High-pressure and temperature extraction of phenolic compounds from corn silage

Corn silage refers to stalks, leaves and cobs of maize plants that remain in fields after the corn harvest. Commonly it is used as a cattle feed, but recently it has been more often used together with cattle manure in biofuel production in anaerobic co-digestion. In this work high-pressure and temperature extraction of phenolic compounds from corn silage was performed. Process parameters (temperature, T = 90 - 180 °C; extraction time, t = 40 - 120 min; liquid - solid ratio, 10 - 20 mL/g; and solvent concentration (10 - 90 % aqueous ethanol, v/v) were studied. Box-Bhenken design was used in order to obtain the maximal extractability of phenolic compounds (namely total phenolic compounds- TPC and total extractible proanthocyanidins - TPA) and the maximal antiradical power (ARP) of obtained extracts. Experimental results of TPC, TPA, and ARP of corn silage extracts were in the range from 10.01 - 72.43 mgGallicAcid Equivalent/gdrybiomass, 0.27 - 3.21 mg/gdrybiomass and 1.25 - 16.76 mgDPPH/mLextract, respectively. Statistical results confirmed that temperature was the most significant factor affecting the observed responses (p < 0.05). Optimal extraction conditions for TPA and ARP were achieved at 180 °C, 120 min using 65 % ethanol and L/S ratio 10 while optimal conditions for TPC were achieved at 180 °C, 120 min using 10 % ethanol and L/S ratio 20. The results of this study evidenced that extracts from corn silage can be a good source of antioxidant compounds which can be used for production of food, cosmetic and pharmaceutical products.