Physicochemical, Nutritional and In Vitro Antidiabetic Characterisation of Blue Whiting (Micromesistiuspoutassou) Protein Hydrolysates

Abstract

Protein hydrolysates from low-value underutilised fish species are potential sources of high-quality dietary protein and health enhancing peptides. Six blue whiting soluble protein hydrolysates (BW-SPH-A_F), generated at industrial scale using different hydrolysis conditions, were assessed in terms of their protein equivalent content, amino acid profile and score and physicochemical properties in addition to their ability to inhibit dipeptidyl peptidase IV (DPP-IV) and stimulate the secretion of insulin from BRIN-BD11 cells. Furthermore, the effect of simulated gastrointestinal digestion (SGID) on the stability of the BW-SPHs and their associated in vitro antidiabetic activity was investigated. The BW-SPHs contained between 70–74% (w/w) protein and all essential and non-essential amino acids. All BW-SPHs mediated DPP-IV inhibitory (IC50: 2.12–2.90 mg protein/mL) and insulin secretory activity (2.5 mg/mL; 4.7 to 6.4-fold increase compared to the basal control (5.6 mM glucose alone)). All BW-SPHs were further hydrolysed during SGID. While the in vitro DPP-IV inhibitory and insulin secretory activity mediated by some BW-SPHs was reduced following SGID, the activity remained high. In general, the insulin secretory activity of the BW-SPHs were 4.5–5.4-fold higher than the basal control following SGID. The BW-SPHs generated herein provide potential for anti-diabetic related functional ingredients, whilst also enhancing environmental and commercial sustainability.

Blue Whiting Protein Hydrolysates Exhibit Antioxidant and Immunomodulatory Activities in Stimulated Murine RAW264.7 Cells

“…In this study, the in vitro antioxidant and immunomodulatory potential of six protein hydrolysates generated at industrial scale from the low-value underutilised species blue whiting, using different hydrolysis conditions, were assessed. All BWSPHs contained high protein contents ranging from 70.37 ± 0.33-73.60 ± 0.53 g/100 g [26]. Physicochemical data such as DH, molecular mass distribution, RP-UPLC, and free amino acid profiles demonstrated that the variation in hydrolysis conditions resulted in the generation of BWSPHs with distinctly different characteristics [26].…”

“…All BWSPHs contained high protein contents ranging from 70.37 ± 0.33-73.60 ± 0.53 g/100 g [26]. Physicochemical data such as DH, molecular mass distribution, RP-UPLC, and free amino acid profiles demonstrated that the variation in hydrolysis conditions resulted in the generation of BWSPHs with distinctly different characteristics [26]. In summary, BW-SPH-A, BW-SPH-B, BW-SPH-E had significantly higher DH values (43.19-45.79%, p < 0.05) compared to all other samples with an abundance of low MW peptides, i.e., <1 kDa (69.74-77.86%).…”

“…The six BWSPHs (BW-SPH-A to -F) samples provided by BioMarine Ingredients Ireland Ltd. (Lough Egish Food Park, Castleblaney, Co. Monaghan, Ireland) were generated from minced blue whiting as previously described by [26]. Simulated gastrointestinal digestion (SGID) of the BWSPHs (BW-SPH-A-GI to -F-GI) was performed as described in [26] using pepsin (pH 2, 37 • C, 90 min, E:S of 2.5% w/w) and Coralase PP (pH 7, 37 • C, 150 min, E:S of 1% w/w). Samples were heated at 85 • C for 15 min, freeze-dried and kept at −20 • C until used.…”

“…RAW264.7 cells were grown in Dulbecco's Modified Eagles' Medium (DMEM) supplemented with 10% (v/v) FBS. Cells (between passage numbers [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] were cultured in an atmosphere of CO 2 -air (5:95 (v/v)) at 37 • C and were maintained in the absence of antibiotics. The BWSPHs and SGID BWSPHs were diluted directly with sterile DMEM, unless stated otherwise, sterile-filtered using 0.45-micron filters, and stored at −20 • C. Reduced serum media (DMEM supplemented with 2.5% FBS) was used for cell-based experiments.…”

“…Recently our group generated distinct blue whiting soluble protein hydrolysates (BWSPHs) at commercial scale using various food-grade microbial-derived proteolytic enzyme preparations and hydrolysis conditions (enzyme:substrate (E:S) ratios ranging from 0.005% to 0.900% (w/w), 50 • C, 45-120 min, [26]). Although these hydrolysates differed in their DH and molecular mass distribution, all BWSPHs tested demonstrated in vitro antidiabetic activity through dipeptidyl peptidase-IV (DPP-IV) inhibitory and insulin secretory activity.…”