Please enable JavaScript.
Coggle requires JavaScript to display documents.
Week 11: Vitamins & Minerals - Coggle Diagram
Week 11: Vitamins & Minerals
Vitamins: minor components of foods that play an essential role in human nutrition :check:
Functionality :check:
As coenzymes or their precursors
As components of antioxidative defense system
As factors involved in genetic regulation
In specialised functions
Variation/ Losses of Vitamins in Foods :green_cross:
Inherent Variation in Vitamin Content: Concentration of vitamins varies with stage of maturity, site of growth, and climate
Vitamin concentration during maturation of fruits and vegetables is determined by the rates of synthesis and degradation
Biological control mechanism and diet of animal governs the vitamin content of animal products
Postharvest changes in Vitamin Content of Foods
Deterioration of cellular integrity and enzymatic compartmentation results in the release of oxidative and hydrolytic enzymes
Post harvest losses in meat are usually minimal under typical conditions of refrigerated storage
Extent of change depends on:
Physical damage during handling
Possible temperature abuse
Length of time between harvest and processing
Preliminary treatments
Washing: exposure of cut to water or aqueous solution results in lost of water-soluble vitamins by extraction
Extent of losses depends on factors that influences the diffusion and solubility of vitamins includes:
pH
Ionic strength of extractant
Temperature
Volume ratio of food to aqueous solution
Surface to volume ratio of food particles
Trimming: removal of skin or peel fractions
Milling of cereal grains involves grinding and fractionation to remove bran and embryo
Blanching and thermal processing
Inactivation of enzymes
Blanching in hot water results in large losses of water soluble vitamins
Thermal induced vitamins loss depends on
Chemical nature of food
Chemical environment
Stabilities of individual forms of vitamins present
Opportunity for leaching
Post processing
Vitamin stability is strongly influenced by water activity
Degradation rates for fat-soluble vitamins is minimal at ~0.2-0.3 aw but increases above or below this value
Degradation rates for water-soluble vitamins increase in proportion to water activity (greater solubility of vitamins)
Factors that contribute to small losses:
Reaction rates relatively slow at ambient temperature
Dissolved oxygen may be depleted
pH changes during processing
Processing chemicals: Chemical composition of food strongly influence stability of vitamins
3 examples
Sulfite and sulfiting agents
Used in wines for antimicrobial effects
In dried foods to inhibit enzymatic browning
Have protective effect on ascorbic acid
Reacts with thiamin and results inactivation
Converts Vitamin B6 aldehydes to their inactive derivatives
Nitrite
Ascorbic acids added to nitrite containing meats to prevent formation of N-nitrosamines
Used in preservation and curing of meats
Chlorine
Interactions with vitamins by electrophilic substitution, by oxidation, or by chlorination of double bonds
Applied to foods as hypochlorous acid (HOCl), hypochlorite(OCl-), molecular chlorine (Cl2) or chlorine dioxide (ClO2)
2 groups :check:
Water Soluble
Vitamin B
Main Functions
Support and increase the rate of metabolism
Maintain healthy skin, hair and muscle tone
Enhance immune and nervous system function
Promote cell growth and division, including that of the red blood cells that help prevent anemia
Types
Vitamin B1 (Thiamin)
One of the most unstable vitamins
Heat, oxygen, sulfur dioxide, leaching, neutral/ alkaline pH can result in destruction of thiamin
Processing results in considerable reduction of thiamin in food matrix
Present in all living tissues
Good sources – whole cereal grains, organ meats, lean pork, eggs, nuts, potatoes
Available in chloride or nitrate form
Acts as coenyzme in the metabolism of carbohydrates
Vitamin B2 (riboflavin)
A constitutent of two co-enzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
Sources
Other sources are beef muscle, liver, kidney, poultry, tomatoes, eggs, green vegetables and yeast
Very good sources of riboflavin are milk and milk products
Properties
Very sensitive to light & degrades to form two inactive compounds - lumiflavin and lumichrome
Stable to oxygen and acid pH but unstable in alkaline medium
Vitamin B3 (niacin): Refers to two main compounds nicotine acid and nicotinamide
Sources
Good dietary source: liver, kidney, lean meat, chicken, fish, wheat barley, rye, green peas, yeast, peanuts and leafy vegetables
Tryptophan can be converted by the body into niacin
Most stable of vitamin B
Unaffected by heat, light, oxygen, acid or alkali
Heating of food can increase the amount of niacin available as it changes bound niacin to free form
Regulates breakdown of carbohydates
Vitamin B5 (pantothenic acid)
Essential for all living things
Widely distributed among meats, cereal grains, eggs, milk, and many fresh vegetables
Functions
Essential for carbohydrate, protein & fatty acid synthesis
Synthetic pantothenic acid is used in food fortification and vitamin supplements in the form of calcium pantothenate
Functions metabolically as a component of coenzyme A
Vitamin B6 (pyridoxine)
Plays important role in metabolism of amino acids
Exists in three diff forms:
Pyridoxine
in plant products
Pyridoxal
in animal tissue
Pyridoxamine
in animal tissue
Properties
