基于电学参数的货架期红巴梨无损检测

    Nondestructive determination of the quality of Red Bartlett pear during shelf life by electrical characteristics

    • 摘要: 以红巴梨为材料,利用HIOKI 3532-50型LCR测量仪和自制平行板铜电极,在100 Hz~5 MHz频率范围,对果实7 d货架期电学参数的变化进行无损伤测定,研究其与果实品质指标硬度、可溶性固形物含量的相关性,基于此找到与红巴梨果实成熟衰老相关的电学参数,并筛选出电指标最佳测试频率。结果表明,随着测试频率升高,果实阻抗和电感呈幂函数递减,电容和电导呈不规则变化。随着货架期延长,果实阻抗和电感显著下降(P=0.01),电容和电导呈上升趋势。100 Hz~1 MHz范围内,随测试频率升高,果实阻抗、电感和电容与果实硬度相关性逐渐增大,相关系数分别由100 Hz时的0.45、0.45、0.37升高到1 MHz时的0.84、0.83、0.73,高于1 MHz时相关性下降或变化不大。果实阻抗、电容和电感可以作为标志红巴梨果实成熟衰老的电学指标,1 MHz为最佳测试频率。

       

      Abstract: Electrical parameters of Red Bartlett pear fruits were non-destructively measured during seven-day shelf-life storage at 20℃ over a frequency range from 100 Hz to 5 MHz with a parallel-plate copper electrode and HIOKI 3532-50 LCR meter. Fruit firmness and soluble solids content were measured as quality attributes for correlation with the dielectric properties. The optimum frequency for electrical properties test was identified. The results showed that with the increase of frequency, fruit impedance and inductance decreased in exponential form, while capacitance and conductance were changed irregularly. Fruit impedance and inductance decreased significantly(P=0.01)with fruit ripening, while capacitance and conductance changes had an increasing trend. Within 100 Hz~1 MHz frequency, the correlation coefficient between fruit impedance, inductance, capacitance and fruit firmness increased from 0.45, 0.45 and 0.37 at 100 Hz to 0.84, 0.83 and 0.73 at 1 MHz, respectively, while decreased or not changed significantly at the frequency above 1 MHz. Impedance, capacitance and inductance can be taken as the electrical indices for fruit ripeness, and 1 MHz is the optimum test frequency.

       

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