The Inhibitory Effects of Hydroxytyrosol, α-Tocopherol and Ascorbyl Palmitate on Lipid Peroxidation in Deep-Fat Fried Seafood.

This study aimed to investigate the inhibitory effects of hydroxytyrosol, α-tocopherol and ascorbyl palmitate on lipid peroxidation in squid, hoki and prawn during deep-fat frying and refrigerated storage. Fatty acid analysis using gas chromatography (GC) showed that the seafood had a high omega-3 polyunsaturated fatty acid (n-3 PUFAs) content, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The total content of n-3 fatty acids in their lipids was 46% (squid), 36% (hoki) and 33% (prawn), although they all had low lipid contents. The oxidation stability test results showed that deep-fat frying significantly increased the peroxide value (POV), p-anisidine value (p-AV) and the value of thiobarbituric acid reactive substances (TBARS) in squid, hoki and prawn lipids. Meanwhile, antioxidants delayed the lipid oxidation in fried seafood and sunflower oil (SFO) used for frying, albeit in different ways. The least effective of all the antioxidants was α-tocopherol, as the POV, p-AV and TBARS values obtained with this antioxidant were significantly higher. Ascorbyl palmitate was better than α-tocopherol but was not as effective as hydroxytyrosol in suppressing lipid oxidation in the frying medium (SFO) and in the seafood. However, unlike the ascorbyl palmitate-treated oil, hydroxytyrosol-treated oil could not be used for multiple deep-fat frying of seafood. Hydroxytyrosol appeared to be absorbed in the seafood during multiple frying, thus leaving a low concentration in the SFO and making it susceptible to oxidation.

Seaweed Phenolics as Natural Antioxidants, Aquafeed Additives, Veterinary Treatments and Cross-Linkers for Microencapsulation.

Driven by consumer demand and government policies, synthetic additives in aquafeed require substitution with sustainable and natural alternatives. Seaweeds have been shown to be a sustainable marine source of novel bioactive phenolic compounds that can be used in food, animal and aqua feeds, or microencapsulation applications. For example, phlorotannins are a structurally unique polymeric phenolic group exclusively found in brown seaweed that act through multiple antioxidant mechanisms. Seaweed phenolics show high affinities for binding proteins via covalent and non-covalent bonds and can have specific bioactivities due to their structures and associated physicochemical properties. Their ability to act as protein cross-linkers means they can be used to enhance the rheological and mechanical properties of food-grade delivery systems, such as microencapsulation, which is a new area of investigation illustrating the versatility of seaweed phenolics. Here we review how seaweed phenolics can be used in a range of applications, with reference to their bioactivity and structural properties.

Valorization of seed and kernel marcs and evaluation of their antioxidant potential.

The processing and consumption of mango (Mangifera indica) generate a sizeable amount of kernel waste with enormous and largely unexplored potential, while by-products from njangsa (Ricinodendron heudelotii) seed and bush mango (Irvingia gabonensis) kernel oil extraction are often discarded. This study aims to repurpose these kernels and seed wastes into added/high-value products and evaluate the ethanolic and methanolic extracts of their pressed marcs for polyphenolic content and potential antioxidant activity. The total phenolic content (TPC) and total flavonoid content (TFC) in the marc extracts ranged between 47.87 and 376.0 mg GAE/g and 4.85 and 13.70 mg Rutin/g, respectively. Both mango kernel marc extracts showed higher potent reducing power, ABTS+ radical and DPPH radical scavenging activities with half effective concentration (EC50) values (0.20-0.22 mg/mL) comparable to the reference compound; ascorbic acid (0.20 mg/mL). The TPC and TFC of the marc extracts generally strongly correlated with antioxidant activity. Relatively higher contents of xanthophyll and ß-carotene were detected in bush mango kernel methanolic extract than in the other extracts. Extraction solvent affected the composition and content of bioactives in pressed marcs of njangsa seed and mango kernel.

