Quality of Protein Isolates and Hydrolysates from Baltic Herring (Clupea harengus membras) and Roach (Rutilus rutilus) Produced by pH-Shift Processes and Enzymatic Hydrolysis

Abstract

Fractionation is a potential way to valorize under-utilized fishes, but the quality of the resulting fractions is crucial in terms of their applicability. The aim of this work was to study the quality of protein isolates and hydrolysates extracted from roach (Rutilus rutilus) and Baltic herring (Clupea harengus membras) using either pH shift or enzymatic hydrolysis. The amino acid composition of protein isolates and hydrolysates mostly complied with the nutritional requirements for adults, but protein isolates produced using pH shift showed higher essential to non-essential amino acid ratios compared with enzymatically produced hydrolysates, 0.84–0.85 vs. 0.65–0.70, respectively. Enzymatically produced protein hydrolysates had a lower total lipid content, lower proportion of phospholipids, and exhibited lower degrees of protein and lipid oxidation compared with pH-shift-produced isolates. These findings suggest enzymatic hydrolysis to be more promising from a lipid oxidation perspective while the pH-shift method ranked higher from a nutrient perspective. However, due to the different applications of protein isolates and hydrolysates produced using pH shift or enzymatic hydrolysis, respectively, the further optimization of both studied methods is recommended.

Lingonberry (Vaccinium vitis-idaea) press-cake as a new processing aid during isolation of protein from herring (Clupea harengus) co-products

“…The formation of hexanal, (E)-2-hexenal, heptanal, octanal and 2,4-heptadienal, all of which are breakdown products of lipid hydroperoxides ( Aitta et al, 2021 , Kakko et al, 2022 ), was monitored during the 21-day ice storage of protein isolates. Hexanal can be produced by beta scission of the lipid hydroperoxide on either side of the radical and is primarily associated with the oxidation of n-6 PUFAs ( Gómez-Cortés et al, 2015 , Nogueira et al, 2019 ).…”

“…The MS was operated in electron ionization mode and ions were scanned in the range of 10–250 amu. Hexanal, (E)-2-hexanal, heptanal, octanal and 2,4-heptadienal were selected as lipid oxidation markers since they were among the most abundant volatiles detected and since they are common to oxidized fish and other samples rich in n-3 or n-6 PUFAs ( Aitta et al, 2021 , Kakko et al, 2022 ). The retention time and SIM mass for identification of the volatile aldehydes used as lipid oxidation markers are presented in Supplementary Table 2 .…”

Combined Effects of Defatted Hydrolyzed Collagen from Salmon Skin and Vitamin C on Proliferation and Migration of Human Fibroblast Cell

“…When the amino acid composition of HC was determined (Table 1), HC obtained from salmon skin in this study had lower imino acids (13.46 g/100 g HC) than that derived from seabass skin prepared using two-step hydrolysis (papain at 0.3 units/g dry matter for 90 min, followed by Alcalase at 0.3 units/g dry matter for 90 min) (20.43 g/100 g HC) [5]. The difference in raw material and enzymatic hydrolysis processes used is the important factor affecting the amino acid composition of hydrolysate [20,21]. Apart from imino acids, hydrophobic amino acids were found at a high content for defatted HC obtained from salmon skin (47.55 g/100 g HC), which might be related to several biological activities of peptides, including fibroblast and osteoblast proliferation [14,16].…”

Protein hydrolysates derived from aquaculture and marine byproducts through autolytic hydrolysis

“…These techniques include enzymatic hydrolysis, microbial fermentation, and autolysis using visceral and muscle proteases (Benjakul et al., 2014; Nikoo et al., 2016; Tacias‐Pascacio et al., 2021). The enzymatic hydrolysis is performed in reactors under controlled conditions for a specific time, followed by downstream processing to separate BAP fractions from the remaining residues (Kakko et al., 2022; Toldrá & Mora, 2021; Wubshet et al., 2019). Enzymes with different cleavage specificities break down the proteins into peptides of varying sizes (i.e., polypeptides, oligopeptides, dipeptides and tripeptides, and free amino acids), amino acid composition, sequence, and hydrophobicity (Udenigwe & Aluko, 2012).…”