Showing 6 results for Molecular Weight
Volume 0, Issue 0 (1-2024)
Abstract
Poly- gamma- glutamic acid (γ-PGA) is a natural polymer with diverse applications across multiple industries. However, its use in agriculture is limited due to high production costs. This study aimed to optimize the cost-effective production of γ-PGA through Solid-State Fermentation (SSF) using Bacillus velezensis UTB96, evaluate the concentration and molecular weight of γ-PGA suitable for agricultural applications, particularly in strawberry cultivation, and explore the impact of γ-PGA on extending the shelf-life of strawberry fruits during cold storage. Initially, the production of γ-PGA using SSF with B. velezensis UTB96 was investigated, along with an evaluation of the influence of physicochemical factors on the molecular weight of γ-PGA. Based on the results, three different molecular weights of γ-PGA were identified: 1156.43 kDa, 734.38 kDa, and 296.55 kDa. These were selected for greenhouse trials to assess their effectiveness in controlling gray mold on strawberry plants. The results showed that by utilizing agricultural wastes, including sesame flour, wheat straw, and banana peel in SSF methodology, γ-PGA could be produced at a rate of 70 g/kg of dry weight of the culture medium. Analyzing the impact of γ-PGA on reducing gray mold revealed that this compound could enhance the plant's defense. A significant increase in the activity of ascorbate peroxidase and phenylalanine ammonia-lyase (PAL) enzymes was observed, along with the production of polyphenolic compounds such as ellagic acid. Consequently, these mechanisms improved the plant's flexibility and tolerance to the fungus, helping to maintain the quality of the fruits during cold storage.
Nafiseh Sadat Mousavi, Mehdi Tabarsa, Hassan Ahmadi,
Volume 11, Issue 2 (5-2022)
Abstract
Polysaccharides possess diverse biological properties, mostly owed to their structural complexity and molecular heterogeneity, that could be improved through engineering methods and application of structural modifications. The objective of the present study was the assessment of antioxidant properties of hydrolyzed fucoidan from seaweed Nizamuddinia zanardinii and the correlation of molecular weight with biological function. After the removal of pigments and low molecular weight compounds, crude extracted polysaccharide was hydrolyzed at 100 C for 10, 20, 40 and 60 minutes using 0.01N HCl. The average molecular weight of crude fucoidan 1254.4 × 103 g/mol and for hydrolysates FH10, FH20, FH40 and FH60 was 974.5, 891.8, 806.5 and 705.5 × 103 g/mol, respectively. With the decrease of molecular weight, hydrolysates, compared with the crude fucoidan, exerted considerable DPPH (61.27-84.54%) and ABTS (40.1-88.5%) radical scavenging and Fe3+ reducing power (0.49-0.81 Abs) activities. Among different samples, hydrolysate FH20 showed the greatest capacity for DPPH radical scavenging activity (70.45-84.54%) and Fe3+ reducing power (0.49-0.81 Abs). Overall, the results of the current study showed that hydrolysis and reduction of molecular weight significantly improved the antioxidant activities of the fucoidan while time did not result any significant differences in antioxidant properties of hydrolysates which could be due to alterations in functional groups. Hence, fucoidan isolated from the examined species could be utilized as antioxidant agents in forms of native or hydrolysates.
Masoumeh Ghanbari Kiasara, Mehdi Tabarsa, Hassan Ahmadi, Amin Mokhlesi,
Volume 11, Issue 4 (12-2022)
Abstract
The aim of the current study was the evaluation of stepwise recovery of fucoidan extracted from seaweed Nizamuddinia zanardinii and the assessment of relationship between sulfate content and molecular weight with its antioxidant activity. After the removal of pigments and low molecular weight compounds, fucoidan extracted with water was precipitated using different concentrations of ethanol at three levels (30, 50 and 70%). Three fractions of Fuc30, Fuc50 and Fuc70 showed molecular weights of 731.62, 655.76 and 10.41 × 103 g/mol, respectively. The content of sulfate esters in the obtained fractions were measured between 6.49-25.03%. The color evaluation of produced fucoidans by a digital chroma meter indicated the highest lightness index for Fuc50 fraction. Antioxidant results were varying in DPPH radical (43.93-89.40%) and ABTS radical (25.05-96.10%) scavenging activities as well as Fe3+ reducing power (Abs of 0.142-0.259). Overall, the findings of the present study indicated that stepwise precipitation of fucoidan from N. zanardinii leads to production of fractions with different chemical and molecular weight characteristics and antioxidant activities. Besides, although all isolated fucoidan fractions are introduced as potent antioxidant compounds, polymers possessing lower molecular weight and greater sulfate content exert higher antioxidant activities.