Investigation of enhanced oxidation stability of microencapsulated enzymatically produced tuna oil concentrates using complex coacervation.

Tuna oil was selectively hydrolysed using Thermomyces lanuginosus lipase for 6 h to prepare omega-3 acylglycerol concentrate with the DHA content significantly increased from 24.9% in tuna oil to 36.3% in the acylglycerol concentrate. The acylglycerol concentrate was subsequently encapsulated into the "multi-core" microcapsules using gelatin-sodium hexametaphosphate complex coacervates as the shell material. Rancimat, Oxipres and thermogravimetric analyses all showed that the microencapsulated acylglycerol concentrate had unexpectedly improved oxidation stability, compared to those produced using tuna oil, even though the concentrated oils themselves were significantly less stable than tuna oil. The incorporation of enzymatic tuna oil acylglycerol concentrate also significantly improved the oxidation stability of microencapsulated standard refined unconcentrated tuna oil. A wide range of characteristics including lipid and fatty acid composition, oil-in-water (O/W) emulsion properties, morphology, nanomechanical strength and physicochemical stability of acylglycerol, acylglycerol oil-in-water (O/W) emulsion and final microcapsules were investigated throughout the preparation. The result suggests that high levels of monoacylglycerol (about 35%) and diacylglycerol (about 8.5%) were produced in the acylglycerol. The acylglycerol O/W emulsion exhibited significantly smaller droplet size, lower zeta-potential and higher surface hydrophobicity, which contributed to the formation of the microcapsule with a significantly smoother surface and more compact structure, finally leading to improved oxidative stability compared to those prepared from native tuna oil.

Revisiting the scope and applications of food enzymes from extremophiles.

Microorganisms from extreme environments tend to undergo various adaptations due to environmental conditions such as extreme pH, temperature, salinity, heavy metals, and solvents. Thus, they produce enzymes with unique properties and high specificity, making them useful industrially, particularly in the food industries. Despite these enzymes' remarkable properties, only a few instances can be reported for actual exploitation in the food industry. This review's objectives are to highlight the properties of these enzymes and their prospects in the food industry. First, an introduction to extremophilic organisms is presented, followed by the categories and application of food enzymes from extremophiles. Then, the unique structural features of extremozymes are shown. This review also covers the prospective applications of extremozymes in the food industry in a broader sense, including degradation of toxins, deconstruction of polymers into monomers, and catalysis of multistep processes. Finally, the challenges in bioprocessing of extremozymes and applications in food are presented. PRACTICAL APPLICATIONS: Enzymes are important players in food processing and preservation. Extremozymes, by their nature, are ideal for a broad range of food processing applications, particularly those that require process conditions of extreme pH, temperature, and salinity. As the global food industry grows, so too will grow the need to research and develop food products that are diverse, safe, healthy, and nutritious. There is also the need to produce food in a sustainable way that generates less waste or maximizes waste valorization. We anticipate that extremozymes can meet some of the research and development needs of the food industry.

Polydatin-fatty acid conjugates are effective antioxidants for stabilizing omega 3-containing bulk fish oil and fish oil emulsions.

Candida antarctica lipase B-catalysed synthesis of lipophilic esters of polydatin was investigated along with their antioxidant activities. The effects of synthesis parameters such as solvent, substrate molar ratio, enzyme concentration, addition of molecular sieves, reaction temperature and time on the production of ester were studied and optimised. The highest production of esters was obtained with acetone as the reaction solvent. The antioxidant activities of the esters were compared with those of commercial butylated hydroxytoluene (BHT) and α-tocopherol. All polydatin esters inhibited the oxidative destruction of ß-carotene more effectively than did BHT and α-tocopherol. Results of thiobarbituric acid tests showed that in bulk fish oil, all esters were more effective than α-tocopherol at 2 mmol/kg concentration but were not as effective as BHT. In fish oil-emulsions, all esters were more effective than both BHT and α-tocopherol at 2 mmol/kg concentration. The synthesized polydatin esters are promising antioxidants for oil/fat-based foods.

