Research And Applications Of Key Techniques For Quick-frozen Hill Potherbs

Hill potherbs were vegetables grown in the mountain forests.In recent years due to its rich nutritional value and medicinal value,hill potherbs gradually became the current research focus.Hill potherbs were easy to aging and not easy to long-term storage that limits further deep processing and utilization.There were many reports on the nutritional value and medicinal value of hill potherbs.However,there were few reports on retaining freshness.Because of its convenience,high efficiency and other advantages,quick-frozen have become a common retaining freshness technology of fruits and vegetables and the process of quick-frozen has been more mature.Therefore,Acanthopanax senticosus(Rupr.Maxim.),Aralia elata Seem and Artemisia integrifolia.were selected in this test and key technology of the quick-frozen was studied,which provided basis and guidance to quick-frozen technology and further use of deep processing of hill potherbs.The main research results were as follows:The optimum pretreatment parameters were as follows: blanching temperature was 95?,blanching time was 3 minutes and solid-liquid ratio was 1:15,under these conditions,the peroxidase activity of hill potherbs was completely inactivated.On the basis of the single factor test results,the optimum conditions of blanching time,blanching temperature and solid-liquid ratio were optimized by design Expert 8.0 software.The optimal parameters were as follows: blanching time was 187 s,blanching temperature was 95?,solid-liquid ratio was 1:15,verify experiments showed that the peroxidase activity of all hill potherbs under the conditions were inactivated.Ascorbic acid,citric acid and Na Cl were biophyll protect agents of Acanthopanax senticosus(Rupr.Maxim.),Aralia elata Seem and Artemisia integrifolia.The optimal concentration of ascorbic acid was 2.00 g/L,the optimal concentration of citric acid was 1.50 g/L,the optimum concentration of Na Cl was 1.50 g/L,the concentration of the three biophyll protect agents was optimized by Design Expert 8.0 software.The optimized results were as follows: The concentration of ascorbic acid was 2.12 g/L,the concentration of citric acid was 1.63 g/L and the concentration of Na Cl was 1.63 g/L,the chlorophyll content of Acanthopanax senticosus(Rupr.Maxim.)was the highest under this condition,the chlorophyll content was predicted to be 0.2902 mg/g.The concentration of ascorbic acid was 2.07 g/L,the concentration of citric acid was 1.56 g/L,and the concentration of Na Cl was 1.57 g/L.The chlorophyll content of Aralia elata Seem was the highest under this condition.The concentration of ascorbic acid was 2.07 g/L,the concentration of citric acid was 1.56 g/L,the concentration of Na Cl was 1.56 g/L,and the predicted value was 0.2639 mg/g.The chlorophyll content of Artemisia integrifolia was the highest and the predicted value of chlorophyll content was 0.2663 mg/g.The difference between the test results and prediction test results were not significant,which indicated that the models were credible.The results showed that frozen speed of-20?,-30? and-40? different final frozen temperatures was different,and different quick frozen rates were achieved.The ice crystal state of hill potherbs' surface,moisture content,chlorophyll content,vitamin C content,and hardness characteristics of Acanthopanax senticosus(Rupr.Maxim.),Aralia elata Seem and Artemisia integrifolia were researched to determine the best final frozen temperature.The results showed that the optimal final temperature was-30? in the range of quick-frozen temperatures,the time went through the zone of maximum ice crystal formation was about 105-110 s under the condition,the time of-30? as the final frozen temperature of the Hill potherbs went through the zone of maximum ice crystal formation was shorter than-20? as the final frozen temperature of the hill potherbs went through the zone of maximum ice crystal formation about 15 s,the time of-30? as the final freeing temperature of the hill potherbs went through the zone of maximum ice crystal formation was as much as the time of-40? as the final frozen temperature of the hill potherb went through the zone of maximum ice crystal formation.However,given the energy loss,-30? was more suitable as the final frozen temperature of hill potherbs.The results showed that surface ice crystal state,moisture content,chlorophyll content,vitamin C content and hardness characteristics of hill potherbs under the condition of-30? was the final frozen temperature were better than surface ice crystal state,moisture content,chlorophyll content,vitamin C content and hardness characteristics of hill potherbs under the condition of-20 ? was the final frozen temperature and surface ice crystal state,moisture content,chlorophyll content,vitamin C content and hardness characteristics of hill potherbs under the condition of-40? was the final frozen temperature.Researched the surface ice crystal state,moisture content,chlorophyll content,vitamin C content and hardness characteristics of hill potherbs storaged at different frozen temperatures of-10?,-20?,-30?,-40? respectively to determine the best frozen storage temperature.The results showed that surface ice crystal state,moisture content,chlorophyll content,vitamin C content and texture characteristics of hill potherbs storaged at frozen temperature of-20? were better than surface ice crystal state,moisture content,chlorophyll content,vitamin C content and hardness characteristics of hill potherbs storaged at frozen temperatures of-10?,-30?and-40?,so-20 ? was the best frozen storage temperature of hill potherbs.