Total phenolic compounds (TPC) TPC of different food processing waste extracts were determined on the basis that the Folin–Ciocalteu method measures the reduction of the reagent by phenolic compounds via the formation of a blue complex that can be measured at 760 nm against GAE as a standard. The amount of TPC varied in the different extracts, ranging from 0.89 to 261.69 mg GAE g−1 extract (Table 1). In general, the results stated that ethanol 80% and ethyl acetate were better than hexane in extracting phenolics from PP and PS owing to their higher polarity and good solubility (Siddhuraju and Becker, 2003 and Kequan and Liangli, 2004). On the other side, hexane extracted the highest amount of phenolics from OP followed by ethanol 80% as shown in Table 1.