Rogers, K.M. 2014 Why is New Zealand honey failing sugar adulteration tests? : a final report for AGMARDT and co-authors. Lower Hutt, NZ: GNS Science. GNS Science report 2014/02 25 p.
Abstract: Between 2010 and 2012 more than $6M of New Zealand manuka honey exports failed an internationally accepted sugar adulteration test (AOAC 998.12 method) at overseas borders, causing market access issues and damaging the integrity of the New Zealand honey industry. As a result, an 18 month AGMARDT and industry funded project to examine different honey varieties (676 manuka and 324 monofloral varieties) commonly produced in New Zealand was undertaken by Dr Karyne Rogers, supported by staff of the Stable Isotope Laboratory at GNS Science, to see which honeys are prone to failure and further testing showed that C-4 sugar feeding (a common practise among bee keepers to give extra sustenance to bee populations during nectar dearth) at inappropriate times was not the key cause for these fails. Instead frequent test fails were found to be mostly associated with bioactive (having some moderate to high level of methylglyoxal content) manuka honey. Through AGMARDT and industry funding, this study was able to show that during the process of storage and/or heating of bioactive manuka honey, the protein carbon isotope ([delta]13C) values in the honey (used as an internal comparison with the honey isotope value) were often changing over time. This change was usually sufficient to shift the protein isotope value more than 1 away from the corresponding honey isotope value. However, the widely accepted interpretation of the AOAC 998.12 test states that when honey and protein isotope values have a difference of more than 1 (the unit of isotopic measurement) the honey is considered to be adulterated with C-4 sugar. The research outcomes were disseminated at bee industry meetings, field-days and conferences around New Zealand, as well as through popular press, media articles and peer-reviewed publication. It permitted industry awareness of the frequency of sugar testing fails and the consequences for not testing honey before export (rejection and destruction of the product at receiving ports), as well as emphasising the continued need to reduce sugar feeding to ensure sugar fails were not due to excess sugar syrup feeding of bees. (auth)
