The effect of the RN¯allele and production system on meat quality and the formation of heterocyclic amines in pork

This thesis summarises and discusses results of four separate studies on the combined effects of RN genotype and production system on technological and nutritional pig meat quality. That RN genotype considerably affects technological meat quality is well known but little attention has been directed towards potential effects on the nutritional quality of the meat. Mutagenic/carcinogenic heterocyclic amines (HCAs) in fried meat are an important nutritional safety issue and the high muscle glycogen content in RN¯ carriers could affect HCA formation. Further, despite an increased interest in alternative production systems for pig meat there are few and inconsistent reports on meat quality implications.

Three animal materials, representing different aspects of alternative production systems, formed the basis for the experimental work. Besides production conditions, RN genotype and sex of the animals were known. The water-holding capacity, colour, texture and chemical composition of the meat were analysed. In two studies the meat was fried and the level of heterocyclic amines formed was determined and in one study the fatty acid composition and the level of the antioxidant α-tocopherol were analysed. In the last study, a questionnaire complemented with colour photographs was used to obtain information on dietary practices and preferences regarding home-prepared pork chops of different RN genotypes.

The results stress the importance of combinatory effects of different production factors on final meat quality. Alternative production systems did not have a large impact on final pig meat quality, but in non-carriers of the RN¯ allele organic production with increased physical activity lead to impaired water-holding and texture of the meat. The high glycogen content of meat from RN carriers prevented negative effects of pre-slaughter treatment on meat quality. Free-range reared pigs with access to green feed resulted in more polyunsaturated fatty acids and α-tocopherol in the meat compared to indoor reared pigs. The high glycogen content in carriers of the RN¯ allele led to a browner crust and considerably lower levels of HCAs in fried meat compared to that of non-carriers. It was indicated that pork chops only marginally contribute to the daily intake of HCAs; nonetheless, by choosing meat of carriers of the RN¯ allele and by using lower cooking temperatures, this intake can be further reduced.