Quality Changes Of Bitter Apricot Seed In Peeling Process And Its Cause Exploration

In this paper, bitter apricot seed was regarded as the research object. In view of the existed problems of bitter apricot seed quality changes in the peeling process, the research was developed in the aspects of enzymatic browning and browning control, bitter apricot seed color change, and the factors influencing the loss of active ingredients, and in order to discuss the reasons that result in the bitter apricot seed quality damage. The results were expected to improve the peeling process and guide the industrial production practice, so as to promote the development of apricot seed industry. The main contents of this paper were as flow:extraction and purification of bitter apricot seed polyphenol pxidase and analysis of its related properties; researched of the color variation of bitter apricot seed after being blanching peeled; the changes of bitter apricot seed polyphenols, flavonoids, laetrile activity, and amygdalin under different peeling conditions.The results are showed as follow:1. Bitter apricot seed polyphenol oxidase was treated by ammonium sulfate precipitation and Sephadex G-75 column chromatography. Bitter apricot seed polyphenol oxidase was get after freeze drying, and the purification factor was 49.03 times. Thermal analysis tests showed that PPO thermal denaturation temperature was 60.03℃, and its molecular weight was between 21-23 kD after electrophoresis treated. Thus, the peeling temperature was higher than denaturation temperature, the effect of reducing enzyme activity could be caught and avoided high temperature effect on the quality of bitter apricot seed.2. By measuring the absorbance at 420 nm, it showed that the browning degree of bitter apricot seed had not a significant increase after being peeled a few days. This may due to the enzyme activity which had been reduced by high temperature blanching peeled process. The experiment results showed that bitter apricot seed’ value of Lab* after removing oil was lower than the fat remaining. With oil remaining, the value of L* had a gradual increase with time went on, but value of both a* and b* decreased. The change degree of Lab* value were totally smaller than fat remaining, and the change trend was slowly.In order to have a further proving that the exit of oil had an effect on the bitter apricot seed color, the essential was to measure the Lab* value of bitter apricot seed oil stored in different days and analysis the physicochemical property. The results showed that, with the extension of storage time, the oil brightness of L* value had a slightly increase, red tone of a* value was almost unchanged, while the yellow tone ofb* values showed a gradual downward trend, indicating that the oil color would occurred certain changes. And the acid value was not change so much with time go on, but peroxide value had presented a approximately linear growth trend, which meant that peroxide value was more sensitive to light and heat, and oil was easily to be oxidized. Therefore, the quality of oil had an obviously effect on the bitter apricot seed color and quality. So after peeling, bitter apricot seed should avoided light and heat, determining storage environment dry, thus keeping the bitter apricot seed away from oil oxidation.3. The higher blanching temperature and longer soaking time, leading to a higher rate of bitter apricot seed peeled and better reduce of enzyme inactivity, in addition the larger amount loss of bitter almond polyphenols, flavonoids, and amygdalin. Specifically, when the ratio of material to liquor was 1:4 g/mL, bitter apricot seed were close to completely peeled under the blanching condition of 100℃ and 4 min. The higher blanching temperature and the longer soaking time, and the bigger the solid-liquid ratio, contributing to a larger loss of bitter apricot seed polyphenols and there existed a maximum losing amount. The losing weight of bitter apricot seed flavonoids could reach the maximum in the conditions of blanching temperature was 80℃, blanching time was 4 min, so lid-liquid ratio was 1:6 g/mL. Besides, the enzyme activity decreased more, the degree of browning was lower and the losing weight of amygdalin was greater with the precondition of higher scalding temperature and longer peeling time. Therefore, peeling rate, enzyme deactivation effect, and the destroy degree of bitter apricot seed quality should be taken to consideration in plant practice, so as to seek the best process conditions.