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Home » Archive » 2020

TDK conference 2020

Detection of honey adulteration with redox potential measurements
Németh Réka - year 6
University of Veterinary Medicine Budapest, Department of Food Hygiene
Supervisors: Dr. Katalin Szakmár, Dr. Dóra Tőzsér

Abstract:

Honey has a significant antimicrobial effect, which is mostly due to its content of hydrogen peroxide, the phytochemical methyglyoxal and a peptide called defenisin-1 which is extract by honey bees. According to some research results, its anti-inflammatory properties are due to polyphenols and flavonoids. The enzyme contents of honey start to break down over temperatures above 40°C.

Premium honey is quite expensive, it’s been the main target of food adulteration since the 70s. Producers tend to to adulterate honey with cheap sweet foreign components which they don’t mark or mix high quality honey with a worse one so they could sell it for higher price, labeled as pure honey. Most of the agricultural producers have to guarantee product traceability throughout the food chain however this rule isn’t apply to honeys in the European Union. Thus, good quality honey mixed with low quality, imported honey may be sold. In order to retain honey’s worldwide popularity and consumers’ confidence, people have been researching a variety of reliable, yet fast and simple methods to identify adultered honeys. And even now, it seems that no single method is sufficient alone to do so.

During our research, we graded the antimicrobial properties of honey samples based on redox potential measurements using a MicroTester device. We studied the proliferation of Escherichia coli and Staphylococcus aureus in ½ concentration tryptic soy broth (TSB) on a temperature of 30°C and on a brilliant green bile lactose broth (BBL) medium on a temperature of 44°C. At the same initial microbial count bacterial growth is affected only by the medium; the inhibitory compound increases the detection time required for a defined decrease in redox potential.

We presumed that in the course of producing adultered honey, the amount of biologically active content responsible for the proliferation inhibition decreases. Therefore, adultered honey might be identified by its lower proliferation inhibition effect.

During our research, we noticed significant differences between the microbial proliferation inhibitor properties of different types of honey based on their plant source (polyfloral, acacia, lime, sunflower, rapeseed, pine) and, at the same time, we noticed significant differences between honey samples made of the same plant source (acacia, polyfloral) but by different producers. The results might provide further information about the quality of honey and different methods of manipulation.



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