| Hemerocallis citrina baroni, which edible part is bud, belongs to day lily of Liliaceae and is characteristic vegetable in our country. It is nutritious and tastes delicious, so is popular with customers. Area of planting day-lily has been expanded and its output is increasing with the development of consumer market, nowadays it has become local industry with large scale and plays vital role in readjusting the industrial set-up for countryside and increasing income for peasants. Dehydrated day-lily is main product of processing day-lily, however, it is produced by traditional drying technology, by which drying time is too long and product quality is poor. In order to improve traditional drying method, the technology of processing dehydrated day-lily on the basis of studies on the determination of nutrition in relation to dehydration, the conditions for controlling browning, the methods of drying, the drying characteristic of different breeds and the determination of colchicin in day-lily was discussed comprehensivly and systematically. There are some results below:1. The contents of total carbohydrate, saccharose, reducing sugar and vitamin C in fresh day-lily were determined, and for the first time the content of amino acid was determined. The results showed that the content of total carbohydrate of day-lily was high, and the content of amino acid which was compared with that of ordinary food was relative low, particularly, the content of alkali amino acid was very low, so the degree of impact of non-enzymatic browning on the product quality was not great.2. The POD activity was determined and variation of POD in fresh day- lily were researched when it was harvested and processed, which provided the optimal conditions for killing enzyme. The results showed that POD activity is various in different parts of fresh day-lily, the POD activity of stem and external petal is strong and that of inner petal is weak. According to comparison between methods of killing enzyme by heat or boiling water, steam and non-steam such as drying atmosphere, far infrared ray and microwave, it indicated that heat or boiling water and non-steam did not kill the POD efficiently, and atmosphere with steam killed enzyme more efficiently than drying atmosphere did, theoptimal technology for killing enzyme is to blanch the material by steam for 70-80 seconds.3. In order to establish the optimal method for drying thin layer day-lily, the drying experiment was carried out by microwave with high, media and low power, far infrared ray which temperature were 90 , 100 , 110 and hot air which temperature were 60 , 70 , 80 , 90 and 100 . The results show that when the drying temperature of hot air is less than 80 , drying time is 3.5 to 5 hours and product quality is better, while, when the drying temperature of hot air is more than 90 , drying time is 1.5 to 2 hours and product quality is poor , so the optimal temperature for drying thin layer day-lily is 80-90 . Compared with hot air drying, whatever power of microwave drying needs much less drying time, however, all their product quality is poor. It took less drying time for combining microwave and hot air, and hot air drying will produce poor quality after material is dried by microwave, while, microwave drying will produce good quality after material is dried by hot air.4. The mathematical modelling of hot air drying of thin-layer day-lily was established. Three empirical equations are the exponential equation, the Pick diffusion equation, and the Page equation. It was found that the Page equation MR= e-rtn (r=e-4.3154+0.05631T, n=0.5228+0.01007T) for drying thin layer day-lily can best describe relation between moisture content and drying time in the processing of dehydrated thin layer day-lily.5. Comparing analysis of yield and rehydration characteristic between Mengzi flower and Chongli flower which are indigenous breeds in Qidong county was carried out, and the crude fibra content and Peroxidase activity in different parts of two breeds...
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