(594b) Parameters for in-Situ Extraction and Impregnation of Walnut Husk and Beet Root into Polymer Films

Many plants used in food production contain a variety of compounds that exhibit antioxidant properties, however the edible part of the plant frequently contains a fraction of the harvested plant matter by mass. The inedible portion of the plant that is discarded post-processing may contain a wealth of polyphenolic compounds, tannins, and other useful chemicals, that may potentially be recovered. For example, only the kernel of the walnut is typically edible, but the husk is commonly discarded. Likewise in beet root production, while the stem and leaves may be edible, they are typically not preserved, and may be discarded. The antioxidant compounds in both walnut husks and beet roots may be extracted using supercritical carbon dioxide with an ethanol modifier. Supercritical carbon dioxide is a highly effective extraction solvent due to its high diffusivity. Likewise supercritical carbon dioxide may cause polymers to swell or relax, thereby enabling the impregnation of chemicals within the polymer matrix. This paper evaluates the simultaneous extraction and impregnation of compounds present in walnut husk, as well as beet root, into polyethylene films. Process parameters such as proportion of plant material to exaction solvent and temperature were evaluated using supercritical carbon dioxide with 15 wt-% ethanol in an agitated batch extractor. The total phenolic content of the resulting extraction residue was quantified. The polymer films were evaluated by a variety of methods including FTIR, Raman Spectroscopy, UV-VIS spectroscopy, fluorescence spectroscopy, reduction of cytochrome c., visually, and gravimetrically. These results demonstrate that compounds are indeed simultaneously extracted and impregnated into polyethylene films and may indicate effects of operating conditions of the extractor.