Industrial hemp, with low levels of the intoxicating cannabinoid tetrahydrocannabinol (THC), is grown for fibre and seeds. The industrial hemp industry is poised for expansion. The legalisation of industrial hemp as an agricultural commodity and the inclusion of hemp seed in foods is helping to drive the expansion of the hemp food ingredients industry. This paper discusses the opportunity to build an industrial hemp industry, with a focus on the prospects of hemp seed and its components in food applications. The market opportunities for industrial hemp products are examined. Various aspects of the science that underpins the development of an industrial hemp industry through the food supply chain are presented. This includes a discussion on the agronomy, on-farm and post-harvest considerations and the various types of food ingredients that can be made from hemp seed. The characteristics of hemp seed meal, hemp seed protein and hemp seed oil are reviewed. Different processes for production of value-added ingredients from hemp seed, hemp seed oil and hemp seed protein, are examined. The applicability of hemp seed ingredients in food applications is reviewed. The design of hemp seed ingredients that are fit-for-purpose for target food applications, through the selection of varieties and processing methods for production of various hemp seed ingredients, needs to consider market-led opportunities. This will require an integrated through chain approach, combined with the development of on-farm and post-farm strategies, to ensure that the hemp seed ingredients and foods containing hemp seed are acceptable to the consumer.

Background: Myxospermy is a process by which the external surfaces of seeds of many plant species produce mucilage-a polysaccharide-rich gel with numerous fundamental research and industrial applications. Due to its functional properties the mucilage can be difficult to remove from the seed and established methods for mucilage extraction are often incomplete, time-consuming and unnecessarily wasteful of precious seed stocks. Results: Here we tested the efficacy of several established protocols for seed mucilage extraction and then downsized and adapted the most effective elements into a rapid, small-scale extraction and analysis pipeline. Within 4 h, three chemically-and functionally-distinct mucilage fractions were obtained from myxospermous seeds. These fractions were used to study natural variation and demonstrate structure-function links, to screen for known mucilage quality markers in a field trial, and to identify research and industry-relevant lines from a large mutant population. Conclusion: The use of this pipeline allows rapid analysis of mucilage characteristics from diverse myxospermous germplasm which can contribute to fundamental research into mucilage production and properties, quality testing for industrial manufacturing, and progressing breeding efforts in myxospermous crops.

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Seed mucilage polysaccharide production, storage and release in Plantago ovata is strikingly different to that of the model plant Arabidopsis. We have used microscopy techniques to track the development of mucilage secretory cells and demonstrate that mature P. ovata seeds do not have an outer intact cell layer within which the polysaccharides surround internal columellae. instead, dehydrated mucilage is spread in a thin homogenous layer over the entire seed surface and upon wetting expands directly outwards, away from the seed. observing mucilage expansion in real time combined with compositional analysis allowed mucilage layer definition and the roles they play in mucilage release and architecture upon hydration to be explored. The first emergent layer of hydrated mucilage is rich in pectin, extremely hydrophilic, and forms an expansion front that functions to 'jumpstart' hydration and swelling of the second layer. this next layer, comprising the bulk of the expanded seed mucilage, is predominantly composed of heteroxylan and appears to provide much of the structural integrity. Our results indicate that the synthesis, deposition, desiccation, and final storage position of mucilage polysaccharides must be carefully orchestrated, although many of these processes are not yet fully defined and vary widely between myxospermous plant species. Abbreviations DPA Days post-anthesis ML Mucilage layer MSC Mucilage secretory cell SEM Scanning electron microscopy Upon exposure to aqueous environments, seeds from myxospermous species extrude a polysaccharide-rich gel from their seed surface, often called mucilage. Numerous species display myxospermy and there are a range of possible evolutionary advantages of synthesising such a carbon-rich and energy-expensive substance 1. Of all myxospermous species, the seed mucilage system of Arabidopsis is the best characterised. Arabidopsis seed mucilage has been used extensively as a proxy for the study of plant cell wall polysaccharide biosynthesis, enabling increased molecular characterisation of pectin biosynthesis, its main polysaccharide component 2 , as well as the biosynthesis of cellulose 3,4 and several hemicelluloses 5-8 , which are minor but integral components. Mucilage from other species can be highly diverse 1 and while P. ovata mucilage is also a complex mixture of polymers, it is predominantly heteroxylan with only a minor pectin component. While the pectin component is a near-linear rhamnogalacturonan 9-11 , the P. ovata heteroxylan (accounting for around 90% of the mucilage polysaccharides) is highly complex with the current scientific consensus defining P. ovata heteroxylan comprising a β-(1,4)-linked-d-xylopyranose backbone, heavily substituted at O-2 and/or O-3 positions with various mono-, di-and oligosaccharide substitutions of α-l-arabinofuranose and β-d-xylopyranose 9,11,12. It is likely that, as with other eudicots, the β-(1,4)-linked-d-xylopyranose backbone is synthesised by several members of