Bio-preservation of Pineapple Juice Using Candidate Probiotic Lactic Acid Bacteria

Abstract

Background & Aims: Pineapple juice (Ananas comosus) is susceptible to microbial spoilage because of its nutrient content and high water activity. This study evaluated the survival and biopreservation potential of three candidate probiotic lactic acid bacteria, Weissella confusa, Levilactobacillus brevis, and Lactiplantibacillus pentosus, during storage of pineapple juice. Study Design: A controlled storage study compared pasteurised pineapple juice inoculated with three lactic acid bacteria with uninoculated controls, including a potassium sorbate control, under room-temperature and refrigerated conditions for 28 days. Place and Duration of Study: Food Biotechnology and Microbiology Laboratory, Food Science and Technology Research Department, Nangui Abrogoua University, between March and June 2025. Methodology: Pineapple juice was prepared from 6 kg of pulp with 3 L of water, filtered, dispensed into 250 mL jars, and pasteurised at 85 °C for 5 min, except for an unpasteurised baseline sample. Pasteurised juice was either left uninoculated, supplemented with potassium sorbate (0.2 g/L), or inoculated with 1 mL of a 10^5 CFU/mL working bacterial suspension per 100 mL of juice. Samples were stored at 25-30 °C or 4 °C for 28 days and analysed on days 0, 7, 14, and 28 for pH, titratable acidity, and selected microbiological indicators. Results: The inoculated juices maintained high culturable lactic acid bacterial counts during storage, generally reaching approximately 10^7 CFU/mL. The pH of inoculated juices remained acidic and, in several treatments, decreased during storage. Titratable acidity changed substantially with time and treatment. Presumptive staphylococci and coliform counts differed between room-temperature and refrigerated storage, with refrigerated samples generally showing lower recovery of the hygiene-indicator organisms reported in this study. Yeast and mould counts remained within approximately 10^3-10^4 CFU/mL in the reported observations. Conclusion: The three lactic acid bacteria remained culturable in the pineapple-juice matrix and were associated with changes in acidity and microbiological profiles during storage. Refrigeration provided an important additional preservation hurdle. The findings support further evaluation of these strains as candidate cultures for pineapple-juice biopreservation; confirmation should include strain-level identification and safety assessment, validated challenge studies, sensory testing, and in vivo evidence before probiotic or commercial claims are made.