In order to improve the thawing qualities of aquatic products, shrimps (Penaeus vannamei) as a representative of aquatic products, were thawed with high voltage electric field (HVEF) at different voltages. It was compared with an air-thawed control on the basis of thawing time and the post-thawing quality of the shrimps. The results showed that HVEF can reduce the thawing time of shrimps significantly. Compared with air-thawed control, the thawed shrimps under HVEF had better post-thawing qualities such as lower thawing loss, lower total bacteria count and lower total volatile basic nitrogen (TVB-N). HVEF thawing has advantages. This suggests an application potential for HVEF treatment in the thawing and storage of frozen aquatic products.

Abstract. In order to study the mechanism of high voltage pulsed electric field pretreatment on the food drying technology. In this paper, water was treated with high pulse electric field (HPEF) in different frequency, and different voltage, then, the viscosity coefficient and the surface tension coefficient of the water were measured. The results showed that indicated that the viscosity coefficient and the surface tension coefficient of the treated water can be decreased, and while HPEF pre-treatment was applied for 22.5kV at a frequency of 50Hz and 70 Hz, the surface tension and the viscosity coefficient of the pre-treatment treatment were reduced 13.1% and 7.5%, respectively. IntroductionFresh fruits and vegetables have a moisture content ranging from 75 to 90%. They are highly heat sensitive and are apt to be highly perishable. Drying is defined as the reduction of moisture from the products and is an efficient and cheap method for the preservation of fruits and vegetables. Hot air drying is one of the most commonly used procedures in dried food with main disadvantages being prolonged duration and high energy consumption. Therefore it is necessary to explore low power consumption processing for hot air drying.Dry pretreatment technology is utilized to treat food through some physical methods before drying it. Pretreatment can not only improve the quality of dried food but also increase drying rate and thus reduce energy consumption. For example, during the process of drying and dehydration for fruits and vegetables, ultrasound pretreatment certain intensity will enhance their drying rate and thus reduce the drying energy consumption [1][2][3].In recent years, a novel pretreatment technique, high voltage pulsed electric field drying pretreatment technology has been developed only recently, Angers Bach et al. showed an increase in permeability of potato tissue by high intensity electrical field pulse treatment, which resulted in improved mass transfer during fluidized bed drying [4]. Ade-Omowaye et al. found that high voltage pulsed electric field pretreatment could increase the cell membrane permeability and improve the drying rate [5]. Gachovska found that pulsed electric field treatment could increase the drying rate of carrots and enhance the quality of dried carrots [6]. Electrically assisted drying would reduce the processing time, operating temperature, and energy consumption [7]. Other papers reported similar results that pulsed electric field pretreated samples could significantly improve the drying rate [8][9].But, it is not a profoundly explored method of drying pretreatment, and, its mechanism has not been accurately determined, therefore, study the mechanisms of high voltage pulsed electric field pretreatment is one of the important theoretical basis for the technology industrialization application use.

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