Vitamins in Honey

Assay of B Vitamins and other Water-soluble Vitamins in Honey... 

The vitamin content of honey is very low and its contribution to the human daily intake is generally negligible. Pollen is considered the main source of vitamins in honey and commercially clarified samples often show low concentrations of these analytes (Haydak et al. 1943). Table 13.3 reports the ranges of vitamin concentrations found in nectar honeys of different floral origins. 

Very little work has been done until now on the determination of water-soluble vitamins in honey. Many factors contribute to this situation. Among them, the low amount of these analytes in honey has probably played a key role. 

Due to the low concentration of B group vitamins in honey, the measurement of the analyte requires a very sensitive method. Colorimetric, spectrophotometric, spectrofluorimetric, microbiological and reversed-phase HPLC (RP-HPLC) analytical approaches have been used until now. 

In recent years, RP-HPLC with UV (or fluorescence) detection methods have also been successfully used for the determination of B vitamins in honey. Vinas et al. (2004a, 2004b) proposed quantifying vitamins B2 and Bg with chromatographic methods using fluorescence detection. In their protocol for B2, the stationary phase is an end-capped amide-based column and the mobile phase is a 10 90 v/v acetonitrile/phosphate buffer (pH = 5). The protocol for Bg is... 

Microbiological methods used for the determination of B group vitamins in honey. 

Given the low concentrations of vitamins in honey, the choice of LoD and the method used to validate are of particular importance. Table 13.5 summarizes the most representative validation parameters for LoD and LoQ reported in the literature. Notwithstanding its importance, the LoD is rarely reported in published methods. Moreover, when a LoD is indicated all too often the approach used for its evaluation remains unknown. As a consequence, it is not uncommon to see similar published methods exhibiting LoD values differing by several orders of magnitude ... 

A CRM for vitamins in honey does not exist at present and it is unlikely that one could prepare a RM due to the known instability of analytes. Therefore, to evaluate the bias, one must analyse the material by independent methods (Leon-Ruiz et al. 2011) or, more commonly, evaluate the recovery of known amounts of analytes spiked to honey. The first method is based on the fact that there is a negligible statistical probability that two independent methods may provide data affected by same bias, whereas in the spiking/recovery technique, recovery values statistically indistinguishable from 100% e.g. for a two-tailed t-test) indicate the absence of a bias. Table 13.5 shows recovery values of between 85 and 108.7%. Although a number of these recoveries different from 100% probably indicate some bias, it has been previously observed (AOAC 1998) that for low concentration levels recoveries can normally differ from 100%. AOAC guidelines (AOAC 1998) consider recovery levels between 80%... 

The amount of water-soluble vitamins in honey and their concentrations can be a strong indicator of the geographical origin and the freshness of the honey. 

Water-soluble vitamins in honey have been often determined using methods not specifically developed for this matrix. 

While data published in the literature are quite homogeneous regarding the amount of B group vitamins in honey, the reported concentration of vitamin C in honey varies widely over several orders of magnitude. 

The amount of vitamins in honey is low and only water-soluble vitamins are usually found in honey. 

There is a general lack of analytical methods capable of determining contemporary water-soluble vitamins in honey. 

Analytical protocols used to measure water-soluble vitamins in honey have rarely been validated. 

Ciulu M, Solinas S, Floris L, Panzanelli A, Pilo MI, Piu PC, et al. RP—HPLC determination of water-soluble vitamins in honey. Talanta 2011 83 924—9. 

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