The Influence Of Not From Concentrate Apple Juice Processing On Quality And Its Process Optimization

Not From Concentrate(NFC)apple juice has low thermal processing intensity and low loss of nutrients,and can better maintain the flavor and activity of nutrients in fresh fruits and vegotables.In recent years,domestic and foreign consumers have continued to increase demand for NFC juice.Because of easy to brown of processing,more precipitation and shorter time during storage,the development of the NFC juice industry is severely restricted.In this study,Aksu rock sugar heart Fuji apples were used as experimental materials,the effect of sugar and acid content in NFC apple juice processing inclu ding raw materials,juice extraction,enzyme inactivation,homogenization,ultrasound,sterilization,and canning were studied.Then the relationship between sugar and acid content and respiratory rates in various pathways.The impact of different machining process on its quality indicators and flavor substances were explored and the main processes that caused changes in the quality of NFC apple juice were identified.The optimum process parameters for NFC apple juice were determined,and provide theoretical basis and technical support for the quality control and low temperature preservation of NFC apple juice industrial production.The main findings are as follows:1.The change of sugar and acid flavor quality during the processing of NFC apple juice can be divided into two stages:raw material-juice extraction and enzyme inactivation-canning.In the first stage,the glucose and sorbitol content in soluble sugar increased by 49.12%and 20.59%,the malic acid content in organic acids increased by 8.06%,the oxalic acid content decreased significantly by 7.01%,and the TCA respiration rate increased by 0.64 times,CP respiration rate decreased by 0.85 times;In the second stage,the changes of fructose,glucose,malic acid,oxalic acid content and solid acid ratio showed a normal distribution,which was related to the changes of respiration rate of EMP,TCA pathway and AP.Therefore,during the processing of NFC apple juice,attention should be paid to the regulation of sugar and acid flavor by juice extraction and enzyme inactivation.2.By studying the influence of different process on the color index,turbidity,total soluble solids,titratable acid content and flavor substance changes during the processing of NFC apple juice,it was found that in addition to the canning process,raw materials,juice extraction,color protection,enzyme inactivation,homogenization,ultrasound and sterilization processing all have an effect on the physical and chemical indicators and flavor substances of the juice.Among them,the operation units such as juice extraction,enzyme extraction,and homogenization all have a significant impact on the bringtness L,chroma C,and flavor substances of the juice.The ultrasonic and sterilization processing steps significantly increase the turbidity and reduce the flavor substance content of the juice.3.The 12 different processes designed based on random centroid mapping optimization design software(RCO)have different effects on the quality of NFC apple juice during storage.Analysising comprehensively of factors such as color,turbidity,TSS and TA content and sensory evaluation,and considering juice efficient and safe production,the most suitable NFC apple juice processing technology parameters are determined:Vc addition is about 0.45 g·L^-1,enzyme inactivation time and the temperature is 13?14 s and 85?,the homogenization time is 4?5 min,the sterilization time and temperature are about 17 s and 90?,the NFC apple juice processed under this condition has rich color,stable turbidity,TSS And TA content and sensory evaluation scores are higher,and are more popular with consumers.