DIELECTRIC PROPERTIES OF POTATO TUBERS RELATED TO STORAGE CONDITIONS

Document Type : Original Article

Authors

1 Prof. of Food Eng., Fac. of Ag., Alexandria Univ., Egypt.

2 Res., Ag. Eng. Res. Inst., Ag. Res. Center, Dokki, Giza, Egypt.

Abstract

The objective of this work is to study the dielectric properties of potato tubers asa criteria for predicting of freshnessfor each of fresh and storage commodity under traditional (Nawala) and cold conditions. Dielectric measurementswere measured using LCZ meter,andwere conducted on fresh and stored tubers, for measuring of capacitance (Farad, f), and conductance (Siemens, S) over a range of frequencies from 10 to 1000 kHz. The measured value were used to calculate permittivity (f/m), conductivity (S/m), relative permittivity, complex permittivity (S.sec/f), complex conductivity (f/m.sec) and dissipation factor or "loss tangent" (tan δ) of potato tuber. The capacitance,relative permittivitydecreases rapidly with increasing frequency.Dissipation factor Tan (δ) decreases gradually with increasing the storage time. Complex permittivity and Complex conductivity were decreases with the increases of the storage time. The quality factor Q was expressed as a percentage value of the ratio between conductance at high frequency to that at low frequency (GH/GL) for the stored tissue to that for the fresh tissue to indicate the degree of freshness. The quality factor Q decreases with the increasing ofstorage time, storage temperature and storage load stressand isa fairly goodindication of the loss of freshness. The storage ages of potatoes were predictedwith very sensitive equation using the quality factor, tuber weight and storage temperature.

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References

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