Honey contains natural biologically active compounds, and its preventive and healing properties are primarily linked to its antioxidant activity. The antioxidant properties of honey can be related to the botanical origin and content of phenolic compounds. We tested 84 honey samples from Poland, representing eight honey varieties: acacia, phacelia, buckwheat, linden, rapeseed, heather, goldenrod, and honeydew. High-performance liquid chromatography with photodiode-array detection (HPLC-DAD) was used to determine the phenolic compound composition of honey extracts. Total phenolic compounds (TPC) and DPPH radical-scavenging activity were also evaluated. We detected vanillin aldehyde, vanillic acid, caffeic acid, p-coumaric acid, and trans-ferulic acid, as well as flavonoid pinocembrin, in all honey varieties. The results of our study showed that honeys with high antioxidant activity were characterized by significantly higher total phenolic compounds content. Neither clustering method nor principal component analysis (PCA) showed clear separation of each honey variety, possibly due to high intra-variety diversities. We suppose that the variability of qualitative and quantitative phenolic compound composition within honey varieties may result from the region of origin, secondary nectar sources, and the time of harvest.

Summary: Coniferous honeydew honey, mainly Abies alba was characterised. Samples chosen for the study had organoleptic traits characteristic for the variety: greenish, opalescence tone of brown colour, mild, sweet flavour with pleasant, slightly resinous aftertaste and aroma as well as electrical conductivity over 0.95 mS/cm. To define composition and physicochemical parameters of the variety, contents of water and total sugars were determined. In addition various carbohydrates were identified and their contents were assessed as well. These were: fructose, glucose, sucrose, maltose, turanose, trehalose, isomaltose, malezitose. Other examined parameters related to honey quality were: free acidity, pH, the content of 5-hydroxymetylofurfural (HMF), the main amino acid - proline, and the activity of α-amylase enzyme (Diastase Number). The following properties were proven to be characteristic for this variety: high electrical conductivity with the average value of 1.14 mS/cm, ranging from 0.96 to 1.32 mS/cm; content of monosaccharides lower by few percent in relation to other honey varieties (from 58.2 to 67.4 g/100 g; on average 62.0 g/100 g) and a higher content of disaccharides and trisaccharide - melezitose. The presence of this sugar confirms that a considerable part of the honey was produced from honeydew. The average value of melezitose was 3.2 g/100 g, ranging from 0.9 to 5.9 g/100 g. Also, the results of the pH measurements were slightly higher than in other honey varieties (from 4.23 to 4.99; on average 4.63). The colour value in mm Pfund ranged from 74 to 105, with the average of 93.

A method was elaborated to determine phenolic compounds (vanillin, caffeic, p-coumaric and salicylic acids, and flavonoids: rutin, hesperetin, quercetin, pinocembrin, apigenin, kaempferol, isorhamnetin, chrysin, and acacetin) in bee pollen loads using highperformance liquid chromatography with a diode array detector (HPLC-DAD). Phenolic compounds from bee pollen were isolated on Cleanert C18-SPE columns (500 mg/6 mL, Agela Technologies). Polyphenols were identified by comparing the retention times and spectra of compounds found in pollen load samples with the ones of the standard mixture. Quantitative analysis was conducted using the external standard method. In addition, basic validation parameters for the method were determined. For the identified compounds (except for the salicylic acid), satisfactory (≥0.997) linear correlations were obtained. The elaborated method showed high repeatability and inter-laboratory reproducibility. Variability coeffcients of the majority of phenolic compounds did not exceed 10% in conditions of repeatability and inter-laboratory reproducibility, and for the total polyphenolic content they were 1.7 and 5.1%, respectively. The pollen load samples (n = 15) differed in qualitative and quantitative composition of the phenolic compounds. In all the samples, we identified the p-coumaric and salicylic acids and flavonoids rutin, hesperetin, and apigenin nevertheless, these compounds’ contents significantly differed among individual samples. The total phenolic content in the tested samples of pollen loads ranged from 0.653 to 5.966 mg/100 g (on average 2.737 mg/100 g).

In recent time, it has become a common practice to use different kinds of starch syrups available on the market as a winter food for bees. However, the physicochemical composition of these syrups and their suitability for winter feeding of honeybee colonies are still insufficiently investigated. Therefore, our study analyzed the composition of three commercially available starch syrups, inverted saccharose syrup and homemade saccharose syrups, and tested winter stores processed by bees from these syrups. The following physicochemical parameters were investigated: water, sugars composition, maltodextrins (DP4–DP7) and 5-hydroxymethylfurfural (HMF) content, pH and free acidity, as well as electrical conductivity. We found that the sugar composition of starch syrups ensures the suitable sugar composition of winter stores processed by the bees from these syrups. Winter stores compared to fresh syrups had a high content of total fructose and glucose (50 g/100 g), and some amounts of maltose (15 g/100 g), maltotriose (4 g/100 g), and maltodextrins (4 g/100 g). The small percentage of maltodextrins is responsible for maintaining the liquid consistency of the winter stores in honeybee combs during storage. Water content not exceeding 17.2% and adequate pH value (around 4.00) guarantee the stability of winter stores during storage in honeybee combs. A HMF content of up to 50 mg/kg was safe for bee colonies during wintering.

The aim of this study was to determine the influence of storage temperature and time on physicochemical parameters of starch syrups recommended for the winter feeding of bee colonies. The studies included commercially available three starch syrups and an inverted saccharose syrup that were stored at different temperatures: ca. 20 °C, 10–14 °C, and ca. 4 °C. Physicochemical parameters of fresh syrups (immediately after purchase) and syrups after 3, 6, 9, 12, 15, 18, 21, and 24 months of storage at the abovementioned temperatures were measured. It was observed that the rate of unfavorable changes in chemical composition of starch syrups and the inverted saccharose syrup, mainly the changes in the 5-hydroxymethylfurfural (HMF) content, depended on the type of a syrup and storage conditions (temperature, time). Properties of tested starch syrups intended for winter feeding of bees stored at ca. 20 °C maintained unchanged for up to 6 months, whereas the same syrups stored at lower temperatures (10–14 °C) maintained unchanged physicochemical parameters for about 12 months. In higher temperatures, the HMF content increased. To date, the influence of this compound on bees has not been thoroughly investigated.

Organic acids shape the organoleptic properties of honey and are linked to its health-beneficial properties. Their composition is affected by botanical and geographical origin, and some acids have even been proposed as markers for authentication of varietal honeys. Organic-acid composition was determined using high-performance liquid chromatography with photodiode-array detection (HPLC-DAD) in 152 samples of monofloral (willow, acacia, rape, phacelia, linden, heather, buckwheat and goldenrod) and honeydew (deciduous and coniferous) honeys from Poland. The deciduous and coniferous honeydew honeys were distinguished by high content of L-(+)-lactic acid and the presence of succinic acid as well as high total content of acids. Buckwheat honey was the only variety for which the presence of D-(−)-tartaric acid was quantified. These three honey varieties were clearly separated from the others using principal component analysis (PCA). Samples from the other varieties formed one cluster. We conclude that while some promising results were obtained for distinguishing honeydew and buckwheat honeys from other varieties, further investigation is needed, including analysis of additional acids and possibly other physicochemical parameters.