Overseas laboratories claiming New Zealand manuka honey is being adulterated with cane sugar have been out-scienced.

Claims New Zealand manuka honey is being adulterated with cane sugar are proven false.

Dr Karyne Rogers at GNS Science has proven internationally-accepted laboratory tests for cane sugar contamination in honey often give false results, causing problems for manuka honey in overseas markets.

Manuka honey's unique properties mean the high bioactivity in the honey affects the results of the test used to detect added cane sugar, says Karyne – the leader of a joint study with participants from 10 international honey testing laboratories examining testing issues.

High bioactive manuka honey shipments worth about $6million failed border tests in 2010, threatening to close market access into the United States and China.

The results led overseas agencies to assume the honey had added sugar, resulting in automatic disqualification by importing countries.

Karyne says the results were false, and her research has led to the acceptance of new, correct test criteria to accommodate New Zealand honey.

'The test itself remains the same, but the interpretation of unusual varieties of honey such as manuka has been changed slightly. Its carbon isotope value is now the main indicator of purity rather than its ‘apparent' cane sugar level.”

So far the United States is the only country to adopt the new test criteria. Other countries are expected to follow.

Last year about $110M of honey was exported, with manuka honey making up the bulk of this. The testing issues meant a considerable amount of the harvest was not immediately exportable to markets such as China, Europe and USA.

A recent consumer survey of manuka honey in Hong Kong has also raised the testing issues.

Of 55 manuka honey samples tested, 14 exceeded the allowable level of added sugar.

To be acceptable to importing countries, honey must have a cane sugar content below 7 per cent by volume.

The new criteria allow atypical honey, such as manuka, to have slightly higher cane sugar levels as long as its carbon isotope value is within a certain limit.

New Zealand honey products were not routinely tested on arrival in destination countries before 2010. However, overseas countries became more vigilant with testing in 2010 in the wake of a sharp increase in honey fraud originating from Asia.

Asian countries were selling inferior sugar-adulterated honey, some of which also contained harmful residues and antibiotics, into premium markets world-wide. The increased testing was useful to detect issues with Asian honey, it but also found that New Zealand manuka honey is prone to failing the cane sugar test.

As a result of test failures in the past three years, bee keepers have either been holding on to their high-value bioactive manuka honey, or blending it with lower activity manuka containing a lower sugar content to bring down its ‘apparent' cane sugar levels.

Changing the test criteria frees up about $40 million of export manuka honey, which previously did not meet the standard laboratory test.

Comvita CEO Brett Hewlett says the results from the HK Consumer Council Honey report, indicating that New Zealand honey's are adulterated with sugar, is a reminder that the trading environment can be tough for New Zealand food producers. Concern about food safety is a global phenomenon says Brett.

Consumers around the world and regulatory authorities from our foreign trade partners are always going to be under pressure to reassure consumers their food is safe, says Brett.

'I don't believe however, that this is an immediate problem; of more concern is the doubt around the testing method that was used in Hong Kong and that it may not cater for the unique nature of Manuka Honey.”

Consumers can be reassured that sugar is not added to actual honey and Comvita's honey is routinely checked as part of its quality control system, says Brett.