Volume 18, Issue 119 (12-2021)
Abstract
In the present study, the antioxidant properties of different molecular weight fractions and different concentrations of protein hydrolysate from Common carp (Cyprinus carpio) head were investigated. Fish heads were hydrolyzed by Alcalase enzyme (1% v/w) at 55˚C and pH 8 during 180 min. The supernatant was fractionated to three different molecular weight fractions of <3, between 3 and 10 and >10 KDa by ultrafiltration. The results showed a significant difference between DPPH radical scavenging activity of the different molecular weight fractions, and the highest and the lowest values were observed in the fractions of 3-10 and less than 3 KDa, respectively (p <0.05). The fraction with molecular weight of 3-10 KDa showed the lowest IC50 (1.15±0.015 mg/ml) for DPPH scavenging activity. As the concentration increased, ferric ion reducing power of all molecular weight fractions were increased, and the highest value was observed in the molecular weight of more than 10 kDa (p <0.05). Significant differences of ABTS radical scavenging activity were observed between the different molecular weight fractions at all concentrations, and the highest and the lowest values were observed in the molecular weight fractions of 3-10 and less than 3 kDa, respectively (p <0.05). The molecular weight fraction of 3-10 kDa, exhibited the lowest IC50 value for ABTS radical scavenging activity (1.1±0.01 mg/ml). In general, according to the positive function of Common carp head protein hydrolysate at different concentrations and different molecular weights on DPPH and ABTS radical scavenging activity and ferric ion reducing power, it can be stated that this protein hydrolysate can be considered as a natural antioxidant for use in the food industry or animal, poultry and aquatic feed.
Volume 19, Issue 130 (12-2022)
Abstract
The present work aimed to study the effect of enzymatic hydrolysis of sarcoplastic and myofibrillar proteins from pangasius sutchi fish on the chemical compositions, the solubility, degree of hydrolysis (DH), peptide content and amino acid compositions was evaluated and their molecular weight recorded. The fish sarcoplasmic protein hydrolysates (SPHs) and myofibrillar protein hydrolysates (MPHs) were produced using three types of proteases: papain, alcalase and flavourzyme. Physicochemical properties of proteins and molecular weight were investigated. Results indicated that type of protease affected the degree of hydrolysis (DH), where all of the enzymes showed high rate of hydrolysis during the first hour, and then gradually decreased. The type of enzyme and the extent of the DH greatly influenced the amino acid residue composition and the molecular weight of the protein hydrolysates. Different amino acid composition of proteins and their hydrolysates was observed. The soluble protein and peptide content of hydrolysates significantly increased by the increase in time of incubation. The high amount of hydrophobic and aromatic amino acids in the SPH and MPH can enhance the biological activities of the peptides. Results suggest that the protein hydrolysates derived from patin may be used in functional food and supplements.
Volume 22, Issue 5 (4-2022)
Abstract
Ultra-High molecular weight polyethylene (UHMWPE) fibers are among the strongest and lightest fibers available and are widely used in high-performance ballistic applications. Despite the great advancement of computational analysis in recent years, precise calculations have not been performed to identify the failure of these fibers due to the complexity of the material behavior to impact. In this research, using the most advanced finite element modeling method of composites (Abaqus-Explicit) has been used to study the composite behavior of these fibers subjected to high-velocity projectile impact. Fiber and matrix are designed using solid elements and 3D Hashin failure criterion was used to determine the behavior of the material. Since this criterion is not available in Abaqus, the VUMAT subroutine has been used to implement this criterion. Velocity diagrams and damage evaluation have been reported. To evaluate and validate this method, six samples of Ultra High Molecular Weight Polyethylene (UHMWPE) Composite panels, consisting of 20 and 45 layers, respectively, were experimentally studied by high-velocity projectiles at different velocities. The simulation results are in good agreement with the experimental results.
