Studies on Quality of Honey

Part II Changes in quality caused by heating

Abstract

As a part of study on the changes in quality of honey by heating, the changes of content, acidity, color and antibacterial activity were investigated.
1) With increasing temperature and time of heating. the content ratio of fructose to glucose and that of sucrose to sum of fructose and glucose declined, but, on the contrary, the ratio of lactone acidity to free acidity increased.
2) When honey was heated, the amount of hydroxymethylfurfural (HMF) increased and color darkened by browning reaction. It was observed that, in the browning reaction under acidic medium like honey, fructose reacted more rapidly than glucose, and under this condition the reaction proceeded through HMF in spite of absence of amino acids. But the reaction was difficult to proceed in the system wherein HMF was the starting material.
3) Hydrogen peroxide which gives major antibacterial activity against Staphylococcus aureus in honey was produced from glucose through the action of glucose oxidase. The loss of the antibacterial activity of honey by heating was considered to attribute to absence of the peroxide due to inactivation of glucose oxidase by heating.