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

Abstract

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.

Use of Salmonella enterica serovar Typhimurium DT104 expressing lux genes to assess, in real time and in situ, heat inactivation and recovery on a range of contaminated food surfaces

“…It was interesting to observe that, on skinless chicken samples, recovery of bioluminescence began almost immediately after heating with a greater than 1000-fold increase in the first 10 h of the monitoring period, whereas when the chicken skin was left on no recovery of activity was observed. The cidal effects of heat on bacteria attached to chicken skin have previously been reported by Piette, Hundt, Lapointe, and Jacques (2000), who suggested the observed reduction in viable counts might be due to fat released from adipocytes at 80°C. This may account for the very marked difference observed here between heat inactivation on chicken skin, compared to skinless chicken.…”

Study of the thermal behavior of rosemary extract and its temperature‐related antioxidant effect on chicken fat

“…Normally, the chicken fat undergoes 100–140°C for hours in processing, during which the oxidation distinguishes from ambient‐temperature storage (Piette et al, 2000). This research aims to provide a better understanding in terms of the thermal behavior and antioxidant stability of RE by simultaneous thermal analysis and total phenolic content (TPC) measurement, as well as its protective effect on chicken fat when heated at 90–150°C to simulate cooking and rendering process.…”