苹果果肉可溶性固形物、可溶性糖与光学性质的关联

为加深理解光学技术检测果实可溶性固形物含量的机理,采用单积分球技术定量分析苹果低温贮存(0 ℃,150 d)期间可溶性固形物、总可溶性糖、果糖、葡萄糖和蔗糖与吸收和散射性质的关系,并利用偏最小二乘回归建立含量预测模型。结果显示,贮存期间,可溶性固形物和可溶性糖含量的下降伴随着吸收系数和约化散射系数的减小,呈现很高的正相关关系(r为0.768~0.992)。其中,这些可溶性成分与吸收系数的相关性更高。在3 种可溶性糖中,可溶性固形物与蔗糖最相关(r=0.961)。且两者与吸收系数和约化散射系数的平均相关性(r为0.890~0.963)均高于果糖和葡萄糖(r为0.813~0.910),对应的预测模型也更优,预测决定系数Rp分别为0.886~0.893和0.864~0.906。结果表明,光学性质能够预测可溶性固形物含量的原因可能是可溶性糖(尤其是蔗糖)与光学性质高度相关。该研究为光学技术检测果实品质提供理论参考。

Relationship between Soluble Solid and Soluble Sugar Contents and Optical Properties of Apple Flesh

In order to gain a deep understanding of the principle of an optimal method for the determination of soluble solid contents in fruits, we quantified the relationships between the contents of soluble solid, total soluble sugar, fructose, glucose and sucrose and absorption and scattering properties of apple flesh during storage (150 d at 0 ℃) using the single intergrating sphere technology. Besides, predictive models were established by partial least squares regression. The results showed that the contents of soluble solids and soluble sugars decreased during storage, and so did the absorption coefficient (μa) and reduced scattering coefficient (μ’s); highly significant positive correlations occurred between the two groups of parameters (r = 0.768–0.992). In particularly, the correlations between these soluble components and μa were higher. Among the three soluble sugars, soluble solids were the most correlated with sucrose (r = 0.961). The average correlations of soluble solids and sucrose with μa and μ’s (r = 0.890–0.963) were higher than those of fructose and glucose (r = 0.813–0.910). Furthemore, the prediction models for soluble solids and sucrose were better, with determination coefficient for prediction (Rp) of 0.886–0.893 and 0.864–0.906, respectively. The results showed that the high correlations between soluble sugars (especially sucrose) and optical properties may provide evidence that optical properties could be used to predict soluble solid contents. This study provides a theoretical rationale for optical detection of fruit quality.