Research On Quality Control Of Packed Rice During Processing And Cold Distribution

There are two ways of distribution in the packed rice industry, cold chain and thermalchain. Cold chain is the distribution mode that after cooking, cooling the rice to below10℃rapidly, and keeps the center temperature of the rice below10℃in the subsequent processing,storage, transportation, distribution and retail. This paper aimed to study on the coolingmethods of cooked rice, quality change rule and its improvement of rice storage process incold distribution, Microwave reheating on rice quality influence. Those studies could providetheoretical reference and guidance for the industrialized production of cold and thermaldistribution of cooked rice.1、In order to study the influence of cooling technology in cold chain rice, this paperinvestigated the effects of different cooling methods (natural cooling,10℃cooling andvacuum cooling) on cooling efficiencies and the rice main physical and chemical indexeschanges. Results:(1) Under vacuum cooling, it only took10minutes for rice core temperatureto drop to20℃which was most efficient. Cold wind cooling needed60min,10℃coolingneeded88min and natural cooling190min. Vacuum cooling had the lowest temperaturedifference between inside and outside, less than1℃, while the highest temperaturedifference of natural cooling,10℃cooling and Cold wind cooling reached6.3℃,16.7℃and20℃respectively; as to weight losing rate, vacuum cooling had the highest, at about5.19%, natural cooling,10℃cooling and cold wind cooling were2.09%,1.71%and2.4%respectively.(2)Under four kinds of cooling technologies, the whiteness kept rising; vacuumcooling rice increased fastest, natural cooling rice increased slowest.(3) Under four kinds ofcooling technologies, the pH value kept falling. Natural cooling rice decreased fastest,vacuum cooling rice decreased slowest.(4) Under four kinds of cooling technologies,hardness were increasing, the adhesiveness and adhesiveness were falling; vacuum coolingrice had the best hardness and springiness, but the worst adhesiveness.(5) Cooling technologyhad a significant influence on rice cooling, aerobic arterial count and subsequent shelf periodlength, the hygienic quality of vacuum cooling rice was the best, its shelf life could reach3d.(6) In conclusion, vacuum cooling is a suitable method for rice cooling, owns high coolingefficiency, can keeps the good quality of rice and good hygienic quality etc. 2、In order to study the quality change rule in cold chain rice, this paper investigated theeffects of the different temperatures (0℃,4℃,10℃), different storage time (1~7d) of ricequality indexes. Results:(1) As the storage time increased, whiteness value increased underthree kinds of storage temperatures, and the increase in the former12h was most obvious;whiteness increased faster under0~4℃than10℃.(2) Under three kinds of storagetemperatures, as the storage time increased, the hardness of the rice was on the rise, and rosefastest in the first day, the comparison of rice hardness showed:0℃>4℃>10℃; theadhesiveness of rice was in decline, and declined fastest in the first day, the comparison ofrice adhesiveness showed:10℃>4℃>0℃; the springiness of the rice were falling, anddeclined fastest in the first day, then remained at a stable rate of descent in2~7days, thelower the storage temperature is, the worse the springiness was.(3) Under three kinds ofstorage temperatures, as the storage time increased, rice’s pH value declined, the overall trendshowed the higher the temperature, the faster the pH value declined.(4) storage under0~4℃，the shelf life of rice is about4d, under10℃,the shelf life of rice is about3d.3、In order to study the way of starch Anti-retrogradation. This paper investigated theeffects of the effects of different modifying agents (β-cyclodextrin, trehalose and stearoylsodium lactate), different additive amounts on rice sensory quality improvements. Results:(1)Under three kinds of storage temperatures, as the storage time increased, fragrance andappearance structures did not have obvious changes; palatability, flavor and texture of coldrice was declining and changed obviously in4~6days under0~4℃storage.(2) Adding0.5%trehalose had the most obvious improvement on the rice quality, which obviously delayed theaging of rice and increased its fragrance, as well as extended its shelf life for1-2days under4℃storage.