河套蜜瓜机械特性及其与硬度和糖度关系的试验

Research on the Relationship between Mechanical Properties and Stiffness Refractive Sugar Concentration of Hetao Muskmelon under Compressing

通过对不同硬度完整形态的河套蜜瓜准静态机械特性参数和相对应样品折光糖度的测定和分析,建立了机械特性参数与折光糖度关系的回归方程,并通过偏回归系数标准化,反映出机械特性参数与糖度指标关联的重要程度的次序为:杨氏模量>变形能>破坏能>破坏极限>屈服极限。经检验,所建立的回归方程有意义并且显著,因此可通过机械特性参数对河套蜜瓜果实的糖度指标变化情况进行预测。试验结果表明,随果实硬度降低,其屈服极限和变形能明显减小。完整果实受压初期,随应变增加而应力下降;应力下降达到最低点以后,硬度越大,应力—应变曲线斜率越小,曲线越平坦。较低硬度的果实受压时较早进入屈服状态,果实内部微观组织易损伤。

Regression equation of relationship between the mechanical property parameters and refractive sugar concentration （RSC） of the intact Hetao muskmelon fruits was developed through mechanical experiment under A quasi-static compressing. The order of effect of mechanical property parameters on RSC of the fruits may be observed through the standardized regression coefficients. It was suggested by Statistic analysis that the regression equation was meaningful and suitable for predicting and examining RSC of Hetao muskmelon non-destructively during storage and transportation. The results showed that the mechanical property parameters were all significantly affected by the stiffness. There was an obvious fall in both yield force and deforming energy with decreasing fruit＇s stiffness. The micro tissues of the fruits with smaller stiffness were more easily destroyed. The strain-stress curves ：indicated that there was an obvious fall in stress with increasing strain at early compressing stage because of simultaneous change of loading and contact area. Correlation was obviously observed between the mechanical property parameters.