both filtrations removed part of the suspended solids and microorganisms without harming the quality and benefits of kombucha, proving that the techniques were efficient for the proposed purpose. [resumo fornecido pelo autor]