C4 Sugar And Moisture Results From Last Season

Friday, January 14, 2022, Author: Leanne McGill

A review of test results can give interesting insights into how honey produced in one season compares with other seasons. In this article we compare the results of two common tests that are important indicators of honey quality—C4 sugars and moisture—over the past two years. We filtered our database of results from the past two years to focus on samples of recently extracted honey tested in 2019/20 and 2020/21 (the most recent season). Many more C4 sugar results were below 3% in 2020/21, which was a big improvement on the prior year. Perhaps this indicates a positive effect of changes in the way sugar syrup is used by beekeepers to feed hives in the winter and spring. Moisture content above 18% represents an increasing risk of honey fermenting, and there were more samples with a higher moisture content in the 2020/21 season. Labs have only limited information about the samples they receive for testing. To try and ‘compare apples with apples’ for this article, we have compared freshly extracted honey from 2019/20 (the extraction season before last) and 2020/21 (the most recent harvest). We identified this honey by choosing results from samples received between November and May (the period when most extraction of fresh honey is taking place) with a low HMF (of 5 mg/kg or less). Most samples had some mānuka content.



This test has gone from being very uncommon five or six years ago, to being one of the most common tests carried out in mānuka honey today. It is used to check whether the honey will meet the import regulations of some countries, and a limit of 7% C4 sugars is usually applied. It is a published testing method, originally developed in the 1980s (AOAC 998.12), to detect honey that had been adulterated by adding cane sugar syrup or high-fructose corn syrup. The New Zealand BeeKeeper has published numerous articles about C4 sugar testing for those wanting to learn more about the test and how it works (Chernyshev, 2017; Rogers & Braggins, 2018; Chernyshev, 2018). The issue with C4 sugar testing in mānuka honey is that test results do tend to increase over time, especially in higher-grade honeys. So low test results (ideally less than 3%) at extraction are important if honey is to test below 7% C4 sugars when mature (12–24 months later). Figure 1 compares the percentage of samples in different ‘bands’ of results in the two extraction seasons. Colour coding has been used to highlight the risk of the honey having a C4 sugar test result greater than 7% when mature, based on the increase commonly seen in mānuka honey over time. The good news is that a much higher percentage of honey had a low C4 sugar result at extraction in the most recent season when compared with 2019/20—about twice as much, in fact. Beekeepers have been developing practices that aim to reduce the amount of sugar syrup from early season feeding that makes its way into honey. These results may be showing a positive impact of these practices. There is still some honey produced with very high C4 sugar results. In both seasons the highest sample was over 50% C4 sugar using this test, and the average of the 20 highest samples was 29% (2019/20) and 20% (2020/21). These could be from hives used in pollination, where a lot of sugar syrup can be fed. Some people question the value of the C4 sugar test, especially given the way results change in mānuka honey. Unfortunately, while our overseas markets are using the test as part of their regulations, we will be stuck with it. There are a range of other sugar adulteration tests used around the world, using instruments with acronyms like NMR, HRMS, LC-MS/MS, and LCIRMS. These tests are very expensive (they can be hundreds of dollars a sample) and at this point there has not been enough testing of New Zealand honey using these to provide any comparisons like the ones above.