Suggested mechanism for the effect of sweeteners on radical scavenging activity of phenolic compounds in black and green tea

Abstract

The present work aims to evaluate the relation between the antioxidant activities and phenolic compound contents of two tea samples (green and black) mixed with or without sweeteners (sucrose or aspartame). The aqueous extracts were screened for total polyphenol and flavonoids contents. Antioxidant activities of extracts were tested using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical method and 2, 2 -azino-bis [ethylbenzthiazoline-6-sulfonic acid] (ABTS) methods using butylated hydroxyl anisole as standard compound. In addition, we identified polyphenols compounds using high performance liquid chromatography (HPLC). The results indicated that the antioxidant activity was higher against ABTS radical more than DPPH radical. Also, there is positive correlation between the antioxidant activity and phenolic compounds content presented in water extracts of tea samples. The results also indicated that addition of table sugar to green tea significantly decreased the antioxidant activity (from 95.8% to 90.6% with 4.0% sucrose). However, the same table sugar in black tea increased the antioxidant activity (from 87.0% to 91.9% with 4.0% sucrose). The analysis using HPLC showed that caffeine was the most predominant individual compounds in green and black tea without and with 1.0% sucrose (6081.8, 8772.1, 6474 and 3755 µg/100g, respectively). However, cinnamic acid showed the lowest content in the same tea samples (0.21, 0.25, 0.19 and 0.18 µg/100g respectively). Pyrogallol, catechol, epicatechin, ellagic, protocatchuic were significantly higher in green tea than in black tea. ARTICLE HISTORY

Phenolics release kinetics in sugared and sugar‐free chewing gums: microencapsulated pomegranate peel extract usage

“…This phenomenon might be caused by a possible condensation reaction between the hydroxyl groups in sucrose molecule and the hydroxyl group of phenolic compounds in MEPPE and formation of the glycoside. The similar result was observed by Shalaby et al (2016). Table sugar addition caused a significant reduction in antioxidant activity of green tea using two tested methods (DPPH and ABTS radical).…”

“…The similar result was observed by Shalaby et al . (). Table sugar addition caused a significant reduction in antioxidant activity of green tea using two tested methods (DPPH and ABTS radical).…”

Effect of sweeteners and storage on compositional and sensory properties of blackberry jams

“…Additionally, the inconsistent trend in antioxidant activity change can be attributed to various reasons, including the hydrolysis of the flavonoid glycosides, delivering an additional -OH moiety that can react with the ABTS cation radical [32]. Moreover, the interaction of the phenolic compounds or their oxidized form with the sugar molecules and the consequent formation of the reduced form of phenolic compounds that can interact with ABTS radicals [35] orto a lesser extent-the presence of non-polyphenol antioxidants can also contribute to the observed lack of correlation between polyphenol content and ABTS radical scavenging activity obtained in our study. Other authors attribute the phenomenon to other factors, such as increased antioxidant power of polyphenols at an intermediate state of oxidation, increase in reducing sugar and formation of Maillard products, known to show a high antioxidant activity, which is often exerted in mechanisms similar to that of the ABTS assay [36].…”

Low frequency, high power ultrasound: a non-thermal green technique improves phenolic fractions (free, conjugated glycoside, conjugated esters and bound) in fermented seabuckthorn beverage

“…The same is observed when comparing P+US (315.42 ± 1.76 µmol TE/L) on day 0 to K+S+US (282.66 ± 11.22 µmol TE/L) and K+US (305.87 ± 0.85 µmol TE/L) on day 5. Shalaby et al (2016) reported a decrease in antioxidant activity in green tea with addition of sucrose potentially attributable to the condensation reaction between hydroxyl groups of phenolics and sucrose molecules to form glycosides. No significant difference was observed in ORAC between P (298.30 ± 2.35 µmol TE/L), P+US (300.40 ± 1.58 µmol TE/L), K+US (308.98 ± 8.15 µmol TE/L) and K+S+US (289.09 ± 5.97 µmol TE/L) on day 21 while K (280.01 ± 7.18 µmol TE/L) and K+S (283.39 ± 14.06 µmol TE/L) had significantly lower ORAC values.…”