Characterization of Nipa Vinegar vis-à-vis Production Method in Lingayen, Pangasinan, Philippines

Nipa vinegar is a traditional fermented food product produced from nipa palm (Nypa fruticans) sap and remains an important component of local food practices and livelihood activities in Lingayen, Pangasinan, Philippines. Variability in traditional production practices and the occurrence of product deterioration, particularly blackening and shortened shelf life, underscore the need to characterize the microorganisms associated with its production. This study characterized Nipa vinegar in relation to the traditional production methods employed by local producers and identified bacterial isolates recovered from different stages of production. Willing Nipa vinegar producers in Lingayen, Pangasinan were selected as key informants through survey and interview procedures to document practices involving sap collection, fermentation, storage, packaging, and observed spoilage. Samples were collected aseptically at corresponding production stages and subjected to microbiological characterization. Bacterial isolates were evaluated based on colony morphology, Gram reaction, and biochemical characteristics using oxidase, catalase, Triple Sugar Iron, indole, methyl red, Voges-Proskauer, citrate utilization, MacConkey agar, and blood agar tests. The analysis identified eleven bacterial taxa across the sampled stages of Nipa vinegar production: Proteus mirabilis, Escherichia coli, Bacillus cereus, Lysinibacillus sphaericus, Enterococcus faecalis, Enterobacter cloacae, Pseudomonas aeruginosa, Bacillus subtilis, Streptococcus oralis, Staphylococcus intermedius, and Bacillus thuringiensis. The bacterial identities obtained through laboratory characterization were subsequently confirmed through independent bacterial identification testing at an accredited regional medical laboratory, with the confirmed identifications corresponding to those obtained from the initial analyses. These findings demonstrate the presence of diverse bacterial populations across the traditional Nipa vinegar production process and provide a microbiological profile of the product within its local production context. The study establishes baseline evidence for understanding the bacterial ecology associated with traditionally produced Nipa vinegar and provides a basis for further investigation of microbial contributions to product quality, spoilage, sanitation, and process control.