Optimization of enzymatic hydrolysis of red tilapia scales (Oreochromis sp.) to obtain bioactive peptides

Unraveling the biological potential of chicken viscera proteins: a study based on their enzymatic hydrolysis to obtain hydrolysates with antioxidant properties

Chicken meat production has increased over the years, leading to a proportional increase in waste generation, which often contains high levels of proteins, such as viscera. Therefore, this study aimed to investigate the enzymatic hydrolysis of chicken viscera proteins as a strategy to value solid waste from the poultry industry. The hydrolysates were characterized for their antioxidant properties and molecular weight distribution. Additionally, the enzymatic hydrolysis process was scaled up from 125 mL flasks with 50 mL of protein solution to 3 L using a 6 L bioreactor. The enzymatic hydrolysis of chicken viscera proteins using a binary mixture of proteases (85.25 U/mL of each enzyme, Alcalase and Flavourzyme, totaling 170.5 U/mL) resulted in an increase of up to 245% in 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, 353% 2,2-diphenyl-1-picryl-hydrazyl (DPPH) in radical scavenging, 69% in Ferric Reducing Antioxidant Power Assay (FRAP) and 146% in total reducing capacity (TRC). The antioxidant properties of the protein hydrolysates are preserved during the scale-up of enzymatic hydrolysis. Protein fractions smaller than 5 kDa showed the highest ABTS and DPPH radical scavenging activities, while fractions greater than 30 kDa showed the best results for the FRAP method.

Mastering the art of taming: Reducing bitterness in fish by-products derived peptides

Processed fish by-products are valuable sources of peptides due to their high protein content. However, the bitterness of these peptides can limit their use. This review outlines the most recent advancements and information regarding the reduction of bitterness in fish by-products derived peptides. The sources and factors influencing bitterness, the transduction mechanisms involved, and strategies for reducing bitterness are highlighted. Bitterness in peptides is mainly influenced by the source, preparation method, presence of hydrophobic amino acid groups, binding to bitter receptors, and amino acid sequence. The most widely utilized techniques for eliminating bitterness or enhancing taste include the Maillard reaction, encapsulation, seperating undesirable components, and bitter-blockers. Finally, a summary of the current challenges and future prospects in the domain of fish by-products derived peptides is given. Despite some limitations, such as residual bitterness and limited industrial application, there is a need for further research to reduce the bitterness of fish by-products derived peptides. To achieve this goal, future studies should focus on the technology of fish by-products derived peptide bitterness diminishment, with the aim of producing high-quality products that meet consumer expectations.

Optimization and scale up of the enzymatic hydrolysis of Californian red worm protein (Eiseniafoetida)

Although the best-known use of the different species of earthworm is the production of organic fertilizer, they can also be considered a rich source of biologically and pharmacologically-active compounds, for use in the treatment of various diseases. In recent decades, with the development of biochemical technologies, research on the pharmaceutical effects of compounds extracted from different species of earthworms has begun. Enzymatic hydrolysis is the most common and widely used technique for producing bioactive hydrolysates, because it uses moderate operating conditions, with a certain specificity for the substrate. In the present study, the objective was to optimize and scale up the enzymatic hydrolysis of Eisenia foetida protein to obtain peptides with biological activity. The substrate characterization was carried out according to AOAC, a response surface design was performed for the optimization of the enzymatic hydrolysis and then the scaling was performed by means of dimensional analysis. The results show that the major component of the paste is protein, 65% of which is albumin, and the absence of pathogenic microorganisms was also found. Regarding optimization, it was found that the optimal hydrolysis conditions are achieved with pH = 8.5; temperature = 45 °C; amount of substrate = 125 g and volume of enzyme = 1245μL. For the scaling, 4 dimensionless pi-numbers were calculated which describe the process with no statistically significant differences between the model and the prototype; it can be concluded that the enzymatic hydrolysate of Eisenia foetida presents high values of antioxidant activity evaluated by different methodologies.

Silver Carp (Hypophthalmichthys molitrix) Scales Collagen Peptides (SCPs): Preparation, Whitening Activity Screening and Characterization

This study involves the preparation of scale collagen peptides (SCPs) with whitening activity from silver carp (Hypophthalmichthys molitrix) and their characterization and peptide sequence identification. In this article, scanning electron microscopy (SEM) was used to observe structure changes of sliver carp scales; enzymatic hydrolysis was optimized through protease screening and response surface optimization. The ultrafiltration was used to separate SCPs and the whitening activity was comprehensively evaluated using radical scavenging rate and tyrosinase-inhibiting activity, among others. An optimal component was characterized and identified using various modern spectral analysis techniques. The results showed that the surface of silver carp scales after decalcification was smooth and clear. The pepsin had the highest peptide yield and tyrosinase-inhibiting activity (90.01% and 82.25%, respectively). The optimal enzymatic hydrolysis conditions were an enzyme dosage of 16.1%, a solid–liquid ratio of 1:15.6 and a time of 4.9 h. The proportions of hydrophobic and basic amino acids in the peptide composition were 32.15% and 13.12%, respectively. Compared with SCPs2, SCPs1 (6096.68–9513.70 Da) showed better ·OH scavenging ability, tyrosinase-inhibiting activity and moisture absorption. SCPs1 was a macromolecular fragment of type I collagen with a triple helix structure, containing three peptide sequences with the potential for tyrosinase activity inhibition (AGPPGADGQTGQRGE, SGPAGIAGPAGPRGPAGPNGPPGKD and KRGSTGEQGSTGPLGMRGPRGAA). These results show that SCPs1 is a collagen peptide product with whitening potential.

Marine Products As a Promising Resource of Bioactive Peptides: Update of Extraction Strategies and Their Physiological Regulatory Effects

Marine products are a rich source of nutritional components and play important roles in promoting human health. Fish, mollusks, shellfish, as well as seaweeds are the major components of marine products with high-quality proteins. During the last several decades, bioactive peptides from marine products have gained much attention due to their diverse biological properties including antioxidant, antihypertensive, antimicrobial, antidiabetic, immunoregulation, and antifatigue. The structural characteristics of marine bioactive peptides largely determine the differences in signaling pathways that can be involved, which is also an internal mechanism to exert various physiological regulatory activities. In addition, the marine bioactive peptides may be used as ingredients in food or nutritional supplements with the function of treating or alleviating chronic diseases. This review presents an update of marine bioactive peptides with the highlights on the novel producing technologies, the physiological effects, as well as their regulation mechanisms. Challenges and problems are also discussed in this review to provide some potential directions for future research.

Bioactive Peptides: A Promising Alternative to Chemical Preservatives for Food Preservation

Bioactive peptides used for food preservation can prolong the shelf life through bacteriostasis and antioxidation. On the one hand, bioactive peptides can inhibit lipid oxidation by scavenging free radicals, interacting with metal ions, and inhibiting lipid peroxidation. On the other hand, bioactive peptides can fundamentally inhibit the growth and reproduction of microorganisms by destroying their cell membranes or targeting intracellular components. Besides, bioactive peptides are biocompatible and biodegradable in vivo. Therefore, they are regarded as a promising alternative to chemical preservatives. However, bioactive peptides are easily affected by the external environment in practical application, which hinders their commercialization. Currently, the studies to overcome the weakness focus on encapsulation and chemical synthesis. Bioactive peptides have been applied to the preservation of various foods in experimental research, with good results. In the future, with the deepening understanding of their safety and structure-activity relationship, there may be more bioactive peptides as food preservatives.