Mango is the second most consumed tropical fruit after banana and the by-products of mango processing (peel, kernel and seed) roughly comprise 35–60% of the total fruit weight, thus representing a potentially high volume resource of exploitable biobased chemicals and materials. Herein, conversion and characterisation of waste mango peels from three different cultivars (Alphonso, Honey and Tommy Atkins) into pectin and porous cellulose using low temperature microwave-assisted acid-free hydrolytic conditions is reported. Microwave-assisted acid-free extraction yielded up to 11.63% (dry weight basis) of pectin which was characterised by IR, NMR (both solution and solid phase) and TGA which showed close similarity to commercial (acid extracted) pectin. The degree of esterification of pectin was determined by 13C NMR (75.6–86.2%) and titrimetry (79.3–87.7%) and the pectin showed excellent gelling ability. The molecular weight as determined by GPC was in the range 14 130 (Honey)–25 540 (Tommy Atkins). Porosity measurements on the depectinated residue, i.e., residual cellulosic matter showed mesoporous characteristics: average pore diameter, 9.3 nm (Alphonso)–10.5 nm (Honey), however with poor surface area 16.3 m2 g−1 (Honey)–26.0 m2 g−1. Interestingly, a second microwave hydrothermal treatment on these residues retained mesoporosity whilst significantly increasing surface area (88.8 m2 g−1 (Honey)–124.0 m2 g−1 (Alphonso)) and pore volume by approximately six-fold. This is the first detailed combined study of microwave-assisted extraction to yield pectin and mesoporous cellulose towards a potential zero waste mango biorefinery.
Humanity is currently facing a crisis of excess, with a growing population and the trend towards disposable goods, and the world’s resources are under tremendous pressure. This is especially evident in the textiles industry, with increasing consumer numbers and the trend of ‘fast fashion’ causing demand to be at an all-time high, with non-renewable feedstocks depleting and production of natural fibres also under strain. Considering the future of textile production, it can be beneficial to investigate our past for inspiration towards more sustainable approaches. Much of the research into regenerated protein fibres was performed out of necessity during wartime, and while this demonstrates the potential for food waste to be exploited as a resource, the manufacturing methods used at the time now present issues for a circular economy due to the high amounts of toxic waste produced. Using a range of historical and modern literature sources, including journal articles, patents and conference papers, this review presents the historical precedent and research performed into azlons, regenerated fibres produced from waste protein-rich materials. Historical evidence shows that the success of these azlon fibres was short-lived, partly due to negative associations with deprivation and hardship, alongside the emergence of alternative man-made fibres, which were devoid of these connotations with never-before-seen physical properties. The social and political climate leading to the creation, and ultimate demise, of azlons is explored along with the influence of evolving technologies and the marketing of these textile products to consumers. Although the creation of products from waste is not a new concept, the literature has identified that the synergy between the challenges faced in a time of resource scarcity and the current trend of problematic excess reveals an exciting opportunity to learn from our past to create a greener future. Lessons that could help with the current crisis within the textile industry are extracted and presented within the concept of a circular textiles economy. Our findings show that there is notable potential for one regenerated protein fibre, made from casein extracted from milk waste, to be manufactured within a localised, circular economy in conjunction with the principles of green chemistry and sustainable textiles technology.
With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage.
Sustainable methods of practice within the fashion and textile industry (FTI) often strive to employ a circular economy that aims to eliminate waste through the continual use of resources. Complex problems such as waste, consumption, and overproduction are heavily intertwined; the main aim of this paper is to report on research focused on re-examining the potential of food waste streams as a commercially viable and circular source of raw materials for the FTI. Herein, regenerated protein fibres (RPFs) from food production waste streams rich in protein have been chosen as the main topic of focus. RPFs have a rich and relevant history from a local manufacturing perspective during wartime and post-war clothing rationing (1941–1949) in the UK. RPFs were used to meet civilian needs for wool-based textiles as part of a wider series of ‘make do and mend’ strategies designed to manage the consumption of new textile products. However, RPFs demonstrated inferior quality in terms of durability when compared to wool-based textiles, a significant contributing factor to the consequent commercial phasing out of RPFs. In today’s take–make–waste model, the FTI landscape can be defined by speed, from slow (high-quality materials and construction, long-lasting products) to fast (seasonal, disposable, low-quality materials and construction), the latter infamous for dire environmental impacts. A key objective of this research is to review the association of quality and longevity within the context of a local and circular fashion economy in which textile quality and lifecycle analysis are holistically matched to the longevity of the textile, garment, or product to reduce waste across the supply chain.