Policosanol, α-Tocopherol, and Moisture Content as a Function of Timing of Harvest of Switchgrass (Panicum virgatum L.)

Using switchgrass (Panicum virgatum L.) as a cellulosic feedstock for the production of ethanol could lead to the extraction of co-products prior to the pretreatment step, thereby adding value to the ethanol conversion process. Policosanols, registered as 142583-61-7, are present in Poaceae and are a mixture of long-chained primary alcohols. Policosanols are composed mainly of docosanol (C22), tetracosanol (C24), hexacosanol (C26), octacosanol (C28), triacontanol (C30), and dotriacontanol (C32). This study determined changes in moisture, policosanol, and α-tocopherol concentrations of Cave-in-Rock and Blackwell switchgrass cultivars during maturation from July to December in Arkansas and Oklahoma. Moisture content on a dry weight basis declined from 150 to 50% with progressive harvests. The total policosanol concentration ranged between 89 mg/kg for July harvested Cave-in-Rock switchgrass from Arkansas and 182 mg/kg for August harvested Cave-in-Rock switchgrass for Oklahoma, and these values remained relatively constant throughout the season. This is the first report on the presence of policosanols in switchgrass. Total switchgrass policosanol concentrations were lower than those typically reported for sorghum grains; however, switchgrass-extracted policosanols contained different policosanol ratios, wherein C30 and C32 alcohol ranges were 36−41 and 43−50%, respectively. α-Tocopherol extracted from both switchgrass cultivars varied between 320 and 400 mg/kg but decreased in the October harvest after frost.