Saving Resources Through Innovative Concepts and Technologies

Alexander Mathys

Extended Abstract

The concept of the bioeconomy covers the agricultural economy and all manufacturing sectors and associated service areas that develop, produce, process, handle or utilise any form of biological resources, such as plants, animals and microorganisms. There are five priority fields of action for further development: global food security, sustainable agricultural production, healthy and safe foods, the industrial application of renewable resources, and the development of biomass-based energy carriers. Considering this broad field of activities several new developments are proposed to focus not only on renovation of existing food production, but also innovations to create completely new food R&D routes and value chains.

Sustainable food processing as key driver of the bioeconomy covers process-product-operation interactions, where selected examples of innovative thermal, electro-magnetic, mechanical and combined processes were presented and are introduced hereafter. 

Modular thermal microprocess engineering was effectively applied to improve upscaling of microbial inactivation processes and therefore save significant time and resources to implement the generated laboratory results. As the micro-reaction modules can be quickly and simply combined with each other, different thermal pasteurisation and sterilisation lines could be generated. Different up-scale strategies were evaluated by using experimental inactivation kinetics of Lactobacillus in micro (max 1.8 L/h) and pilot scale (max 200 L/h). By using a micro high pressure capillary, inactivation studies of a certified biological sterilisation indicator (Geobacillus stearothermophilus spores) showed the highest inactivation at around 750 MPa and a stabilisation zone over 750 MPa. A hypothesised inactivation mechanism at different pressure levels on the basis of different spore germination processes was proposed to explain this phenomenon, which is very relevant for food preservation and safety. These micro process systems support upscale strategies and offer a useful tool to investigate the different effects of thermal and non-thermal treatment on the inactivation of microorganisms, enzymes and nutrients. 

Electro-magnetic-based pulsed electrical field (PEF) processing enables an efficient use of biomass and energy within different value chains. Consequently, PEF was successfully implemented into the potato and fruit juice processing chains with a maximum capacity for cell disintegration up to 80 tons per hour. Disintegration based on electroporation via PEF could generate cell stress and at higher energy inputs a gentle disintegration for the release of heat sensitive ingredients such as functional proteins. Gentle PEF disintegration is a cost (ca. 1 EUR cent/kg) as well as energy efficient disintegration technology. Additionally, PEF is able to inactivate microbial contamination at energy inputs higher than 50 KJ/kg and could therefore gently pasteurise liquid foods.

During mechanical high pressure processing in batch, focused investigations on the property changes within pure water and more complex systems, such as proteins and microorganisms, enabled a detailed understanding of the respective process-product-operation interactions. Special focus was laid on bacterial spores, the target of sterilisation. After studying spore inactivation in detail, classical high pressure preservation could be optimised through combined thermal and mechanical processes such as high pressure thermal sterilisation as well as continuous ultra-high pressure processing up to 400 MPa as innovative multi-hurdle technologies for gentle sterilisation of healthy and high quality food. Advanced approaches relying on innovative raw materials and biorefinery concepts to create new and innovative value chains could even increase the impact of sustainable food processing. Such innovative value chains could be linked to novel opportunities to value alternative protein sources. By using novel proteins from algae and insects, food security and sustainability of the protein supplies can be significantly improved. 

Algae, bearing large amounts of proteins (up to 70% of dry matter), can serve as an enormous biological protein source. They enable food production concepts considerably more sustainable than the existing value chains as they could grow on infertile land with a high biomass productivity, by using combustion gas as CO2 source to generate a wide range of material and energetic products with an almost 100% fertilisers use efficiency. Arthrosphira (commonly known as Spirulina) biomass is a beneficial protein source containing all essential amino acids, though with reduced amounts of methionine, cysteine and lysine when compared to the proteins of meat, eggs and milk. It is, however, superior to typical plant protein, such as that from legumes.

Insects use for food and feed purposes also provides a solution to decrease the intensity of protein deficit problems in many regions of the world. Insects are also claimed as a more sustainable option compared to other sources of proteins (meat, vegetable, mycelium, etc.). Due to early stages of insect production technologies development and low technology readiness levels of certain process solutions for food and feed, the diversity of species and nutritional composition make the generalised environmental estimation and comparisons not applicable for all the cases of insect production and use, yet.

Connected biorefinery approaches within these innovative value chains realise the sustainable material and energetic utilisation by applying combined processes. These models realise zero waste concepts with a valorisation of all streams and optimal carbon sequestration into proteins, secondary products, fuel, soil and organic products.

Holistic life cycle sustainability assessment, aligned with the introduced process innovations, can evaluate the suggested solutions on a multi parameter base, in terms of improved food production sustainability. As an example, specific hurdles of insect-based food and feed Life Cycle Assessment (LCA) were discussed. Variations in possible technologies of insect killing and slaughtering, chitin exclusion or transformation, defatting and combination with other ingredients play a significant role of LCA score changes. Insect feeding diets play a vital role for LCA scores as they could change environmental impact significantly. A focused knowledge transfer via food processing workshops in our facilities but also abroad at emerging markets as well as student and expert exchanges are needed to assure the mid and long term impact of the presented solutions.

Keywords: bioeconomy, sustainable food processing, sterilisation, biorefinery, algae, insect, life cycle sustainability assessment

Dr  Alexander Mathys is Assistant Professor  in Sustainable Food Processing and Head of the DIL Bioeconomy Department at ETH Zurich, Switzerland; email: alexander.mathys@hest.ethz.ch