Abstract
A study of the effects of single and combined protease hydrolysis on myofibrillar versus collagenous proteins of poultry by-products has been conducted. The aim was to contribute with knowledge for increased value creation of all constituents of these complex by-products. A rational approach was implemented for selecting proteases exhibiting the most different activity towards the major protein-rich constituents of mechanically deboned chicken residue (MDCR). An initial activity screening of 18 proteases on chicken meat, turkey tendons and MDCR was conducted. Based on weight yield, size exclusion chromatography (SEC) and SDS-PAGE, stem Bromelain and Endocut-02 were selected. Studies on hydrolysis of four different poultry by-products at 40 °C, evaluated by protein yield, SEC, and SDS-PAGE, indicate that the proteases’ selectivity difference can be utilized in tailor-making hydrolysates, enriched in either meat- and collagen-derived peptides or gelatin. Three modes of stem Bromelain and Endocut-02 combinations during hydrolysis of MDCR were performed and compared with single protease hydrolysis. All modes of the protease combinations resulted in a similar approximately 15% increase in product yield, with products exhibiting similar SEC and SDS-PAGE profiles. This shows that irrespective of the modes of combination, the use of more than one enzyme in hydrolysis of collagen-rich material can provide means to increase the total protein yield and ultimately contribute to increased value creation of poultry by-products.
Highlights
To be able to normalize the amount of protease used in later steps involving investigations of substrate preference in the hydrolysis of different poultry raw materials, 18 proteases were subjected to a protease assay based on degradation of the synthetic substrate azo-casein
Use of a neutral pH allows for an easy implementation of the methodology for by-product enzymatic protein hydrolysis (EPH) processing plants working at these conditions
To the authors’ knowledge, this study shows for the first time shows that if selecting the appropriate protease, a process based on a one-step EPH hydrolysis of mechanically deboned chicken residue (MDCR)
Summary
The value creation of side streams and by-products from food processing sectors, collectively called by-products, is one of the global efforts to sustainably utilize marine and agricultural resources. These by-products contain proteins with potentially bioactive properties, eligible for recycling and upgrading for higher-value products, e.g., for human, pet food and feed purposes. If aiming at the feed, pet food, and human markets, strict regulations exist, governed by for example European Union (EU) regulations. If following existing food regulations and provided the materials are not included in the animal by-product categories, there are many industrial by-products that can be used for human consumption [1]. Despite the successful developments of a few highvalue products, especially animal-based by-products remain underutilized or utilized to applications with low value [1,2]
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