| The production of concentrated apple juice had become one of the primary means of export for all the major apple producing areas in our country, but in the process of producing concentrated apple juice, there would be some natural apple flavour and a mass of apple pomace. The apple flabour which had not been exploited was the good source for the base stock with apple perfume. Besides, the overwhelming majority of the pomace was discarded as waste, causing great waste of resources and environment pollution. To solve these problems, this thesis studied the effect of natural apple flavor concentrated by RO and the extraction efficiency of pectin, hemicellulose and cellulose extracted with ultrasonic from apple pomace. This study included four parts of content as follows:1.The extraction of pectin with ultrasonic assist was studied. Single factor experiments were designed to study the effects of the time of the ultrasound, pH, extraction temperature and solid-to-liquid ratio on extraction efficiency of pectin. The experiment was arranged with L9(34). Results showed that the optimal values of the above parameters were determined as follows: solid-to-liquid ratio 1:20 (g/mL), 80℃, extraction time 100min and pH1.5. Under such conditions, the yield of pectin was 15.12%. The result was higher than extraction efficiency of pectin extracted by the traditional method or other methods.So,there were certain advantages in ultrasonic assisted extraction of apple pectin. This study also examined the effect of the ultrasound frequency on the extraction efficiency of pectin extraction, the results showed that the ultrasonic frequency almost had no influence. Besides,the gelling characteristics of the pectin was investigated.The gelling characteristics of the pectin was good.2.The extraction of hemicellulose with ultrasonic assist was studied.Single factor experiments were designed to study the effects of the concentration of sodium hydroxide,the time of the ultrasound, pH, extraction temperature and solid-to-liquid ratio on extraction efficiency of hemicellulose. The experiment was arranged with L9(34). The results showed that the optimal values of the above parameters were determined as follows: concentration of sodium hydroxide 2 mol / L, ultrasonic time 90min, extraction temperature 85℃and solid-to-liquid ratio 1:15. Under such conditions, the extraction efficiency of hemicellulose A was 14.83%, the extraction efficiency of hemicellulose B was 15.61%.The extracted method with ultrasonic assist not only improved the extraction efficiency of hemicellulose, also lowered the extraction temperature and shortened the extraction time.3.The decoloration of cellulose with ultrasonic assist was studied.Single factor experiments were discussed to study the effects of pH, concentration of peroxide, decoloration temperature,ultrasonic time,solid-to-liquid ratio on the decoloration of cellulose.The experiment was arranged with L16(45).The results showed that the optimal values of the above parameters were determined as follows: pH 10, concentration of peroxide7%, decoloration temperature 30℃, solid-to-liquid 1:8,ultrasonic time 80 min. Under such conditions, the relative whiteness of cellulose was 50.94%. The extracted method with ultrasonic assist could shorten the decoloration time, reduced the decoloration temperature, and obtained a better decoloration effect. Moreover, the water holding capacity and swelling force were improved after decoloring.4.The effect of concentration of natural apple flavour by reverse osmosis technology was preliminarily studied. The content of the trans-2-hexenal and volatiles in apple flavour were regarded as standard.GC was used to detect the content of the trans-2-hexenal and volatiles in apple flavour.The results showed the concentration effect of the natural apple flavor with reverse osmosis technology was good.However, concentration effect gradually decreased with the increase of the concentration times , because reverse osmosis membrane had certain adsorption. |
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