Valorization of fiber bio-waste products from food production

Fibers are a bio-product of many food industries; a single food producer could generate approximately 8,000 tons of fiber waste per year (https://www.oatly.com/communication/production-residues). Considering the market growth in plant-based foods, this value is only meant to increase consistently. Fibers are well known to positively contribute to health benefits, such as lowering LDL-cholesterol, slowing glucose absorption in the intestine, and reducing the risk of coronary diseases, obesity, and diabetes, among other related health benefits.  Despite that, fiber bio-waste is mainly intended for feed consumption due to the short shelf-life of the product. The general composition of fiber, for example, oat fibers, consists of protein, fat, and carbohydrates. The latter are the major components, divided into starch, insoluble and soluble fibers (Diaz et al., Innov Food Sci Emerg Technol 2022; Manthey et al., Cereal Chem 1999).

In addition, phenolic components, such as tocopherol, are also present. The composition of the fiber is a very suitable substrate for fermentation, which could be considered a valuable approach to valorize these bio-products.

The present study consists of four topics:

1. Characterization of fiber bio-waste substrates.
   The metabolites present in substrates, as well as the presence of possible microbial contaminants, will be determined. 
2. Screening of bacteria able to inhibit microbial growth and  produce organic acids.
   Microbial strains from the Sacco collection (e.g., Lactobacillus acidophilus, Lactobacillus helveticus, Lactiplantibacillus plantarum, Acetobacter ssp., Leuconostoc ssp., Pediococcus ssp., Lentilactobacillus parabuchneri/buchneri, Limosilactobacillus reuteri; and Bacillus coagulans/subtilis) will be tested for their ability to grow on the substrate and to produce organic acids. 
   Growth-inhibition assays of yeast and mould will be carried out.
3. Screening of bacteria producing enzymes of interest and characterization of bio-products produced in the substrates.
   The production of secreted enzymes such as esterases (including ferulic acid esterase) and proteases will be determined, as well as the amount of polyphenols produced.
4. Design of new food which will be positively accepted by consumers.
    

• Novel microbial solutions to valorize fiber bio-waste products into food applications, such as bakery and confectionary products, meat and/or fish alternatives. 
• The generated knowledge will allow not only to increase the shelf-life of the current fiber bio-waste but also to improve the nutritional value via fermentation.