Physical and chemical characterization of yacon tuberous roots at different altitudes and planting times

ABSTRACT The post-harvest quality of yacon tuberous roots produced at different altitudes and planting times were characterized in this study. The experiment was conducted in the South of Espírito Santo State in two locations, one at 837 m altitude and the other one at 113 m altitude. The experimental design, in each place, was randomized blocks with four replications, and the treatments consisted of three planting seasons: April (autumn), July (winter) and September (spring). After harvest of the tuberous roots, we evaluated pH, titratable total acidity, moisture content, soluble solids, reducing sugars, crude fiber and ash, as well as color, hardness (maximum force recorded in the first penetration or compression cycle) and chewiness index (energy required to chew food, given by gumminess x elasticity). Tuberous roots grown at 837 m altitude, independent of planting times, presented higher soluble solids content and lighter juice, conferring better quality. However, at 113 m altitude, from April to July, the roots showed better quality, since it presents lower hardness and lighter juice.

摘要 本研究对不同海拔与种植时段产出的亚贡（yacon）块根的采后品质特征进行了系统表征。实验于巴西圣埃斯皮里图州南部两个试验点开展，分别设置于海拔837米与113米处。各试验点均采用随机区组试验设计，设置4次重复，处理组包含3个种植季：4月（秋季）、7月（冬季）与9月（春季）。待块根收获后，本研究测定了其pH值、可滴定总酸度、含水率、可溶性固形物含量、还原糖含量、粗纤维含量与灰分含量，同时评估了块根的色泽、硬度（首次穿刺或压缩循环中记录的最大作用力）以及咀嚼性指数（由胶粘性与弹性的乘积计算得到的食物咀嚼所需总能量）。结果表明，无论种植季如何，海拔837米处种植的亚贡块根均具有更高的可溶性固形物含量与更浅的汁液色泽，品质更优；而在海拔113米处，4月至7月种植的块根品质更佳，表现为更低的硬度与更浅的汁液色泽。