Study On The Effect Of Critical Processing Steps On The Quality Of Tomato Juice

Ligeer 87-5 tomato is a major variety for tomato juice in Xinjiang. While the equipments of processing of tomato juice in Xinjiang are mainly bought from foreign equipment company, at the same time, the technics and parameters are used suit for foreign tomato varieties. But maybe the technics and parameters are not suit for Ligerer 87-5, that will lead to the quality of tomato juice is not good. This study choosed 'qianhong-1' and Ligeer 87-5 as raw materials to compare the processing characters of two tomato varieties and study the qualities of tomato juice changes through 'hot-break' and 'cold-break', homogenization, concentration etc., then found that Ligerer 87-5 had better characteristics in processing, and optimized the processing flow and the parameters of tomato juice aiming to give some theory guide for the plant processing. All results of this dissertation are following:The maturity of tomatoes can affect the quality of tomato juice, the tomatoes maturity of red stage are suit for processing.The heat-inactivation of three key endogenesis enzymes, PME, PG, LOX affecting the quality of tomatoes juice during processing are researched. Among two pectin enzymes, PG is hard to heat inactivate and when heated 60s at 80℃,10s at 85℃ and 90℃, it is inactivated. So 'hot-break' range is beyond these heating conditions. LOX loses 80% activity when heated 4min at 65 ℃, so the temperature range of'cold-break' is below 65 ℃.Juicing method of Break, heating to inactivate enzymes, then juicing (BHJ) for processing tomato juice is better then that of juicing then heat to inactivate enzymes (JH), so BHJ juicing method is chosen to process tomato juice.Different 'hot-break' conditions affects the viscosity of tomato juice, and has no effect on the cloud stability, content of pectin, color and brown color of tomato juice. The content of pectin and cloud stability of 87-5 tomato juice are better than 'qianhong-1' tomato juice, while the brown color of two kinds of juice are same. After heating, the change range of visicosity of 87-5 tomato juice is smaller than 'qianhong-1 'toamto juice with different hot-break conditions, and the content of lycopene of 87-5 tomato juice had no change, while which decrease in 'qianhong-l'tomato juice, that shows that 87-5 is better than 'qianhong-1' for tomato juice processing. The better quality of tomato juice can be obtained with parameter of hot-break is 90 ℃ 10s.'Cold-break' can decrease the viscosity and cloud stability of tomato juice, but can make the flavor of tomato juice better. 'Cold-break' had no effect on the content of lycopene and color. The best flavor tomato juice can be obtain when 'cold-broken' at 35℃ 10min. Homogenization at pressure of 30Mpa can increase the cloud stability of tomato juice and can keep it stable in 90d without cloud loss.Finally, the processing flows for better quality of concentrated tomato juice and better flavored tomato juice are built.