Capped Honey Moisture Content from Four Honey Bee Species; Apis dorsata F., Apis florea F., Apis cerana F, and Apis mellifera L. (Hymenoptera: Apidae) in Northern Thailand

INTRODUCTION

Water content is a crucial quality parameter for practically all food products and their ingredients. Water has a substantial, if not decisive, influence on the quality and especially the shelf life of practically all materials of biotic origin. Water content is an important aspect of overall “quality control” for food products and this also applies to honey. Excess honey moisture can be a problem for beekeeping in tropical areas. A potential problem for high moisture honey is fermentation as it has been shown that the probability of fermentation is highly linked to moisture content (White, 1975). Honey fermentation is activated by the presence of osmotolerant yeast species utilizing the primary honey sugars (fructose and glucose), producing ethyl alcohol and carbon dioxide. Most yeast species associated with honey fermentation are within the genus Saccharomyces but there are reports of other yeast genera as well (Snowdon and Cliver, 1996). Moisture content is also connected to additional honey quality issues e.g., viscosity and crystallization.

There are five honey bee species in Thailand; the indigenous Apis andreniformis Smith, A. florea F., A. cerana F. and A. dorsata F. along with A. mellifera L. the western honey bee, an introduced exotic species. Honey from all indigenous species is sought after in traditional honey hunting scenarios. The Thai Ministry of Public Health found excessive honey moisture content in randomly examined retail honey products, moreover, yeast and some fungi infected wild honey which resulted in excess fermentation (MGR online, 2017). The authors have also observed indigenous “wild” honey at the retail level, frequently exhibits outward signs of fermentation. The Thai Ministry of Public Health has established a standard for moisture content in honey as 21 g/100 g (≤21%) (The Ministry of Public Health, 2000). CODEX (FAO, 2001) and the EU require that no honey should have a moisture content exceeding 20%, although these longstanding international standards apply to A. mellifera only (Bogdanov and Martin, 2013). Beekeeping organizations in various countries (e.g., Germany, Belgium, Austria, Italy, and Switzerland) have set a maximum moisture content not to exceed 18~18.5% for A. mellifera honey (Swiss Bee Research Centre, 2000). Chirife et al. (2006) measured some essential features of the relationship between water activity and moisture content in honey. A noteworthy relationship was found between both parameters in the range examined (15~21% moisture).

Honey moisture content has been reported from numerous investigations for Asian Apis species (i.e., Joshi et al., 2000; Balasubramanyam, 2011; Iftikhar et al., 2011). Traditional reports of honey moisture result from samples of centrifugally extracted honey and/or honey removed from storage cells via a crush and drain technique, both of which represent an aggregate honey taken from many hundreds to many thousands of honey storage cells. Often these extractions of honey from cells will include a combination of both capped honey cells and uncapped honey (nectar) cells. Our objective was to elucidate honey moisture values as found in capped honey storage cells for 4 Apis species as encountered in northern Thailand. We approached this by examining honey only from individual capped honey storage cells. It is assumed that honey beneath capped storage cells has been dehydrated by the worker bees to as low as ambient and colony conditions allow. This is opposed to uncapped honey storage cells which contain nectar in the process of being dehydrated. Concerning A. mellifera Maurizio (1975) states that honey storage cells are sealed when the moisture is below 20%.

MATERIALS AND METHODS

Honey combs from seven A. florea, six A. dorsata, nine A. cerana, and seventeen A. mellifera colonies were collected from January to December 2016. All colonies were located within a 15 km radius of metropolitan Chiang Mai in northern Thailand (18°58ʹN). All honeycombs possessed both capped and uncapped storage cells. Individual capped honey cells were carefully decapped and the honey removed by micropipette. Honey moisture from individual capped cells was determined using a hand-held honey refractometer (Atago model N-3E).

RESULTS

Table 1 summarizes the findings. The data demonstrate that the average honey moisture from only one species (A. mellifera) falls below a “mandated” 20%, although A. florea honey averaged only slightly higher than 20% while A. cerana and A. dorsata exceed 20% at levels of 21.2 and 22.7% respectively. It should be noted that the average honey moistures results from a wide range of moisture with capped honey high moisture outliers found in all species sampled (≥24.5%). A comparative study by Iftikhar et al. (2011) provided similar results with the caveat that their honey sample collection methodology was by straining entire combs as opposed to our examining individual capped cells. The Joshi et al. (2000) report examined honey from A. mellifera, A. dorsata and A. cerana and again our results are similar. They provide no explanation as to how the honey samples were obtained other than saying from cut honey comb, but we assume that both their samples, as well as those from the Iftikhar et al. (2011) study, represent honey moisture values from an aggregate of honey storage cells. Balasubramanyam (2011) states his A. cerana honey samples were obtained by centrifugal extraction of honey combs and that the A. florea and A. dorsata samples by crushing and draining honey combs, which again results in aggregate samples from hundreds to thousands of honey and nectar cells. Their results in a comparison to what we report, are summarized in Table 2.

