Characterization of pork bones by means of shelf-life property, nutritional composition, and their gelatin's bioactivity.

The millions of tons of pork bones produced annually by the meat industry are widely used for human consumption and applied in other industries. This study aimed to evaluate the shelf-life and nutritional composition of pork bones and to develop an efficient method for extracting their bioactive gelatin. Pork bone samples collected at 24 h after slaughter were aerobically packaged and stored at 4°C for 21 days, then evaluated for total aerobic bacteria, discoloration, and fat and protein oxidation. Nutritional composition (fatty acids, amino acids, and collagen contents) was also analyzed. For gelatin extraction, the bone samples were swollen with 0.3% vinegar (4°C for 24 h) and hydrolyzed with 2.0% (v/w) crude ginger or kiwifruit extract for 5 h at 55°C. Results showed that pork bones lost approximately 43.69%-63.76% of their red color values and had high levels of lipid oxidation only after 14 days of storage. The total collagen, essential amino acid, and polyunsaturated fatty acid contents in the bones were 6-11 g/100 g, 403-554 mg/100 g, and 8%-10%, respectively. The hydrolysis with crude enzyme extracts yielded gelatins with multiple molecular weights, mainly in the range of 20-15 kDa. At a 0.7 mg/mL concentration, gelatin samples had DPPH free radical scavenging and ferrous chelating activity of 76%-89% and 67%-81%, respectively. Pork bone is a nutrient-rich by-product, and using vinegar and plant-derived enzyme extracts could be an effective and safe alternative for extracting bioactive compounds from pork bones.