Effect Of High Pulsed Electric Field On Quality Of Fruits And Vegetables

High pulsed electric field(HPEF) can be used to blunt bactericidal enzyme, dry pretreatment, thaw and so on, as a non-thermal processing technology it has broad application prospects. HPEF as pre-processing for drying on fruits and vegetables in the vacuum freeze drying can reduce drying time, energy consumption and production costs.It has a good effect, but we need to study how it affects the quality of fruits and vegetables. Our group has made plenty of experiments and comprehensive analysis, finally, the optimal parameters of HPEF for drying were obtained, howerver, this pretreatment conditions affect the quality of fruits and vegetables is unclear. So this study was to investigate the effect of HPEF pretreatment of fruits and vegetables on the nutrient content and physical properties, explain the changes in nutrient content from the perspective of physical properties, The main research contents of this paper as follows:(1) Experimental study of the effect of HPEF on the nutritional quality of fruits and vegetables, I used the optimal parameters of HPEF to deal with apple, pear, melon and other fruits and vegetables, evaluate the content of total sugar, total acid, VC, iron and other nutrients, compared with the control group, the nutrient content is slightly reduced, the mathematical models between the nutrients and nutritional quality were established through principal component analysis.(2) Experimental study of the effect of HPEF on the sensory quality of fruits and vegetables, study how pulse strength, pulse width and pulse number affect the physical properties of fruits and vegetables, use the texture profile analysis to evaluate physical properties of fruits and vegetables, compared with the control group, the physical properties of fruits and vegetables (hardness, elasticity, chewing, etc.) shown a downward trend. By response surface regression analysis and ridge analysis, the mathematical models between HPEF parameters and physical properties were established, pulse strength is the main factor affecting the physical properties of fruits and vegetables, followed by pulse width and pulse number, the optimal parameters of HPEF for drying were obtained as follows:pulse strength1100-1300V/cm, pulse width80-110μ s, and pulse number5-30pulses. (3) Study of the influential mechanism of HPEF, explain the changes in nutrient content from the perspective of physical properties.The parameters of HPEF pretreatment as follows:pulse strength1000V/cm, pulse width120μs, and pulse number30pulses, do not have significant effect on the nutritional quality of fruits and vegetables, so we can use this condition to pretreatment fruits and vegetables to reduce drying time. Study of the effect of HPEF on the nutritional quality and sensory quality of fruits and vegetables have certain guiding significance in understanding the influential mechanism of HPEF, as well as choosing pretreatment process of vacuum freeze-drying processing technology.