Background and Methodology:
Secondary phenolic metabolites play an important role in plant defense mechanism and increasing evidence indicates that many are important in human health (Asami et al, 2003). Asami et al (2003) measured the total phenolic (TP) content of marionberries, strawberries and corn grown by sustainable, organic or conventional cultural practices. The impact of three common postharvest processing methods, controlled freeze-drying, air-drying and flash freezing on the levels of TPs and AA were compared.
Sustainably grown and frozen strawberries contained higher levels (20.3%) of ascorbic acid (AA) as compared to conventionally grown strawberries. The average AA levels in sustainably grown and free-dried or air dried fruit were significantly lower (P<0.05) at 44.2 and 16.2% of levels in frozen strawberries. The AA concentrations of organic and sustainably grown and frozen corn were 52.4 and 66.7% higher respectively than conventionally grown and frozen corn. Statistically, higher levels of TPs were consistently found in organically and sustainably grown foods as compared to those grown by conventional agricultural practices.
Asami, D. K., Hong, Y-J., Barrett, D. M. & Mitchell, A. E. (2003). Comparison of the total phenolic and ascorbic acid content of freeze-dried and air-dried marionberry, strawberry and corn grown using conventional, organic and sustainable agricultural practices. J. Agric. Food Chem. 51(5):1237-1241.