羊油干法分提条件对其得率、熔点及脂肪酸组成的影响Effects of dry fractionation conditions of mutton tallow on its yield, melting point and fatty acid composition

为寻找羊油分提过程中脂肪酸变化的关键控制因素，提高分提效率和羊油品质，以绵羊臀脂肪组织为原料制备粗提羊油，采用干法分提得到液油，考察分提条件（养晶温度、降温速率、养晶时间）对液油得率、熔点和脂肪酸组成及含量的影响。结果表明：液油得率和熔点随着养晶温度的升高而升高，饱和脂肪酸含量随养晶温度的升高总体升高；降温速率对液油得率影响不显著，在降温速率8 ℃/h下液油的熔点和饱和脂肪酸含量最低；养晶时间对液油得率、熔点及脂肪酸含量影响均较小；羊油干法分提的最佳工艺条件为养晶温度28 ℃、降温速率8 ℃/h、养晶时间8 h，在此工艺条件下液油得率为39.33%，熔点为23.8 ℃，不饱和脂肪酸含量从粗提羊油的46.37%提高至50.85%，饱和脂肪酸含量从粗提羊油的50.69%降低至45.69%。综上，在羊油干法分提过程中影响脂肪酸比例的关键因素是养晶温度和降温速率，养晶时间对羊油脂肪酸含量的影响不显著；合适的干法分提条件可在确保分提效率下最大限度降低羊油中饱和脂肪酸含量，提高羊油利用价值。 To identify key factors controlling fatty acid changes during mutton tallow fractionation, thereby enhancing fractionation efficiency and product quality, crude mutton tallow was prepared from sheep rump fat. Mutton tallow olein was obtained via dry fractionation, and the effects of fractionation conditions（crystallization temperature, cooling rate and crystallization time）on mutton tallow olein yield, melting point, and fatty acid composition and content were investigated. The results indicated that the yield and melting point of mutton tallow olein increased with the increase of crystallization temperature, and the saturated fatty acid (SFA) content overally increased. The cooling rate had no significant effect on mutton tallow olein yield, while the lowest melting point and SFA content were observed at 8 ℃/h. Crystallization time exerted a minor influence on mutton tallow olein yield, melting point, and fatty acid content. The optimal process conditions for dry fractionation of mutton tallow were crystallization temperature 28 ℃, cooling rate 8 ℃/h, and crystallization time 8 h. Under these conditions, the mutton tallow olein yield reached 39.33%, with a melting point of 23.8 ℃. The unsaturated fatty acid content increased from 46.37% in crude mutton tallow to 50.85%, while the SFA content decreased from 50.69% in crude mutton tallow to 45.69%. In summary, the key factors influencing fatty acid ratios during the dry fractionation of mutton tallow are crystallization temperature and cooling rate, while crystallization time has no significant effect on fatty acid content. Optimal dry fractionation conditions can substantially reduce SFA content in mutton tallow while achieving considerable yields, thereby enhancing its utilization value.