Transcript Slide 1
The concern with n-3 Lipid Oxidation Alexandria B. Marciante Dr. Steve Talcott • Used as an additive in food products and supplements to support metabolic functioning and prevention of diseases, including cancer and cardiovascular disorders. • A highly nutritive and beneficial n-3 fatty acid is omega-3 polyunsaturated fatty acids. • Can be used for treatment of depression and schizophrenia. (Polyunsaturated fatty acids) • Result from low temperature acclimatization and transfer to sea water, to form fish oils • Two most common and most nutritive types are long-chain eicosapentaenoic fatty acid (EPA) and docosahexaenoic fatty acid (DHA) • Most effective in the case of fatal cardiovascular disease and prevention of progression in some stages of cancer • Essential for growth and energy, organ differentiation, and immune function. Long-chain Fatty Acids • Although these have many benefits and are essential for growth and health, the debate to use these in food systems is challenging. • The longer the chain and the higher the degree of unsaturation in a fatty acid, the less energy is needed for lipid oxidation; which is caused by a catalytic event and has negative effects. The oxidative deterioration of lipids containing a number of carbon-carbon double bonds. •Has an initiation, propagation, and termination sequence • Initiation: caused by a catalytic event (light, temperature, air, etc.) • Propagation: cocktail of radicals formed, including peroxyl radicals and reactive oxygen species (ROS), causing another initiation step • Termination: addition of oxidation inhibitors (like antioxidants) that terminate propagation The chemistry of why degree of unsaturation influences the rate of lipid oxidation. • Initiation step •Hydrogen is abstracted in the presence of initiator • alkyl radical formation allows radical delocalization across the double bond • Propagation step • addition of oxygen to the alkyl radical to form the peroxyl radical which has higher energy than alkyl • peroxyl radical abstract H from another PUFA to produce LOOH and a new alkyl radical • Termination • interaction of two free radicals to form non-radical species Detecting volatile by-products • Thiobarbituric Acid (TBA) reactive substances are used to detect aldehydes in a variety of food products, using malondialdehyde (MDA) • Gas chromatograph can be used for further analysis to quantify ketones, peroxides, alcohols and other by-products • Lipid oxidation can result in the production of off flavors and smells that are undesirable to consumers. • Oxidation can also interfere with normal metabolic functioning and can be toxic from the formation of free radicals. • Reduction in nutritional value of lipidcontaining food products. Protection of PUFA’s from light and heat damage • Provides more prolonged shelf life by using encapsulating agents like milk protein, gelatine, modified starch, etc. and is determined based on capacity to stabilize and protect the oil from degradation during processing and storage conditions • Freeze-drying is the most cost effective method Anti-oxidative compounds • Compounds known to function as scavengers in 1 and 2 oxidation processes •Vitamin E •Carotenoids •Flavanoids •Anthocyanins •Phenolic compounds •Factors affecting degree of anti-oxidative power includes polarity and solubility of food system Protecting food systems from lipid oxidation • Radical scavenging • Metal chelation • Oxygen scavenging Commercially • Studies have been done to prepare Omega-3 PUFAs as a 4:1 (16%:4%) ratio of refined fish oil with corn oil as a way to decrease lipid oxidation • Antioxidants were also used (butylated hydroxytoluene and butylated hydroxyquinone with alpha-tocopherol. • This increased stability during contact with air and temperature fluctuations Using modified atmosphere packaging (MAP) • Oxidation is especially problematic in meat because of the pro-oxidants present • MAP resulted in: •Better quality •Increased shelf life 1. 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