Stable to heat and strong alkali or acid,
Sensitive to light especially ultraviolet light when present in alkaline solution
Rapidly destroyed when exposed to air, heat, and light
Widely distributed in many foods
Meats, liver, vegetables, whole grain cereals, egg yolk
Vitamin B7 (biotin)
Properties
Very stable to heat, light, and oxygen
Extreme pH can cause degradation as it promotes hydrolysis of –N-C=O (amide) bond of the biotin ring
Bicyclic, water soluble vitamin
Functions as coenzymatically in carboxylation and transcarboxylation reactions
Occurs in two forms D-biotin and biocytin
Sources
Majority of biotin in foods exists in protein bound biotin
Synthesized by bacteria in lower intestine
Vitamin B9 (folate)
Folic acid main representative of a series of related compounds
Pterin
P-aminobenzoic acid
Glutamic acid
Occurs in a variety of foods,
especially liver, fruit, leafy vegetables and yeast
Folate in vegetables occurs mainly in the conjugated form
Folate in liver occurs in the free form
Vitamin B12
Structure
Unique – has a metallic element, cobalt
Most complex structure of any vitamin
Functions
Acts as a component of several coenzymes
Has an effect on nucleic acid formation
Key role in normal functioning of brain & nervous system
Good sources – lean meat, liver, kidney, fish, shellfish, and milk
Property
Not destroyed to a great extent by cooking except food boiled in alkaline solution
Vitamin C
Properties
Influence oxidation-reduction reactions
Widely used as food ingredients/ additive because of its reducing and antioxidative properties
Least stable – easily destroyed during processing and storage
Occurs in all living tissues
Major sources in vegetables and fruits
Functions
Deficiency leads to Scurvy – bleeding of gums and poor wound healing
Inhibits enzymatic browning
Reductive action in dough conditioners
Protection against reductive effects, free radicals and oxygen scavengers
Inhibits nitrosamine formation in cured meats
Reduction of metal ions
Ascorbate in various hydroxylation reactions
Fat-soluble :check:
Vitamin A (retinol): An alcohol that occurs predominantly in the form of fatty acid esters (retinyl palmitate) in animals & in the form of carotenes (alpha, beta & gamma) in plants
Sources
Other important sources - liver, egg yolk, milk and milk products
High level found in fish liver oils (e.g. cod and tuna)
Properties
Synthetic vitamin A is made as acetate or palmitate
Relatively stable to heat in the absence of oxygen
Susceptible to oxidation
Stable in alkali
Functions
Most abundant lipid soluble antioxidant in human body
Required as retinal (aldehyde metabolite of retinol) by eye retina for both low-light & colour vision => Deficiency can lead to impaired vision & night-blindness
Retinoic acid (acid metabolite) is shown to maintain normal skin health
Vitamin D: Fat-soluble secosteroids. Not an essential dietary vitamin as it can be synthesized in adequate amount from cholesterol when sun exposure is sufficient
Occurs in several forms:
Vitamin D2 (ergocalciferol), sources included portabella & shiitake mushrooms
is formed by uv irradiation of ergosterol
Vitamin D3 (cholecalciferol), sources included fatty fishes, whole egg, fish liver oil, beef liver
produced by: uv irradiation of 7-dehydrocholesterol in skin of animals and milk
Properties
Does not occur in plants
Extremely stable & not affected by pasteurisation, boiling or sterilisation.
Functions
Vitamin D --> calcidiol (liver) --> calcitriol (kidney) (active form)
Regulates [Ca] and [P] in bloodstream
Promotes healthy growth and remodeling of bones
Deficiency causes osteomalacia (rickets in children) (softening of bones)
Vitamin E: group of eight fat-soluble compounds that include both tocopherols and tocotrienols
divided into two groups: four are tocopherols and four are tocotrienols
identified by prefixes alpha-, beta-, gamma-, and delta-
Properties
Very nonpolar and exist mainly in the lipid phase of foods
Concentration of dietary Vitamin E in animals has influence on the oxidative stability of meats after slaughter
Exhibit reasonably good stability in the absence of oxygen and oxidizing light
Oxidative degradation is strongly influenced by oxidation of unsaturated lipids
Functions
Fat-soluble antioxidant that stops the production of reactive oxygen species formed when fat undergoes oxidation
Vitamin E contributes to oxidative stability of other compounds by scavenging singlet oxygen
Used in curing of bacon to reduce formation of nitrosamine
Deficiency leads to mild hemolytic anemia i.e. breakdown of red blood cells → anemia and tiredness
Vitamin K
Forms
Functions
For clotting blood. Deficiency will lead to bleeding problems
Properties
Decompose slowly by atmospheric oxygen but readily degraded by light
Stable against heat but unstable against alkali
Sources
Cauliflower, peas, cereals
Dark green vegetables (spinach, cabbage leaves)
Synthesized by intestinal flora (animal products contain very little vitamin K except for pork liver)
Key Terms with Nutrient Addition :check:
Restoration: Addition to restore original concentration of key nutrients
Fortification: Addition of nutrients in amounts significant enough to render food a good to superior source of added nutrients
Enrichment: Addition of specific amounts of selected nutrients
Bioavailability: degree to which an ingested nutrients undergoes intestinal absorption and metabolic function within the body
