Mechanism And Industiral Process Optimization Of Roasting Rice For Rice Wine Using Superheated Steam

At present, the annual output of Chinese rice wine is1.5million tons with a rapid rate ofdevelopment. Meanwhile, the development of the Chinese rice wine industry has encounteredsome bottlenecks, such as low level of processing technology and production efficiency, highpollution and excessive energy consumption, and the low degree of Equipment level andautomation. The further system research is necessary to enhance the level of productiontechnology and equipment in order to achieve a modern Chinese rice wine industry, resultingin a path of sustainable development based on the traditional characteristics.During rice wine production process, the production units of soaking and rice cooking arethe main source of pollutants and high energy consuming.0.9million tons of waste water withhigh concentrated organic waste, containing27thousand tons of COD pollutants, are generatedannually in the soaking phase. Meanwhile, it takes0.48million tons of vapor for rice cookingevery year, converting into64.8thousand tons of standard coal. The roasting technique withoutsoak water, significantly reduces emissions of waste water and other pollutants. However, thistechnique causes several extra problems, such as exhaust gas pollution by roasting, highprecision and investment requirement on roasting equipment, a large cost on control andmaintenance. In addition, study on roasting technique and substance variation is not in depth,causing the lack of theoretical basis guidelines on roasting process control and equipmentamplification.A new technique, called superheated steam roasting, could overcome the air pollution andenergy waste during roasting, and thus implement "green" brewing of Chinese rice wine.Therefore, the systematic study focused on the Chinese rice wine brewing with superheatedsteam rice roasting process. The main results are concluded as follows:(1) The experimental fluidized device is designed according to the fluidizationcharacteristic of rice based on the theories of dilute phase fluidized bed and shallowfluidized bed with high capacity of heat transfer. And the operating parameters areoptimized to achieve the optimal heat transfer rate of roast: input amount of10g,fluidized gas velocity of4m s-1which is1.5times higher than initial velocity. In thecase of optimal heat transfer, the technological parameters of roasting are optimized andthe hydration property and expansion rate is compared. The results showed that theexpansion rate of rice had no significant differences during the30~50seconds ofroasting time at superheated steam200oC without occurrence of secondary reactions.The above technological parameters are considered to be the optimal condition for riceroasting since certain retention time is available during the continuous operation.Comparative study of the different heating medium roast rice find gelatinization rate ofsuperheated steam rice and air roasted rice is similar and gelatinization rate ofsuperheated steam rice superheated steam is slightly higher.(2) Analysis of change information of rice microstructure, properties and crystallineduring roasting process, that under the optimal operation condition, roasting processcan be divided into two stages, heating and puffing. The heating stage can be divided into the two period: preparation period and rapid gelatinization period. The sharp risein the temperature of rice during heating stage, molecular structure and characteristicof internal change sharply. The heating rate significantly decreased during puffing,but rice begins puffing due to the temperature over the melting point of it. Greatchanges have taken place in the volume and the macro structural changes of rice. Thedividing point of the two stages is between20~25seconds. Changes in the riceinternal temperature distribution during roasting process have been analyzed using theexperimental model, so the best mode roasted rice temperature changes duringroasting is determined, the standard temperature control curve for roasting is proposed.The roasting process design and amplifying strategy is proposed: According to thetemperature change characteristics of roastcheng process control temperaturevariation of rice. Change of rice average temperature should conform to the standardtemperature control curve.(3) By using the method of numerical simulation, industrial process models of continuousrice roasting using superheated steam were constructed respectively. Roasted rice usingsuperheated steam model contains the initial steam condensation simulations.Influence of the structure of fluidized bed and operating parameters on the roastingprocess were analyzed using a section roasting process model. According to therequirement of industrial process, two sections roasting technology has been proposed.The roasting model analysis found that the average temperature curve of rice in the twosections roasting system is close to the standard temperature control curve. Productioncapacity is far higher than the capacity of the experimental device. The ordinary plugflow fluidized bed can be used for two sections roasting. The optimization results showthat processing ability of the two sections roasting system is7~8times the processingability of experiment equipment, that is12.88~14.72kg (s-1m-2). The heating sectionoperating conditions are the superheated steam temperature of270~280?, residencetime of12.5s, the superheated steam empty bed velocity4m s-1. Insulation section ofsuperheated steam temperature of200?, residence time of27.5s, superheated steamempty bed velocity3m s-1.Industrial roasting system design and process design procedures have beenproposed. Complete program is provided for the implementation of pilot andindustrialization.(4) The thermal denaturation of rice protein occurred in the roasting stage is studied byprotein solubility analysis. It is found that the thermal denaturation of rice proteinoccurred in the early roasting stage, and a greater degree of degeneration. But roastedrice protein denaturation degree is smaller than the traditional soaking and cooking rice.The degree of degeneration of no waxy rice and waxy rice is basically the same. Use ofdifferent heating medium has no effect on rice protein denaturation.The change of oil content in rice during roasting is mensurated. It is found thatvolatilization of free oil is larger and volatilization of bound oil is smaller. No waxy riceoil difficultly volatile and waxy rice oil easily volatile. Comparative study on the effects of different feeding methods on the rice winefermentation. Preliminary identification of fed batch fermentation method is suitable forroasted rice wine brewing technology. Through the determination of physicochemicalproperties, sensory analysis and flavor analysis that the use of roasted rice wine with thetraditional flavor can be brewed. But with the traditional rice wine, there are still somegaps. Therefore roasted rice by superheated steam can be used for rice wine production.