Survival of selected lactic acid bacteria isolated from pineapple waste in refrigerated pineapple juices

Abstract

ABSTRACTThe aim of this research was to isolate and identify lactic acid bacteria (LAB) from pineapple waste. The survival in refrigerated pineapple juices, of a selected isolate with potential probiotic properties, was also studied. The 16S rRNA andpheSpartial genes were used to identify LAB, multilocus sequence typing (MLST) genes were used in order to separate strains grouping withLactobacillus caseiandL. paracaseiphylogenetically. Tests for survival at pH 2.0, resistance to lysozyme and tolerance to bile salts were used to screen the strains for potential probiotic properties. AL. fermentumisolate was used for the survival study. Three types of pineapple juice made from pulp, a blend of pulp and peel (80:20), and peel extract were inoculated to approximately 106CFU/mL withL. fermentumand stored at 4 °C for up to six weeks. The physicochemical composition of juices, including concentration of fermentable sugars and organic acids, total solids content, soluble solids content, titratable acidity and pH, was determined during the survival study. Two genera and five species were identified. Pineapple juices supported the survival ofL. fermentumduring refrigerated storage but the population of the bacteria decreased over time regardless of the juice type. Juice made from pulp was a more suitable vehicle for the survival of the selected LAB. Some of the juice physicochemical properties, including sugars and organic acids content, pH and titratable acidity, varied significantly (P<0.05) during storage. Further sensory studies are necessary to evaluate consumer acceptance of juices containing the selected isolate.IMPORTANCELactic acid bacteria (LAB), isolated from pineapple waste, were phylogenetically analyzed and characterized in regards to their tolerance to pH 2.0, lysozyme and bile salts; showing their potential as probiotic strains, if health benefits associated to their ingestion are eventually confirmed. Moreover, pineapple juice supported the survival ofLactobacillus fermentum, isolated from the same food matrix, during refrigerated storage at 4 °C. Among the three pineapple juices tested (pulp, pulp + peel and peel),L. fermentumsurvived better in juice made from pulp. However, significant variations were observed overtime in some of the physicochemical properties of the juices including sugars and organic acids content, pH and total titratable acidity.