The Correlation Of Different Processing Mode And Change Of Bitter In Grapefruit

The heavy bitter taste, which is a great characteristic that is different from other citrus fruits, restricted the original fruit planning and products deep processing of grapefruit. Futhermore, bitter (the typical materials are naringin and limonin) undertakes complex biochemical changes with condition, which is difficult to control, especially in processing.Therefore, the change law of bitter in grapefruit has been a main point researched by investigators.Now, study of bitter in citrus fruits more focused on the remove of it,and the improvement of flavor is more give priority to mixing.The whole fruit and juice of grapefruit was used as experiment material in this article, the author designed to use some physical or chemical methods to seek the possibility of flavor change of grapefruit.This study mainly research on the effect of different ways of storage (cold storage, gas storage), processing units (heat treatment, concentration) and additives (PVPP, agar) on bitter and other quality index. The research on one hand offers technological parameters for controlling bitter of grapefruit, on the other hand, it also offers the correlation of change low of quality index and processing methods.The results are as follows:1. Grapefruit was used as experiment material, which was stored in cold storehouse with different temperature (0℃,5℃、10℃、ambient temperature) and gas condition (3%O2、6%O2、10%O2). Results indicated that the content change of bitter was significantly influenced by temperature. Within 0-30 days period, bitter content of four groups all increased, and it has a downtrend after that. While compared to control group, bitter content of the three groups increased or decreased when gas condition changed, but it doesn’t present certain regularity. Within 30-105 days period, the fluctuation of bitter content decreased with the increase of O2 ratio,and 10%O2 group has the lowest bitter content.2.The experimental results of processing uint showed:(1)Heat treatment:The content of naringin and limonin both increased with the increase of heating temperature. With the extension of time, limonin content increased, while naringin content decreased after 15min. (2)Concentrate:With the increase of TTS, enrichment effect of naringin and limonin are obvious under the two kinds of enrichment processes. While compared, content of naringin and limonin in frozen concentrate are lower.3. The experimental results of additive showed:(1) PVPP:PVPP has a good adsorption effect of naringin in grapefruit juice.Through single-factor test and orthogonal test, the optimal technological parameters is:the amount of PVPP 90g/L,the pH of juice 4, the adsorption time 20 min,the adsorption temperature 2℃.(2)Agar:The clarification effect of agar is obvious,and the clarified juice transmittance of optimal technology reach up to 98.1% high.When compared with normal juice, limonin content increased while naringin content has a fluctuation in the process of clarification.