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Test on Honey Reveals Antibiotic & Pesticide Residues in 13 Samples Wide Variation in Freshness, Foreign Sugar Adulteration in 7 Samples

  • 2018.07.16

In the quest for health, many consumers habitually include honey in their diet.  Fueled by recent claims of Manuka honey having antibacterial properties, Manuka honey costing easily over $1,000 still gains wide popularity notwithstanding scant clinical medical research validating such claims available.  The Consumer Council carried out a test on 45 models of honey commonly available in the market and thus revealed the presence of possibly carcinogenic antibiotic residues in 2 of the samples, one of which has since ceased to be sold.  Consumers should be aware that antibiotic residues could trigger allergic reactions in some people.  There is currently no maximum residue level (MRL) set for antibiotic and pesticide residues in honey in Hong Kong.  The Council suggests that the Government draw reference from the international standards or EU regulation, and devise related guidelines for the honey manufacturing industry to follow to strengthen consumer health protection.

In addition, the test also revealed quality issues in the honey. Foreign sugars was found in 7 samples and the freshness of 9 samples was found to be less than satisfactory.  These findings indicated that there has not been any notable improvement in quality in terms of foreign sugar adulteration and also freshness since the product was last tested by the Council in 2013.  In contrast, significant improvement was found in the Manuka samples with regard to claims in antibacterial activity and their actual measured performance.  In order to safeguard consumer rights, the Council urges honey producers to improve the quality of honey and to ensure that their products are as described in their claims.

In this research, 45 honey samples, comprising 35 general honey and 10 Manuka samples, were tested for their product safety and general quality in accordance with the standards of the Codex Alimentarius Commission (CODEX), the World Health Organization (WHO) and the International Honey Commission (IHC).  The overall performance rating of each model was a summation of their scores in product safety, general quality, the source of origin analysis and packaging claims.  The results showed considerable variations among the 35 general honey samples.  Despite 12 samples scoring the highest with 5 points, 5 samples scored poorly, achieving a rating of only 2 points or below.

Safety Test 

Of the 2 models with antibiotic residues, both were found to be general honey, 1 sample was found to have up to 8 antibiotics including metronidazole which has been proven to be carcinogenic when tested on laboratory animals and this honey is not being sold any more.  The other sample was found to contain 2 antibiotics including nitrofurans, a genotoxic carcinogen that may induce genetic mutation affecting male reproductive system.  According to the CODEX standards and the regulations in the Mainland, European Union (EU) and the United States (US), both antibiotic metronidazole and nitrofurans are not allowed to be fed to food-producing animals.  The Council has since referred the test findings for follow-up by the Centre for Food Safety (CFS).

Of the other antibiotic residues detected in the 2 samples in question are sulfonamides, and streptomycin, etc.  Despite their being slight level in the sample, the University of Hong Kong’s Centre for Infection has indicated that 1% to 3% of the population may be allergic to various kinds of antibiotics, in particular, the antibiotic sulfonamides and even small quantities may trigger allergic symptoms, for instance, skin rash and swelling of the face, mouth and tongue. In the most severe case it could even be life-threatening.

In the EU and the US, the use of antibiotics in beekeeping is strictly regulated with Switzerland and the United Kingdom having established action limits for each antibiotic group.  Since WHO has recently classified the issue of antimicrobial resistance (AMR) to drugs in agricultural foods as one of the global public health crises that needs to be addressed.  The Council recommends the Government to draw reference of international standards in setting up related food safety guidelines.

Quality Test

In accordance with the CODEX standards, honey should not be adulterated with foreign sugars or other substances.  However, 7 samples were detected with foreign sugar adulteration.  Among them, 6 were general honey samples.  In the 4 most serious cases, the measured level of sugar adulteration was as high as 13% to 85%.  In particular, 1 sample sold as “Centifloral Honey” and labelled containing “centifloral honey, fructose” as the ingredients found to contain a sugar adulteration content (of C4 plant sugar), which mainly comes from sweet corns and sugar cane syrup, of up to 85%.   This is similar to a sample produced by the same brand but sold with a different name in the Council test in 2013.  The 2013 test also showed similar sugar adulteration in 6 general honey samples. 

