Hexane is a solvent used extensively in the food industry for the extraction of various products such as vegetable oils, fats, flavours, fragrances, colour additives or other bioactive ingredients. As it is classified as a “processing aid”, it does not have to be declared on the label under current legislation. Therefore, although traces of hexane may be found in final products, especially in processed products, its presence is not known to consumers. However, hexane, and in particular the n-hexane isomer, has been shown to be neurotoxic to humans and has even been listed as a cause of occupational diseases in several European countries since the 1970s. In order to support the European strategy for a toxic-free environment (and toxic-free food), it seemed important to collect scientific information on this substance by reviewing the available literature. This review contains valuable information on the nature and origin of the solvent hexane, its applications in the food industry, its toxicological evaluation and possible alternatives for the extraction of natural products. Numerous publications have investigated the toxicity of hexane, and several studies have demonstrated the presence of its toxic metabolite 2,5-hexanedione (2,5-HD) in the urine of the general, non-occupationally exposed population. Surprisingly, a tolerable daily intake (TDI) has apparently never been established by any food safety authority. Since hexane residues are undoubtedly found in various foods, it seems more than necessary to clearly assess the risks associated with this hidden exposure. A clear indication on food packaging and better information on the toxicity of hexane could encourage the industry to switch towards one of the numerous other alternative extraction methods already developed.

Lignocellulosic waste material serves as a considerable renewable feedstock that could be used to replace oil refineries with biorefineries.

This tutorial review focuses on the valorisation of biomass by sonochemical and mechanochemical activation.

Humic-like substances obtained by alkaline hydrolysis of composted organic wastes are known to improve plant productivity. Little is known concerning the effect on plant growth of hydrolysates obtained by alkaline treatment of non-composted vegetal residues.The aim of this study was to prepare, characterize, and apply in horticulture the soluble and the insoluble fractions obtained by alkaline hydrolysis of exhausted tomato plants. The hydrolysates were prepared in a pilot plant from the tomato plants residue in powder form and characterized by solid state 13C NMR spectrometry, elemental analysis and potentiometric titration. The characterization of the soluble hydrolysate gave evidence of lignin and hemicellulose moieties, together with protein, peptide or amino acids while most of the cellulose was found in the insoluble fraction. Plant beans were grown on a peat and sand substrate fertilized with low application rate of the tomato plant powder and of the corresponding hydrolysates. The effect on bean plants was assessed by determination of plant growth, chlorophyll content, nitrate reductase, glutamine synthetase, glutamate synthase activities and soluble proteins.The tomato plant powder had no effect on all parameters measured on the grown bean plants. On the contrary, the insoluble and soluble substances sourced by alkaline hydrolysis of the tomato plant powder exhibit strong effects, mainly the increase of nitrogen assimilation typical of biostimulants.The results suggest that residual plant biomasses are source of efficient biostimolant and propose the hydrolysis of residual biomass as a viable profitable process to contribute important improvements also for waste management practices. © 2014 Elsevier B.V