Abstract:

Fruits from two different cultivars of red raspberry, ‘Fertod Zamatos’ and ‘U.S. Raspberry’, were selected for
extracting polyphenols using ethanol as the solvent. Optimization of extraction parameters was carried out using onefactor-
at-a-time method and an orthogonal array design L9 (34). Ethanol concentration, extraction temperature, solid-tosolvent
ratio, extraction time and number of extraction cycles were chosen as the independent variables. The response was
the extraction yield of polyphenols. Duncan’s Mutiple-Range test was adopted to examine the significance of differences
among various treatments. The optimal extraction conditions for polyphenols were established as follows: 70% (V/V) ethanol
(pH 6), 45 ℃, solid-to-solvent ratio of 1:6 (g/mL), 2 extraction cycles, and 3.5 h each cycle for ‘Fertod Zamatos’; and 65%
(V/V) ethanol (pH 6), 45 ℃, solid-to-solvent ratio of 1:5 (g/mL), 2 extraction cycles, and 3.5 h each cycle for ‘U.S.
Raspberry’. The corresponding yields of polyphenols from these two cultivars were (373.78 ± 4.08) mg/100 g and (287.08 ±
4.91) mg/100 g, respectively. These results indicated that the extraction procedure was reliable, stable and practical.

Key words: red raspberry, polyphenols, extraction, orthogonal array test, Duncan’s mutiple-range test