微波气流预干燥和微波真空组合干燥生产甜瓜片

研究了微波气流预干燥(MAD)和微波真空(MVD)组合干燥甜瓜片,表明这是一种有潜力的干燥方法。样品先通过微波气流干燥脱去一些自由水,然后通过微波真空干燥到最终水分含量低于7%(湿基)。甜瓜片利用微波气流(MAD)和微波真空(MVD)组合干燥后测得Vc保留率和物性(收缩率,色差,质地和复水率)然后同冷冻干燥(FD)、微波气流干燥(MAD)、气流干燥(AD)和常规热风干燥(HAD)分别进行比较,表明,MA+MVD方法干燥的甜瓜片的Vc保留率接近冻干的甜瓜片,大大优于传统的热风干燥。当前方法干燥的样品表现出的复水率、色差、质构与冻干的产品非常相似,但是出现了明显的膨化现象,然而,这正是生产果蔬脆片所期望得到的结果。

Combined microwave-airflow predrying and microwave-vacuum drying of melon slices

A combination of microwave-airflow+microwave-vacuum(MA+MVD) drying and freeze drying was investigated as potential means for drying melon chips.The sample was first dried by microwaveairflow to dehydrate some amount of internal free water and then by microwave-vacuum drying to a final moisture content of less than 7%(wet basis).Chemical properties(Vc retention)and physical properties(color,shrinkage,rehydration ratio and texture)of melon slices dried by this method were evaluated and compared with those dried by microwave-airflow drying,freeze drying alone,airflow drying and conventional hot air drying,respectively.The comparison showed that the Vc retention of melon slices dried by the current method were close to those of freeze-dried melon slices and much better than those of conventional hot air-dried ones.The samples prepared by the current method exhibited very close color retention,texture,and rehydration capacity with those of the freeze-dried ones but with a phenomenon of puffing.However,the samples showed the attractive external appearance with this phenomenon.