Seafood CompositionReasons for studying seafood compositionSlide Number 3Fish and shellfish as foodFish and shellfish as foodWhat is in fish muscle?Major components of seafoods WaterWaterCrude ProteinLipidsDark vs. White MuscleDark vs. White MuscleLipidsLipidsLipids - Fatty AcidsWhy are we interested in marine lipids?Importance of lipids in human nutritionCalories in Fat, Protein and CarbohydratesFatty acids ‘omega’ nomenclature: Carboxylic acidsStructure of acylglycerols (‘glycerols’)Calories in Fat, Protein and CarbohydratesThe w-6 and w-3 essential fatty acids familiesSlide Number 24Fats: Terrestrial vs. marine animalsFats: Terrestrial vs. marine animalsGood fat versus bad fatGood fat versus bad fatWhy omega-3 fatty acids are good for you?Why omega-3 fatty acids are good for you?Why omega-3 fatty acids are good for you?The ‘goodies’ in fish oils (fish lipids)Increasing fish oil consumptionThe fats in plant oils versus eulachon oil (type of fish oil)The lipids in some fish oilsOmega-3 intake American Heart AssociationSlide Number 37Essential vitamins in fish lipidsMinor Components of SeafoodMinor Components of SeafoodMinor Components of SeafoodSlide Number 42Seafood CompositionReasons for studying seafood composition To evaluate quality of fish and shellfish To determine nutritional attributes of fish and shellfish products To predict shelf life and ensure safety of processed fish and shellfish To develop processing methods for underutilized fish and shellfish To determine the important components affecting sensory attributes (flavor, odor and appearance)New food pyramid - USDAFish and shellfish as foodImportant things to know:Different from other animal proteins (primarily in muscle structure)Specific texture attributes (muscle texture)Limited shelf life (fish and shellfish spoil v. fast)Hundreds of fish and shellfish (to a lesser extent) species with different characteristics and nutritional benefitsFish and shellfish as foodImportant things to know:The fat in fish can be very high in omega-3 fatty acids (e.g. Pacific salmon = sockeye, chinook, coho, chum, and pink)Consumption Related to Prevention of Coronary Heart DiseasesSeafood has balanced amino acids make up and high protein content (healthy + nutritious)Shellfish tends to have high sterol levels, mainly cholesterol (e.g. shrimp)What is in fish muscle?Water and fat usually combine for 80% of the total composition of fish muscleWater and fat are interchangeable, that is, higher fat content lower water content and vice-versaProteins are the building blocks of living organismsFats (lipids) are the primary energy source for living organismsFats in terrestrial animals are VERY DIFFERENT from the fats found in marine animalsMajor components of seafoods The three major components of fish and shellfish are: Water Protein Lipids (fat) These three types of compounds make up as much as 95% of the total gross composition of fish and shellfish Average composition of fish muscleWater ~ 75%Protein ~ 15%Lipids (fat) ~ 5%Ash (minerals) ~ 5%Water Muscles contain 50% to 85% water, depending on species and condition Plays important roles: solvent for organic and inorganic materials reaction media for enzymes (perfect environment for enzymes to ‘do their work’) hydration of proteins (texture) Water binds with many of the proteins Water also influences proteins and lipids in forming ordered structuresWater Free water: is lost during freezing/thawing, muscle storage and handling Bound water: is not easily lost (~4-5% of the water in a muscle food) Water is critical to:processing characteristicstexturenutritive valuesensory qualityshelf lifeCrude Protein Crude protein refers to the total of nitrogen containing compounds in a sample. This includes proteins, enzymes, amino acids (e.g. lysine), nucleic acids (DNA), and nucleotides (e.g. ATP). Muscle proteins are of three classes: Water soluble proteins: found in abundance in the extra cellular fluid (between cells). Make up ~ 30% of total protein in fish muscle Salt soluble proteins: make up the "flesh" and are ~ 40-60% of the total protein in fish muscle (muscle cells) Collagen: make up 3% of total protein in fish muscle (connective tissue – ‘cement’, ‘glues’ muscle cells together)Lipids Lipid content in fish muscle is often times used to classify fish from ‘lean’ to ‘fatty’ Classification of seafood regarding its lipid content (Ackman,1990):Lean (<2% fat) - cod, haddock, shellfishLow fat (2-4% fat) - sole, halibut, flounderMedium fat (4-8% fat) -salmonHigh fat (>8% fat) - herring, mackerelDark vs. White Muscle Distribution and amounts of dark muscle are different among fish speciesSections through the bodies of several fish showing depth of dark muscle. (a) Herring; (b) Mackerel; (c) Tuna; (d) Haddock; (e) Cod; (f) Whiting. Source: Love, 1988Dark vs. White Muscle Fat content is markedly different between dark and white muscle Dark muscle contains: higher levels of myoglobin (hemoglobin in blood has iron and it promotes oxidation) than white muscle More enzymes present than in white muscle More fat than white muscle Combination of three factors listed above makes dark muscle loose quality faster then white muscle Removal of dark muscle is advisable during filleting (whenever possible) to reduce lipid oxidation and consequently development of off flavorsLipids Lipid content of fish muscle refers to the total amount of the following compounds:Phospholipids – important constituents of cell membranes (STRUCTURAL LIPIDS)E.g. Lecithinemulsifying agent used in the food industry (e.g. ice cream)Sterols – in fish mainly in the form of cholesterol; however, in mollusks and shellfish a wide variety of ‘sterols’ are present (cholesterol is related to proper growth and overall health)LipidsTriglycerides (TAG) - main source of energy in fish - FAT TAG are mainly stored in the liver of fish classified as leanFatty fish have TAG reserves mainly in their muscle and belly flap areaWax esters – used for buoyancy and found in large quantities in deep water fish; present in fish scales (waxes)E.g. Bee wax is composed of wax estersLipids - Fatty Acids Triglycerides (TAG) are composted of fatty acids Fatty acids are carboxylic acids E.g. Acetic acid is the
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