Donatella Leonardi

Geographical, botanical and chemical profile of monofloral Italian honeys as food quality guarantee and territory brand

Abstract Bees represent an important element for the preservation of plant biodiversity. During their activities, bees cover a large area around the hive and their products strictly reflect the distinctive traits of these environments. In honey, the floral diversity of the areas inspected by bees is revealed by their pollen spectra. The present work characterized 460 Italian unifloral honeys by melissopalynological and physicochemical analyses. Obtained data contributed to: confirm the botanical identity of the samples; determine the plant biodiversity revealed in each honey; differentiate the samples of the same monofloral typology in relation to their geographical origin; and identify peculiar floristic associations in the Italian regions. Moreover, gas chromatographic analysis was carried out on rare unifloral honey to study their sugar profiles. This work provided the scientific base to create a valid tool able to assign a territorial brand and an authenticity guarantee to the honey, protecting the consumers from adulterations.

Seed structure in Crocus sativus L. ×, C. cartwrightianus Herb., C. thomasii Ten., and C. hadriaticus Herb. at SEM

Crocus sativus L. (Iridaceae) is a sterile triploid geophyte widely cultivated for the production of the spice saffron and only reproduced by means of corms. Extensive research has identified Crocus cartwrightianus Herb. as being a probable progenitor of C. sativus. However, other diploid Crocus species of the same C. sativus group, such as C. thomasii Ten. and C. hadriaticus Herb., have been considered as possible progenitors of saffron. Of the characteristics for distinguishing critical genera, species and intraspecific taxa of angiosperms, the most widely adopted have been seed organisation and patterns of spermoderma microstructure detected at SEM. The aim of this study is to use SEM to analyse the seeds of C. sativus ×, a cross obtained by C. sativus with pollen of C. cartwrightianus Herb. and the seeds of allopollinated C. cartwrightianus, C. thomasii Ten., and C. hadriaticus Herb. Results indicate that the seed surface microstructure of C. sativus × is very similar to that of C. cartwrightianus while being different from those of C. thomasii and C. hadriaticus.

Nutritional and botanical interest of honey collected from protected natural areas

Abstract Due to numerous episodes of contamination through illegal beekeeping practices, the certification and re-evaluation of honey is required to guarantee a clean, natural and healthy product. The aim of this work was to demonstrate the good quality of honey produced in protected areas by demonstrating both its nutraceutical content and its role in monitoring the plant species present in protected areas. All the physico-chemical parameters necessary for defining the quality of honey (botanical origin; conductivity; diastase activity; pH; free, lactonic and total acidities; water content; fructose, glucose and sucrose content; hydroxymethylfurfural) and total flavonoid and phenolic contents were analyzed and evidenced its high quality. Moreover, melissopalynology allowed us to establish a floristic census within the nature reserves and parks.

Intracellular localization of calcium, phosphorus and nitrogen in common bean seeds (Phaseolus vulgaris L. cv. Borlotto) by SEM, ESI and EELS techniques

ABSTRACT Scanning, transmission electron microscopy, electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS) were used to localize calcium, phosphorus and nitrogen in seeds of Phaseolus vulgaris. Prismatic, straight and kinked twin calcium oxalate crystals were detected in the crystalligen layer of seed teguments. Cytoplasmic calcium and phosphorus-rich particles, probably of phytin, were detected in cotyledon parenchyma cells by ESI and EELS. Moreover, higher levels of calcium were mapped on osmiophilic droplets close to cell walls. Crystals, cytoplasmic phytin particles, osmiophilic droplets and calcium in cell walls disappeared after treatment with critic acid. By chemical assays, 1.1 g/100 g of phytic acid was detected in control seeds, and an 81% decline was observed in citric acid-treated samples. These data suggest that crystals and phytin complexes could play a role in determining the low calcium availability in common beans. Also, nitrogen found in protein bodies of cotyledons could represent an important site of protein reserves.

Botanical influence on phenolic profile and antioxidant level of Italian honeys

Honeybees directly transfer plant compounds from nectar into honey. Each plant species possesses a specific metabolic profile, the amount and the typology of plant molecules that may be detected in honey vary according to their botanical origin. Aim of the present work was the spectrophotometrical determination of concentration ranges of simple phenols and flavonoids in 460 several Italian monofloral honeys, in order to individuate specific intervals of plant metabolites for each typology of honey. Moreover, an LC–MS analysis was performed to determine amount of various secondary metabolites in the samples, with the purpose to use them as potential molecular markers in support to honey melissopalynological classification. As plant molecules have a strong reducing power, the antioxidant activity of the honeys was evaluated by two antiradical assays, DPPH and FRAP. The free radical scavenging effect of each monofloral group was correlated to the concentration of simple phenols and flavonoids, with the aim to deduce the existence of possible relationships between these parameters. In conclusion, dark honeys (Castanea sativa, honeydew, Erica sp. and Eucalyptus sp.) appeared to be the richest in secondary metabolites and, consequently, showed higher antioxidant activity. However, all analyzed monofloral honeys showed to be good sources of antioxidants.

Effect of thermal liquefying of crystallised honeys on their antibacterial activities

Thermal liquefying of crystallised honey is the most convenient option for beekeepers to fully liquefy honey. A controlled mild thermal treatment is widely used for effective and safe liquefying of crystallised honey. In this study, we demonstrated that thermal liquefying at different temperatures of 45, 55 and 65 °C does not affect the overall honey antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus, and, in some cases, it may even increase the antibacterial potential of honey. A mild thermal treatment of crystallised honey was able to significantly increase its glucose oxidase (GOX) enzyme activity. On the other hand, the increased GOX activity in treated honey samples did not affect levels of accumulated H2O2, suggesting that some phytochemicals may contribute to or modulate antibacterial activity. Taken together, a mild thermal liquefaction of crystallised honey may increase the potential bioactivity of this matrix, which is also affected by the botanical origin.