Research On Cooking Characteristics And Improved Technology Of Coix Seed

Coix Seed is the dried ripe kernel of Gramineae Coix lacryma-jobi,also known as pearl barley,semen coicis. In recent years,scholars study the chemical composition,nutrition,function and value of barley for a lot of experimental research,which show that Coix Seed has many functions that can resist cancer, put down blood pressure, loss weight,strengthen the immune system and so on. The unique value in health care making it the hotpot of recent research in the field of food industry. However, due to its hard cooking, long time for being soaked, it limits the widespread use of Coix Seed in the food field. However,there is few relatively studies on the cause of Coix Seed’s hard cooking.This study investigated the Coix Seed soaked absorbent properties, using the low-field NMR techniques, measured the transverse relaxation time barley soaked in the process of proton T2for analyzing the changes in the migration of moisture and the moisture status. The absorbing kinetic equations of Coix Seed within30-60℃range was simulated by constructing Peleg equation. This experiment also investigated the impact of factors of cooking Coix Seed include starch content, thermal properties, protein content, the particle size and the characteristics of the starch. In addition, the paper also studied the role of ultrasound in reducing barley optimum cooking time and it’s impact mechanism.These researches aim to provide the basis of production. The main results were as follows:(1) The suitable soaking of Coix Seed is about3h, suitable soaking of glutinous rice is about40min. The higher the temperature, the absorb water of rice is faster,the time of water balanced is shorter; the water absorption of Coix Seed was increased with time prolonged during soaking, the initial water absorption is quickly, after a certain time,ti is reached saturation, no water absorbed. The Peleg equation was used to measur water absorption data between temperature (T) of30℃and60℃.The water absorption characteristic equation of Coix Seed is:M=Mo+1/[0.01488-0.82×T ×10-5+(0.03975-T×1.77×10-5)×t].The equation can be used to describe the relationship between water content of Coix Seed and the soaking temperature and time, so it can compute the water content of Coix Seed during soaking process.According to MRI image analysis, moisture endosperm particles through the center of Coix Seed to spread around,Coix Seed grain structure is complete during soaking,hindering the penetration of moisture, resulting it’s difficult to cooking. According to T2map analysis,when the water temperature increased by10℃the s soaking time can be shortened10min in the range of30～60℃.(2)Mechanism of cereal cooking:According to correlation coefficient, rank the effect sequence of gelatinization degree by every factor:Starch enthalpy value> initial gelatinization temperature> protein content> water content> starch content> grain size of cereal.Compared with another5grains (glutinous rice, rice, indica rice, maize, sorghum), Coix Seed has high protein content(12.65%) and starch enthalpy (10.39J/g); the initial gelatinization temperature (65.18℃) and the grain size (7.65mL/100pills) are higher than others, but the water content (9.76%) and starch content (57.89%) are lowest The results shows that:Coix Seed is difficult to cook thoroughly because of the higher initial starch gelatinization temperature, enthalpy and protein content, lower starch content and water content, and bigger grain size and so on. The high enthalpy is the main factor in it.(3)Through a stereo microscope and scanning electron microscope,the surface of the ultrasonic treated Coix Seed has a large number of cracks and losed their shape,thus improving the cooking process Coix Seed moisture penetration rate, which can shorten the optimum cooking time of Coix Seed.Coix Seed was ultrasonically treated in a tank at temperatures of25℃,40℃and55℃for80.5min,respectively.The most of the chemical composition was remained in Coix Seed kernel, the optimal cooking time of treated Coix Seed were75.8min,71.3min and67.3min.Textural characteristics of the test results showed that the hardness of ultrasonic treated Coix Seed has reduced and the chewiness and elasticity has increased with the rised temperature,the cohesion and adhesion has little changes during that period of before and after treated. Ultrasonic treatment significantly improved the cooking quality of Coix Seed. Sensory evaluation results showed that Coix Seed treated by ultrasonic at25℃has the highest composite score. The use of ultrasonic in brown rice cooking processing is a promising technology.