The Research On Explosion Puffing Drying With Difference Temperature And Pressure For Carrots

As a method of drying, the explosion puffing with difference temperature and pressure is a new technology of processing for fruits and vegetables, which began to be studied overseas in 1980s, and it was usually used to produce puffed fruits and vegetables. The earliest study in China was reported in 1990s. But the systematic study on process and mechanism of explosion puffing drying was lack. In thispaper, as the raw material, carrots were puffed in the puffing equipment (QDPH10-1) to optimize the puffing process and analyze the effect factors for the explosion puffing, and also the mechanism for explosion puffing drying, aiming at supplying technologies for puffed carrots drying products.The researched contents in this paper as follows: Optimizing the technology of explosion puffing drying for carrots with difference temperature and pressure; through the pretreatment of carrots, quality changing of physics and chemistry during puffing , contrasting of three drying methods, the mechanism for explosion puffing drying were studied. Conclusions can be summarized as follows: The appropriate pre-treatment condition is: freezing processes at -6℃for 12h, osmotic dehydration by 40% maltose solution the suitable pretreatment drying conditions is at 80℃for 120 min,which is determinated by the single factors experiments.The technique parameters by mono-factors experiment were determined as follows: Puffing temperature is 100℃, vacuum drying temperature is 80℃, vacuum drying time is 150min, and puffing pressure is 0.2MPa, the dwell time is 10min. A comprehensive evaluation of the products was obtained using factor analysis, response surface method and frequency analysis were adopted to optimize the technology of explosion puffing drying with difference temperature and pressure and the optimization technology: Puffing temperature is between 92.99℃to 99.08℃, vacuum drying temperature is between 77.10℃to 80.34℃, and vacuum drying time is between 140.19 min to 159.81min.The mechanism for explosion puffing drying was studied, and the main research includes: the effect of the difference pretreatment (blanching; low temperature; osmotic dehydration) on the puffed drying products; quality changing of physics and chemistry which include color, nutrition component and flavor content; moisture absorption of the drying product and the contrasting of three drying methods were also studied. Conclusions can be summarized as follows:It is found that low temperature and short time blanching have less effect on carrots slices texture. Freezing causes significantly worsen the carrots slices; the mass transfer of carrots was strongly dependent on the type and concentration of osmotic solution. 40% maltose osmotic dehydration is better. The suitably temperature is 80℃for the pretreatment drying. During the explosion puffing drying for carrots, the content of the product'sβ-carotene,fiber and protein are lower than raw carrots; The product's flavor content is more significant. By contrast of the hot airing, the freeze drying and explosion puffing products'multiple indexes, the result is the physic and chemistry properties of explosion puffing is between hot airing to freeze drying ,and the SEM photos and flavor of explosion puffing is the best among the three type drying methods.(3)The paper confirm the index of the products for evaluation; also the quality standard of the technology and products of the explosion puffing drying with difference temperature and pressure for carrots.