Researches On Apple Cuticular Wax And Its Changes During Developing And Storage Period

An excellent waxy covering is one of good characteristics of fruits and vegetables. The researches on wax covering characteristic and its metabolic process are important to improve fruits and vegetables storage resistance, disease resistance and water retention. In this paper, the methods of apple fruits (Malus domestica Borkh c.v.Fuji) cuticular wax extraction and detection were optimized. The cuticular wax content, composition and changing during growth and development stages of Starkrimson, Fuji, Ralls apples, and the cuticular wax content, composition and changing during cold storage of Sansa, Gala, Qiujin, Maton 1, Starkrimson apples were also studied. Also the effection of wax during the room temperature storage of Starkrimson apple was researched by cotting or removing the cuticular wax. And the effects of ethylene on cuticular wax content, composition and change during cold storage of Fuji apple were studied after 1-MCP or ethephon treatment. Main results were as follows:The optimal wax extraction agent is chloroform, with extracting for 10 seconds at 25℃, and the best temperature program which is used on GC is as follow: the beginning temperature is 120℃, held for 2 min, then were raised by 10℃/min to 190℃, then raised by 2℃/min to 216℃, held for 5 min, then raised by 3℃/min to300℃and held for 5 min. Wax components were identified by MS with He as carrier gas and the mass spectrometric detector (70 eV, m/z 50-850), the inlet pressure were constant at 30 kPa. Twenty kinds of wax substance were obtained by this method.Through the studyies on the waxy components and changes of Rall, Fuji, Starkrimson apple during the growth and development, it was found that the wax quality distribution density (WQDD) in this three apples were higher in young fruit period and mature period, and lower in rapid expansion period. During the whole development, fatty acid with chains length less than 18 carbon were accumulated lower than that with above 18 carbon. In young fruit period, acids had the highest content in all the composition of each kind of apples wax, in mature stage, each kind of apple has its own highest levels of wax component: the substance with highest content in Fuji, Rall, and Starkrimson was ester, alcohol and acid, repectively.The changes of cuticular wax during the cold storage of Sansa, Gala, Qiujin, Mato 1, Starkrimson were not completely consistent: the WQDD of Mato 1 and Starkrimson showed a rising trendence, The Sansa and Gala declined. At 0 days of storage, the aldehyde substance in Mato 1, Qiujin, Sansa, Gala, Starkrimson apple was the lowest of all the epidermis wax contents, while the acid substance, alkanes, acid substance, alkanes, acid substances is higher. At the end of the storage period, the ester substance, acids, esters, alcohols, acids is higher, and the ldehydes substance, aldehydes, alkenes, alkanes, substance, aldehydes was lower. During the entire process of storage, the ester substances content in the epidermis wax of various varieties of apple showed a rising trendency, and the alcohols content showed a rising trendency only in apples of Sansa and Mato 1.Both cotting and removing wax can inhabite the increasing of the SSC and TA content at the early stage of storage. Two treatments both inhibited the respiration and ethylene release rate and membrane permeability of Starkrimson apple during room temperature storage.The aldehyde contents in the cuticular wax of Starkrimson apple fruits during cold storage (0℃) were lower in the treatments of 1-MCP, ethephon and CK,while acids and esters contents were higher.1-MCP increased the contents of aldehyde, esters, alcohols and acids, but decreased the contents of alkene substance, alkanes. Ethylene increased the contents of of acids and alkanes, and decreased the contents of alkene and esters.