广西宽皮柑橘“蓝皮”果产生的生理原因初探

Physiological Mechanisms for the Phenomenon of“Blue albedo”Fruits of Citrus reticulata in Guangxi

近些年,部分柑橘产区相继报道宽皮柑橘(Citrus reticulata Blanco)果实出现白皮层呈蓝色的"蓝皮"果现象,表现为在白皮层近囊衣侧出现蓝色斑块或蓝色区域。为探明其原因,以广西3个产区采集的‘沃柑’、‘贡柑’和‘马水橘’的正常果及其各自的"蓝皮"果为材料,分别对白皮层中花青苷等类黄酮物质、矿质元素进行了检测和分析;同时,利用GC–MS分析成熟期白皮层和汁胞中可溶性糖和有机酸,以明确风味品质的变化情况。结果表明:该蓝色并非花青苷类和黄烷酮类物质积累所致;成熟期"蓝皮"果白皮层中5种聚甲氧基黄酮的含量显著上升;蓝色白皮层中Ca、Mg、S、Zn、B和Ba含量均与对照有显著差异,但变化趋势没有一致性,基于21种矿质元素含量的OPLS-DA分析可以将"蓝皮"果和正常果区分开,其标志性元素为K,其次是S;蓝色白皮层及其汁胞中的苹果酸和蔗糖含量较正常果均有显著提升。因此,蓝色白皮层的形成可能与逆境胁迫下多种矿质元素络合物或螯合物的积累有关。

In recent years,abnormal fruits of Citrus reticulata Blanco with commonly known as“Blue albedo”were reported to appear in some citrus producing areas.The phenomenon of blue patches or blue areas near the segment membrane side of the albedo arouses the common concern of consumers and growers.In an attempt to clarify the reason behind,the normal fruits of three loose-skinned mandarins,including Orah mandarin,Gonggan mandarin and Mashuiju tangerine,and their respective“Blue albedo”fruits were collected from three production areas in Guangxi.Anthocyanins and other flavonoids,mineral elements in the albedo were detected and analyzed.Simultaneously,soluble sugar and organic acids in the albedo and juice sacs were analyzed by using GC-MS,so as to illustrate the changes of flavor quality.The results showed that the blue color was not caused by the accumulation of anthocyanins and flavanones;the contents of 5 polymethoxyflavones in the albedo of“Blue albedo”fruit increased significantly at ripening;compared with the control,the contents of Ca,Mg,S,Zn,B and Ba in the blue albedo had significant differences,but without consistent trend.OPLS-DA analysis based on 21 mineral elements could distinguish the“Blue albedo”from the normal albedo,with K as the first marker element and S as the second.Compared with normal fruits,the content of malic acid and sucrose in blue albedo and its juice sacs increased significantly.Therefore,the formation of“Blue albedo”fruit may be related to the accumulation of various mineral element complexes or chelates under stress.