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The aim of this study was to investigate the functional properties of bioactive peptides produced from shrimp wastes in processing centers in three degrees of hydrolysis. For this purpose, the wastes of shrimp processing centers were hydrolyzed in three times of one, two and three hours using protamex enzyme and the functional properties of the resulting peptides (SPH₁, SPH₂ and SPH₃) were evaluated. The results showed that with increasing the hydrolysis time from one to two and three hours, the degree of hydrolysis and nitrogen recovery of the process increased significantly (p<0.05). According to the findings, the solubility of SPH₃ was significantly higher than SPH₁ and SPH₂ and its maximum was reported at pH=10, equal to 97.82±1.54% (p<0.05). SPH₁ had higher emulsifying activity and emulsion stability index than SPH₂ and SPH₃. In this peptide, the highest value of emulsifying activity index was reported 68.15±2.84 m²/g, which was related to pH=10. But the maximum emulsion stability index was reported at pH=6 (166.84±5.08 minute). The highest measured foaming activity was 165.52±5.91% which was recorded at SPH₁ and pH=10. Also, the maximum foam stability among the peptides was measured 118.32±3.23%, which was related to SPH₁ at pH=6. SPH₁ had a higher oil absorption capacity (5.92±0.33 ml/g) than SPH₂ and SPH₃ (p<0.05). The highest water holding capacity (5.18±0.71 ml/g) was related to SPH₃ (p<0.05). According to the findings, the functional properties of peptides produced from wastes of shrimp processing centers using protamax enzyme are at an acceptable level for use in various foods.

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The aim of this study was to evaluate the different properties of bioactive peptides encapsulated with a combined coating of nanoliposome and chitosan. Therefore, the wastes of shrimp processing and packaging centers were hydrolyzed using Neuterase enzyme and the antibacterial, antioxidant and antihypertensive properties of the product were evaluated in the form of five treatments of P (free peptides), NP (peptide-carrying nanoliposomes), NP-CH-0.05 (peptide-carrying nanoliposomes with a coating of 0.05% chitosan), NP-CH-0.1 (peptide-carrying nanoliposomes with a coating of 0.1% chitosan) and NP-CH-0.5 (peptide-carrying nanoliposomes with a coating of 0.5% chitosan). The results showed that all research treatments have certain antibacterial, antioxidant and antihypertensive properties. P and NP treatments provided almost equal values for all three properties and their properties did not differ significantly (p>0.05). Chitosan-coated treatments had significantly more antibacterial, antioxidant and antihypertensive properties than P and NP treatments (p<0.05). In chitosan-coated treatments, with increasing the amount of chitosan in the coating, all three mentioned properties were significantly increased (p<0.05). The highest growth inhibition activity of Escherichia coli, Bacillus cereus and Staphylococcus aureus (45.89±0.96, 34.82±0.75 and 49.67±1.45%, respectively), the maximum amount of inhibition of DPPH, ABTS and linoleic acid peroxidation (63.52±2.86, 73.91±0.29 and 89.06±2.11%, respectively) and also the most effective antihypertensive property (37.91±1.29%) were related to NP-CH-0.5 treatment.

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Fish epidermal mucus protein extraction for bioassay-guided screening is challenging and variable. In this study, four different protein extraction methods, including acetone, trichloroacetic acid (TCA)-acetone, methanol, and solid-phase extraction (SPE), were investigated to study their efficiency in ultrafiltration and to obtain the appropriate peaks in HPLC to measure biological activities. The presented data shows that the solid phase extraction method is better than the other three tested methods in quantity (total protein yield) and quality (protein profile observed in SDS-PAGE) of proteins and peptides from the epidermal mucus of Caspian monkey goby. On the other hand, due to the epidermal mucus hydrophobic nature, all three extraction methods including acetone, (TCA)-acetone and methanol led to the irreversible proteins aggregation, makes ultrafiltration, HPLC, and consequently bioactivity screening impossible. In this study, the highest amount of protein (4.676 μg/ml) (P<0.01) and the best protein profile (13 bands) were related to solid phase extraction. Also, this method simultaneously leads to the extraction, concentration, and initial purification of the samples and therefore improves the efficiency ultrafiltration and HPLC. Thus, we introduce this method for the isolation of active proteins and peptides from various complex biological samples, including fish epidermal mucus.

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Given the concerns regarding the use of synthetic antiviral compounds in the pharmaceutical industry, it seems necessary to pay attention to natural sources with antiviral activity. Sea cucumbers are one of these sources that numerous physiological properties are discussed in the scientific community. The present study aimed to produce bioactive peptides from Holothuria leucospilota using two microbial enzymes, alcalase and flavourzyme, and to evaluate their antiviral activity against Herpes simplex types 1 and 2, Chikungunya, and Dengue viruses. The results showed that the whole body of the sea cucumber has about 13% protein, which this amount reached more than 67% in the resulting hydrolyzed powders. The amount of protein, as well as the degree of hydrolysis in the hydrolyzed protein using alcalase enzyme (71.58±0.16 and 48.37±0.3%, respectively) was higher than the powder produced with flavourzyme (67.88±0.26 and 41.42±0.6%, respectively) (p<0.05). It was further found that both types of peptides produced at both concentrations of 4 and 5 mg/ml have antiviral properties. In this study, the type of enzyme used to produce bioactive peptides and also the concentration of peptides had a significant effect on their antiviral activity (p<0.05). The peptides produced using alcalase enzyme had significantly more antiviral activity against the studied viruses, while increasing the concentration of peptides from 4 to 5 mg/ml led to a significant increase in the antiviral activity (p<0.05). Among the studied viruses, Herpes type 1 and Dengue virus were the most resistant and susceptible viruses, respectively (p<0.05). According to the results of the present study, bioactive peptides extracted from the sea cucumber have the potential to be used in the pharmaceutical industry as a natural antiviral compound, however, it is necessary to carry out additional tests to evaluate their possible toxicity effects.