Effect of low extraction temperatures on microbiological quality of rendered chicken fat recovered from skin

Ground or finely homogenized skin, inoculated with circa 7 log10 cfu/g of an Acinetobacter sp., Brochothrix thermosphacta, Candida tropicalis, Debaryomyces hansenii, Enterobacter agglomerans, Enterococcus faecalis, a Lactobacillus sp., or Pseudomonas fluorescens, or not inoculated, was heated to 50 or 80 C to release fat from adipocytes, and the released fat was separated by centrifugation. Extraction at 80 C resulted in nearly complete inactivation of indigenous and inoculated flora, resulting in microbiological counts generally below detection level in skin residue and rendered fat. In contrast, large numbers of organisms (3.69 to 7.28 log10 cfu/g) survived the 50 C extraction process. Even though the majority (91.5 to 99.9%) of these organisms remained in the residual skin at the time of fat separation, some organisms were also found occasionally in fat at concentrations of 2.85 to 3.74 log10 cfu/g. Therefore, an additional step such as flash pasteurization is recommended for safety, should extraction temperatures below 80 C be selected.