This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts. Because of the huge number of chemical products that can be potentially manufactured, a selection of starting materials and targeted chemicals has been done. Also, thermochemical conversion processes such as biomass pyrolysis or gasification as well as the synthesis of biofuels were not considered. The synthesis of chemicals by conversion of platform molecules obtained by depolymerisation and fermentation of biopolymers is presently the most widely envisioned approach. Successful catalytic conversion of these building blocks into intermediates, specialties and fine chemicals will be examined. However, the platform molecule value chain is in competition with well-optimised, cost-effective synthesis routes from fossil resources to produce chemicals that have already a market. The literature covering alternative value chains whereby biopolymers are converted in one or few steps to functional materials will be analysed. This approach which does not require the use of isolated, pure chemicals is well adapted to produce high tonnage products, such as paper additives, paints, resins, foams, surfactants, lubricants, and plasticisers. Another objective of the review was to examine critically the green character of conversion processes because using renewables as raw materials does not exempt from abiding by green chemistry principles (368 references).

Conversion of biomass to selected chemical products

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

Conversion of Biomass into Chemicals over Metal Catalysts

The demand for petroleum dependent chemicals and materials has been increasing despite the dwindling of their fossil resources. As the dead-end of petroleum based industry has started to appear, today's modern society has to implement alternative energy and valuable chemical resources immediately. Owing to the importance of lignocellulosic biomass being the most abundant and bio-renewable biomass on earth, this critical review provides insights into the potential of lignocellulosic biomass as an alternative platform to fossil resources. In this context, over 200 value-added compounds, which can be derived from lignocellulosic biomass by various treatment methods, are presented with their references. Lignocellulosic biomass based polymers and their commercial importance are also reported mainly in the frame of these compounds. This review article aims to draw the map of lignocellulosic biomass derived chemicals and their synthetic polymers, and to reveal the scope of this map in today's modern chemical and polymer industry.

Increasing demand for fuels and chemicals, driven by factors including over-population, the threat of global warming and the scarcity of fossil resources, strains our resource system and necessitates the development of sustainable and innovative strategies for the chemical industry. Our society is currently experiencing constraints imposed by our resource system, which drives industry to increase its overall efficiency by improving existing processes or finding new uses for waste. Food supply chain waste emerged as a resource with a significant potential to be employed as a raw material for the production of fuels and chemicals given the abundant volumes globally generated, its contained diversity of functionalised chemical components and the opportunity to be utilised for higher value applications. The present manuscript is aimed to provide a general overview of the current and most innovative uses of food supply chain waste, providing a range of worldwide case-studies from around the globe. These studies will focus on examples illustrating the use of citrus peel, waste cooking oil and cashew shell nut liquid in countries such as China, the UK, Tanzania, Spain, Greece or Morocco. This work emphasises 2nd generation food waste valorisation and re-use strategies for the production of higher value and marketable products rather than conventional food waste processing (incineration for energy recovery, feed or composting) while highlighting issues linked to the use of food waste as a sustainable raw material. The influence of food regulations on food supply chain waste valorisation will also be addressed as well as our society's behavior towards food supply chain waste. “There was no ways of dealing with it that have not been known for thousands of years. These ways are essentially four: dumping it, burning it, converting it into something that can be used again, and minimizing the volume of material goods – future garbage – that is produced in the first place.” William Rathje on waste (1945–2012) – Director of the Tucson Garbage project.

Food waste as a valuable resource for the production of chemicals, materials and fuels. Current situation and global perspective

Substrate and product inhibition kinetics in succinic acid production by Actinobacillus succinogenes

The unnerving price of petroleum will push a major change from a petroleum based economy to a natural feed- stock based economy. Production of polyhydroxyalkanoates (PHAs) using industrial and agriculture by-products can al- low the use of low-cost feedstock to produce materials with specific monomer composition and therefore, with the appro- priate physicochemical properties to be used in a broad range of applications. Depending on the monomer composition, PHAs properties can range from thermoplastic to elastomeric materials. Even though PHA has been described as useful polymers due to thier intrinsic biodegradability and biocompatibility, their high price has limited their application signifi- cantly. The raw material cost has been known to contribute significantly to the manufacturing cost of PHA. Therefore, much research has been carried out using renewable cheap raw materials to replace the expensive commercial medium, which should reduce the overall production cost. In this review, the production of PHAs using low-cost sustainable raw materials such as molasses, whey, lignocelluloses, fats and oils, glycerol and wastewater are described. Finally, the phys- icochemical properties of PHAs produced from various carbon sources are discussed.

Polyhydroxyalkanoates Production From Low-cost Sustainable Raw Materials

A wheat biorefining strategy based on solid-state fermentation for fermentative production of succinic acid

A wheat biorefining strategy based on solid-state fermentation for fermentative production of succinic acid Bioresource Technology

The biosynthesis of succinic acid from wheat flour was investigated in a two-stage bio-process. In the first stage, wheat flour was converted into a generic microbial feedstock either by fungal fermentation alone or by combining fungal fermentation for enzyme and fungal bio-mass production with subsequent flour hydrolysis and fungal autolysis. In the second stage, the generic feedstock was converted into succinic acid by bacterial fermentation by Actinobacillus succinogenes. Direct fermentation of the generic feedstock produced by fungal fermentation alone resulted in a lower succinic acid production, probably due to the low glucose and nitrogen concentrations in the fungal broth filtrate. In the second feedstock production strategy, flour hydrolysis conducted by mixing fungal broth filtrate with wheat flour generated a glucose-rich stream, while the fungal bio-mass was subjected to autolysis for the production of a nutrient-rich stream. The possibility of replacing a commercial semi-defined medium by these two streams was investigated sequentially. A. succinogenes fermentation using only the wheat-derived feedstock resulted in a succinic acid concentration of almost 16 g l(-1) with an overall yield of 0.19 g succinic acid per g wheat flour. These results show that a wheat-based bio-refinery employing coupled fungal fermentation and subsequent flour hydrolysis and fungal autolysis can lead to a bacterial feedstock for the efficient production of succinic acid.

Sze Ki Carol Lin

Papers

Substrate and product inhibition kinetics in succinic acid production by Actinobacillus succinogenes

Polyhydroxyalkanoates Production From Low-cost Sustainable Raw Materials

A wheat biorefining strategy based on solid-state fermentation for fermentative production of succinic acid

A wheat biorefining strategy based on solid-state fermentation for fermentative production of succinic acid Bioresource Technology

Succinic acid production from wheat using a biorefining strategy