Dissertation
Dissertation > Agricultural Sciences > Crop > Cereal crops > Rice

Study on the Effect of Quality and Microbial Activities of Paddy during Storage by Temperature and Ozone

Author ZhangRui
Tutor ZhouJianXin
School Nanjing University of Finance and Economics
Course Of Food Science
Keywords paddy temperature Ozone microbial quality correlation
CLC S511
Type Master's thesis
Year 2012
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China is a major origin of paddy,the planting area ranks first in the world,thetotal yield close to the sum of wheat and corn.In the south,because of the reason ofdiet habit,paddy is the main source of food for consumers.For the needs of army andresident,paddy becomes the most important grain for storage and transaction,it’sstorage task is arduous.Most of paddy producing areas and national repositories aremainly distributed in the south of the Yangtze River,where the environment is hightemperature and high humidity each year,so how to keep the quality and freshnessbecomes the important and difficult work during the storage of paddy.The husk of paddy is hard,it will protect grain and resist the effection of pestsand temperature、humidity outside to a certain extent,but paddy can’t tolerate hightemperature and is also vulnerable to insects and microbes,especially fungiagainst,high-temperature conditions and insects、mold damage will accelerate thedecline in paddy quality and affect it’s safety,therefore,the control of temperature andthe content of pest and mold during storage is particularly important.Now,at home andabroad,we slow deterioration of the quality of paddy through the control of storagetemperature and oxygen concentration mainly,however,these two methods of paddystorage require high tightness for warehouse,many warehouses are difficult to do,thecost of conversion is too high to meet the enclosed requirement.Although mechanicalrefrigeration can be used to store paddy,but the cost of storage is high so there is nopractical value. With the development of economy and the improvement of people’sliving standards,people’s health and environmental awareness increasedgradually,food industry need advanced and economic green storage technologyurgently,however,the current research is limited to the qualitative research of thetemperature effection on quality and microbial of storage paddy、Ozone is used to theemergency treatment of high moisture grain.the quantitative study of temperatureeffection on quality and microbial of storage paddy、the impact of Ozone treatment onquality and microbial of paddy and the variation rule of paddy quality and microbialduring storage after Ozone treatment have little report or no report.The subject make the paddy and the paddy(moisture content:13.5%,meetsrequirement of safety moisture content) that after Ozone treatment under the conditionof different temperature(15℃,20℃,25℃,30℃,35℃)、70%-75%relativehumidity to simulate store,test the related physical and chemical indicators andmicrobiological indicators of paddy. The experimental results as follows: (1)The effection of temperature and storage time on quality and microbialactivity of paddyAs the temperature increases and the time extending, moisture content、huskedrice yield、head rice yield、germination rate、aerobic bacterial count and mould countof paddy decline faster, fatty acid value rise faster,the quality of storage paddy agingfaster.Analysis of ANOVA shows:storage temperature and time had very significantlyeffect on the change of quality and microbial of paddy.To fit the indexes above andstorage temperature、time for binary linear regression equation through SPSS analysissoftware,all meet Y=aT+bD+c(P<0.01),shows:temperature and time have verysignificantly binary linear relationship with physical and chemical indicators andmicrobiological indicators of paddy;(2)The effection of Ozone treatment on the quality and the change of microbialcontent of paddyAfter Ozone treatment, fatty acid value of paddy increased0.039%, head riceyield and germination rate of paddy decreased0.32%and1%by each, husked riceyield from paddy have no change, aerobic bacterial count and mould count of paddydecreased60%and42%, shows: after Ozone treatment to paddy,it’s quality has noeffect,but the bactericidal effect is obvious.(3)The change rule of quality and microbial of paddy during storage after OzonetreatmentCompared with the control group(has no Ozone treatment),the change rule ofquality of paddy during storage after ozone treatment had the similar variation,in thesame temperature,the same time,the quality of paddy is lower slightly than the controlgroup,but bacterial count and mould count increased significantly,occur reboundphenomenon,even higher than the control group at the same temperature and the sametime.(4) Association with the quality inidicators and microbial biomass of paddyunder different temperatureUnder15℃and20℃, the quality inidicators had no significant correlation withmicrobial biomass;under25℃, moisture content、husked rice yield from paddy、germination rate of paddy had significant correlation with aerobic bacterial count,head rice yield of paddy had very significant correlation with aerobic bacterial count;fatty acid value、husked rice yield from paddy had significant correlation with mouldcount, head rice yield of paddy、germination rate of paddy had very significant correlation with mould count;under30℃, husked rice yield from paddy、head riceyield of paddy、germination rate of paddy had very significant correlation withaerobic bacterial count; husked rice yield from paddy、head rice yield of paddy hadsignificant correlation with mould count, germination rate of paddy had verysignificant correlation with mould count;under35℃, fatty acid value、germinationrate of paddy had significant correlation with aerobic bacterial count, moisturecontent、head rice yield of paddy had very significant correlation with aerobicbacterial count; head rice yield of paddy had significant correlation with mould count,husked rice yield from paddy、germination rate of paddy had very significantcorrelation with mould count.The result of the research will provide scientific basis for slowing qualitydeterioration of paddy through the control of temperature during storage and for thedevelopment and promotion of storage technology with Ozone.

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