The Impact Of Nonthermal Processing Methods On The Quality Of HanFu Apple Chips And Juice

Apples belong to Malus Rosaceae plants. China is the world’s largest apple producer and consumer country. Apple rich in nutrients, such as sugars, organic acids, dietary fiber, minerals, vitamins and polyphenols, less fat and protein, they are benefit to weight control and preventing of cardiovascular, liver, and lung diseases.For now, chips and juice are the most important apple products. The main drying methods include hot air drying, explosion puffing drying and vacuum freeze-drying. The loss of heat-sensitive nutrients and appearance damaged could easily caused by hot air drying. Instead, the nonthermal processing techniques such as vacuum freeze-drying, preferred to retain the apples nutrients but high cost. Currently, researches mainly focus on nonthermal processing technology, such as high pressure homogenization, high hydrostatic pressure, electrical pulse technology. Compared with the thermal processing technology, nonthermal processing technology reducing the number of microorganisms, it also can effectively avoiding the destruction of nutrients in the juice, and color browning. Therefore, during processing of apple chips and apple juice, thermal or nonthermal processing technology is the key technology. In this paper, the aim to for the impact of nonthermal and thermal processing technology for apple chips and juice quality, respectively selecting the vacuum freeze-drying, hot air drying and explosion puffing drying for comparison in apple chips processing, selecting high hydrostatic pressure (HHP), high-pressure homogenization (HPH) and pasteurization (PA), high temperature short time sterilization (UHT) for comparison in apple juice processing, revealing the impact of the production treatment on apple chips and juice quality and provide of theoretical basis for reference in apple slices and juice production. The conclusions of this study are as follows:1. Impact of nonthermal processing methods on the quality of HanFu apple chipsVacuum freeze-drying chips total sugar and reducing sugar retention rates are highest, the value are 86.29% and 85.34%. The lowest is explosion puffing drying chips, compared to vacuum freeze-drying, total and reducing sugar retention rate decreased by 28.15% and 27.35%. There was no significant difference (P>0.05) of the total phenol retention rate of vacuum freeze-drying and explosion puffing drying chips, hot air drying chips total phenols retention rate was lowest, the value is 35.36%. Hot air drying apple chips crude fiber retention rate is 54.16%, significantly lower than the other two types of apple chips2. Impact of the nonthermal and thermal sterilization on the quality of apple juiceHHP clear apple juice OD660 was 0.024, cloudy juice was 0.558, suspension stability of HHP apple juice significantly higher than the heat-treated apple juice (P<0.05). The impact of heat treatment on the color of the clear juice was slight, but the larger impact on the cloudy juice:HHP cloudy juice L value was 49.02, significantly higher than the L values of thermal processing cloudy juice (,P<0.05), less browning. HHP cloudy juice b value is 19.98, significantly higher than the other two treatments (P＜0.05), the color is more yellow. UHT cloudy juice apple juice and total phenol content was significantly lower than the other two sterilized apple juice (P<0.05). Clear apple juice and cloudy juice antioxidation ability level of variation is consistent with the level of total phenol content of the same trend.3. Impact of high pressure homogenization on quality of apple juiceHigh pressure homogenization significantly reducing the total number of colonies in apple juice, homogenization pressure higher, total number of colonies lower, L value is decreased, b* value is increased, color tends to dark yellow. PA apple juice L* value is 72.58, significantly lower than HPH and CK apple juice (P<0.05). PA apple juice soluble solids content is 16.9%, significantly higher than CK and HPH apple juice (P<0.05). Compared with CK, HPH processing significantly reducing the juice average pulp particles size (P<0.05), but size is not decreased with the increased number of homogenization. HPH juice has higher Zeta potential, HPH juice improves stability. With the increasing of homogenization pressure, the suspension stability of juice significantly increased (P<0.05). There was no significant difference (P>0.05) of suspension stability with HPH, CK and PA juice. The value of total phenol content of PA juice is 293.5mgGAE/L. The both are significantly higher than CK and HPH juice. Homogenization pressure is a key factor to affect the quality of apple juice characteristics.4. Impact of high pressure homogenization on quality of apple juice in storage4℃ storage:0-7d, browning OD420nm of fruit juice were significantly increased,7-28d browning speed slow down.0～7d juice pulp particle size small increase a little, pulp particles gathered,7～14d juice pulp particle size decreased and 14-28d juice pulp particle size substantially unchanged.0-28d juice total phenol content in small range.25℃ storage:With the increase of the storage time, the L* value decreases, fruit juice browning deepened. Compared with 4℃ storage apple juice, juice browning increased faster and seriouser. Pulp particle size increases modest.14～21 d, total phenolic content of juice decreased significantly. With the increase of homogenization pressure and temperature of HPH juice, total phenol content of fruit juice increased significantly (P<0.05).