RESUMEN

The nutritional composition of honey is determined by environmental conditions, and botanical and geographical origin. In addition to carbohydrates, honey also contain pollen grains, proteins, free amino acids, and minerals. Although the content of proteins in honey is low, they are an important component that confirms the authenticity and quality of honey; therefore, they became a popular study object. The aim of the study was to evaluate protein content and composition of monofloral red clover and rapeseed honey collected from five different districts of Lithuania. Forty-eight proteins were identified in five different origin honey samples by liquid chromatography. The number of red clover proteins identified in individual honey samples in monofloral red clover honey C3 was 39 in polyfloral honey S22-36, while in monofloral rapeseed honey S5, S15, and S23 there was 33, 32, and 40 respectively. Aphids' proteins and lactic acid bacteria were identified in all honey samples tested. The linear relationship and the strongest correlation coefficient (r = 0.97) were determined between the content of Apilactobacillus kunkeei and Apilactobacillus apinorum, as well as between the number of faba bean (Vicia faba) pollen and lactic acid bacteria (r = 0.943). The data show a strong correlation coefficient between the amount of lactic acid and aphid protein number (r = 0.693). More studies are needed to evaluate the relationship between the pollination efficiency of red clover by bees and the multiplicity of red clover proteins in honey protein, as well as microbiota diversity and the influence of nature or plant diversity on the occurrence of microbiota in honey.

RESUMEN

This review covers a comprehensive overview of the phytoconstituents and bioactivities reported to date for clover honeys produced from various Trifolium spp. against the backdrop of a more general discussion of the chemistry and bioactivity of these important agricultural species. While research into the phytochemical composition of various honeys and their associated bioactivities is growing, this review demonstrates that the literature to date has seen only a limited number of studies on clover honeys. Surprisingly, there appear to be no comparative data on the concentration of flavonoids in general or isoflavonoids specifically in different clover honeys, although the latter have been identified as a main group of bioactive compounds in red clover plants. Based on the findings of this review, the presence of phytoestrogenic isoflavonoids (e.g., formononetin, biochanin A, genistein, daidzein, glycitein) in clover plants and, by extension, in clover honeys should be further investigated, specifically of clover species outside the three popular perennial clovers (red, white and alsike clovers) to exploit new opportunities of potential benefit to both the pharmaceutical and apiculture industries.

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This study reports the physicochemical characterization of clover (Trifolium hybridum) and citrus (Citrus sinensis) honeys produced in Fayoum, Egypt, by evaluating the analysis of moisture content, pH, total soluble solids (TSS), electric conductivity (EC), total sugars, crude protein, ash content, total acidity, hydroxymethylfurfural (HMF), and total phenolic compounds (TPC). Antioxidant and antimicrobial activities of honey extracts and their flower extracts were determined. The results clearly indicated that ethanol gave the highest extraction yield of both clover and citrus flowers, while ethyl acetate showed the highest extraction recovery for the phenolic compounds, with TPC amounting to 338.5 and 536.4 mg gallic acid equivalent kg-1 fresh weight in clover and citrus flower extracts, respectively. Honey samples have less TPC than their flowers. The results showed that the TPC of citrus honey and its flowers was higher than clover honey and its flowers, respectively. Antioxidant activity was higher in extracts obtained from citrus flower than extracts of clover flower. The same trend was noticed for honey samples. Both clover and citrus honeys showed antimicrobial effects against tested microorganisms. HPLC analysis showed that p-coumaric acid was the main phenolic component in ethanol extracts of clover and citrus honeys, contributing about 83.0% and 52.2%, respectively. In citrus and clover flower extracts, syringic acid and quercetin were the main phenolics, respectively. It would be expected that characteristics of honey samples are mainly depended on the floral origin of nectar foraged by bees.

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RESUMEN

BACKGROUND: The authenticity of honey is of great importance for commercial and health reasons, because adulteration of bee honey with cheaper sweetening materials is sometimes carried out for financial gain. The objectives of this study were to evaluate clover honey quality according to physicochemical characteristics, to measure light transmission through honey samples using a visible laser technique (He-Ne laser at 632.8 nm) and to predict types of adulterants of clover honey according to the transmission intensity of the laser beam through the sample. RESULTS: The transmission intensity of pure clover honey was 3520 lx. Addition of water or sugar solution at various concentrations led to increased transmission intensities in the range 4720-6980 lx, while addition of glucose honey led to increased transmission intensities in the range 3570-4120 lx. However, addition of starch suspension or black honey led to decreased transmission intensities in the ranges 3440-120 and 2770-85 lx respectively. The physicochemical properties of pure clover honey were within the standard limits. The light microscope image of pollen in the honey indicated that the pollen came from the clover plant. CONCLUSION: The transmission intensity method using visible laser light to predict the type of adulteration of clover honey can be considered a fast and accurate method. © 2018 Society of Chemical Industry.

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