title: Pomegranate and mint syrup addition to green tea beverage stabilized its polyphenolic content and biofunctional potentials during refrigerated storage.
abstract: The chemical stability of the green tea (GT) preparation during refrigerated storage was investigated following the addition of mint (MS) or pomegranate (PS) syrups, a common habit in the Mediterranean countries that improves the savor of this popular beverage. The supernatants recovered by centrifuging GT supplemented or not with mint (GTMS) or pomegranate (GTPS) syrup were examined for their polyphenolic profiles using the high performance liquid chromatography with diode array detection and electrospray ionization-mass spectrometry. Following storage at 4 °C for 15 days, not-supplemented GT showed a significant decrease (≈92 %) of its phenolic content. However, the decrease was relatively lesser in GTPS (≈36 %) and in GTMS (≈40 %). The observed slight increase of the extractable polyphenolics in PS and MS during the storage might explain in part the relatively limited decrease of GTPS and GTMS total phenolic content. However, chromatographic examination proved that some tea compounds, particularly caffeine, were preserved following PS and MS supplementation. Likewise, syrups'addition to GT significantly (P < 0.5) limited the reduction of its antioxidant capacity as revealed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis-(3-ethylbenz-thialzoline-6-sulfonic acid)) assays. As expected, the antimicrobial trials showed that Gram (+) Staphylococcus aureus and Staphylococcus epidermidis were the most sensitive strains to tea polyphenols. The syrups supplementation noticeably preserved the tea bacteriostatic and bactericide activities during storage. The obtained analytical results demonstrate that MS or PS addition to green tea beverage stabilized its polyphenolic content and biofunctional properties during refrigerated storage, thus, scientifically supporting this popular practice in the Mediterranean countries.
authors.affiliation: Laboratory of Protein Engineering and Bioactive Molecules (LIP-MB), INSAT, University of Carthage, Carthage, Tunisia ; Laboratory of Agricultural Production Systems and Sustainable Development, College of Agriculture, University of Carthage, 1121 Mograne, Zaghouan, Tunisia.
authors.forename: Karima
authors.initials: K
authors.lastname: Dhaouadi
authors.affiliation: Laboratory of Protein Engineering and Bioactive Molecules (LIP-MB), INSAT, University of Carthage, Carthage, Tunisia.
authors.forename: Manel
authors.initials: M
authors.lastname: Belkhir
authors.affiliation: ISAJC, Bir El Bey, University of Tunis, Tunis, Tunisia.
authors.forename: Faten
authors.initials: F
authors.lastname: Raboudi
authors.affiliation: Institute of Chemical and Biological Technology (ITQB), Lisbon, Portugal ; Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.
authors.forename: Elsa
authors.initials: E
authors.lastname: Mecha
authors.affiliation: Laboratory of Protein Engineering and Bioactive Molecules (LIP-MB), INSAT, University of Carthage, Carthage, Tunisia.
authors.forename: Imen
authors.initials: I
authors.lastname: Ghommeme
authors.affiliation: Institute of Chemical and Biological Technology (ITQB), Lisbon, Portugal ; Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal.
authors.forename: Maria Do Rosario
authors.initials: Mdo R
authors.lastname: Bronze
authors.affiliation: Laboratory of Agricultural Production Systems and Sustainable Development, College of Agriculture, University of Carthage, 1121 Mograne, Zaghouan, Tunisia.
authors.forename: Hajer
authors.initials: H
authors.lastname: Ammar
authors.affiliation: Laboratory of Protein Engineering and Bioactive Molecules (LIP-MB), INSAT, University of Carthage, Carthage, Tunisia.
authors.forename: Sami
authors.initials: S
authors.lastname: Fattouch
keywords: Antimicrobial; Antioxidant; Green tea; Mint syrup; Pomegranate syrup; Stability