Shelf Life and Quality of Dehydrated Pet Food with Antioxidants and Natural Bar Development

Abstract

This study was made to understand how antioxidant enrichment and formulation influence the safety and functional stability of dehydrated pet food bars over time. Two base products, chicken stew and pork roast, were divided into control samples and samples enriched with either vitamin C or vitamin E. All were packaged under standardized conditions to reproduce the original ratio of the original product and stored at room temperature protected from light. Microbiological quality was tracked from time zero throughout a nine-month storage period using a comprehensive panel of selective and non-selective culture media. Total aerobic mesophilic bacteria, yeasts and molds, fecal coliforms, Escherichia coli, Staphylococcus aureus, Salmonella, Shigella and Enterobacteriaceae were enumerated under appropriate incubation conditions. In parallel, the antioxidant capacity of each formulation was assessed by ABTS, DPPH and ORAC assays, combined with moisture and water activity of the formulated bar measurements to contextualize microbial behavior and oxidative stability. Across storage, all the samples remained microbiologically safe. Total mesophilic counts raised modestly but stayed far below established thresholds for pet food. Yeasts and molds increased slightly but never exceeded 10³ CFU/g. E. coli and Salmonella were absent from all samples, while indicators of hygiene such as fecal coliforms and Enterobacteriaceae stayed at low levels. Antioxidant testing revealed clear benefits of enrichment with vitamins. In both matrices, controls showed a progressive decline in radical-scavenging activity (higher IC₅₀ and lower TEAC/ORAC values) during storage. In contrast, vitamin-supplemented bars retained significantly more activity over time, demonstrating a slower loss of functional compounds and better protection against oxidative degradation. This stabilizing effect was evident from month three onwards and consistent across the three analytical methods. The water activity and moisture content of bars with varying glycerin levels during drying. Water activity ranged from 0.666 ± 0.018 to 0.709 ± 0.008, indicating low potential for microbial growth. Moisture content correlated with glycerin concentration, with higher glycerin (10% and 15%) resulting in increased moisture, while the 5% glycerin bars (9.516 ± 0.100%) remained within the recommended range for bars. The results demonstrate that these formulations provide stable, safe, and shelf-ready bars with appropriate textural properties.