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Further Particulars
Synopsis of Project “New Enzymatically Produced Interpenetrating StarchCellulose Gels”
Gels are becoming commonplace in everyday products, particularly as rheological modifiers in
foods, but also as carriers for medicines and excipients in the pharmaceutical industries.
Currently, oxidized cellulose nanofibril gels are produced using top-down approaches derived
from the paper industry to split plant cell walls using high energy homogenisation, or refining.
These fibrils are then combined in water, or with other polysaccharide components in a multistage process. Even with the addition of enzymes to aid this disruption, or via the use of
oxidizing agents (e.g. TEMPO), there is still a need to use relatively high energy processes. The
resultant fibrils also tend to be heterogenous, with a large degree of disorder introduced into
their microstructure, and hard to redisperse in water if dried. This latter issue adds costs to their
transport and has been a concern previously for Unilever and Croda. Our IB approaches use
existing technology, developed from the paper industry, but modified, allowing low energy
processing without the need for new plant. We aim to use a single processing stage - enzymes
that catalyse the starch saccharification, producing sugars which will be reverse hydrolysed into
polymer chains and fibrils to produce fine structured, interpenetrating netwrork (IPN) gels. We
propose to develop gel materials for rheological modification of food and for personal care
products that compete with the top-down approach both on performance and cost. Our approach
will dramatically cut production costs (currently $1500-1900/ton [Cellulose (2011) 18, 1097])
by reducing energy inputs - top down enzymatic approaches have been shown to reduce energy
costs 20-30 fold [Carbohyd Polym. (2014) 99, 649] - our approach will further reduce this. As
a structural component of plants, cellulose is considered to be one of very few truly sustainable,
renewable and multifunctional natural materials. Due to the abundance of cellulose, and its
sustainable credentials, it is a viable replacement for oil-based plastics. Starch is another
abundant polymer, being found in staple foodstuffs (e.g. potatoes, rice). Reduced energy
consumption during processing will additionally reduce CO2 emissions and use less harmful
chemicals. Worldwide starch consumption is predicted to reach around 130 million metric tons
by 2018, with a market set to be worth $11bn by 2020. A staggering 50% of the UK's potatoes
end up in landfill and are never eaten - a large amount of biomass is therefore left unused.
Cellulose and starch are natural polymeric materials with enormous potential to replace
traditional oil-based polmers, so this waste material could be put to much better use. The
development of nanocellulose fibres/fibrils has brought enormous potential to a number of
markets including food and personal care – the market for 'nanocellulose' is predicted to reach
$250m by 2019. Unfortunately, high energy costs prohibit its use at scale.
This project addresses several challenges identified by industry: to find high volume
applications for nanocellulose and to develop new and low cost ways to make gels that are
scaleable for industrial manufacture and perform to industry standards. These issues were
highlighted at a recent BBSRC funded IBCarb meeting on 'Food, Fuels and Materials' and also
a sandpit meeting of the EPSRC funded Directed Assembly Network in Birmingham. There are
significant scientific challenges to overome, including being able to produce the sugars at a rate
commensurate with the reverse hydrolysis process. Given that existing materials are out there
in the market (Unilever, Croda and others have developed gels using top down processes that
are already in foods and creams) we have a challenge to demonstrate that our materials can
compete on equal terms - application, rheological properties etc. Therefore physical properties
of our gels will be fully characterized and tested against existing marketed products. This will
enable us to better understand their market potential (e.g. cost of production) alongside
understanding the role, location and movement of water and their mechanical performance.
Human Resources
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31/07/2017