Effect of Post-Extraction Ultrasonication on Compositional Features and Antioxidant Activities of Enzymatic/Alkaline Extracts of Palmaria palmata.

Palmaria palmata is a viable source of nutrients with bioactive properties. The present study determined the potential role of post-extraction ultrasonication on some compositional features and antioxidant properties of enzymatic/alkaline extracts of P. palmata (EAEP). No significant difference was detected in terms of protein content and recovery, as well as the amino acid composition of the extracts. The nitrogen-to-protein conversion factor of 5 was found to be too high for the seaweed and EAEP. The extracts sonicated by bath for 10 min and not sonicated showed the highest and lowest total phenolic contents (p < 0.05), respectively. The highest radical scavenging and lowest metal-chelating activities were observed for the non-sonicated sample, as evidenced by IC50 values. The extract sonicated by bath for 10 min showed the most favorable in vitro antioxidant properties since its radical scavenging was not significantly different from that of the not-sonicated sample (p > 0.05). In contrast, its metal-chelating activity was significantly higher (p < 0.05). To conclude, post-extraction ultrasonication by an ultrasonic bath for 10 min is recommended to increase phenolic content and improve the antioxidant properties of EAEP.

Oxidation and oxidative stability in emulsions.

Emulsions are implemented in the fabrication of a wide array of foods and therefore are of great importance in food science. However, the application of emulsions in food production is restricted by two main obstacles, that is, physical and oxidative stability. The former has been comprehensively reviewed somewhere else, but our literature review indicated that there is a prominent ground for reviewing the latter across all kinds of emulsions. Therefore, the present study was formulated in order to review oxidation and oxidative stability in emulsions. In doing so, different measures to render oxidative stability to emulsions are reviewed after introducing lipid oxidation reactions and methods to measure lipid oxidation. These strategies are scrutinized in four main categories, namely storage conditions, emulsifiers, optimization of production methods, and antioxidants. Afterward, oxidation in all types of emulsions, including conventional ones (oil-in-water and water-in-oil) and uncommon emulsions in food production (oil-in-oil), is reviewed. Furthermore, the oxidation and oxidative stability of multiple emulsions, nanoemulsions, and Pickering emulsions are taken into account. Finally, oxidative processes across different parent and food emulsions were explained taking a comparative approach.

Characterization of fish sausage manufactured with combination of sunflower oil and fish oil stabilized with fish roe protein hydrolysates.

The present study aimed to determine the effect of adding protein hydrolysates obtained after 30, 60, and 90 min enzymatic hydrolysis of fish roe on properties of silver carp sausages enriched with fish oil during storage at 4 °C for 30 days. Properties of the fortified sausages were determined by assessment of primary and secondary oxidation, fatty acid composition, microbial spoilage, texture, and organoleptic properties. The results indicated that the hydrolysates could retard oil oxidation and microbial spoilage and preserve n - 3 fatty acids in fish sausages during the refrigerated storage. Also, they rendered firmer microstructure with smaller oil droplets to the sausages. Fish sausages fortified with the hydrolysates were lighter and exhibited better textural and sensory properties. It can be concluded that enzymatic hydrolysates from discarded fish roe can be added to fish sausages containing fish oil to retard oil oxidation and microbial spoilage and improve sausage properties.

Extraction of unsaturated fatty acid-rich oil from common carp (Cyprinus carpio) roe and production of defatted roe hydrolysates with functional, antioxidant, and antibacterial properties.

BACKGROUND: Common carp roe is a rich protein and oil source, which is usually discarded with no specific use. The aims of this study were to extract oil from the discarded roe and examine functional, antioxidant, and antibacterial properties of defatted roe hydrolysates (CDRHs) at various degrees of hydrolysis (DH). RESULTS: Gas chromatography of fatty acid methyl esters revealed that common carp roe oil contained high levels of unsaturated fatty acids. The results of high-performance liquid chromatography-mass spectrometry indicated that enzymatic hydrolysis of defatted roe yielded higher content of essential amino acids. CDRHs displayed higher solubility than untreated defatted roe, which increased with DH. Better emulsifying and foaming properties were observed at lower DH and non-isoelectric points. Furthermore, water and oil binding capacity decreased with DH. CDRHs exhibited antioxidant activity both in vitro and in 5% roe oil-in-water emulsions and inhibited the growth of certain bacterial strains. CONCLUSION: Common carp roe could be a promising source of unsaturated fatty acids and functional bioactive agents. Unsaturated fatty acid-rich oil extracted from common carp roe can be delivered into food systems by roe oil-in-water emulsions fortified by functional, antioxidant, and antibacterial hydrolysates from the defatted roe. © 2017 Society of Chemical Industry.

Peptides: Production, bioactivity, functionality, and applications.

Production of peptides with various effects from proteins of different sources continues to receive academic attention. Researchers of different disciplines are putting increasing efforts to produce bioactive and functional peptides from different sources such as plants, animals, and food industry by-products. The aim of this review is to introduce production methods of hydrolysates and peptides and provide a comprehensive overview of their bioactivity in terms of their effects on immune, cardiovascular, nervous, and gastrointestinal systems. Moreover, functional and antioxidant properties of hydrolysates and isolated peptides are reviewed. Finally, industrial and commercial applications of bioactive peptides including their use in nutrition and production of pharmaceuticals and nutraceuticals are discussed.

Physical and oxidative stability of fish oil-in-water emulsions fortified with enzymatic hydrolysates from common carp (Cyprinus carpio) roe.

Physical and oxidative stability of 5% (by weight) cod liver oil-in-water emulsions fortified with common carp (C. carpio) roe protein hydrolysate (CRPH) were examined. CRPH was obtained by enzymatic hydrolysis of discarded roe by using Alcalase 2.4L for 30, 60, 90, and 120min to yield different degrees of hydrolysis (DH). All the hydrolysates showed in vitro antioxidant activity in terms of radical scavenging and chelating properties. CRPH-containing emulsions had significantly smaller droplets than control (p<0.05). Besides, CRPH rendered rheological stability to the emulsions. It also prevented the loss of tocopherol and polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). CRPH retarded primary and secondary oxidation in emulsions as evidenced by peroxide values (PVs) and secondary volatile oxidation products, respectively. All the mentioned effects were compared among CRPHs with varying DH (7.6-10.2%). However, CRPH-containing emulsions had high levels of 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-butanone after storage.