Effects Of Filter And Homogenization On The Stability Of Particles In Cloudy Apple Juice

Poor stability was one of the important factors to restrict development of the NFC?Not From Concentration?cloudy apple juice industry.In this paper,eight representative apples from western Liaoning were used as raw materials to analyze the cloudy particle system and stability difference among the cloudy juices prepared by different apple varieties.Ralls apple which was the characteristic variety in western Liaoning was chosen to systematically research the filtration and homogenization in the processing process.The two processing technic were have an important influence on the cloudy particle structure,and the effects of them on the particle microstructure and stability of cloudy apple juice were analyzed.In addition,the effects of pH and K⁺concentration of juice solution environment on juice stability were also discussed.This study could provide a basis for maintaining the stability of apple turbid juice during processing,and give some reference for promoting the development of cloudy apple juice industry.The main results were as follows:1.The quality and stability of cloudy apple juice prepared from different apple variety materials were analyzed.The viscosity of apple turbid juice decreased sharply when the shear rate was 0⁴0 s^-1.And with the shear rate increased,the viscosity of apple turbid juice tended to be stable,which indicated that the apple turbid juice was a pseudoplastic fluid.Ralls apple juice was a high-sugar and high-acid type,and tasted sweet and sour,which was more suitable for processing juice.Indo had a low juice yield,and the median diameter was larger,which was easy to brown in the process of beating,so it was not suitable for processing juice.The color of Jonagold apple turbid juice was bright,the cloud stability was relatively higher,and the median diameter was small;the juice yield of Wangshanhong was the highest,86.8%;the cloud value of Huafu turbid juice was relatively higher;The color saturation of the Hanfu juice was high,the color was full,and the cloud value was relatively higher;the color of Orin turbid juice was yellowish and the cloud value was relatively higher;the turbidity,cloud stability and the absolute value of the Zeta potential of the Golden Delicious juice were large and the stability was relatively better.The correlation analysis between particle index and stability of cloudy apple juice showed that the particle size analysis parameter D₅₀0 and juice Zeta potential could better characterize the stability of each cloudy apple juice.2.Both filtration and homogenization of apple turbid juice had a great influence on the cloud-like granule system and stability of apple turbid juice.With the condition of 300 mesh filtration for 1 time,the slope of the TSI line of apple turbid juice was relatively lower,which indicated that the stability was better.At this condition,the turbidity of the juice was the largest,at 2928 NTU;the centrifugal sedimentation rate was the smallest,at 1.59%;the particles were relatively smaller,and there was no aggregation phenomenon.Therefore,300 mesh filtration for one time was a preferred filtration condition.The cloud value and the centrifugal sedimentation rate could better characterize the effects of filtration conditions on the stability of cloudy apple juice.In the homogenization process,20 MPa homogenized for 1 time,the absolute value and turbidity of Zeta potential were the highest;the cloud stability was the highest,which was 90.31%;the lowest sedimentation rate was1.42%.The particles were smaller than that at non-homogeneous and 50MPa homogeneous for 2 times,and the particle distribution was uniform,and there was no obvious aggregation phenomenon.Therefore,20 MPa homogenization for 1 time was the best homogenization condition.D₅₀and D₉₀0 could better characterize the effect of homogenization conditions on the stability of cloudy apple juice.3.The solution environment of cloudy apple juice also had an impact on juice stability.When the pH was at 2.5,the juice particles in juice were smaller,the cloud value and cloud stability were relatively higher,and the centrifugal sedimentation rate was lower.The Zeta potential of cloudy apple juice decreased with the increasing of pH.The stability analyzer showed that the juice stability index TSI at pH 2.5 was the lowest at the same standing time,which indicated that the stability was the best.And the slope of the TSI spectrum line at this pH was the lowest,which indicated that the stability change was smaller.When the K⁺concentration was 10^-33 mol/L,the particle size of the juice was smaller,the absolute value of the Zeta potential was the highest,the cloud stability was the highest,and the centrifugal sedimentation rate was the lowest.At the same standing time,the stability index TSI of the cloudy apple juice with a K⁺concentration of 10^-33 mol/L was the smallest.Therefore,when the environmental condition of pH at 2.5 and K⁺concentration was 10^-3mol/L,the stability of apple cloud juice was better.