Determination and standardization of the kefiran extraction protocol for possible pharmacological applications

•Extraction of the Kefiran exopolysaccharide using three different methodologies.•Physico-chemical and biological characterization of the extracted kefiran.•One of the three protocols evaluated stood out for presenting a kefiran with better characteristics of thermal resistance, purity index, extraction yield and high antimicrobial activity.•The protocol with the longest heating time and the presence of constant agitation extracted the kefiran with better conditions.•Antimicrobial tests have shown that kefiran, at concentrations of 5 g/L and 10 g/L, presents an inhibitory behavior of microorganisms like that obtained with the use of currently available antimicrobial drugs.•The selected extraction protocol provided a material with potential pharmacological application. The use of biopolymers in medicine and pharmacology is of great scientific, technological, and commercial interest. A possibility of biopolymer for use in pharmacological applications is the kefiran, an exopolysaccharide (EPS) produced by bacteria that form kefir grains during the milk fermentation process in which the grains are growing. The EPS extraction method can modify its concentration and structure. To establish the most appropriate kefiran extraction protocol and standardize this method, three different extraction processes were evaluated, which differ in the boiling times and in the presence (or not) of agitation. Kefiran obtained by different methods were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), electron scanning field emission microscopy (FESEM), and determination of antimicrobial potential. The samples showed differences in yield, chemical composition, degree of purity, thermal properties, and antimicrobial capacity. The results analyzed indicated that extraction protocol 1 (EP 1) with a longer heating time and constant agitation was able to provide the best thermal resistance, with a high degree of purity (93%), and yield (22.18 mg of kefiran obtained for each gram of kefir grains used). In addition, this method provides good biological activity as a potential antimicrobial agent and can be a potential biopolymer for pharmacological application. [Display omitted]