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Direct and indirect biorefinery technologies for conversion of organic side-streams into multiple marketable products

Periodic Reporting for period 1 - InDIRECT (Direct and indirect biorefinery technologies for conversion of organic side-streams into multiple marketable products)

Reporting period: 2016-11-01 to 2018-04-30

Diverse side-streams are generated at the farmers and post-harvesting level as well as in the associated retail sector. A part of these biomass streams are not exploited or under-exploited. The Indirect project targets biorefinery of under-spent side-streams as feedstock, aiming at ‘closing loops’ and ‘producing more with less’. Feedstocks considered are under-spent side streams/residues originating from the agro-sector (like biomass left on the field or removed after harvesting), processing sector (plant part, biomass that did not pass the quality control, press cakes, etc.) as well as from the retail sector (expired biomass, inferior quality products, etc.). Valuable compounds can be recycled from this biomass via different biorefinery approaches.
• Direct biorefinery of plant biomass is a biomass specific approach with adapted biorefinery procedures for each biomass type. As such a direct approach is challenging to scale for small biomass streams and is expected to be seasonally dependent and not operational all year. On the other hand, it is an approach that can generate a large variety of potentially high value compounds when applied in a cascading mode (proteins, carbohydrates, fibers, and multiple minor compounds like carotenoids, polyphenols).
• Indirect biorefinery converts side-streams into crude extracts via a two-step process consisting of (1) conversion of biomass by insects and subsequent (2) biorefinery of the insect biomass. The aim of the first step is to convert heterogenic feedstock into a homogenous biomass via insects. Insects are able to convert a variety of feedstock into a more homogenous biomass, being their own biomass. The indirect approach is expected to have potential for a year-round relatively stable production of mainly chitin, proteins, lipids and N-light compost.
In a subsequent step, the crude fractions obtained via both approaches (like proteins, lipids, chitosan, carbohydrates & minor compounds) need to be further purified and processed towards marketable products in different sectors. At this point the possibilities of the compounds need to be matched with the needs in the sector, hereby taking into account the whole value chain and the associated economic, environmental, legal and practical aspects.
An inventory of side-streams was composed based on existing information and served as a basis for the selection of side-streams to work on in WP2 & WP3. Further an overview of legislative barriers related to an insect-based economy was prepared and made available via the project website.

For the direct biorefinery, green leaves were targeted for extracting proteins and minor compounds. The composition of the three green leaves (leek and sugar beet leaves, besides alfalfa as reference) has been determined. Two approaches for the wet fractionation process to extract the protein fraction from the reference material alfalfa were evaluated. Based on mass and nitrogen balances, a strategy was chosen to fractionate both leek and sugar beet leaves. Leaf protein concentrates with a protein (N x 6.25) purity of about 68% up to 80% were obtained. However, a very low protein extraction yield <11% regardless the type of leaf raw material. In respect to minor compounds, the majority of the carotenoids and especially the polyphenols were found in the liquid fraction. Experiments to characterize functional properties and allerginicity of the leaf protein concentrates from alfalfa, leek and sugar beet leaves have been initiated. Finally, the chemical composition of green leaves was also determined according to transport, storage and ensiling conditions of the leaves in order to identify the most suitable preservation technology to avoid the degradation of valuable compounds.

For the indirect biorefinery, single and mixed side-streams were evaluated as feed for 2 insect species. In respect to the black soldier fly (BSF), 8 single side-streams and 4 mixed side-streams were screened for suitablility as feed for BSF larvae. As side-stream mixtures performed significantly better, a more elaborated feed trial was performed with 5 feed mixtures comprising apple pomace, rapeseed, Olive pomace and/or DDGS. Feed uptake efficiencies of 20 % (feed conversion ratio of 5) could be obtained. Growth of BSF on manure was evaluated theoretical, and found less interesting. For the lesser mealworm (LMW), mixed feeds were anticipated from the start and consisted of wheat middling (standard food) with a certain percentage of DDGS, rapeseed, rice bran or corngluten feed. With lower amount inclusions (5 -10 %) of side-streams, the best results were obtained (feed conversion ratios of about 3). Economic interesting mixtures were identified. The chemical composition of selected pairs of feed and larvae grown on the feed were determined and compared. Overall the impact of the feed on the larvae composition was rather small when good larvae growth was observed. A correlation analysis is ongoing.
Two biorefinery concepts for insect biomass were elaborated for practical evaluation with BSF and LMW biomass. The first concept is a multi-step approach envisioning separate fractions rich in chitin, proteins and lipids. Purification and conversion of chitin into small sized chitosan is included in the concept. Small scale tests were set-up to optimise the different process steps. Comparable results were obtained for both insects. First upscalings and integration of the process steps were initiated. As a second approach, enzymatic-assisted extractions of protein material from raw insects were evaluated. Towards characterization of the protein processing a tool box of methods was established. First protein extracts were characterized via a shut gun proteomics approach and amino acid analyses. Activities to evaluate the technical functionalities of the extracted insect proteins were initiated.

To develop nutritional co-balancing side-stream based feed for insects, the nutritional needs of BSF & LMW are being mapped. First steps were also taken to evaluate the safety of insect-derived products. More specifically, the presence of mycotoxines, pesticides pathogens and heavy metals in promising side-streams was determined. In respect to allergies, preliminary results indicate
The InDIRECT project aims to contribute to lower barriers towards implementation of insect-based value chains in Europe.