A review on selenium-enriched proteins: preparation, purification, identification, bioavailability, bioactivities and application

Microalgae: A good carrier for biological selenium enrichment

Selenium is a crucial micronutrient for human well-being, with significant contributions to antioxidant, anti-ageing, and antiviral activities. However, over one billion people globally struggle with selenium deficiency, leading to a pressing need for selenium supplementation. Conventional selenium-enrich food from plants and animals provides challenges in achieving precise selenium supplementation. Thus, it is crucial to discover selenium carriers that can be cultured in a controlled environment. Multiple studies have shown that microalgae are excellent carriers for selenium enrichment due to their rapid growth, suitability for plant consumption, ease of industrialization, high efficiency in converting organic selenium, and many others. This review focuses on single-celled microalgae, comprehensively reviewing their metabolic pathway, biological transformation, and valuable forms of selenium. Additionally, it forecasts the current application status and prospects of selenium-enriched microalgae in agriculture and global human health. This review provides a reference for the industrial supply of precise selenium-rich raw materials.

Selenium-Rich Black Soldier Fly Supplementation Enriches Serum Indexes and Egg Selenium Content in Laying Hens

A certain amount of selenium (Se) is usually added to the diet of laying hens to improve the quality and nutritional value of eggs. The present study was carried out to investigate the effect of selenium-rich black soldier fly (BSF) supplementation in diets on laying production performance, egg quality, serum indexes, and egg selenium content of Hy-line variety brown laying hens. A total of 288 at 49-week-old healthy laying hens were divided into 3 treatment groups with 6 replicates per group and 16 hens per replicate using a single-factor completely randomized design. Treatments consisted of (1) control (basal diet without supplemental Se), (2) 0.30 mg/kg supplemental Se, (Se as sodium selenite, SS), and (3) 0.30 mg/kg supplemental Se (Se as selenium-rich black soldier fly, SE-BSF). Laying performance was not affected by dietary Se. There was no effect of selenium-rich BSF on egg quality (P > 0.05). The contents of malonaldehyde (MDA) were significantly reduced (P < 0.05). On the contrary, dietary Se supplementation increased the activity of superoxide dismutase (SOD, P < 0.05) and catalase (CAT, P < 0.05) and increased the concentration of reduced glutathione (P < 0.05). In addition, selenium-rich BSF supplementation significantly increased the Se content of eggs (P < 0.05). These results indicate that Se supplementation did not affect laying production performance and egg quality of laying hens, but the supplementation could improve antioxidant capacity and increased the Se content of eggs.

Characterization of selenium-containing broccoli (Brassica oleracea L. var. italica planch) proteins and evaluation of antioxidant activity by electron spin resonance

Selenoproteins found in selenium (Se)-enriched vegetables play a vital role in maintaining human health. In this study, four Se-containing broccoli proteins (Se-BP: albumin, globulin, prolamin, and glutelin) were continuous extracted by Osborne method. Three ultrafiltered fractions were subsequently obtained from the glutelin hydrolysate, composed of Se-contained broccoli peptides (Se-Bp) with different molecular weights (MW), namely, < 1 kDa, 1-3 kDa, and 3-10 kDa. Glutelin exhibited the highest protein yield (65.60 ± 1.07%), purity (78.39 ± 0.95%), nutritional value, organic Se content (88.05 ± 0.32% of total Se content), and Se speciation distribution (selenocystine, selenomethionine, methylselenocysteine, and selenoethionine). Additionally, the antioxidant activity of different MW of Se-Bp was assessed using electron spin resonance spectroscopy. The results revealed that antioxidant activity of the candidate peptide is dependent upon its Se content, amino acid composition, and MW, especially Se-Bp with MW of 1-3 kDa displayed the strongest free radical scavenging ability.

Exploring the impact of selenium-enriched peptides from yeast autolysate on dough properties: Insights into mechanisms from gluten perspectives

This study investigated the impact of Selenium (Se)-enriched yeast autolytic peptides (SeYAP) with different Se levels on dough properties as well as the related mechanism by focusing on gluten. SeYAP prolonged the dough's development time by up to 131 % and stability time by up to 28 %. It also decreased dough's viscoelasticity and rendered dough softer. Additionally, SeYAP diminished the binding capacity of dough to water and augmented the fluidity of water. Protein composition, disulfide bonds and fluorescence spectroscopy revealed that SeYAP could induce depolymerization of glutenin aggregate through sulfhydryl/disulfide bond exchange and hydrophobic interactions. Seven Se-enriched peptides were identified from the fraction with strong ability to depolymerize gluten. Specifically, six peptides contained selenocysteine, while another peptide contained selenomethionine. Molecular docking indicated that Se-enriched peptides could interact with amino acids (such as glutamine, tyrosine and proline) in gluten via hydrophobic interactions and/or hydrogen bonds.

Investigation of selenium and selenium species in Cardamine violifolia using in vitro digestion coupled with a Caco-2 cell monolayer model

Inadequate Se intake can enhance vulnerability to certain health risks, with supplementation lessening these risks. This study investigated the bioavailability of Se and Se species in five Se compounds and in Se-rich Cardamine violifolia using in vitro digestion coupled with a Caco-2 cell monolayer model, which enabled the study of Se transport and uptake. Translocation results showed that SeCys2 and MeSeCys had high translocation rates in C. violifolia leaves (CVLs). The uptake rate of organic Se increased with time, and MeSeCys exhibited a higher uptake rate than that for SeCys2 and SeMet. The translocation mechanisms of SeMet, Se(IV), and Se(VI) were passive transport, whereas those of SeCys2 and MeSeCys were active transport. The bioavailability of organic Se was higher than that of inorganic Se, with a total Se bioavailability in CVLs of 49.11 %. This study would provide a theoretical basis for the application of C. violifolia in the functional food.

Egg Yolk Selenopeptides: Preparation, Characterization, and Immunomodulatory Activity

In this study, egg yolk selenium peptides (Se-EYP) were prepared using double-enzyme hydrolysis combined with a shearing pretreatment. The properties of the selenopeptides formed were then characterized, including their yield, composition, molecular weight distribution, antioxidant activity, in vitro digestion, and immunomodulatory activity. The peptide yield obtained after enzymatic hydrolysis using a combination of alkaline protease and neutral protease was 74.5%, of which 82.6% had a molecular weight <1000 Da. The selenium content of the lyophilized solid product was 4.01 μg/g. Chromatography-mass spectrometry analysis showed that 88.6% of selenium in Se-EYP was in the organic form, of which SeMet accounted for 60.3%, SeCys2 for 21.8%, and MeSeCys for 17.9%. After being exposed to in vitro simulated digestion, Se-EYP still had 65.1% of oligopeptides present, and the in vitro antioxidant activity was enhanced. Moreover, Se-EYP exhibited superior immune detection indices, including immune organ index, level of immune factors in the serum, histopathological changes in the spleen, and selenium content in the liver. Our results suggest that Se-EYP may be used as selenium-enriched ingredients in functional food products.