An experiment was conducted to determine if rapid enumeration of populations of Pseudomonas fluorescens by standard methods and by measuring capacitance could be used to predict the potential shelf life of fresh broiler chicken. Fifty whole ready-to-cook broiler chicken carcasses were obtained fresh from the chiller and separated into five groups (10 carcasses each) in three replicate trials. The first 10 carcasses were sampled by rinsing on day 0. Ten carcasses each were sampled by rinsing after holding for 3, 6, 9, or 12 days at 3°C. For each carcass, psychrotrophic plate counts (PPC), P. fluorescens plate counts (PFPC), P. fluorescens detection times (PFDT), and subjective odor evaluations (ODOR) were determined. PPC, PFPC, and ODOR on groups of carcasses significantly increased after 3 days of storage at 3°C and every day thereafter throughout the storage period. The log Pseudomonas fluorescens detection times (LPDT) significantly decreased throughout storage from 0 to 12 days, indicating a significant increase in bacterial populations. Significant linear and quadratic correlations, respectively, were observed between PPC and day of storage (DAY) (R2 = .86 and .84), PFPC and DAY (R2 = .85 and .89), LPDT and DAY (R2 = .86 and .85), ODOR and DAY (R2 = .73 and .86), PPC and ODOR (R2 = .80 and .72), PFPC and ODOR (R2 = .87 and .81), LPDT and ODOR (R2 = .85 and .77), and LPDT and PPC (R2 = .96 and .97). A significant linear correlation was observed between LPDT and PFPC (R2 = .93). Enumeration of P. fluorescens from fresh chicken at day of processing should be beneficial because (i) the potential shelf life of fresh chicken can be determined at day of processing; (ii) processing sanitation hygiene may be determined; and (iii) carcasses exposed to temperature abuse may be identified.
Reduction of Shelf-life of Dairy Products by a Heat-stable Protease from Pseudomonas Fluorescens P26
