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.
Mina Esmaeili Kharyeki, Shima Mansouri Moghadam,
Volume 11, Issue 4 (12-2022)
Abstract
The present study was conducted with the aim of protein isolate production from the muscle of grass carp (Ctenopharyngodon idella) and investigation of the effect of extraction pH on different properties of isolated protein. Proteins were produced by pH-shift method in two treatments including dissolution in alkaline pH (11.5), and acidic pH (3), and then evaluated in terms of nutritional value, functional properties, and structural changes. According to the results, the yield of protein production was significantly higher in alkaline conditions than in acidic conditions. The evaluation of emulsifying and foaming capacity and water absorption capacity showed that the protein obtained from alkaline pH was better than acidic treatment. Also, the extracted proteins contained all essential amino acids within the recommended limit for daily consumption of adults. The evaluation of color indices showed that the protein obtained from acidic pH had a brighter and whiter color than alkaline pH. The images obtained from the scanning electron microscope and the FTIR spectra of samples showed that the pH-shift method did not lead to extensive destruction of the protein structure and both protein isolates had all the absorption peaks related to the main bonds of the proteins structure. In general, it can be concluded that the pH-shift method is an efficient method for extracting high quality protein from grass carp tissue, and different alkaline and acidic conditions lead to the production of proteins with different characteristics that can be used based on the application that is intended for the final product.
Mohsen Nobakht, Masoud Rezaie, Shahab Naghdi,
Volume 12, Issue 2 (4-2023)
Abstract
In this study, the effect of different hydrolysis times (45, 90, 135, 180, and 225 minutes) by alcalase enzyme on the yield and quality of oil extracted from common kilka fish (Clupeonella cultriventris caspia) was investigated. The results showed that the highest extraction yield (40.41%) was in the hydrolyzed treatment for 135 minutes, which was not significantly different from other treatments. The qualitative indices of TBA, FFA, and CD of the extracted oils increased by increasing hydrolysis time, so the highest value of the mentioned indices was at 225 minutes, while the highest value of the PV index was at 180 minutes. Because the treatment of oil extracted in 45 minutes had lower values in the investigated oxidative spoilage indicators, it was selected as the treatment. The composition of its fatty acids was investigated, and it was found that monounsaturated fatty acids were the predominant fatty acids. Also, the amounts of saturated and polyunsaturated fatty acids did not show significant differences (p < 0.05). According to the obtained results, it was found that different hydrolysis times have different effects on the yield and quality of the obtained oil. Therefore, more research and studies are needed to fully investigate the effect of hydrolysis time on the quality characteristics of the oil extracted from Kilka fish.
