Vast amount of food industry protein- and fiber-rich side-streams are left unattended and usually discarded, whereas demand for products with high nutritional value is constantly increasing. In this Prowaste project the main focus was on underutilized food production side streams, such as brewer’s spent grain (BSG), canola oil presscake (CPC), and oat hulls (OH). The BSG and CPC was provided by the project partners, but OH and additional BSG materials were screened from Finland and project partner countries, respectively. Various chemical analyses methods were evaluated in interviews with stakeholders.
To facilitate further conversion of various raw materials (BSG, CPC, or OH) into food and feed grade protein and dietary fiber products, different fermentation and enzymatic pre-treatment processes were developed. Most promising outcomes with used raw materials were obtained after enzymatic treatments. For example, pre-treatment of BSG with proteases increased the solubility of proteins significantly (up to 80%), producing different proteinaceous fractions, including water-soluble peptides and free amino acids. Therefore, depending on the final functional properties, such pre-treated samples could be further used as alternatives in different food products. In parallel, the development of the extraction process and optimization of the concentration approach to receive protein and dietary fibers from BSG and CPC was carried out. The optimized enzymatic pre-treatments and extraction conditions were efficiently scaled up and collected fractions were used for producing protein and fiber-rich powders.
Different drying methods were used to select and optimize drying process conditions. Optimization of the drying of the extracts of BSG pre-treated with enzymatic operations in pilot scale was carried out for spray drying technology, which was the best in case of economy and timeframe of the process, with savings of the physicochemical and functional properties of the materials, which is further used in the food product concepts. Development of the composition, technological processing conditions as well as product properties, including sensory acceptance, were already established for bakery products, such as cookies and bread. Now, the studies are carried out on the application of the dried BSG, CPC and OH in yoghurt and other fermented dairy products, and on the selected catering food products (convenient foods). Regis Ltd. responsible for the meat products development is also making trials to optimize the pre-treated and dried BSG and other materials application in the design of an innovative meat products.
This project has given a comprehensive overview how underutilized side streams could be used for different food products. The created methodologies and outcomes are good base for new projects and further studies for food side-stream valorization.
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Mr. Oskar Laaksonen
University of Turku, Finland