Lipase-catalysed synthesis of palm oil-omega-3 structured lipids.

In this work, Candida antarctica lipase A was applied to selectively remove saturated fatty acids from palm oil to prepare palm oil acylglycerol concentrate (POAC), where palmitic acid decreased from 40.0 to 28.7% and oleic acid increased from 40.0 to 50.5% after 3 h of hydrolysis. Lipozyme RMIM from Rhizomucor miehei was then used to incorporate either alpha linolenic acid (ALA) or eicosapentaenoic acid (EPA) into the resulting POAC. Optimum omega-3 incorporation was achieved when POAC to omega-3 ratio was 6 : 3, reaction temperature was 40 °C and reaction time was 18 h. Under these conditions, the ALA content in the separated ALA incorporated structured lipid (POAC-ALA) was 27.1%, and the EPA content in the EPA incorporated structured lipids (POAC-EPA) was 30.9%. The formed structured lipids had lower levels of saturated fatty acids, and significantly lower melting points, in both cases below 8 °C. The enzymatic process developed produces new structured lipids, with lower saturated fat and higher omega-3, with potential as a healthy palm oil derived lipid ingredient.

Investigating the Mechanism for the Enhanced Oxidation Stability of Microencapsulated Omega-3 Concentrates.

Enzymatically concentrated anchovy oil (concentrate) is known to be much less stable than unconcentrated anchovy oil. However, we previously showed that concentrate surprisingly forms more stable microcapsules, when produced by complex coacervation, than does unconcentrated anchovy oil. Here we investigate the mechanism of this unexpected stability. We also investigate whether or not incorporation of concentrate can be used as an additive to improve the stability of unconcentrated anchovy oil microcapsules. Results showed that microcap stability increased as the amount of added concentrate increased. Decreased emulsion droplet size, lower positively charged zeta potential, and higher surface hydrophobicity were observed in the oil/water (O/W) emulsion, with the incorporation of concentrate in the oil phase, compared with the unconcentrated anchovy oil O/W emulsion. Both the decreased zeta potential and the increased hydrophobicity of concentrate in the mixed oil phase may improve droplet agglomeration, leading to enhanced oxidative stability of the concentrate-containing microcapsules. Decreased repulsive forces between droplets result in a more compact structure, thicker outer shell, and smoother surface, resulting in enhanced oxidation stability of the concentrate-containing microcapsules.

Influence of conventional and recent extraction technologies on physicochemical properties of bioactive macromolecules from natural sources: A review.

The incorporation of bioactive macromolecules from natural sources into marketable functional foods and nutraceuticals is of major significance to the agri-food sector. Interest in this area of research stems from the application of purified bioactive macromolecules in enhancing food quality and as an alternative to some pharmaceutical drugs for delivery of potential health benefits, with less associated adverse effects. To obtain bioactive macromolecules of high quality, appropriate use of extraction techniques and its influence on sensory and physicochemical properties is paramount. With the advent of technology-aided processes, there has been remarkable improvement in the extraction efficiency of these bioactive agents. An overview of the influence of these new techniques on extraction efficiency and physicochemical properties of proteins, lipids and fibers, which this detailed review provides, will prove to be a valuable resource to food industries aiming to maximize production of bioactive macromolecules from natural sources as well as the scientific community.

Complex coacervation: Principles, mechanisms and applications in microencapsulation.

Complex coacervation is a highly promising microencapsulation technique that is extensively employed in pharmaceutical, food, agriculture and textile industries. The process involves the interaction of oppositely charged polyelectrolytes in aqueous form. High payload and high encapsulation efficiency (up to 99%), relatively lower cost of processing, ability to use food-grade shell materials and synthesis at ambient temperature makes coacervation an appropriate choice in food and agrochemical industries. Various works have been documented using different polymer systems and core-shell combinations. This review paper intends to summarize some of the recent advances in complex coacervation for use in the food and agriculture areas. Current status and future trends of plant proteins utilization for complex coacervation have been reviewed. It is expected that this review will be a useful resource for material scientists, food technologists and food engineers.

