Dr Delphine Huc-Mathis, Assistant Professor at the Paris Institute of Technology for Life, Food and Environmental Sciences, discusses some novel approaches to extracting cellulose from food by-products. Creating added-value from waste streams is a central element of the circular economy.
Could you outline some of the challenges in efficiently extracting and processing cellulose?
“Although I am no specialist, I would say that finding the proper raw material to obtain the right ingredient while avoiding being in competition with food, and finding the right process to limit the environmental impact, are important challenges. There is always some room for optimisation. From my perspective, our work aims to open up a new way of valorisation with as little processing as possible. Indeed, we are already focusing on food by-products as a source. These have not been exposed to any solvent and can be used right after drying and micronizing (the process of reducing the size of particles).”
You recently conducted a study focused on apple pomace powder. What were the main objectives of this research?
“Apple pomace is one source we are studying, to generate added-value from food by-products for food and cosmetics applications. A first objective is thus ensuring a virtuous circle based on this renewable raw material. A second objective is to understand this ‘new’ ingredient. Using apple pomace as a raw, unmodified material instead of isolates or pure extracts is a bold choice that goes against the grain. We are convinced that if we can master these materials, it will open the door to many applications. This would be the third objective: for these food by-products to be reused in another industry such as cosmetics, for example.”
What were some of the key findings?
“The main finding is that apple pomace – and other food by-products – can be used (only when dried and micronized) as stabilisers in emulsions. The key element is the complementary action of the insoluble (major) fraction, responsible for the control of the oil droplets diameter in time, and the soluble fraction, responsible for the bulk rheology (viscosity and sometimes even gelling properties). We showed that the oil droplet diameter kept a constant diameter during two-month in storage at ambient temperatures with a simple rotor-stator emulsification. The emulsions could also handle accelerated aging. Finally, we successfully carried out a scale-up trial, moving from 200 millilitres to 12 litres.”
What potential benefits could this open up for the food sector?
“The benefits for the food sector are two-fold. Firstly, by valorising food by-products, manufacturers are creating added-value, which could lead to a new chain of value around what could be new ingredients. Secondly, using raw, unmodified and unfractionated materials as a main stabiliser in emulsions could bring real environmental benefits and some clean label claims. This would help manufacturers meet consumer expectations about natural products. Using food by-products in new products would ensure the establishment of a virtuous circle.”
What are the next research steps?
“This research opens up a range of new possibilities. For example: would there be other interesting candidates apart from apple pomace that could bring good stability to emulsions? Could this unmodified, unfractionated raw material be applied to other fields such as cosmetics, buildings, or even pharmaceuticals? And how might these complex materials react in contact with solid fats such as butters or waxes and no oil anymore? Other research questions include: could these new ingredients be interesting for encapsulation and vectorisation? And what about the functionalities of the emulsions, such as texture or more generally the overall perception of the final products? Would they be appreciated? Could they bring some innovation?”
What are your predictions for the next three to five years, in terms of where this research could lead?
“In my opinion, Pickering emulsions (i.e. emulsions stabilised by solid particles) is a field of research that has attracted more and more interest over the past ten years, and for various applications. This interest is likely to continue to increase on the back of the organic, biosourced, biocompatible and biodegradable particles that were selected as the focus of this research. On top of this raw materials could be something other than isolates or concentrates, and that for some applications, using them as raw as possible could be desirable. If we can valorise the proofs of concept that we have just obtained, some new developments would certainly be needed, in order to meet industrial requirements and consumer expectations. I think that with the right strategy, innovative products with desired functional properties could be launched in the next three to five years, based on this technology and combined with real environmental benefits.”