Content of phenolic compounds in monofloral aroeira honey and in floral nectary tissue

Abstract The objective of this work was to quantify the content of total phenolic compounds in monofloral honey from aroeira (Astronium urundeuva) trees and to verify, through histochemical tests, if these compounds are present in the floral tissues. The apiary, with Apis mellifera bees, was installed among aroeira trees in the semiarid region of the state of Minas Gerais, Brazil. From the anatomy of the flowers and of the inflorescence rachis, an ornamented epidermis, tector and glandular trichomes, idioblasts, and a developed secretory system were observed. Aroeira honey has an average phenolic content of 142.5±22.6 mg 100 g-1, a value considered very high when compared with those of other monofloral honeys from Brazil and around the world. Histochemical tests detected the presence of phenolic substances in the idioblasts and secretory ducts associated with the phloem in the floral tissues, especially in the nectar parenchyma, epidermis, and glandular trichomes. Phenolic compounds are present in the floral tissue of both floral morphs, mainly in the nectary where honeybees collect nectar. The obtained results are the first, in the literature, indicative that the phenolic compounds produced by aroeira trees are transferred through the nectar to the honey. This study contributes to the establishment of quality standards for monofloral aroeira honey and to the identification of its botanical origin.

摘要 本研究旨在定量分析阿罗埃拉树（Astronium urundeuva）所产单花蜂蜜中的总酚类物质含量，并通过组织化学试验验证这些酚类物质是否存在于其花组织中。研究将意大利蜜蜂（Apis mellifera）的蜂群安置于巴西米纳斯吉拉斯州半干旱地区的阿罗埃拉树林中。通过对花及花序轴的解剖观察，可见其具有纹饰表皮、被毛与腺毛两类表皮毛、异细胞以及发达的分泌系统。阿罗埃拉蜂蜜的总酚类物质平均含量为142.5±22.6 mg·100g⁻¹，与巴西及全球其他单花蜂蜜相比，该数值被认为处于极高水平。组织化学试验检测到，花组织中的异细胞以及与韧皮部相关的分泌导管内存在酚类物质，尤其在花蜜薄壁组织、表皮及腺毛中分布显著。两种花型的花组织中均含有酚类化合物，主要集中在蜜蜂采集花蜜的蜜腺部位。本研究所得结果为学界首次证实：阿罗埃拉树合成的酚类物质可通过花蜜转移至蜂蜜中。本研究可为阿罗埃拉单花蜂蜜的品质标准制定提供参考，并为其植物来源鉴定提供科学依据。