Furthermore, a Manuka honey sample priced at over $1,000 was also found to contain foreign sugars.  The Council would like to emphasis that if traders adulterated highly-priced natural honey with low-cost syrup, they could be misleading consumers.  The industry is strongly urged to make every effort to address this serious problem. 

Freshness is always an important consideration for food purchase.  But the freshness of many of the honey samples was found to be less than satisfactory, with some of the samples found to have fermented or there was a change in smell.  The test inspected the hydroxymethylfurfural (HMF) content in the product.    The results showed 5 samples had a HMF content of more than 80mg/kg which means that they are non-compliance of CODEX guidelines on general honey as well as the honey produced in tropical countries or regions.  Further, the test found that the total yeast count of 6 samples to be high, with 1 sample developing fermentation smell and taste, which makes it suitable for use only as a food ingredient.  Under microscopic analysis, 3 samples were shown to contain large quantities of foreign solid constituents and this falls short of the EU directive on honey standards.

Besides freshness, the source of origin is another important factor to consumers.  Analysis was carried out on the pollen in the honey to determine the source of origin. According to the laboratory test done in Germany commissioned by the Council, among the 41 samples with sufficient pollen for analysis, 3 were labelled with source of origin at variance with the analysis results – 2 labelled from Germany turned out to be from “West Mediterranean” and “South America, Central America and West Mediterranean” respectively, and another 1 labelled from Egypt was judged to have come possibly from China.  The Council stresses that the right to have accurate information a basic consumer right and called on honey producers to improve their labelling to avoid misleading consumers.

Manuka honey claiming to have antibacterial properties has gained wide popularity in recent years, with prices varying from several hundred dollars to more than $1,000 per bottle.  Among the 10 Manuka honey samples, 9 used the Unique Manuka Factor (UMF) or Methyglyoxal (MGO or MG) as the antibacterial activity units.  The test found that the UMF or MGO values declared on the product packaging to correspond with the actual measured values, a marked improvement from the 2013 test findings when only 60% (9 out of 15 samples) measured up to the test findings.  Consumers should pay heed to the fact that while clinical research tested on human mainly focuses on the usage of Manuka honey on top of wounds, for example, healing the wounds after surgical operation, findings validating the benefits of Manuka when eaten are still very limited.  

The prices of the 10 Manuka honey samples ranged from $43 to $268 per 100g.   The 8 samples awarded with the top overall rating (5 points) included both the highest and the lowest priced samples.  1 sample, an average of $218/100g, was detected to contain trace amounts of pesticide residues as well as containing foreign sugar, and scored only 2 points, indicating poor quality of the product. 

Prices of the 35 general honey samples also varied widely from an average of $3 to $134 per 100g.  Consumers can choose according to the flower species, source of origin and word of mouth based on their preference and affordability.  It is worth noting that of the 12 general honey samples with top scores of 5 points, 11 were sold at an average price below $50 per 100g.  Therefore, honey that is of good quality and at an affordable price does available.

Tips for honey consumption:

  • Infants should not consume as it may cause infant botulism;
  • The ideal temperature to store honey is between 18 to 24°C.  Avoid direct sunlight when storing honey in room temperature;
  • When serving, tilt the bottle and use dry clean cutlery to spoon out the honey.  Once opened, honey should be consumed as quickly as possible;
  • When mixing honey with water, the water temperature should be below 60°C so as not to destroy its nutrient content;
  • Honey is acidic so avoid contact with metallic containers or spoons;
  • As honey is a type of free sugars; excessive consumption should be avoided to prevent the risk of obesity and dental cavity, etc.

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