Microwave-assisted extraction of phenolics with maximal antioxidant activities in tomatoes

• Published in: Food chemistry Vol. 130; no. 4; pp. 928 - 936
• Main Authors: Li, Hongyan, Deng, Zeyuan, Wu, Tao, Liu, Ronghua, Loewen, Steven, Tsao, Rong
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.02.2012; Elsevier
• Subjects: Antioxidant activities; Biological and medical sciences; Cultivar; Food engineering; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General aspects; Microwave-assisted extraction; Phenolic compounds; Response surface methodology; Tomato; Antioxidant activities; Microwave-assisted extraction; Response surface methodology; Tomato; Phenolic compounds; Cultivar; Vegetables; Methodology; Microwave; Antioxidant; Phenols; Response surface; Extraction
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2011.08.019

► Optimised MAE extraction conditions for maximal antioxidant activities of phenolic extracts of tomato. ► Use of RSM and CCD (central composite design) for the optimisation. ► Phenolic profiles and antioxidant activities of 20 tomato cultivars, many are unique. ► Correlation between the phenolic contents and antioxidant activities. Microwave-assisted extraction (MAE) was investigated for extraction of phenolic compounds from tomato with maximised antioxidant activities using response surface methodology (RSM) coupled with a central composite design, and in vitro antioxidant assays (FRAP and ORAC). MAE was more efficient for greater antioxidant activities and higher total phenolic contents than solvent extraction. The optimal MAE processing parameters were 96.5°C, 2.06min, 66.2% ethanol for FRAP, and 96.5°C, 1.66min, 61.1% ethanol for ORAC. The models were successfully applied to 20 tomato cultivars, whose total phenolic contents (TPC) and indexes (TPI) were 489.30–997.45mg gallic acid equivalent/100g dry weight (DW) and 281.34–468.52mg/100gDW, respectively. Eight phenolic compounds were identified. Individual phenolics were 6.10–42.73mg/100gDW. The FRAP, but not the ORAC value showed good correlation with the TPC or TPI. The methodologies developed and the knowledge acquired in this study will provide useful information to tomato breeders and food processors.