Production Of Instant Cereal Porridge Using Extrusion Technology

Porridge is widely considered as health food with high quality because of its soft taste,rich nutrition and quick digestion and absorption.Gradually,porridge has become one of the staples in people's daily life and spread widely among the populace.However,the traditional way of cooking porridge is time-consuming,laborious and difficult to achieve industrial production,which cannot meet the needs of the fast social life.Therefore,it is of great significance to produce a convenient,nutritious and healthy porridge for improving people's life quality.Now there are also a variety of instant oat meal,fruit and cereals breakfast,instant meal and other products on the market.Nevertheless,most of these products are filled with vegetable fat powder,essence,pigment,etc.Moreover,the products have a high degree of expansion,poor stability of brewing,sensory and taste can not meet the needs of people.Here,with five kinds of cereals(japonica rice,oat,corn,millet,barley rice)as the main raw materials,the instant cereal porridge was obtained by twin-screw extrusion technology,and then the formula and process parameters were optimized.Finally,the edible quality was also evaluated.The main results are as following:(1)Optimization of the formula for instant cereal porridge.Firstly,the main nutritional components of the five cereals and the physicochemical properties before and after extrusion were analyzed.It was found that the structure of cereals had a significant effect on the degree of expansion.Under the same extrusion conditions,the transversal expansion rates of the five cereals ranked as follows: corn > japonica rice > millet > oat > barley rice.Combined with the previous research,the physical and chemical properties of the three extruded products were compared and analyzed for three better formulations.It was found that the content of the japonica rice should not be less than 60%.Otherwise the extruded product could not be formed.Finally,the best formula was obtained,namely 60% rice,10% oat,15% corn,10% millet,and5% barley rice.(2)Optimization of the processing for instant cereal porridge.The effects of feed moisture,feeding frequency,die temperature and screw speed on the physicochemicaland sensory properties of extruded products were investigated by the single factor test.The optimum range of process parameters is obtained: 20-24 percent of feed water,11-21 Hz of feeding frequency,100-120°C of die head temperature and 14-22 Hz screw speed;Then,based on the results of single-factor experiments,an orthogonal experiment with four factors and three levels was designed.Finally,the optimal level combination is obtained as follows: 22 percent of feed water,16 Hz of feeding frequency,110°C of die head temperature and 18 Hz screw speed.Under these conditions,the gelatinization degree of grain was 98.06%,the transverse expansion rate was 2.87,the appearance size was similar to japonica rice,and the color was even light yellow.(3)Evaluation of the edible quality for instant cereal porridge.With sensory evaluation as the index,the optimum water quantity of instant cereal porridge was determined to be 1:7(W/V).In addition,the difference of stability after brewing between instant cereal porridge and three kinds of representative cereals on the market was analyzed and compared.It was found that instant cereal porridge had the best stability,namely maintaining grain integrity after 100 min.