Influence of Extraction Temperature on Amounts and Quality of Rendered Chicken Fat Recovered from Ground or Homogenized Skin

Abstract

A study was undertaken to determine the influence of extraction process on recovery and quality of fat from chicken skin. In order to do so, 20-kg batches of skin were ground (9.5 mm plate) or homogenized in a colloidal mill (0.2-mm knife set), then heated to 50 or 80 C to rupture fat cells. The fat was recovered by centrifugation and was evaluated for composition, appearance, and stability. A maximum amount of fat (89.6% of the fat initially contained in skin) was recovered from homogenized skin heated to 80 C, whereas heating ground skin to 50 C yielded the lowest fat recovery (51.5% of skin fat content). In general, fat composition and appearance were little affected by extraction conditions, with the exception that the fat extracted from homogenized skin contained more (P < or = 0.001) unsaponifiable cell membrane constituents (0.17 to 0.20%), including antioxidant tocopherol fractions (10.3 microg/ml), than the fat extracted from ground skin (0.08% and 7.5 to 8.3 microg/ml, respectively). This difference likely contributed to the greater oxidative stability of the fat extracted from homogenized skin, which was observed in Schaal oven tests.

Fat contributes to the buffering capacity of chicken skin and meat but enhances the vulnerability of attached Salmonella cells to acetic acid treatment

“…The percentage of fat extracted in our study was similar to the 76.5% reported by Piette et al (2001) (Table 1). This may be because of the grind size of the chicken skin and temperature used were the same for the two studies.…”

“…Bonifer and Froning (1996) reported that chicken skin is composed of 78.5% fat and 19.3% protein. The fat composition found in broiler skin by Piette, Hundt, Jacques, and Lapointe (2001) was 43.4%. The high levels of fat from chicken skin are significantly different as compared to that from chicken meat which is in the range of 0.68-11.7% depending on the breed and muscle types (Mourao et al, 2008;Wattanachant, Benjakul, & Ledward, 2004).…”

“…Fat extraction was performed as described previously (Piette et al, 2001) with modifications. Frozen skin and meat samples were comminuted in a blender (Kenwood, China) equipped with a 9 mm knife set.…”

“…This may be because of the grind size of the chicken skin and temperature used were the same for the two studies. A temperature of 80°C was chosen for our study (instead of the commonly used 50°C) as both were used in Piette et al (2001) but the higher temperature is more effective in reducing microbial contamination. Due to the low amount of fat extracted from the chicken meat, only fat from the skin was used for further experiments in this study.…”

Yield and Quality Characteristics of Rendered Chicken Oil for Biodiesel Production

“…There are several reports that the quantity and quality of fat recovered varied depending on the rendering temperature and conditions [7][8][9].…”