Recovery, physicochemical and functional characteristics of proteins from different meat processing wastewater streams.

Recovery, physicochemical and functional characteristics of proteins recovered from different meat processing wastewater
streams were revealed in the present study. Wastewaters from surimi processing (SPW) and slaughterhouses, namely fish
(FSW), cattle (CSW), poultry (PSW), and goat (GSW), exhibited protein, fat, ash, moisture, and microbial load in the range
of 1.28–7.04%, 0.86–2.34%, 0.02–0.80%, 89.81–97.44%, and 5.33–5.81 CFU/mL, respectively. Among the wastewaters, SPW
presented slightly higher protein (7.04%), fat (2.34%), and ash (0.80%) contents (P < 0.05). Furthermore, proteins recovered
from SPW (SPWP) and FSW (FSWP), CSW (CSWP), PSW (PSWP), and GSW (GSWP) presented yield, protein, fat, ash, and
moisture content in the range of 55.54–76.81%, 65.86–78.22%, 7.26–11.45%, 4.58–11.75%, and 5.67–14.79%. All protein
samples displayed higher essential amino acid (EAA) content with leucine (8.47–14.52 g/100 g) as a predominant amino acid.
GSWP and SPWP scored the highest and lowest EAA contents, respectively. SPWP displayed myofibrillar proteins as dominant
proteins, while slaughterhouses’ wastewater proteins showed blood proteins as major proteins. β-Sheet is the major secondary
structure presented by all protein samples. SPWP showed the highest lightness value as compared to other protein counterparts
(P < 0.05). All protein samples from slaughterhouse wastewaters had the lowest protein solubility at pH 4.5. However, SPWP
presented minimum solubility at pH 5.5. Among all protein samples, SPWP presented slightly higher water holding capacity and
foaming property (P < 0.05), whereas FSWP displayed slightly higher emulsion property (P < 0.05). Overall, all meat processing
wastewater streams served as good sources of high-quality proteins, which could be used as protein ingredients in animal feed
formulation.