红富士果实内部品质的电学法无损检测

Non-destructive Detection with Electric Basis on Internal Qualities of Fuji Apple Fruit

为了建立不同新鲜度红富士苹果品质的无损检测方法,分别于失重率0%、5%、10%、15%下逐果测定9个频率点下的14个电参数值(共126个值)及品质指标。结果得出,随测定频率的增加,红富士苹果果实的串联等效电容Cs,介电常数ε′呈波动性上升趋势,复阻抗Z呈直线型下降趋势;同一频率下,随失重率的增大,串联等效电容Cs,介电常数ε′均逐渐上升;复阻抗Z逐渐下降。可滴定酸,固酸比,VC与其中24种电学参数达到极显著相关水平,通过多元逐步回归分析建立以下回归方程:Y_1=0.082+0.005Z_2-105 116.3Ls_3(P<0.000 1,R^2=0.893),Y_2=221.9+6.838×10^(11)Cp_3+29 132.96Y_3-1.493 Z_3(P<0.000 1,R^2=0.891),Y_3=1.783+1.171×10^(-5)Rp_6(P<0.0001,R^2=0.749),即果实可滴定酸含量(Y_1)、固酸比(Y_2)、V_C含量(Y_3)可通过无损测定1～3个电学参数来计算经对测试样本验证,对3个品质指标的计算相对误差依次为9.93%,5.98%,9.22%。

In order to establish nondestructive testing method for the freshness of Fuji apple. 14 electric parameters under nine frequencies （total 126 values） and 5 quality indices were determined on each apple from 4 grade weight loss rate of 0%, 5%, 10% and 15%. As a result, series equivalent capacitance Cs, dielectric constant ε＇ presented a fluctuated improving trend, complex impedance Z decreased linearly with the increasing of frequency. Under the same frequency, Cs, ε＇ increased with the increase of weight loss rate, however, complex impedance Z decreased; Titratable acid, soluble solid/titratable acid, Vitamin C were all extremely significantly correlated with 24 electric parameters. The regression equations of correlation between quality indices and dielectric parameters were established as Y1 = 0.082 ＋ 0.005Z2 - 105 116.3Ls3 （P〈0.000 1, R2 = 0.893）, Y2 = 221.9 ＋ 6.838x1011Cp3 ＋ 29 132.96Y3 - 1.493Z3 （P〈0.000 1, Rz = 0.891）, Y3 = 1.783 ＋ 1.171x l0^-5Rp6 （P〈0.000 1, R^2= 0.749）, which meant titratable acid （Y1）, soluble solid/titratable acid （Y2） and Vitamin C（Y3） can be calculated by 1-3 electric parameters with non-destructive detection. After the verification of test samples, the relative error of evaluation of three quality indices were 9.93 % （Y0, 5.98 % （Y2）, 9.22 % （Y3） , respectively.