Study On Development And Stability Of The Banana Juice

Banana is one of the fruits with best economy in the world. Due to the difficulty in the process, most of banana was eaten in fresh and least one was processed to other products, especially juice. In the dissertation, banana juice, a novel juice, was aimed to be developed by utilizing banana. Browning of pulp occurred in the process was controlled, and a few methods were adopted to improve the stability of juice. Finally, stable banana juice with yellow color and milky flavor was obtained.The effect of blanching on the polyphenoloxidase was discussed, and parameters of blanching process were confirmed, such as temperature(100℃) and time(7min) of blanching, the ratio of solid (pulp) and liquid(l : 6), and the pH value of boiled water(pH3). At the same time, effects of some antioxidants on preventing pulp browning were compared, and 0.2% Vc and 0.2% citric acid solution was chose.Fragmentized banana pulp was enzymatic hydrolyzed at 50 ℃ for 2 hours with compound of pectinase(0.048%), amylase(0.05%), and cellulase(0.02%). During enzymatic hydrolysis, lots of macromolecule substance in the pulp such as pectin substance, starch and coarse cellulose were broken down, and all that led pulp tissue loosening, magnitude of particle diminishing and viscosity of puree reducing. Consequently the stability of puree was enhanced.Hydrocolloids influences on the stability of banana juice were studied. As far as 20% banana juice, by comparing cloud stability determined from banana juice, xanthan was found has better stability effect when single gum was applied, next was locust bean gum (LBG), guar gum and carrageenan. Since holding time of single xanthan gum stabilizing banana juice was short, the mixture of xanthan and another gum was discussed based on the result of xanthan. The result showed mixture of xanthan and LBG(ratio was 4 :1) had obvious effect on the stability of system, but the juice tasted viscous and thick, and its fluidity obstructed. Therefore the effect of mixture of three gums on stabilizing juice was further investigated. In conclusion, a blend stabilizer consisting of xanthan, LBG and guar gum in ratio of 2 : 1 : 2 was taken as the juice stabilizer, and its addition was 0.15%. Cloud stability and granularity distribution of juice system treated by different pressure (20, 30 and 40MPa) and time (1 or 2) of homogenization were determined, and the result showed juice system treated with homogenization pressure of 40Mpa for 2 times obtained minimal range of granularity distribution and maximal cloud stability. In addition, blend stabilizers of banana juices with different concentrations of pulp (15% and 25%) werediscussed in the dissertation.