Preparation And Properties Study Of Potato Rice By Extrusion Cooking Technology

Having comprehensive nutrition,the potato can meet the requirements to serve as staple food.Potato resources are rich in our country,and with our country's strategy "to treat potato as staple food" being proposed,researches on the application of potato in traditional staple food are increasing.To increase the variety of potato staple food,promote potato consumption and improve the added value of broken rice,potato-rice powders were used to prepare potato rice.Influences of mixed powder material,extrusion technology,quality improvers on qualities of potato rice were studied.The research contents and results are as follows:The pasting properties of mixed powders and sensory,texture and cooking qualities of potato rice were menstruated to study the influences of potato powder content on pasting properties of mixed powders and qualities of potato rice.The results show that with the increase of potato powder content,the mixed powders peak viscosity,hot paste viscosity and final viscosity decreased.Thermal stability enhanced and gel property decreased.The sensory score increased and then decreased,being more when potato powder content was 40% and 50%.The hardness decreased distinctly.The springiness,cohesiveness and chewiness increased then decreased,being maximal when potato powder content was 50%.Cooking loss increased distinctly.Considering the sensory,texture and cooking qualities results,when the potato powder content was ?50%,the potato rice quality was better.There were significant correlations between the potato powder content,pasting properties and the sensory score,hardness and cooking loss.With the comprehensive score being the evaluation index,the impacts of moisture content,extrusion temperature and screw speed on potato rice quality were studied,and on the basis of single factor tests,orthogonal experiment was used to study the optimum process conditions.The results indicated that the degrees of process parameters on potato rice quality were material moisture > extrusion temperature > screw rotation speed.The influences of material moisture and extrusion temperature on quality of potato rice were very distinct.The optimum process conditions were material moisture 23%,extrusion temperature 110 ?and screw rotation speed 140r/min,and in which conditions,the comprehensive score of potato rice was 72.80.In the optimum process conditions,monostearin,sodium alginates and guar gums were chose as improvers to study influences of their contents on the potato rice quality.Orthogonal experiment was used to study the optimum quality improver formula.The results indicated that the degrees of effects were guar gum > monostearin > sodium alginate.The influences of guar gum and monostearin on quality of potato rice were very distinct.The optimum quality improvers' formula was monostearin 0.3%,sodium alginate 0.4%,guar gum 0.4%.Under such conditions,the comprehensive score increased from 72.80 to 85.97.The essential ingredients,sensory quality,texture and other quality characteristics of potato rice prepared under optimum process conditions and improvers' formula were analyzed and evaluated compared with ordinary rice.Results show that the moisture,ash,protein,cellulose contents of potato rice were more than of ordinary rice,while the starch,amylase and fat contents were lower.The sensory score of potato rice was distinctly lower than ordinary rice,among which the exterior,mouth feel and taste were worse.The hardness and gumminess were significantly higher than that of ordinary rice,and springiness and cohesiveness were slightly higher,but chewiness and resilience were lower.Cooking loss,water absorption and expansibility were greater than ordinary rice.Iodine blue and alkali value of potato rice were less distinctly than ordinary rice and gel consistency was greater distinctly.