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Fat is an important part of the pork carcass for the processing industry and the consumers. Fat of good technological and sensory quality has been defined as white and firm, while poor quality fat has been described as soft, oily, wet, grey and floppy. The best fat quality for further processing is, however, often found to be in contrast to the high nutritional quality of the product. Two experiments with 72 slaughter pigs in each were conducted to evaluate the effects of different dietary fat levels, fatty acid compositions and sex (entire male and female) on the body fat distribution and the fat quality in terms of color, texture and fatty acid composition. Entire males and females were individually fed restricted. Palm kernel-, soybean- and fish-oil were used in varying combinations, giving different dietary fat levels (29–80 g/kg) and iodine values ranging from 50 to 131. Shoulder fat was analyzed for fatty acid composition (inner and outer layer), firmness and color.
The entire male and female pigs used in our studies revealed similar lean meat percentage, but females had more stored fat in hind parts compared to entire males. The range of dietary fat levels and fatty acid composition used had little influence on fat distribution. Feeding diets low in PUFA, and especially diets high in palm kernel oil, led to increased fat firmness. Male pigs had higher PUFA and lower MUFA levels, in particular C18:1, in shoulder fat than female pigs. We suggest that the lower content of C18:1 and more 18:0 is due to lower activity of the delta-9-desaturase in entire male pigs. For several of the dietary fatty acids an almost linear deposition in pig fat was found, especially when supplementary fat was added to the diet, while the medium length fatty acids C12:0 and C14:0 seemed to be mainly oxidized or metabolized to longer chain fatty acids. Importantly, the nutritionally positive very long chain n-3 fatty acids seem to be conserved and deposited to a higher extent when pigs were fed high fat diets. Both high and low dietary iodine values changed towards less extreme iodine values in fat.
Low-fat diets enhanced de novo synthesis of fatty acids. Fat firmness, but not color, was influenced by sex and dietary fat source.
E Hallenstvedt, NP Kjos, M Overland and M Thomassen, 2012. Changes in texture, color and fatty acid composition of male and female pig shoulder fat due to different dietary fat sources. Meat Science, 90: 519-527