| In recent years, the dried shrimp was welcomed by consumers because of its high nutritive value, special flavor, storage stability and portability. However, the processing level of white shrimp was still at an initial stage all over the world at present. The lag of processing link had become a bottleneck to its development. The objective of this paper was to study its drying technologies of white shrimps systematically.In order to make its qualities better, the great effects of blanching on the white shrimps were found before drying. The method was applied to investigate the effects of blanching technology on the qualities of white shrimp such as PO activities,the rate of weight loss, color, texture, remanent blanching liquid and total bacteria. The results showed that blanching at 100℃for 1 minute could reduce PO activities badly and improve the qualities of dried shrimp. When white shrimps were blanched for 1 minute in the 2% NaCl solution at 100℃, the rate of weight loss was high and nutrition loss was little. Meanwhile, the ideal color and tissue state could be achieved.Analysis and comparison of some usual drying methods was conducted in order to obtain the suitable one and consequently provide theoretical supports for combination dryings of white shrimps. The effects of different drying methods on qualities were studied including drying characteristics, texture, water activity (Aw), L value, superstructure and recovery rate. The results showed that white shrimps treated by vacuum freeze drying were the best, vacuum drying and microwave secondary, air drying the worst.The results showed the white shrimps treated by vacuum drying were better than other drying methods except vacuum freeze drying. So, it was necessary to make a further study on vacuum drying. The effects of vacuum drying parameters on drying characteristics, texture and recovery rate were studied. The vacuum drying model of white shrimp was established. It was found that model was the most suitable to describe the kinetics of vacuum drying. And the parameters of vacuum drying model under different conditions were determined.On the basis of a previous pilot study, it was shown that the organizational structures of the dried shrimps decreased successively as follows: a combination drying of vacuum freeze and vacuum drying > vacuum freeze and microwave vacuum drying > microwave and vacuum drying. In order to further improve product quality and reduce costs, freeze vacuum drying was combined with vacuum drying and microwave vacuum drying respectively. In order to realize mutually complementary, the optimal drying conditions of microwave vacuum drying combined with vacuum freeze drying were studied in the paper by adopting the L9(34) orthogonal experiment. It was found that the capability of effects of factors on the recovery rate: the conversion point of water content > microwave power > microwave time > microwave vacuum. The optimum compounding was composed by follows: conversion point of water content 50%, microwave time 25s, microwave power 330W, microwave vacuum 0.07MPa. The variance analysis showed that the recovery rate was significantly influenced by the conversion point of water content, microwave power, microwave time except microwave vacuum. The result of the variance analysis was the same as the range analysis. Meanwhile, the ternary quadratic rotary recursive design was chosen to attain the best technology of drying white shrimps by vacuum freeze drying combined with vacuum drying in the paper. The optimal conditions of the combination drying were determined by response surface analysis. When temperature, vacuum pressure of vacuum drying and the water content of white shrimp were 48-53℃, 0.066-0.073MPa and 44.6-47.7%, these were obtained as follows: the absolute hardness difference close to 47g, the recovery rate 71.81% and springiness 0.831g.
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