Optimisation of microwave effect on bioactives contents and colour attributes of aqueous green tea extracts by central composite design

Taşkın B., AKSOYLU ÖZBEK Z.

Journal of Food Measurement and Characterization, vol.14, no.4, pp.2240-2252, 2020 (SCI-Expanded, Scopus) identifier

  • Publication Type: Article / Article
  • Volume: 14 Issue: 4
  • Publication Date: 2020
  • Doi Number: 10.1007/s11694-020-00471-8
  • Journal Name: Journal of Food Measurement and Characterization
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Agricultural & Environmental Science Database, CAB Abstracts, Compendex, Food Science & Technology Abstracts, Veterinary Science Database
  • Page Numbers: pp.2240-2252
  • Keywords: Condensed tannin, DPPH-scavenging, Flavonoid, Green tea, Microwave, Optimisation, Total phenolic
  • Manisa Celal Bayar University Affiliated: Yes

Abstract

The aim of the present study was to investigate the effects of microwave-assisted extraction parameters on total phenolic content (TPC), total flavonoid content (TFC), condensed tannins content (CTC), DPPH-scavenging activity, and colour attributes of aqueous green tea extracts and to optimise the microwaving conditions using response surface methodology. Microwave power (120–360–600 W) and irradiation time (1–3–5 min) were selected as independent variables. Statistical analysis revealed that all responses were significantly affected by extraction parameters. The optimum microwave-assisted extraction conditions were 350.65 W microwave power and 5 min irradiation time to maximise TPC, TFC, CTC, DPPH-scavenging activity, and L* values and to minimise a* and b* values of aqueous green tea extracts. The predicted TPC was 116.58 mg gallic acid equivalents/g (GAE/g), TFC was 49.33 mg catechin equivalents/g (CE/g), CTC was 9.89 mg catechin equivalents/g (CE/g), DPPH-scavenging activity (IC50) was 294.46 µg/mL, L* value was 12.31, a* value was 2.61 and b* value was 7.02 under optimum microwave-assisted extraction conditions. This study revealed that microwave extraction conditions should be controlled to obtain aqueous green tea extracts with both high bioactivity and acceptable colour quality.