Stabilisation of horticultural waste, value adding techniques and recipe development
Testing of stabilisation and conservation techniques on the main horticultural waste streams.
The first stage of processing of horticultural waste streams after collecting the raw material is to stabilise it so that the valuable components will be preserved and can be used (later) as materials in food and feed, cosmetics, etc. A number of techniques such as drying, heating, freezing, fermentation, extraction etc. will be tested on the main waste streams of the three regions. Also the next steps before real processing will be tested such as cleaning, grinding, and conservation techniques.
For the three involved regions the main residual horticultural streams have been inventoried. Based on this inventory 15 crops have been selected for a literature study. This literature study will address stabilisation techniques and methods and key parameters regarding nutritional interesting components.
The full report can be found in the ‘publications’ section.
Based on interactions with farmers and industrial stakeholders a diverse set of activities (literature study, analysis, experiments) was set up by ILVO and VIVES to evaluate the potential of different stabilisation technologies as a first step towards improved utilisation of the horticultural biomass fractions: heating, cooling, fermentation and drying.
The result of the literature study are two excel sheets. One is giving an overview of the most relevant scientific reports about the four different stabilisation methods evaluated (heating, cooling, fermentation and drying). The other is a clear overview of relevant macronutrients, micronutrients and bioactive compounds present in the 15 selected crops.
The results of the stabilisation tests with different methods and techniques are summarised in a report end 2018. That report will be published on the project website in the beginning of 2019.
Different unit operations have been carried out to allow further use of stabilised ingredients. A first evaluation of the following pre-processing steps has been initiated both at ILVO and VIVES:
- Cleaning: rinsing, washing with water, in batches or in a continuous system
- Cutting, grinding, milling: different milling systems were evaluated
- Pressing-dewatering: both a hydropress and the more innovative low-oxygen spiral filter press were evaluated
- Extraction: in collaboration with Bio2Bio
With stakeholders, ILVO and the new partners Tomabel, Comgoed and Sustainable Protein preliminary experiments were set up to evaluate the potential of different value added processing technologies such as the use of a low-oxygen spiral-filter press to produce food & drink ingredients from underutilised tomato fruits . A second example is the use of the low-oxygen spiral-filter press in order to obtain potential food ingredients derived from underutilised class II Belgian endive chicons.
Preliminary experiments were set up in discussion with interested stakeholders. Juice obtained from unsold class II tomatoes was also subjected to heat treatment to increase shelf-life and to guarantee microbiological safety and stability. In addition heat treatments were also evaluated as conservation treatment for the fractions obtained after the spiral-filter process applied on Belgian Endive by-products. Preliminary experiments with Brussels sprouts were also set up in the course of 2018.
We have developed two vegetarian burgers on the basis of horticultural residuals as demonstration projects: the green bean burger and the spent grain burger. At least 50% of both burgers are from residual flows. Both burgers meet the quality demands: source of protein and fibre-rich. Bot burgers can be produced vegan as well. Several breweries have shown interest to start producing the spent grain burger and to sell it as ‘beer’ burgers. Spent brewer grains is a residual product of beer brewing. See also the article at the ‘news’ section.
Also some fermentation products or recipes have been worked out for the use of horticultural residuals: fermented peas dip, fermented tomato salsa and fermented spent grain cookies. Six students of VIVES University brought the dips to the market via a Small Business Project. See also the article at the ‘news’ section.