Reduction in Residual Pesticides and Quercetin Yields in Onion Peel Extracts by Washing

Abstract

This study was conducted to assess the removal of residual pesticides and to obtain high amounts of quercetin in onion peel extracts (OPEs) by 4 washing treatments. Washing is one of the standard processing steps in obtaining functional food ingredients from onion peel. After a first detergent wash (0.2% w/v) (DW) and hot air drying (80 o C, 24 hr) (B), 4 washing treatments were tested, including a second DW (C), ultrasonication (50 o C, 10 min) plus DW (D), 0.3% H2O2 (v/v) plus DW (E), and blanching (95-97 o C, 2 min) plus DW (F). This was followed by 60% (v/v) ethanol extraction and vacuum freeze drying of the OPE. The E treatment yielded 89.04% OPE and a quercetin content of 96.84% in the OPE compared with the B treatment, and had the highest efficiency of all treatments tested. The OPE was tested for the presence of 177 residual pesticides and three compounds were detected in all treatments: cyhalothirn, fluquinconazole and procymidone. Cyhalothirn and fluquinconazole levels were below the permitted levels for fresh onion, while procymidone was present in the high level range of 128.01~133.46 mg/kg in all samples. The E treatment was a better washing method than the others for removal of residual pesticides. It could reduce the level of residual pesticides without changing the functional properties of the OPE.

Study on the Synthesis of Isoquercitrin by Enzymatic Partial Hydrolysis

“…폴리페놀의 일 종인 quercetin (QU)은 양파의 껍질 [2], 구절초 [3], 사과 과피 [4], 참가 시나무 [5] 등에 존재하는 것으로 알려져 있다. QU의 배당체인 isoquercitrin (IQ)은 항산화 [6], 항염증 [7], 항고혈압성 [8] 작용과 항알 러지 [9], 항암작용 [10] 등 다양한 약리효과가 있으나, 그의 연구가 제 한적이었다.…”