Ultrasound-assisted extraction of some branded tea: Optimization based on polyphenol content, antioxidant potential and thermodynamic study

Abstract

Tea is one of the top beverages used around the world every day, which contains a high amount of polyphenols and antioxidants. The main aim of this research is to quantify some marketed black tea (Rabea, Lipton, Alkbous, Green gold and Haritham) for phenolic contents and antioxidant potential evaluation by ultrasound solvent extraction and was compared with conventional extraction. Ultrasonic extraction was optimized by considering frequencies (26 kHz, 40 kHz), temperature (30, 40 and 50 °C), and power (30, 40 and 50%) at a fixed time of 30 min. In both the ultrasonic frequencies, 40 °C temperature and 40% power combination exhibited highest cumulative yield (mg/100 g DW), total phenolic content (mg gallic acid/g DW), flavonoids (mg/g DW) and DPPH radical scavenging activity (%) in all branded tea. Within each brand of tea, at any temperature-power combination at particular frequency results were not significantly different. But, at a similar condition of temperature power results were found significantly different between two frequencies. Furthermore, ultrasonic extraction process was analyzed thermodynamically by selecting some basic parameters. Thermodynamics results showed the extraction process was feasible, spontaneous and irreversible. Also, 26 kHz ultrasonic probe is more appropriate for the extraction purpose and thermodynamically more acceptable as compared to 40 kHz ultrasonic bath. Moreover, Haritham was selected as the best tea brand due to its high polyphenol contents and antioxidant potential.

Antimicrobial and Antioxidant Performance of Various Essential Oils and Natural Extracts and Their Incorporation into Biowaste Derived Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Layers Made from Electrospun Ultrathin Fibers

“…GTE showed an inhibition of 71.77%, conferred by the relative amount of catechins and GA [ 82 ]. Afroz Bakht et al [ 83 ] studied the antioxidant activity from DPPH of five commercial teas, finding percentages of inhibition in the 24–71% range. In addition, Lu and Chen [ 84 ] reported percentages of inhibition between 33% and 62%.…”

“…In addition, Lu and Chen [ 84 ] reported percentages of inhibition between 33% and 62%. In this sense, it is important to highlight that antioxidant activity is dependent on the quantity of secondary metabolites that the plant manages to synthesize in its development stage, which is influenced by the variety of the plant, the environmental conditions [ 85 , 86 , 87 ], and the extraction method used [ 83 ].…”

Coumaroyl Flavonol Glycosides and More in Marketed Green Teas: An Intrinsic Value beyond Much-Lauded Catechins

“…The catechin content of the selected green tea types were compared to that of a green tea catechin-based supplement, whereas the diversity in other phenolic, polyphenolic, and non-phenolic compounds was also evaluated. To this purpose, taking into account that ethanol is a good solvent for polyphenol extraction [24], also for higher molecular weight flavanols, alcoholic extracts were prepared by means of ultrasound-assisted maceration [25]. Previous investigation on black tea highlighted that the use of ultrasonic intensification led to an increase in polyphenols by approximately 15% in respect to conventional maceration [26].…”

An Overview of Effects Induced by Pasteurization and High-Power Ultrasound Treatment on the Quality of Red Grape Juice

“…The propagation of ultrasound waves in a medium generates physical and chemical effects which can be exploited for improving the efficiency of various food processing operations. Thus, the ultrasound technology was explored to enhance the food quality by reducing the process time, energy and increasing shelf life [11,12]. It has been reported that ultrasound energy can be used to increase extraction yields by disrupting cell tissues [12,13].…”