CAJ | 학술논문

为了提高枸杞干燥品质、缩短干燥时间和降低能耗，该文对枸杞分段式变温热风干燥加工工艺进行试验研究。试验表明：恒温恒湿干燥条件下，随热风温度升高，枸杞干燥时间缩短，但枸杞多糖、色泽、复水率等干燥品质变差；采用阶段变温干燥方式可较好地缩短干燥时间，同时防止干燥品质变差。通过试验确定最佳的分段变温干燥工艺条件为40℃(6 h)?50℃(6 h)?60℃，干燥湿度40%，料层厚度3层（单层8 mm），在此条件下，枸杞干制品营养色泽俱佳，复水性良好。另外，碱液（3% NaCO3溶液）浸泡预处理可提高枸杞干燥速率、保留其鲜红色泽。
위료제고구기간조품질、축단간조시간화강저능모，해문대구기분단식변온열풍간조가공공예진행시험연구。시험표명：항온항습간조조건하，수열풍온도승고，구기간조시간축단，단구기다당、색택、복수솔등간조품질변차；채용계단변온간조방식가교호지축단간조시간，동시방지간조품질변차。통과시험학정최가적분단변온간조공예조건위40℃(6 h)?50℃(6 h)?60℃，간조습도40%，료층후도3층（단층8 mm），재차조건하，구기간제품영양색택구가，복수성량호。령외，감액（3% NaCO3용액）침포예처리가제고구기간조속솔、보류기선홍색택。
Lycium barbarum is a kind of fleshy berry in bright red, which is one of the well-known traditional Chinese medicines with rich nutrients. Currently,Lycium barbarum is widely dehydrated using sun-drying. This method is simple and low-cost, which are its advantages. But the drying time is long and its application is limited by the climate and sanitary conditions. Also, the dried product quality is difficult to control. In this paper, the multi-stage varying temperature hot air drying was conducted on Lycium barbarumto shorten the drying time and improve the dried product quality. This drying method was successfully applied in the drying processing of rice, cherry tomatoes, honeysuckle, etc. First, the hot air drying characteristics ofLycium barbarum were investigated under constant air temperature (40, 50 and 60℃), relative humidity (40%, 50% and 60%) and material thickness (8, 24, and 40 mm); and the product quality was evaluated through polysaccharide content, color and rehydration ratio of dried Lycium barbarum. The hot air drying experiments were conducted in a lab-scale SY-5 type fruit and vegetable drying room in which the hot air temperature and humidity could be pre-scheduled by programming. The polysaccharide of driedLycium barbarum was extracted through the ultrasonic-aided water extraction method and then, its percent content was measured using the phenol-sulfuric acid method. The color of dried product was evaluated using the image technology and its red, yellow and blue color value could be obtained. The rehydration ratio was judged through soaking the driedLycium barbarum in hot water (80℃) for 20 min and then measuring the mass of water absorbed. Experimental results under the constant drying temperature and humidity conditions showed that the drying time ofLycium barbarum decreased largely from above 48 to 15 h with the increase of air temperature from 40 to 60℃, also decreased slightly with the increase of relative humidity. The improvement of air temperature had a negative effect on the product qualities such as color, but the relative humidity had a small positive effect on product quality. When air temperature increased from 40 to 60℃, the contents ofLycium barbarum polysaccharides decreased from 7.76% to 7.20%. The red color value reduced from 13.9 to 12.9, the rehydration ratio varied from 50.0% to 51.4%. Thus, the drying temperature is the governing parameter in the hot air drying ofLycium barbarum.Then, several multi-stage varying temperature drying processings ofLycium barbarum were conducted and their dried product qualities were compared. The optimum drying condition obtained for the multi-stage varying temperature drying technology was the drying temperature of 40℃ (6 h)-50℃(6 h)-60℃, relative humidity of 40% and three-layer material thickness. Under the optimum drying condition, the driedLycium barbarum had a red color value of 13.7, polysaccharide content of 9.77% and rehydration ratio of 51.6%. Finally, The drying time and the product quality ofLycium barbarum with/without pre-treatment using 3% alkali solution were also compared and it was found that pre-treatment with 3% alkali solution for 1 min could shorten the drying time from 28 to 25 h, improve the red color value from 13.7 to 15.4 and rehydration ratio from 51.6% to 55.4%, and meanwhile polysaccharide content slightly decreased from 9.77% to 9.23%.