| Inulin as a functional food ingredients in Western countries has been widely used in recent years.Industrially,inulin can be not only used in the production of low-calorie foods as a fat substitute,it also can be used in various foods due to its beneficial nutritional attributes.Positive effects on blood glucose attenuation,lipid homeostasis,mineral bioavailability and immunomodulation effects,along with the ability to add texture and improve theological characteristics and nutritional properties of food allows inulin to be termed a functional food.Jerusalem artichoke is cultivated widely in the northern part of China for environment protection.Jerusalem artichoke tubers with 14～19% inulin can be a valuable source of inulin.According to researching the major components of Jerusalem artichoke tuber harvested from Pianguan city of Shan Xi province,the chemical analysis and detection of inulin was first studied and got the storage methods of Jerusalem artichoke tuber by the research of the storage temperature and time on the content of inulin. And studied on characteristics of Jerusalem artichoke's PPO and Jerusalem artichoke slices of different temperature drying curve to get the pretreatment technology of Jerusalem artichoke. Finally, Four-stage Dynamic Countercurrent Extraction technology was used in inulin extraction, and optimized its operating conditions.Campared with Single-pot Extraction used in inulin extraction, results can be provided theoretical foundation for the future inulin industrial production. The main results were as follows.1.The inulin content was measured with the difference between total carbohydrate and reducing sugars.Fresh Jerusalem artichoke tubers, picked from Pianguan city of Shan Xi provice,include 74.63% water, 15.95% inulin, among which the concentration of proteins, fats,ash and cruse firbers are of 2.12%,1.48%,2.47%和0.83%,respectively.The results of Jerusalem artichoke storage experiment reveal that storage temperature and time play important influence on the concentration of inulin. Jerusalem artichoke can be stored under-18℃for long time, with keeping its concentration relative constant;however, at 4℃and 18℃, after storage for 8weeks, the concentration of Jerusalem artichoke decreased respectively by 20.99%and 61.22%. Hence, the harvested artichoke tubers must be manufactured as soon as possible because the internal hydrolysis and inverting of inulin have a great loss in storage.2.The optimum temperature and pH value for Jerusalem artichoke's PPO are 40～60℃and 4.4～5.2, respectively. The PPO can keep stable at 70℃, whereas the activity of PPO will decrease quickly with temperature increasing up to 85℃and time of treatment delaying. In pretreatment process, the blanching method can make PPO lose activity , the method which is to incubate Jerusalem artichoke's PPO in 90℃for5～10min.Experiencing drying treatment at 120℃for 2.5h and then at 80℃for 10h,the sliced Jerusalem artichoke after blanching can become light yellow slices with 8.24% water.3.In the experiment study of Inulin extraction technology, the main tasks aim to review Single-pot Extraction and Four-stage Dynamic Countercurrent Extraction, meanwhile optimize the operation conditions.The optimum technique parameters of Single-pot Extraction are as follow: the ratio of liquid phase to solid phase is13:1,extraction temperature is 85℃, extraction time is 50min, and extraction efficiency is 61%; meanwhile, The optimum technique parameters of Four-stage Dynamic Countercurrent Extraction are as follow: the ratio of liquid phase to solid phase is13:1,extraction temperature is 80℃, extraction time is 20min, and extraction efficiency is 94%.The comparison of the two techniques results in the conclusion that: the technique of Four-stage Dynamic Countercurrent Extraction have the advantages of higher raw material utilization higher extraction efficiency and saving more water and energy. |
PDF Full Text Request