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Correlations of Dielectric Properties of Cheddar Cheese with Ripening Time and Ripening Index

FAN Guisheng, WANG Lisha   

  1. College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China
  • Online:2017-01-15 Published:2017-01-16

Abstract: The dielectric properties and ripening properties of Cheddar cheese samples from the same batch with different
ripening times (0, 15, 30, 45, 60, 90, 120, 150 and 180 d) at 9 ℃ were evaluated with respect to total nitrogen (TN), pH
4.6-soluble nitrogen (pH 4.6-SN) and trichloroacetic acid-soluble nitrogen (TCA-SN). The testing frequencies were set
to 500, 915, 1 500, and 2 000 MHz. The obtained data were analyzed statistically to establish the correlation between
dielectric properties and ripening indexes. The results showed that as the ripening time increased, the moisture content of
the cheese samples decreased slightly and the water activity evidently dropped; the pH decreased from day 0 to day 45 and
then increased from day 45 to day 180; the ripening indexes pH 4.6-SN/TN ratio and 12% TCA-SN/TN ratio were increased
persistently throughout the ripening time. At all the testing frequencies investigated, the dielectric constant ε’ exhibited a
decreasing trend over the ripening period of 180 days, and it had a linear correlation with the ripening time and ripening
parameters. With the increase in ripening time and ripening indexes, the dielectric loss factors ε’’ in the frequency range of
500 to 2 000 MHz generally showed a decreasing trend. It had significantly linear correlations with ripening time as well as
ripening indexes at 500 and 915 MHz (P < 0.01). But the linear correlations were not significant at 1 500 and 2 000 MHz.
The loss tangent tanδ did not change significantly during the ripening period at all the testing frequencies. These findings
showed that ε’ and ε’’ changed in the same direction to a similar extent.

Key words: Cheddar cheese, dielectric properties, testing frequency, ripening index

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