Evolution of acidity of honeys from continental climates:: Influence of induced granulation

On 35 unheated honeys coming from an area with typical Continental climate, we studied the evolution of pH, free acid, lactones and total acidity throughout 30 months, as well as the influence of induced granulation on acidity evolution. All samples were stored at room temperature and analyzed, in duplicate, each 5 months. We observed that storage had an effect on pH and free acid values. On the contrary, induced granulation did not show any influence on these parameters. In the end of the study, pH average had decreased down to 5%. After 20 months from harvesting, the vast majority of honeys showed a constant increase of free acid, although until 30 months, none sample exceeded the limit of 50 meq/kg. A direct relationship was found between pH and free acid within each time of analysis. Both storage and induced granulation had an effect on honey lactones, parameter that steadily decreased after 20 months, and oscillated less markedly in samples subjected to induced granulation. For honeys from continental climates, taking free acid and lactones into account, 20 months could be proposed as best before period "once opened". Neither storage nor induced granulation had an effect on total acidity, which hardly varied within 30 months storage. We found significant relationships between initial values of free acid and lactones and the values of these parameters at each time of analysis, meaning that aging of these honeys due to acidity could be predicted. (c) 2005 Elsevier Ltd. All rights reserved.