Effect of steam treatment on the chemical composition of hemp (Cannabis sativa L.) and identification of the extracted carbohydrates and other compounds

Abstract

The overarching aim of this study was to investigate the possibility of extracting carbohydrates and other compounds from hemp (Cannabis sativa L.) using a continuous steam treatment that would also separate the fibres from the hurd. Different parts of hemp, such as stalk, leaves, and decorticated hemp with hurd, were extracted by a steam treatment. After processing, the fibers in the stalk could be easily separated. The products obtained at different extraction temperatures were characterized using multiple techniques. The hemicellulose content of untreated dry hemp was reduced from 275 mg/g to 237 mg/g at 160 °C treatment while the corresponding cellulose content increased from 376 mg/g to 418 mg/g. For example, the iron (Fe) content of the extracts increased with elevated treatment temperatures; for dry hemp at 100 °C, the Fe content in extracts was 1.33 mg/kg, whereas at 160 °C, it was much higher, 16.58 mg/kg. The results demonstrate that the extraction temperature influences the composition of the extracts. Compounds with potentially useful applications, such as in medicine and in the chemical industry, were also identified in the extracts. However, more research will be needed to optimize the treatment and the further processing of the products in order to estimate the commercial potential of this technique.