Field Storage of Vegetables in Cold District (I)

In Relation to Freezing Damage

Abstract

The temperatures of atmosphere and radial centers of several important vegetables in the field were measured without stopping in the winter of 1978-1979.
The degree of feezing damage was investigated in consideration of apparent modulus of elasticity and sensory evaluation as well as the change in temperature of them. This work was done to make the fundamental data applicable to energy saving for the storage of farm products.
The results may be summarized as follows:
1. Relation between the minimum temperatures of atmosphere and roots was explained by a straight line with refraction of mid-November and early in December for radishes·carrots and Chinese yams, respectively (Fig. 1).
2. It is considered that the freezing of soil and roots caused the refraction.
3. Mean of temperature fluctuation of a day was about 1 and 7°C for root and leafy vegetables, respectively (Fig. 2).
4. Because of the small cooling rates of root (0.1) and leafy (0.5°C/h), it is inferred that their freezing rates should be very slow (Table 2).
5. The freezing damage to vegetables accompanied the drops both of apparent modulus of elasticity and residual moisture content (Fig. s 3 to 8).
6. And almost the constant residual moisture content of carrots suggests the freezing damage to carrots is especially very slight (Fig. 7).
7. Water holding capacity after cooking of vegetables indicates a degree in freezing damage (Table 4).
8. At Obihiro in general, radishes·Chinese cabbage, cabbage, carrots, and Chinese yam·edible burdock will be stored in the field with the roots at the earliest up to November 24, November 28, December 6 and throughout a winter, respectively.
9. The field storage time for carrots will be extended far by raising furrow of them with soil in the autumn, while for a little injured cabbage by improving its cooking method.