Research on the Relationship between Freshness and Dielectric Spectrum of Postharvest Ling-Wu Long Jujubes

Abstract:

In order to seek the feasibility of freshness prediction of Ling-Wu long jujubes based on dielectric spectrum, the electrical parameters of Ling-Wu long jujube were measured dynamically using HIOKI 3532-50 LCR parallel-plates measuring instrument. The concept of dielectric freshness F was put forward and its freshness index TI was proposed according to local standards. The results indicated that there was significant linear correlation between F value and TI (R²=0.709). The freshness prediction model of Ling-Wu long jujubes was established using the BP - ANN neural network (R²=0.894), the grade recognition rate was up to 82.14%. Freshness prediction of postharvest Ling-Wu long jujubes based on its dielectric spectrum was feasible.

• Periodical: Advanced Materials Research (Volume 1090)
• Pages: 136-141
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1090.136
• Online since: February 2015
• Authors: Xue Lian Ma, Hai Hong Zhang*, Zhong Zhang, Hui Qian Wang
• Keywords: Dielectric Spectrum, Freshness, Ling-Wu Long Jujubes

References

[12] of relationship between the dielectric property and freshness of apples and according to the significant correlation between the storage time and the content of total sugar and acid, it could be concluded that there was significant correlation between the freshness and the content of total sugar and acid. So, it was feasible to use TI to measure the jujube's freshness. The local standard DB64 / T419-(2005).

[13] of Ling-Wu long jujubes of Ningxia prescribed that the content of total sugar (measured as sucrose) and acid (measured as malic acid) of qualified matured fresh Ling-Wu long jujubes are 230. 0 g/Kg and 4. 0 g/ Kg respectively. On the basis of this standard, postharvest Ling-Wu long jujubes are divided into three grades according to their freshness. The freshness grades of the Ling-Wu long jujubes are divided as follows: TI≤270 is the first grade, 270＜TI≤295 is the second grade and TI＞295 is the third grade, which is shown in figure 1 (c). As can be seen in the figure 1 (c), postharvest Ling-Wu long jujubes were basically the first grade during storage of 1~2 days, were basically the second grade during storage of 3~4 days and were basically the third grade during storage of more than 4 days. Results and discussion Determination of characteristic frequency. Polarization phenomenon often occurs when biological tissues are placed in an alternating electromagnetic field. Because the macromolecules of biological tissues need a period of time for changing from non-polarization status into polarization status during the polarization process, there is a relaxation time, and the reciprocal of the relaxation time is the characteristic frequency (Li et al., 2010).

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