Towards a circular bioeconomy: High added value protein recovery and recycling from animal processing by-products

This paper reports the studies on the recovery of proteins from animal by-products (ABPs). Specifically it proposes the use of ABPs Category 2 as secondary raw material as an alternative to ensure a sustainable production of higher added value products, mainly protein biopolymers as retanning agent for leather manufacturing and amino acid-based biostimulants, using an enzymatic process as methodological solution that has proven to be suitable for the treatment of non-tanned hides and processed animal proteins (PAPs) to obtain hydrolysed collagen with good yields and performance. The developed process has proved to allow the recovery up to 85% protein present in the treated animal by-products and it has shown itself to be a versatile process easily customisable to different kinds of ABPs. The validation test for application as biostimulant have been conducted at lab scale through cabbage germination showing an improvement of 25%. In addition, the retanning process results have been satisfactory and the retanned leathers comply with the requirements established to be used in footwear manufacturing. [Display omitted] •Animal byproducts can be a renewable resource of bioproducts for the green chemistry.•Green emerging approaches is the best alternative to ensure their sustainable production.•A broad range of amino acids and peptides-can be obtained depending on a hydrolysis process.•Animal amino acids based biostimulants as sustainable alternative to mineral fertilizers.