Awad Mahmoud

In addition to color, ash and electrical conductivity (EC), the levels of 14 minerals were investigated in 23 varieties of honey from Saudi Arabia and six other countries. The quantities of the macrominerals obtained were as follows (in ppm): K (298.60–491.40), Mg (80.70–199.30), Ca (60.75–99.95), P (21.10–33.29), and Na (15.69–26.93). The quantities of trace minerals were as follows (in ppm): Fe (67.18–98.13), I (12.61–94.68), Mn (4.15–6.04), Zn (3.44–5.72), Li (1.15–4.26), Co (1.00–1.32), and Ni (0.15–0.67). The quantities of the heavy metals Pb and Cd were found to be 0.06–0.23 and 0.00–0.16, respectively. The values of the tested elements—color, ash and EC—varied among the tested honeys according to their botanical origin. Dark honeys, especially acacia honeys, had higher elemental content and EC values than lighter ones. Saudi and Yemeni seder honeys exhibited no distinctive characteristics in their tested parameters. The levels of heavy metals indicated that the tested honeys were safe for human consumption.

BACKGROUND: Growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on vegetable sources and screening of raw materials to identify new antioxidants. The food-processing industry generates substantial quantities of phenolic-rich by-products that could be valuable natural sources of antioxidants. In this study the antioxidant properties and total phenolic, flavonoid and flavonol contents of three industrial by-products, sugar beet pulp, sesame cake and potato peel, extracted with various solvents were examined. Since different antioxidant compounds have different mechanisms of action, several methods were used to assess the antioxidant efficacy of extracts. RESULTS: Among the six solvents tested, methanol gave the highest extract yield of potato peel and sugar beet pulp, while diethyl ether gave the highest extract yield of sesame cake. Methanol exhibited the highest extraction ability for phenolic compounds, with total phenolics amounting to 2.91, 1.79 and 0.81 mg gallic acid equivalent g(-1) dry weight in potato peel, sugar beet pulp and sesame cake extracts respectively, and also showed the strongest antioxidant capacity in the three assays used. All three methods proved that potato peel extract had the highest antioxidant activity owing to its high content of phenolic compounds and flavonoids. CONCLUSION: On the basis of the results obtained, potato peel, sugar beet pulp and sesame cake extracts could serve as natural antioxidants owing to their significant antioxidant activity. Therefore they could be used as preservative ingredients in the food and/or pharmaceutical industries.

Bee products (e.g., propolis and bee pollen) are traditional healthy foods. In this study, antioxidant properties and in vitro antibacterial activity of honeybee pollen and propolis methanol extracts were determined. Propolis with higher phenolic content showed significant greater activity over pollen extracts. Caffeic acid, ferulic acid, rutin, and p-coumaric acid were detected as main phenolic compounds in propolis extract. 3,4-Dimethoxycinnamic acid was the major phenolic component in pollen extract. Propolis extract (5 μg/mL) exhibited 28% antiradical action against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The scavenging activity of propolis and pollen extracts against 2,2′-Azinobis (3-ethylbenzothiazoline-6 sulfonic acid) (ABTS) reached a maximum of 94.3 and 76.5%, respectively, at an extract concentration of 25 μg/mL. Stabilization factor of propolis extract was 13.7, while it was 6 for pollen. Results revealed that both extracts showed highly antibacterial action against gram-positive bacteria with a minimal inhibitory concentration ranging from 0.2 to 0.78 mg/mL. To best of our knowledge, this is the first study showing elevated antibacterial activity against gram-negative bacteria Salmonella enterica. Practical Applications Besides their potential pharmaceutical use, propolis and pollen could be efficient protective agents for use as natural antioxidant and antibacterial additives in food systems. It has been observed that the biological activities of propolis and pollen depend on their chemical composition, which, in turn, depends on geographical diversity and the genetic variety of the queens. On the basis of the present study, propolis extract showed higher antioxidant and antibacterial activities compared with the pollen extract. This may be due to its higher amounts in caffeic, ferulic and p-coumaric acids. To our knowledge, this is the first report comparing the antioxidant and antibacterial activities of Egyptian bee pollen and propolis extracts and their chemical constituents.