Quality attributes of PDO dry-cured hams as affected by low-protein diets and genetic line of pigs

This study aimed to evaluate the effects of decreasing the crude protein (CP) of diets on several quality attributes of traditional dry-cured hams provided by pigs of two genetic groups (GG) characterized by different potential for lean growth. Hams data originated from 96 pigs, the half fed a conventional diet (CONV), representative of those commonly fed to heavy pig in Italy, the others a low-protein (LP) diet, with a 20% lower CP content with respect to CONV. Pigs were slaughtered at 165 kg average BW and all trimmed hams obtained were processed to produce typical San Daniele dry-cured hams. At the end of seasoning, 10 left dry-cured hams for each diet x GG combination were selected and analysed for chemical (fat and salt content, proteolysis index, water activity) and texture traits and fatty acid composition, and evaluated for some sensorial attributes through a consumer test. The effects of diets, GG and their interaction were included in the model of statistical analysis. Pigs fed LP diets provided hams with lower protein content (P < 0.01), whereas a greater fat content was found only in the low lean growth potential GG. Conversely, texture traits and fatty acid composition were unaffected by diet. Hams from high lean growth potential GG showed greater losses at processing and deboning, an only nominal greater salt content, greater protein content and a greater proportion of total polyunsaturated fatty acids (+20%, P < 0.001) and ω6 (+9.2%, P < 0.001) than the other GG. In conclusion, lowering the dietary CP has only minimal effects on dry-cured ham quality. Due to its positive effects on sustainability of dry-cured ham chain by decreasing pig farm nitrogen excretion and feeding costs, lowering the dietary CP content with respect to the current values seems an advisable strategy for the feeding of traditional PDO heavy pigs. Genetic groups of different lean growth potential exerted only minor effects of dry-cured ham quality.