Evaluation of Extrusion Temperatures, Pelleting Parameters, and Vitamin Forms on Vitamin Stability in Feed
Pan Yang, Huakai Wang, Min Zhu, Yongxi Ma
Abstract
Two experiments were conducted to determine the stability of microencapsulated and non-microencapsulated forms of vitamins in diets during extrusion and pelleting. We investigated the recovery of vitamins in swine diets after extrusion at 100 °C, 140 °C, or 180 °C. Next, two diets were conditioned at 65 °C (low temperature; LT) or 85 °C (high temperature; HT), and pellets were formed using a 2.5 × 15.0 mm (low length-to-diameter ratio; LR) or 2.5 × 20.0 mm (high length-to-diameter ratio; HR) die. The extrusion temperature had a significant effect on the recovery of vitamins E, B1, B2, B3, and B5 in the diets. The diet extruded at 100 °C had higher B1, B2, B3, and B5 vitamin recoveries than diets extruded at 140 °C and 180 °C. Microencapsulated vitamins A and K3 had greater stability than non-microencapsulated vitamins A and K3 at 100 °C and 140 °C extrusion. In the diet extruded at 180 °C, microencapsulated vitamins A, D3, and K3 had higher recoveries than non-microencapsulated vitamins A, D3, and K3. The recovery of vitamin K3 in diets after LTLR (low temperature + low length-to-diameter ratio) or HTLR (high temperature + low length-to-diameter ratio) pelleting was greater (p < 0.05) than after LTHR (low temperature + high length-to-diameter ratio) and HTHR (high temperature + high length-to-diameter ratio) pelleting. Our results clearly show that low extrusion temperature and low pellet temperature, and a low length-to-diameter ratio (L:D ratio) for pellet mill die are recommended for pig feed. Moreover, microencapsulated vitamins had greater stability compared to non-microencapsulated vitamins.