Freshness-retaining and preserving method of roselles

Abstract

The present invention discloses a freshness-retaining and preserving method of roselles. Calyxes of roselles are washed clean; the surface water of the washed calyxes is drained; the drained calyxes are placed in a superheated steam environment of 135-140 DEG C for 15-20 min; then the calyxes are hot air-dried at 70-80 DEG C for 20-30 min; and when the calyxes are naturally cooled, the calyxes arefrozen and preserved. The combined technology of the superheated steam drying and hot air drying is used to conduct the treatment of the roselles; the superheated steam is good in heat conductivity;the roselles are even in heating; the method can well maintain the shapes of the calyxes; at the same time, due to the fact that the superheated steam drying is free of oxidation reactions, the colorof the roselles does not fade; and the drying quality is good. The method maximally maintains the shapes, color and luster of the calyxes unchanged, continuously conducts the hot air drying and reduces water in the calyxes. Then the frozen and preserved roselles can maintain a better fresh state, are strong in rehydration and can be preserved for one year.

Description

technical field [0001] The invention relates to the technical field of fresh-keeping of flowers, in particular to a method for fresh-keeping and preservation of roselle. Background technique [0002] Roselle, also known as roselle and Sudan red, is a plant of the genus Hibiscus in the genus Lambaceae. It has value as a food raw material, natural pigment, and medicinal value. Its calyx, seeds and leaves can be used. Fresh roselle has high water content and is easy to rot and deteriorate, and the storage period is only a few days. Most of the existing methods for preserving the roselle are to dry it, that is, to directly air-dry it or dry it with hot air to remove most of the water contained in the calyx, and then seal the obtained dried roselle for preservation. Although this hot air drying method can remove most of the water in the roselle and prolong its storage period, it has obvious shortcomings: First, the heat transfer characteristics of hot air drying will cause uneve...

AI Technical Summary

Problems solved by technology

Although this hot-air drying method can remove most of the water in the roselle and prolong its storage period, it has obvious shortcomings: First, the heat transfer characteristics of hot-air drying will cause the calyx to be heated unevenly, and the drying progress will be delayed. Destroy the morphological structure of the calyx, and its integrity cannot be preserved; second, the surface of the calyx will change color easily if the temperature is too high or too low, destroying its original color, and it will also consume a lot of energy, which is not conducive to energy saving; third, The roselle flower preserved by hot air drying has poor rehydration performance, long rehydration time, light color of rehydration, and low leaching rate of water-soluble anthocyanins

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