| Using the microfiltration membrane makes juice sterilization,in order to innovate new method at the traditional level and offer science basis for new technic.In the experiment squeezed juice as raw material,to clarify the juice through the use of chitosan on optimization of the clarification process,and then use the micro-membrane filtration clarified the juice in order to achieve the purpose of sterilization and prolong the storage period.The main contents are the clarification of fruit juices,micro-membrane filtration sterilization and the cleaning of the membrane.In addition,using electronic nose technology tests the odor of pear juice deal with different treatments,and the microbiological test was studied.First,optimize the conditions of clarified the juice.Single factor experiments is to study the amount of chitosan,clarify temperature and clarify time.Orthogonal experiment determined the most important factor that affect the juice clarification process,and the best conditions to the clarify process:pear juice clarify,the amount of chitosan is the most important influencing factors,and pear juice light transmission rate up to 90%at the best process.Watermelon juice,clarify the temperature is the most important factor and light transmission rate up to 90%at the best process.From energy efficiency,reduce production costs,according to the optimum conditions,chose the appropriate dosage and temperature.Second,I chose the micro-rate options of the membrane,and determine the appropriate material,size,pore size.Test purposes,the correct pore size is 0.2 μm membranes,because this aperture membrane can remove the bacteria away that maybe in the juice.Juice processing after the membrane transmittance is higher than not,the light transmission increases,and through the membrane has no effect on the fruit juice ingredients.Then test the impact to micro-membrane filtration membrane flux on different conditions,they are filter traffic,the operating temperature and filtration time on the membrane flux.Identified these three factors,the flow rate and temperature on the membrane flux are more important,with the flow rate and temperature increase,the membrane flux became larger.In 12 h filtration time,membrane flux changes small.Juice processing by different methods,the test of the composition of the volatile gas is used the electronic nose to detect.The aroma composition of the pear juice filtrated and freshly squeezed pear juice aroma components are very close.Filtrated the water,deionized water and slop and did the microbiological test to detect the purpose.Do the total number of colonies and coliform testing of the juice filtrated by micro membrane,test results are all in line with the requirements of national standards for fruit and vegetable juices.The juice through the membrane refrigerated storage,the slow pace of colony growth.The juice through the membrane under different operating conditions,the total number of colonies and coliform test results are<1.0 CFU·mL-1,<3 × 10-1 MPN·mL-1.So the different operating conditions have little effect to the juice.Kept under seal for 90 days in room temperature and texted the total number of colonies and coliform at regular time,the test results were all up to grade.The longest store time could be 12 months.And the juice not filtrated became bad in two days.Finally,the cleaning method of the micro-membrane filtration components tested.Four types of cleaning methods were tested on the membrane flux recovery rate,pure water cleaning,acid cleaning,ultrasonic pure water cleaning and ultrasonic acid cleaning.Using ultrasonic acid cleaning,the cleaning time was shorten,and the membrane flux recovery rate is the best. |
