Use of spray-dried animal plasma in canned chunk recipes containing excess of added water or poultry fat

Abstract

Spray-dried animal plasma (SDAP) and wheat gluten (WG) are common ingredients in canned pet food. In addition to providing amino acids and energy these ingredients are used because of their technological properties such as gel strength, water retention capacity and fat emulsification. In cat foods (strict carnivore) SDAP (an animal protein) is more palatable than WG (a cereal protein). The purpose of the study was designed to evaluate the effect on physical and chemical characteristics of increasing inclusion of water or poultry fat in a chunck recipe containing either SDAP or WG. Inclusion of SDAP was 15 g/kg while WG was included at 20 g/kg. Water was increased replacing chicken carcass from 170 to 450 g/kg in the formula resulting in a linear reduction in dry matter, protein and ash content. A similar reduction in texture (measured as hardness) of the chunck was observed with increased water addition. However, the reduction in texture was less in the SDAP formula ( y = 11.268 (S.E. = 0.453) − 0.015 x (S.E. = 0.001); r 2 = 0.981) compared to that of the WG formula ( y = 9.578 (S.E. = 0.428) − 0.013 x (S.E. = 0.001); r 2 = 0.979). Water loss, measured as liquid exudates from the chunk, increased as the level of water addition to the recipe increased. However, water loss was less (P<0.05) in the SDAP formula compared to that of the WG formula. Similar results were observed when chicken carcass was replaced by poultry fat from 0 to 350 g/kg, resulting in a linear reduction in protein and ash content but not in moisture of the chunk recipe. Texture of the chunk was reduced with increasing level of added fat while the reduction was less in the SDAP recipe ( y = 8.437 (S.E. = 0.268) − 0.008 x (S.E. = 0.001); r 2 = 0.957) compared to the WG recipe ( y = 7.652 (S.E. = 0.340) − 0.009 x (S.E. = 0.001); r 2 = 0.951). Viscosity of the raw emulsion before cooking was similar in both trials for the SDAP and WG recipes. Palatability of the SDAP and WG formulas were compared in a 2 days test with cats. On first choice SDAP was chosen by 69% of the cats while WG was chosen by 31% of the cats (P<0.05). Total food intake was similar for the SDAP and WG diets.