Although organic acids represent < 0.5% of honey's constituents, they make important contributions to the organoleptic, physical, and chemical properties of honey. To date, approximately 30 nonaromatic organic acids have been identified in honey, but relatively little attention has been paid to these components. This article reviews the current literature related to the significance of nonaromatic organic acids in honey; it was written with a goal of attracting researchers to study these interesting honey components. Previous research contributions on nonaromatic organic acids in honey may be classified into five main areas: (i) the antibacterial activities of these acids, (ii) the antioxidant activities of these acids, (iii) the use of these acids as possible indicators of incipient fermentation, (iv) the use of these acids for treatment of Varroa infestation, and (v) the use of these acids as factors for the characterization of both botanical and geographical origins of honeys. We conclude that nonaromatic organic acids are of interest for diverse reasons and that there is a particular need for studies regarding their possible antibacterial and antioxidant activities.

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For the 1st time, a relationship has been investigated between moisture percentage (M) and water activity (aW) in honeys from 2 different harvesting years and 2 different climatic areas. Moisture was determined by measuring refractive index at 20°C, according to official methods. At the same time, aW of the same samples was assessed at exactly 20°C. Influence on the relationship of the crop's year, aging, and induced fine granulation was evaluated. The results show that, independent of all factors studied, an excellent and statistically significant linear correlation between both parameters [aW = 0.3114 + (0.0170 × M)] was found in all samples with a regression coefficient of 0.8809. The measurement of aW of honey is interesting but time-consuming.This study concludes that this parameter can be easily calculated from the moisture percentage, thus avoiding the use of expensive and slow equipment for aW measurement.

An improved method is reported for the determination of catalase activity in honey. We tested different dialysis membranes, dialysis fluid compositions and amounts, dialysis temperatures, sample amounts, and dialysis times. The best results were obtained by dialysis of 7.50 g sample in a cellulose dialysis sack, using two 3 L portions of 0.015M sodium phosphate buffer (pH 7.0) as the dialysis fluid at 4°C for 22 h. As in previous methods, catalase activity was determined on the basis of the rate of disappearance of the substrate, H2O2, with the H2O2 determined spectrophotometrically at 400 nm in an assay system containing o-dianisidine and peroxidase. Trials indicated that the best solvent for the o-dianisidine was 0.2M sodium phosphate buffer, pH 6.1; the best starting H2O2 concentration was 3mM; the best HCl concentration for stopping the reaction was 6N; and the best sample volume for catalase measurement was 7.0 mL. Precision values (relative standard deviations for analyses of 10 subsamples of each of 3 samples) were high, ranging from 0.48% for samples with high catalase activity to 1.98% for samples with low catalase activity.

The total D-gluconic acid (free D-gluconic acid and D-glucono-δ-lactone) content of 20 Galician (northwestern Spain) honeys has been determined using an enzymatic method. To the author's knowledge, this is the first time this method has been applied to honey. The solution of honey was adjusted to pH 10.5 with 0.1 N KOH; 10 min at room temperature was allowed for hydrolysis of D-glucono-δ-lactone to D-gluconic acid. After this, it was necessary to adjust to test pH (7.8) with 0.1 N HCl. With these conditions, there were no observed interference effects. The enzymatic determination was measured spectrophotometrically at 340 nm, using gluconate kinase and 6-phosphogluconate dehydrogenase. The method combines precision (% CV was 0.30, at worst), good recovery (99.8%), simplicity, and low cost because this cost was reduced by 60% using a microtest. The total D-gluconic acid content of the honeys analyzed ranges between 3.91 and 11.71 g/kg (mean ) 7.37 g/kg), which is in keeping with value ranges obtained by other authors using HPLC methods.

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