Inhibitory effect of pomegranate (Punica granatum L.) polyphenol extracts on the bacterial growth and survival of clinical isolates of pathogenic Staphylococcus aureus and Escherichia coli

In the present study major polyphenols of pomegranate arils and peel by-products were extracted in 50% (v/v) aqueous ethanol, characterized and used in microbiological assays in order to test antimicrobial activity against clinically isolated human pathogenic microorganisms. Total concentration of polyphenols and in vitro antioxidant properties were determined by the Folin-Ciocalteu and DPPH methods, respectively. The most abundant bioactive molecules, including anthocyanins, catechins, tannins, gallic and ellagic acids were identified by RP-HPLC-DAD, also coupled to off-line matrix assisted laser desorption/ionization (MALDI-TOF) mass spectrometry (MS). The inhibitory spectrum of extracts against test microorganisms was assessed by the agar well-diffusion method. Data herein indicated that both pomegranate aril and peel extracts have an effective antimicrobial activity, as evidenced by the inhibitory effect on the bacterial growth of two important human pathogens, including Staphylococcus aureus and Escherichia coli, which are often involved in foodborne illness.

Chemical guide parameters for Punica granatum cv. 'Mollar' fruit juices processed at industrial scale

To contribute for setting reference guideline for commercial juice from the pomegranate variety 'Mollar', chemical composition of eighteen samples directly obtained and commercialised in 2012 from three different fruit juice factories was investigated. According to the findings, the relative density of direct pomegranate juices varied between 1.061 and 1.064, which correspond to 15.15 and 15.71°Brix; titratable acidity changed between 2.6 and 2.8g/L, citric acid between 2.3 and 2.8 g/L, l-malic acid in a range of 1.3-1.4 g/L, and d-isocitric acid at levels less than 20mg/L. Glucose values ranged from 61.4 to 65.0 g/L, whereas fructose displayed values between 65.3 and 68.0 g/L. The predominant mineral was potassium (2,400-2,900 mg/L), followed by phosphorous, magnesium, calcium and sodium at levels of 81-89 mg/L, 17.6-28.5mg/L, 5.8-7.5mg/L and 4.3-5.3mg/L, respectively. Chemical determinations of anthocyanin and ellagitannin profiles and amino acids contents were also carry out. Concentrations of anthocyanins in commercialised samples were Cy3,5dG (19.30 ± 3.47 mg/L), followed by Dp3,5dG (17.87 ± 6.74 mg/L) and Cy3G (12.91 ± 6.32 mg/L). Punicalagin levels ranged between 503.70 and 762.85 mg/L, punicalins between 239.9 and 364.5mg/L, and free ellagic acid level was typically between 268.67 and 389.64 mg/L. The juice samples exhibited high amount of total phenolics (1,136-3,581 mg/L) as well as high ABTS radical scavenging activity (18-31 mmol Trolox/L).