Study On Daylily Vacuum Freeze Drying Processing

Daylily,which edible part is bud,belongs to Daylily of Liliaceae and is characteristic vegetable in our country. Daylily,which have high nutritional value and health effects,is very nutritious.Nurtients of Daylily are higher than the common species. Daylily belongs to green health food of high protein,low calorific value,rich in vitamins and minerals.At room temperature,storage performance of Daylily was extremely poor and prone to browing,that affected its flavor and edible value.Sun drying and baking are Daylily drying of traditional method,that could lead to browning of color,severe loss of nutrients and relatively long production cycle. However,Vacuum freeze drying technology could solve the above problems radically and keep nature color,aroma,taste,shape and nutritional components of Daylily. The main aspects and the results were repersented as follows:(1) The storage characteristics of Daylily:Daylilys,by the different storage treatment, were anlyzed with sensory quality,POD activity,vitamin C, chlorophyll and reducing sugar in different storage treatment and storage days.The results showed that sensory quality would decline with the storage temperature growth. The content of reducing sugar of daylilys showed trents of first increasing then decreasing with the storage days growth. The content of vitamin C of daylilys showed a linear decline.(2) The technology of color protection:The determination of blanching process:blanching temperature95±2℃,blanching time50s.Color protection solution of citric acid,sodium citrate,sodium bicarbonate, zinc sulfate, calcium lactate, magnesium chloride, sodium chloride and phytic acid were used before blanching or blanching and color protecting effects of that were contrasted.Meanwhile,its sensory quality were evaluated and Daylilys of nutrional content of before and after blanching were analyzed.The results showed that effect of color protection solution of1%sodium chloride was best.(3) The technology of vacuume freeze-dyring:The result showed the eutectic temperature was-18℃～-32℃by resistance.Central composite design of the Design-expert was used in the vacuum freeze-drying process of Daylily and regression mathematical model between the index and impact factors was built. Central composite design was used to optimize experiments design and connect with the optimum method of response suraface methodology.The results showed that the optimal parameters of vacuum of freeze-drying process were as follows material loadage was225g and heating plate temperature was50℃.(4) The results of the comparison test by different drying processimg, showed that the vacuum freeze-drying method was superior to hot-air drying method in Reducing sugar content,Vc content and the rehydration.Method of blanching treatment,hot air treatment,frozen treatment and NaCl blanching treatment could remove colchicine of Daylily very effectively. So,after hot air drying treatment and blanching treatment of Daylily could be safe to eat.