Identification of VOCs Responsible of Odour during Field Retting of Hemp Stems

Abstract : Incorporation of natural fibres into polymers to manufacture biocomposites is a way of limiting the environmental impact of these materials. However, the fibres quality is essential to fulfil their assigned role as reinforcement in biocomposites. The extraction of fibres from hemp stems requires a retting step. Retting is a bioprocess applied to plant stems to easily separate fibres from the central woody part. Nowadays, this process is carried out directly on the field in an empirically way due to its dependence on environmental conditions which could cause problems of the inconsistency of the hemp fibres quality. During few weeks of retting, odours are generated by the degradation of plant material by microorganisms. The modification of these odours can be correlated with the progress of the retting degree of hemp stems. This change in odour is obviously combined with a change in the type and quantity of VOCs emitted. Identifying odours and VOCs emitted when the retting is optimal can lead to make sensors able to survey the progress of this biological process. Then, if this process is well controlled, much higher quality with more uniform fibres could be produced. This article will focus on the identification of the odour emitted when the optimal retting of the stems is reached as well as the identification of the VOCs analysed at this stage