钾肥对甘薯块根营养成分的影响及其与烘烤风味的关系

Effect of potassium fertilizer on nutritional components of sweet potato storage roots and its relationship with roasting flavor

【目的】探讨不同施钾量条件下食用型甘薯块根烘烤后风味品质的变化,及其与生块根中关键营养成分和烘烤后特征挥发性物质的关系。【方法】选用烟薯25和北京553两个鲜食型甘薯品种,在山东农业大学农学实验站进行田间小区试验。设置4个钾肥(K2O)用量,分别为0、12、24、36 g/m^2。在甘薯收获期,测定了块根中主要营养成分含量以及烘烤后挥发性物质含量,同时对块根烘烤后的风味进行评价。【结果】施用钾肥不同程度地提高了甘薯块根中可溶性糖、淀粉、可溶性蛋白、维生素C、β-胡萝卜素和纤维素含量,提高了烘烤后甘薯中挥发物质二丙酮醇、苯乙醛、壬酸、4-乙烯基愈创木酚、丁酸丁酯、未知物-1、十五烷酸、植物醇和香叶基香叶醇的浓度,提高了风味评分。4个钾肥处理中,各成分含量以施钾量24 g/m2处理达到或者接近最高。通过逐步回归和通径分析发现,施用钾肥改善块根烘烤后风味品质的关键营养成分是果糖、葡萄糖、氨基酸、可溶性蛋白质、支链淀粉和蔗果三糖,施用钾肥改善块根烘烤后风味的主要特征挥发性物质是丁酸丁酯、苯乙醛和未知物-1。【结论】施用钾肥主要通过提高甘薯收获期块根中营养物质含量和块根烘烤后有益挥发性物质(如苯乙醛、丁酸丁酯等)的浓度,改善块根的烘烤风味。在本试验条件下,K2O用量为240 kg/hm^2为最适用量。

【Objectives】The roasting flavor quality of sweet potato were studied by analyzing the contents of main nutrition components and key volatile substances under different potassium(K)fertilizer application rates.【Methods】A microplot field experiment was carried out in Agronomy Experimental Station of Shandong Agricultural University with two sweet potato cultivars of Yanshu 25 and Beijing 553.Four K fertilizer application level treatments were designed,including K2O 0,12,24 and 36 g/m^2.The contents of main quality indices in root tubers at harvest and the contents of volatile substances after roasting were measured.The roasting flavor of root tubers was graded as well.【Results】The application of K fertilizer increased the contents of soluble sugar,starch,soluble protein,vitamin C,β-carotene and cellulose of root tubers in different extents.The concentration of diacetone alcohol,phenylacetaldehyde,nonanoic acid,4-vinylguaiacol,butyl butyrate,unknown-1,pentadecanoic acid,phytol,geranylgeranio were all increased,and flavor scores of the two varieties were consequently increased.The highest contents of nutrient components and compounds mentioned above all achieved in treatment K2O24 g/m^2.The result of stepwise regression and path analysis indicated that the key factors that improving the roasting flavor were the contents of fructose,glucose,amino acids,soluble proteins,amylopectin and cane fructose.The main volatile substances that deciding the roasting flavor included butyl butyrate,phenylacetaldehyde and unknown compounds.【Conclusions】The application of potassium fertilizer is effective to increase the nutrient quality and roast flavor of sweet potatoes.In addition,proper K nutrition could increase the volatile substances that deciding the roast flavor like butyl butyrate and phenylacetaldehyde,which is also one of the reasons of better flavor.Under this tested condition,the optimum rate of K2O is 240 kg/hm2.