Theoretical And Experimental Study On Fresh-Keeping Of Blackcurrant By Air Conditioning

Quality preservation of perishable foods such as fresh fruits and vegetables,has always been a key issue in the development of agriculture and food industries.Especially in the epidemic period,cold storage and its supply chain have become a very important part of industrial development.Blackcurrant is a small berry abundant in northeastern of China,rich in various nutrients,but it is difficult to transport due to its perishable deterioration.In modern times,modified atmosphere preservation technology has been applied to apples,peppers and other fruits and vegetables.Therefore,this thesis takes the "minority" blackcurrant as the research object,and studies the heat transfer law of the black currant during the preservation and precooling by means of basic theoretical analysis and numerical simulation.Experiments were carried out on two fresh-keeping methods of controlled atmosphere storage and new modified atmosphere packaging to determine the best preservation condition.(1)The heat transfer analysis and numerical simulation of the precooling and cooling process of blackcurrant were carried out.The heat transfer process of blackcurrant is analyzed theoretically,the physical model and mathematical model of blackcurrant are established,and the temperature nephogram of blackcurrant at different time points in the precooling process is simulated.The comparison results show that the simulation results of the temperature of black currants are basically the same as the experimental results.The blackcurrants preserved in controlled atmosphere storage are completely cooled in about 40 minutes,and the blackcurrants preserved in modified atmosphere packaging are completely cooled in about 45 minutes.(2)The experiment of controlled atmosphere storage and preservation of precooled blackcurrant was carried out to explore the best gas volume ratio for Blackcurrant preservation.According to the existing research,the temperature suitable for controlled atmosphere storage and preservation of blackcurrant is 4?.Therefore,five groups of different gas volume ratio schemes are set up.At different time nodes in the experimental process,sensory evaluation,decay rate,hardness,titratable solids and other indicators were measured and recorded at different time points in the experimental process.respectively.Through the analysis of the data,it can be concluded that the most suitable condition for controlled atmosphere storage and preservation of blackcurrant is 5%O2+15%CO2+80%N2.(3)The experiment of modified atmosphere packaging preservation of precooled blackcurrant was carried out to explore the best temperature and fresh-keeping film material for blackcurrant preservation.We set the temperature as 1? and 4? respectively,and the freshkeeping film material was PE and PVDC in four different packaging schemes,recorded and measured the sensory evaluation,decay rate,hardness,titratable solids and other indicators,at different times during the experiment.Through the analysis of the data,it is concluded that the most suitable conditions for the fresh-keeping of modified atmosphere packaging of blackcurrant are 4? and PVDC fresh-keeping film.By comparing the experimental results,it can be seen that the fresh-keeping effect of modified atmosphere packaging and controlled atmosphere storage can basically reach the same level under their respective optimum conditions,which provides a new reference for social production practice and a new idea for the optimization of economic benefits.