| To compare the efficiency of the traditional hot acid and hot water extraction method (method 1) with the cold acid and cold water extraction method (method 2), the oxalate contents of 50 dried herbs and 10 fresh fruits were assessed using both methods. Method 1 extracted more total oxalate compared to method 2 while there was no significant difference in efficiency of extracting soluble oxalate. A secondary objective was to investigate the effect of extraction conditions on oxalate generation from ascorbate; different extraction times, temperatures, and amount of ascorbate added were assessed. Only heating induced a significant conversion of exogenous (added) ascorbate to both soluble and total oxalate. Because all the herbs and most of the fruits tested in our study were not high in ascorbate, an incomplete extraction of total oxalate when using method 2 likely accounted for the significant difference in oxalate values between the two extraction methods. The hot water and hot acid extraction method appeared to yield a more efficient oxalate extraction. |