Table 1.

Average (±SD) and range of capped honey moisture content of four species of honey bees in Northern Thailand

Table 2.

Comparative values of honey moisture reported from SE and Central Asia

DISCUSSION

Our observations support a hypothesis that moisture content in capped honey cells of indigenous honey bee species is most often higher than the international regulations which define honey derived for the western honey bee A. mellifera. Interestingly, the A. mellifera capped honey moisture from this report averaged 18.8±1.2%, the lowest of all species examined. White et al. (1962) in a classic study of American honey, found an average moisture of 17.2±1.5% from a sampling of 490 unifloral A. mellifera honeys. In a survey of commercial A. mellifera honey from northern Thailand, the average honey moisture from unifloral honeys, ranged from 19.9 to 20.2% (Santhasup et al., 2009), which along with our results, demonstrate that even under the temperature and humidity constraints of northern Thailand, honey from the temperately evolved A. mellifera is produced with a moisture content within recognized international standards. As cogently stated by Ward (2000), in tropical regions with high relative humidity (RH) and high temperatures, honey bees must expend more energy to reduce moisture in ripening honey than in temperate regions where the RH and temperatures are lower, which suggests that the indigenous honey bees might ultimately cap honey at higher moisture levels than those traditionally shown for A. mellifera honey. Our finding support that supposition.

The Government of Thailand has noted that wild honey products taken from forest areas have a high moisture content. This has resulted in accusations of alleged production of fake honey or adulterated honey. Our data show that capped honey stores of indigenous species have moisture contents often exceeding 21%, with the exception of A. florea. While Maurizio (1975) states that A. mellifera capped honey possesses a moisture content ≤20%, such cannot be said for several Asian honey bee species, i.e., A. cerana and A. dorsata, which averaged 21.2% and 22.7% moisture respectively. In the future development of national and/or international honey standards, it needs to be taken into account that honey moisture from indigenous tropical species can frequently be in excess of 20%.

References

• Balasubramanyam, M. V., (2011), Chemical characteristics of multifloral wild and apiary honey from Western Ghats of Karnataka, Bioscan, 6(3), p467-469.
• Bogdanov, S., and P. Martin, (2002), Honey authenticity, Mitteilungen aus dem Gebiete der Lebensmitteluntersuchung und Hygiene, 93, p232-254.
• Chirife, J., M. C. Zamora, and A. Motto, (2006), The correlation between water activity and % moisture in honey: Fundamental aspects and application to Argentine honeys, J. Food Eng., 72(3), p287-292. [https://doi.org/10.1016/j.jfoodeng.2004.12.009]
• FAO/WHO, (2001), CODEX Standard for honey, p8.
• Iftikhar, F., M. A. Masood, and E. S. Waghchoure, (2011), Comparison of Apis cerana, Apis dorsata, Apis florea and Apis mellifera honey from different areas of Pakistan, Asian J. Exp. Biol. Sci., 2(3), p399-403.
• Joshi, S. R., H. Peckhacker, A. Willam, and W. von der Ohe, (2000), Physico-chemical characteristics of Apis dorsata, A. cerana and A. mellifera honey from Chitwan district, central Nepal, Apidologie, 31(3), p367-375.
• Maurizio, A., (1975), How bees make honey, p77-105, in Honey a Comprehensive Survey, ed. byE. Crane, Chapter 2, Heinemann, London.
• MGR online, (2017), The standard check of the Department of Medical Science found infested yeast and fungi in wild honey, not standardized [In Thai], Available: http://www.manager.co.th/QOL/ViewNews.aspx?NewsID=9600000062998 June 20, 2017.
• Santhasup, C., P. Kongpitak, P. Chantawannakul, S. Pakuthai, and K. Sringarm, (2009), Study of honey quality and safety criteria and good agricultural practices manual for bee farms. (In Thai), Faculty of Agriculture, Chiang Mai University, p118.
• Snowdon, J. A., and D. O. Cliver, (1996), Microorganisms in honey, Int. J. Food Microbiol., 31, p1-26. [https://doi.org/10.1016/0168-1605(96)00970-1]
• Swiss Bee Research Centre, (2000), Honey quality, methods of analysis and international regulatory standards: review of the work of the international honey commission, p15.
• Thai Ministry of Public Health, (2000), Notification of the Ministry of Public Health (No.211) B.E. 2543 “Honey” [In Thai], p3.
• Ward, R., (2000), Psychometrics and the problem of excess moisture in tropical honey, Proceedings Seventh IBRA Conference on Tropical Bees: Management and Diversity, Chiang Mai, Thailand, p49-53.
• White, J. W., (1975), Physical characteristics of honey, p207-239, in Honey a Comprehensive Survey, ed. byE. Crane, Chapter 6, Heinemann, London.
• White, J. W., M. L. Riethof, M. H. Subers, and I Kushnir, (1962), Composition of American honeys, USDA Technical Bulletin No. 1261, p124.