Enzymatic production and analysis of antioxidative protein hydrolysates

Advancements and challenges in microalgal protein production: A sustainable alternative to conventional protein sources

The increasing global demand for sustainable protein sources necessitates the exploration of alternative solutions beyond traditional livestock and crop-based proteins. Microalgae present a promising alternative due to their high protein content, rapid biomass accumulation, and minimal land and water requirements. Furthermore, their ability to thrive on non-arable land and in wastewater systems enhances their sustainability and resource efficiency. Despite these advantages, scalability and economical feasibility remain major challenges in microalgal protein production. This review explores recent advancements in microalgal protein cultivation and extraction technologies, including pulsed electric field, ultrasound-assisted extraction, enzyme-assisted extraction, and microwave-assisted extraction. These innovative techniques have significantly improved protein extraction efficiency, purity, and sustainability, while addressing cell wall disruption and protein recovery challenges. Additionally, the review examines protein digestibility and bioavailability, particularly in the context of human nutrition and aquafeed applications. A critical analysis of life cycle assessment studies highlights the environmental footprint and economical feasibility of microalgal protein production compared to conventional protein sources. Although microalgal protein production requires significant energy inputs, advancements in biorefinery approaches, carbon dioxide sequestration, and industrial integration can help mitigate these limitations. Finally, this review outlines key challenges and future research directions, emphasizing the need for cost reduction strategies, genetic engineering for enhanced yields, and industrial-scale process optimization. By integrating innovative extraction techniques with biorefinery models, microalgal proteins hold immense potential as a sustainable, high-quality protein source for food, feed, and nutraceutical applications.

Therapeutic potential of mackerel-derived peptides and the synthetic tetrapeptide TVGF for sleep disorders in a light-induced anxiety zebrafish model

Introduction

Anxiety-like insomnia is a known risk factor for the onset and worsening of certain neurological diseases, including Alzheimer's disease. Due to the adverse effects of current anti-insomnia medications, such as drug dependence and limited safety, researchers are actively exploring natural bioactive compounds to mitigate anxiety-like insomnia with fewer side effects. Mackerel (Pneumatophorus japonicus), a traditional Chinese medicine, is known for its tonic effects and is commonly used to treat neurasthenia. The use of mackerel protein extract has been shown to effectively improve symptoms of light-induced anxiety-like insomnia in a zebrafish model.

Methods

This study examines the effects of mackerel bone peptides (MW < 1 kDa, MBP1) and the synthetic peptide Thr-Val-Gly-Phe (TVGF) on light-induced anxiety-like insomnia in zebrafish. The evaluation is conducted through behavioral observation, biochemical marker analysis, and gene transcriptome profiling.

Results

MBP1 significantly alleviated abnormal hyperactivity and restored neurotransmitter levels (dopamine and γ-aminobutyric acid) to normal. Moreover, it mitigated oxidative stress by reducing reactive oxygen species production and malonaldehyde levels, while enhancing antioxidant enzyme activities (superoxide dismutase and catalase). This was further attributed to the regulation of lipid accumulation and protein homeostasis. Furthermore, MBP1 ameliorated sleep disturbances primarily by restoring normal expression levels of genes involved in circadian rhythm (per2 and sik1) and visual function (opn1mw2, zgc:73075, and arr3b). Molecular docking analysis indicated that TVGF exhibited good affinity for receptors linked to sleep disturbances, including IL6, HTR1A, and MAOA. TVGF exhibited sedative effects in behavioral assays, mainly mediated by regulating the normal expression of genes associated with circadian rhythm (cry1bb, cry1ba, per2, per1b and sik1), visual function (opn1mw1, gnb3b, arr3b, gnat2), purine metabolism (pnp5a), and stress recovery (fkbp5).

Discussion

These findings suggest that MBP1 and TVGF could be promising therapies for light-induced anxiety-like insomnia in humans, offering safer alternatives to current medications. Additionally, the regulation of genes related to circadian rhythm and visual perception may be a key mechanism by which MBP1 and TVGF effectively relieve anxiety-like insomnia.

Direct hydrolysis of einkorn whole grain flour proteins for the generation of bioactive peptides using various proteases

In this study, it was aimed to investigate the direct release of BAPs from einkorn flour in one-step process. Thus, the protein extraction step was eliminated, thereby reducing processing cost. Commercial proteases (Alcalase, Flavourzyme, Neutrase, and Trypsin), and crude enzyme from Bacillus mojavensis sp. EBTA7 were used for hydrolyzing einkorn flour (30 %, w/v) solutions at 50-60 °C. The supernatants after centrifugation were used for bioactivity and techno-functionality tests. All hydrolysates demonstrated significant antioxidant capacities, with values ranging from 17.7 to 33.0 μmol TE/g for DPPH, 107 to 190 μmol TE/g for ABTS, and 0.09 to 3.08 mg EDTA/g for ion-chelating activities. Alcalase and Flavourzyme hydrolysis had the highest DPPH activities, while Bacillus mojavensis sp. EBTA7 enzyme yielded relatively high ABTS and ion-chelating activities. Notably, Bacillus mojavensis sp. EBTA7 crude enzyme hydrolysates demonstrated higher oil absorption capacity (2.94 g oil/g hydrolysate), robust emulsion (227 min), and foam stability (94 %) compared to commercial enzymes. FTIR spectroscopy confirmed variations in the secondary structure of peptides. All hydrolysates exhibited negative zeta potentials. The SDS-PAGE showcased MW ranged from 14 to 70 kDa, which was influenced by both the enzyme type and the degree of hydrolysis. Overall, Bacillus mojavensis sp. EBTA7 hydrolysates revealed considerable bio and techno-functional characteristics.

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.

Metal-binding peptides and their potential to enhance the absorption and bioavailability of minerals

Minerals including calcium, iron, zinc, magnesium, and copper have several human nutritional functions due to their metabolic activities. Body tissues require sufficient levels of a variety of micronutrients to maintain their health. To achieve these micronutrient needs, dietary consumption must be adequate. Dietary proteins may regulate the biological functions of the body in addition to acting as nutrients. Some peptides encoded in the native protein sequences are primarily responsible for the absorption and bioavailability of minerals in physiological functions. Metal-binding peptides (MBPs) were discovered as potential agents for mineral supplements. Nevertheless, sufficient studies on how MBPs affect the biological functions of minerals are lacking. The hypothesis is that the absorption and bioavailability of minerals are significantly influenced by peptides, and these properties are further enhanced by the configuration and attribute of the metal-peptide complex. In this review, the production of MBPs is discussed using various key parameters such as the protein sources and amino acid residues, enzymatic hydrolysis, purification, sequencing and synthesis and in silico analysis of MBPs. The mechanisms of metal-peptide complexes as functional food ingredients are elucidated, including metal-peptide ratio, precursors and ligands, complexation reaction, absorbability and bioavailability. Finally, the characteristics and application of different metal-peptide complexes are also described.