Study On Different Drying Methods Of Stichopus Japonicas

The sea cucumber is precise sea food which has good nutritive value and commodity value contains abundant bioactivator.Because of the autolytic enzyme,fresh sea cucumber will soon be autolyzed without water.So,fresh sea cucumber needs immediate processing after being catched.Nowadays 80%fresh sea cucumbers are processed into dried sea-cucumbers.Traditional drying method of sea cucumber is rough and complicated,aiming at prolonging the storage time.But the products of traditional methods have bad quality and are easy to adulterate.It also has insurmountable drawbacks.For example,It always needs more than 3 days to rehydrate the dry sea cucumber.These drawbacks hindered the development of the sea cucumber industry a lot.The traditional methods are used up to now,and the products are still take a major status which illustrates that the drying technology of sea cucumber is hysteretic.In a nutshell,deeper research and more application of new technology are required.Acting as a representative species of sea cucumbers in China,stichopus japonicas has a good market recognition.The experiment on nutrition analysis,drying methods and drying process were performed.The specific details are as followed,1.Measurement and analysis of nutrition of stichopus japonicas:Experiments shows that stichopus japonicas is nutritious with high content of protein and abundant microelement,low fat and heavy metal contamination.2.Optimization of vacuum freeze-drying method on stichopus japonicas:In order to optimize the process of vacuum freeze-drying,single factor experiment,central composite experiment and response surface analysis are performed successively.Based on sensory evaluation,products shrinkage,rehydration properties,through single factor experiment indicators of precool temperature,precool time,max heating temperature and vacuum degree are determined.And the range is also determine(precool temperature:-20℃~-40℃;precool time:2.5h-7h;max heating temperature:60℃-90℃).Next,deviation standardization and normalization is used to get a aggregative indicator which acts as response value.Response surface analysis showed that precool temperature influences the VFD stichopus japonicas comprehensive quality more significantly than precool time and the maximum heating temperature.The response surface analysis results showed that the optimized modified conditions were as followed:precool temperature is 34.59℃,precool time is 4.26h and the maximum heating temperature is 80.27℃.To improve the conditions,parameters are set as followed:precool temperature is 35℃,precool time is 4h and the maximum heating temperature is 80℃.The results are able to fit reality.3.Comparison of different drying methods:In order to get good drying manner,four technologies which are common in sea food processing are used to dry stichopus japonicas.Analyzing the quality and value of draught stichopus japonicas of the four manners,it is found that vacuum freeze drying is the best stichopus japonicas,the shape keeping rate is higher than 90%and the rehydration rate is higher than 10.Stichopus japonicas processed by microwave drying and air drying are worse relatively.Microwave vacuum freeze-drying can keep the quality of stichopus japonicas in some degree.It can shorten the time by 40%and the energy consumption by 45%.But more research on Microwave vacuum freeze-drying should be performed to get a good effect.