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. 2024 Oct 1;22(10):452.
doi: 10.3390/md22100452.

Exploring the Physicochemical Characteristics of Marine Protein Hydrolysates and the Impact of In Vitro Gastrointestinal Digestion on Their Bioactivity

Deepanshi Sharma  1 , Snehal Gite  2 , Maria G Tuohy  1   3
Affiliations

Exploring the Physicochemical Characteristics of Marine Protein Hydrolysates and the Impact of In Vitro Gastrointestinal Digestion on Their Bioactivity

Deepanshi Sharma et al. Mar Drugs. .

Abstract

Fish protein hydrolysates (FPHs) were obtained from different fish sources using a combination of microbial enzymes. The industrially produced FPHs from blue whiting (Micromesistius poutassou) and sprat (Sprattus sprattus) were compared to freeze-dried FPHs generated in-house from hake (Merluccius merluccius) and mackerel (Scomber scombrus) in terms of their physicochemical composition and functionality. Significant differences (p < 0.05) were observed in the protein, moisture, and ash contents of the FPHs, with the majority having high levels of protein (73.24-89.31%). Fractions that were more extensively hydrolysed exhibited a high solubility index (74.05-98.99%) at different pHs. Blue whiting protein hydrolysate-B (BWPH-B) had the highest foaming capacity at pH 4 (146.98 ± 4.28%) and foam stability over 5 min (90-100%) at pH 4, 6, and 8. The emulsifying capacity ranged from 61.11-108.90 m2/g, while emulsion stability was 37.82-76.99% at 0.5% (w/v) concentration. In terms of peptide bioactivity, sprat protein hydrolysate (SPH) had the strongest overall reducing power. The highest Cu2+ chelating activity was exhibited by hake protein hydrolysate (HPH) and mackerel protein hydrolysate (MPH), with IC50 values of 0.66 and 0.78 mg protein/mL, respectively, while blue whiting protein hydrolysate-A (BWPH-A) had the highest activity against Fe2+ (IC50 = 1.89 mg protein/mL). SPH scavenged DPPH and ABTS radicals best with IC50 values of 0.73 and 2.76 mg protein/mL, respectively. All FPHs displayed noteworthy scavenging activity against hydroxyl radicals, with IC50 values ranging from 0.48-3.46 mg protein/mL. SPH and MPH showed the highest scavenging potential against superoxide radicals with IC50 values of 1.75 and 2.53 mg protein/mL and against hydrogen peroxide with 2.22 and 3.66 mg protein/mL, respectively. While inhibition of α-glucosidase was not observed, the IC50 values against α-amylase ranged from 8.81-18.42 mg protein/mL, with SPH displaying the highest activity. The stability of FPHs following simulated gastrointestinal digestion (SGID) showed an irregular trend. Overall, the findings suggest that marine-derived protein hydrolysates may serve as good sources of natural nutraceuticals with antioxidant and antidiabetic properties.

Keywords: amino acids; antioxidant activity; bioactive peptides; diabetes; fish protein hydrolysates; functional properties.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Solubility vs. turbidity profiles of FPHs: (A) BWPH-A: blue whiting protein hydrolysate A; (B) BWPH-B: blue whiting protein hydrolysate B; (C) SPH: sprat protein hydrolysate; (D) HPH: hake protein hydrolysate; (E) MPH: mackerel protein hydrolysate. Error bars are expressed as mean ± SD (n = 3). * Different letters in a category indicate significantly different means (p < 0.05).
Figure 2
Figure 2
Foaming capacity and stability (%) of FPHs measured over a pH range of 2–10; (A) Foaming capacity; (B–F) Foaming stability (%) of FPHs: BWPH-A: blue whiting protein hydrolysate A; BWPH-B: blue whiting protein hydrolysate B; SPH: sprat protein hydrolysate; HPH: hake protein hydrolysate; MPH: mackerel protein hydrolysate. Error bars are expressed as mean ± SD (n = 2). * Different letters in a category indicate significantly different means (p < 0.05).
Figure 3
Figure 3
Scanning electron microscopy of FPHs: (A) blue whiting protein hydrolysate A (BWPH-A), (B) blue whiting protein hydrolysate B (BWPH-B), (C) sprat protein hydrolysate (SPH), (D) hake protein hydrolysate (HPH), (E) mackerel protein hydrolysate (MPH), (F) Soy peptone hydrolysate (Soy-PH). Magnification: 450×.
Figure 4
Figure 4
FT-IR spectra produced by FPHs.
Figure 5
Figure 5
DH (%) of FPHs: BWPH-A: blue whiting protein hydrolysate A; BWPH-B: blue whiting protein hydrolysate B; SPH: sprat protein hydrolysate; HPH: hake protein hydrolysate; MPH: mackerel protein hydrolysate. Error bars are expressed as mean values ± SD (n = 3). * Different letters in a category indicate significantly different means (p < 0.05).
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