Candida antarctica lipase A effectively concentrates DHA from fish and thraustochytrid oils.

The fatty acid selectivity of Candida antarctica lipase A (CAL-A) was applied to produce DHA concentrate by controlling the rate and extent of hydrolysis. Calcium was utilized to achieve a higher degree of hydrolysis. CAL-A was not regioselective but rather fatty acid selective, showing sequential selectivity for saturated, monounsaturated and polyunsaturated fatty acids in the order of increasing double bonds. Based on its strong initial preference for saturates, CAL-A was used to concentrate 82% docosahexaenoic acid (DHA) and 11% omega-6 docosapentaenoic acid (DPA-n6) after partial hydrolysis of algal oil. Thermomyces lanuginosus (TL 100L) lipase was used to partially remove DPA-n6, further concentrating DHA to 89%. CAL-A was immobilized on octadecyl-activated resin without altering its fatty acid selectivity.

Lipid profiles, in vitro digestion and oxidative stability of mutton bird oil.

The lipid profile, in vitro digestion and oxidative stability of mutton bird oil were investigated. Wax ester, triacylglycerol and sterol were the major lipids present as determined using capillary chromatography with flame ionisation detector (Iatroscan). Fatty acid analysis by gas chromatography (GC) showed that wax esters had a higher total omega-3 fatty acids content including EPA, DPA and DHA than TAGs (31 % and 24 %, respectively). In TAGs, (13)C nuclear magnetic resonance (NMR) data showed that EPA was statistically positioned at sn-1,3 and sn-2, while DHA was preferentially at sn-2. In vitro digestion using porcine pancreatic lipase resulted in 75 % of TAG and 10 % wax ester hydrolysis in 120 min. As reflected in the measured conjugated dienes (CD) and thiobarbituric acid reactive substances (TBARS) values during accelerated oxidation at 60 °C for 5 days, the oil was relatively stable against oxidation considering its high omega-3 content.

Pancreatic lipase selectively hydrolyses DPA over EPA and DHA due to location of double bonds in the fatty acid rather than regioselectivity.

The enzymatic hydrolysis of canola, anchovy and seal oils with different types and amounts of polyunsaturated fatty acids was measured using porcine pancreatic lipase (PPL) to establish the fatty acid selectivity of PPL. Substrates were subjected to the same conditions of hydrolysis, with percent hydrolysis monitored using Iatroscan and fatty acid selectivity monitored using gas chromatography (GC). Regardless of their distribution on the glycerol backbone, as monitored by (13)C nuclear magnetic resonance (NMR), α-linolenic acid (ALA) and docosapentaenoic acid (DPA) were rapidly cleaved by PPL while eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and stearidonic acid (STA) were hydrolysed more slowly. Results show that PPL preferentially hydrolyses ALA and DPA over EPA, DHA and STA, and this selectivity is due to fatty acid rather than regioselectivity. The primary structural factor associated with resistance to PPL appears to be the distance of the first double bond from the ester linkage being hydrolysed.

Selective concentration of EPA and DHA using Thermomyces lanuginosus lipase is due to fatty acid selectivity and not regioselectivity.

The selectivity of anchovy oil hydrolysis was optimised for Thermomyces lanuginosus lipase, so that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were concentrated and partially separated from each other. Enzyme concentration and pH control were important factors for effective hydrolysis. Monitoring percent hydrolysis using capillary chromatography with flame ionisation detector (Iatroscan) and fatty acid selectivity using gas chromatography (GC) indicated that during hydrolysis DHA primarily remained on the glycerol backbone, while EPA was progressively removed. (13)C nuclear magnetic resonance (NMR) data showed that selectivity of hydrolysis was primarily due to fatty acid selectivity and not regioselectivity, with hydrolysis from both sn-1,3 and sn-2 sites being equally favoured.