Use of Poultry Collagen Coating and Antioxidants as Flavor Protection for Cat Foods Made with Rendered Poultry Fat

Poultry skins and rendered poultry fat are by-products produced in excess at rendering plants. The use of low value by-products such as poultry collagen, from poultry skins, and fat to improve flavor and quality in dry pet food could be economically attractive. This study examined a poultry collagen coating as a protective barrier against oxidation in dry cat food made with rendered poultry fat. Collagen was extracted from chicken skins, dissolved in an acidic solution, applied to dry cat food and dried to form a surface film. Six treatments were examined: kibble, kibble with fat, kibble with collagen, kibble with fat and collagen, kibble with fat, BHA/BHT and collagen and kibble with fat, tocopherol and collagen. There were two storage conditions: ‘jungle condition’ (42°C and 83% relative humidity) and ‘ambient condition’ (21°C and 51% relative humidity). In ‘jungle conditions’, thiobarbituric acid reactive substances (TBARS) was measured over an eight-day period at day 0, 2, 4, 6, and 8. In ‘ambient conditions’, TBARS was measured over a thirty-day period at day 0, 7, 14, 21, and 30. Water activity and moisture contents were measured. There were significantly higher TBARS (P<0.05) for the control kibble at both storage conditions. There was significantly higher fat percentage (P<0.05) in all treatments with the additional fat coatings. Fatty acid compositions showed slight changes during storage. There were some changes in the aroma profile of the kibble with fat treatment having musty, moldy and plastic aromas at both storage conditions. The volatile aromas might be an indication of oxidation in the poultry fat.