Influence of postharvest processing and storage conditions on key antioxidants in pūhā (Sonchus oleraceus L.)

TY - JOUR

T1 - Influence of postharvest processing and storage conditions on key antioxidants in pūhā (Sonchus oleraceus L.)

AU - Ou, Zong-Quan

AU - Schmierer, David M

AU - Strachan, Clare J

AU - Rades, Thomas

AU - McDowell, Arlene

N1 - © 2014 Royal Pharmaceutical Society.

PY - 2014/7

Y1 - 2014/7

N2 - Objectives To investigate effects of different postharvest drying processes and storage conditions on key antioxidants in Sonchus oleraceus L. leaves. Methods Fresh leaves were oven-dried (60C), freeze-dried or air-dried (25C) for 6 h, 24 h and 3 days, respectively. Design of experiments (DOE) was applied to study the stability of antioxidants (caftaric, chlorogenic and chicoric acids) in S. oleraceus leaves and leaf extracts stored at different temperatures (4, 25 and 50C) and relative humidities (15%, 43% and 75%) for 180 days. The concentration of antioxidants was quantified by a HPLC-2,2′- diphenylpicrylhydrazyl post-column derivatisation method. Antioxidant activity was assessed by a cellular antioxidant activity assay. Key findings The three antioxidants degraded to unquantifiable levels after oven-drying. More than 90% of the antioxidants were retained by freeze-drying and air-drying. Both leaf and extract samples retained > 90% of antioxidants, except those stored at 75% relative humidity. Leaf material had higher antioxidant concentrations and greater cellular antioxidant activity than corresponding extract samples. Conclusion Freeze-drying and air-drying preserved more antioxidants in S. oleraceus than oven-drying. From DOE analysis, humidity plays an important role in degradation of antioxidants during storage. To preserve antioxidant activity, it is preferable to store S. oleraceus as dried leaf material.

AB - Objectives To investigate effects of different postharvest drying processes and storage conditions on key antioxidants in Sonchus oleraceus L. leaves. Methods Fresh leaves were oven-dried (60C), freeze-dried or air-dried (25C) for 6 h, 24 h and 3 days, respectively. Design of experiments (DOE) was applied to study the stability of antioxidants (caftaric, chlorogenic and chicoric acids) in S. oleraceus leaves and leaf extracts stored at different temperatures (4, 25 and 50C) and relative humidities (15%, 43% and 75%) for 180 days. The concentration of antioxidants was quantified by a HPLC-2,2′- diphenylpicrylhydrazyl post-column derivatisation method. Antioxidant activity was assessed by a cellular antioxidant activity assay. Key findings The three antioxidants degraded to unquantifiable levels after oven-drying. More than 90% of the antioxidants were retained by freeze-drying and air-drying. Both leaf and extract samples retained > 90% of antioxidants, except those stored at 75% relative humidity. Leaf material had higher antioxidant concentrations and greater cellular antioxidant activity than corresponding extract samples. Conclusion Freeze-drying and air-drying preserved more antioxidants in S. oleraceus than oven-drying. From DOE analysis, humidity plays an important role in degradation of antioxidants during storage. To preserve antioxidant activity, it is preferable to store S. oleraceus as dried leaf material.

U2 - 10.1111/jphp.12220

DO - 10.1111/jphp.12220

M3 - Journal article

C2 - 24697835

SN - 0022-3573

VL - 66

SP - 998

EP - 1008

JO - Journal of Pharmacy and Pharmacology

JF - Journal of Pharmacy and Pharmacology

IS - 7

ER -