超声波释放橙汁糖苷键合态香气物质的规律及其机制研究

Abstract: The loss of Key aroma componds of orange juice after processing is a major problem for orange industry, and releasing the glycosidically bound volatiles (GBV) in orange is an effective approach to keep or increase the good aroma quality. However, the current hydrolysis methods had some drawbacks, such as strong pungent odour after acid hydrolysis, long enzyme hydrolysis time and so on. It is inferred and verified that ultrasound can release GBV based on the finding that the aroma of citrus juice or peels obviously increased under ultrasound treatments during the previous investigation of sonochemical effects of bioactive compounds in citrus. The objectives of this project are as follows: The investigation on rules of releasing GBV under ultrasound treatments; The mechanism exploration of releasing of GBV under ultrasound treatments: (1) The relationship between sonochemical effects and the breakdown of glycosidically bond, (2) How cavitation of ultrasound activate endogenous β-D-glucosidase. Developing a new releasing GBV method. The methods: SPME-GC-MS, GC-O and theory of cavitation effect and sonochemical effects will be used in the investigation of the project. The project will improve our knowledge on mechanism of releasing GBV and supply method reference for the aromatizing of fruits juice.

特征香气的丧失是目前橙汁产业中的严重问题，释放橙汁内在的糖苷键合态香气物质（glycosidically bound volatiles，GBV）被认为是一种有效的途径，但传统的基于酸和酶的GBV的释放方法存在酸解后刺激性气味浓和酶解时间长等缺点。申请人基于前期超声场中柑橘活性成分声化效应的研究，发现功率超声处理的柑橘样品香气明显增强，推测并初步验证超声波释放了柑橘内的GBV，但超声场中GBV配基与糖之间的糖苷键如何切断释放香气成分等科学问题尚不清楚。本项目拟采用SPME-GC-MS、GC-O的方法，结合超声波空化效应原理，研究橙汁GBV在超声场中的释放规律，阐明多途径释放机理：（1）超声波声化效应切断不同配基与糖之间糖苷键作用机制（2）超声波空化效应激活橙汁内源β-D-葡萄糖苷酶的机制。同时建立释放GBV的新方法。本项目将深化对GBV释放机理的认识，为果汁的增香提供方法学上的借鉴。

特征香气的丧失是目前橙汁产业中的严重问题，释放橙汁内在的糖苷键合态香气物质被认为是一种有效的途径。针对上述产业问题本项目在国际上首次提出并建立了超声波果汁增香的方法，并揭示了相关的增香规律，阐明了超声波增香的机制。该应用基础研究处于国际领先水平。主要创新性结果如下：.（1）揭示了超声场中键合态香气物质的释放规律，超声波通过空化效应能够释放键合态香气物质，超声波与传统酶法相比能够释放更多种类的香气物质，超声条件下释放的香气物质主要是萜烯类、酯类和醛类，而酶法释放的主要是醇类和酯类。香气物质的释放含量及种类显著的受超声波条件的影响。.（2）阐明了超声波释放键合态香气物质的两个机制，机制一：超声波可以通过直接打断糖苷键释放香气物质；机制二：超声波通过激活橙汁中的β-D-葡萄糖苷酶的活性，进而通过酶的作用酶解糖苷键而释放香气物质。. （3）基于上述规律和机制的研究，建立了超声波联合酶法的橙子增香的方法，但是超声波激活酶后再作用的方式更有于提升果汁的香气，但是超声波和酶同时作用的方式在具体应用中有缺陷。. 综合以上结果，本项目的主要创新点在于建立了一种零添加的物理果汁增香的新方法，同时阐明了新方法的内在科学机制。本项目成果有很好的应用前景，可改变目前果汁加工中香味不足及添加香精的现状，为消费者提供营养、安全卫生，可放心食用的特色果汁，保障国民的身体健康。