:check:
Involves both absorption and utilisation/ metabolism of nutrients as consumed
Factors that affect nutritional adequacy of food
Concentration of vitamin at time of consumption
Identification of various chemical species of vitamin present
Bioavailability of these forms of vitamin as they exist in the meal consumed
Factors that influence bioavailability
Composition of diet
Form of vitamin: Affects rate/ extent of absorption, ease of conversion to metabolically active form
Interactions between vitamin and components can interfere with intestinal absorption of vitamin
Minerals
Main vital purposes :check:
They are important for our body functions
Iron for the function of many protein and enzymes, hemoglobin
Calcium for muscle, heart and bone growth
Ionic strength of the food systems
Solubility/stability of the beverage
Flavour of the food
2 groups :check:
Trace elements :check:
Types
Cobalt
Key sources: fish, nuts, oat cereals
An integral part of only metal containing vitamin B12 (cyanocobalamin)
fluorine
Constituent of skeletal bones
Helps in reduction of dental carvies
Copper
Good sources: organ meats, seafood, nuts, seeds
Biological functions
Essential components of oxygen-processing enzymes, superoxide dismutase & cytochrome C oxidase
Facilitate iron uptake
Catalyst for lipid peroxidation, ascorbic acid oxidation, non-enzymatic oxidative browning
Deficiency : anemia & neutropenia
Functions in Food
Texture stabiliser – stabilises egg white foams
Colour modifier – black discoloration in canned or cured meats
iodine
Good sources: iodized salt, seafood, plants and animals
Deficiency result in goiter
Used as dough improver
selenium
Good sources: seafood, organ meats, cereals
Found to protect against liver necrosis
Selenium compounds are volatile and can be lost by cooking or processing
Iron
Good sources: cereals, legumes, meat
Component of heme pigments and of some enzymes
Colour modifier in meat
Fe deficiency is common - Anemia
Zinc
Second most important trace minerals
Good sources: meats, cereals
Essential component in enzymes, e.g. carbonic anhydrase & carboxypeptidase
Deficiency results in lost of appetite, growth retardation, skin changes
Added to green beans to stabilise colour during canning
Manganese
Found in a wide range of foods but not easily absorbed
Associated with activation of a number of enzymes
Molybdenum
Plays a role in several enzyme reactions
Found in cereal grains and legumes, green leafy vegetables, animal organs
Present in foods because
Uptake from soil or feeds or from contamination
From soil – absorption of elements through the roots
Subsequent to processing to foods
May also originate from food processing, packaging, food additives
Major minerals :check:
Calcium
Biological Functions
Structural role in plants and animals
Plays a major regulatory role in numerous biochemical and physiological processes
Functions in Food
Firms canned vegetables when added to canning brine
Texture modifier – forms gels with alginates, low methoxy pectins, caseins, soy proteins
Deficiency will lead to osteoporosis in later life
Key sources: dairy products, green leafy vegetables, tofu, fish bones
Phosphates
Functions in Food
Used as acidulent in soft drinks
Leavening acid (Ca (HPO4)2)
Helps in moisture retention in meats
Used as emulsification aid in comminuted meats and in process cheeses
Biological Functions
Adenosine triphosphate (ATP)
Phosphoproteins for iron storage
Phospholipids major components of membranes
Key sources: animal products
Sodium: In the form of NaCl
Functions in Food
Acts as a flavour modifier
Preservative aid – helps lower water activity in foods
Good leavening agent – sodium bicarbonate
Excessive intake leads to hypertension
Biological function: Regulates blood volume, blood pressure, osmotic pressure and pH
Magnesium
Key sources: whole grains, nuts, legumes, green leafy vegetables
Used as colour modifier – changes chlorophyll from green to olive-brown
Biological functions
Important in DNA & RNA syntheses
Essential as co-factors in many biological enzymes
Chloride
Key source: salt
Biological functions
Necessary for digestion, proper functioning of liver, healthy joints and tendons
Regulates fluid and acid-base balance
Potassium
Key sources: fruits, vegetables, meats
Biological functions
Important for brain & neuron functions
Prevents muscle cramps
Maintains osmotic balance between cells & interstitial fluid
Deficiency : hypokalemia
Functions in Food
Good leavening agent: potassium acid tartarte
Used as salt substitute
Principles of Mineral Chemistry
:check:
Solubility of Minerals in Aqueous Systems
Availabilities and reactivities of minerals depend on solubility in water
Elements such as Na+, K+, Cl-, F-, I- exist as free ionic species.
Low affinities for most ligands
Highly water soluble
Most other minerals are present as complexes, chelates, or oxygen containing anions
Acid- base chemistry
Acids and bases influence functional properties and stabilities of food components
Chelating chemistry
A chelate is a complex resulting from the combination of metal ion and a ligand, resulting in a ring structure that includes the metal ion
Bioavailability: proportion of a nutrient in ingested food that is available for utilisation in metabolic processes.
:check:
(in minerals) is determined primarily by the efficiency of absorption from the intestinal lumen into the blood.
5 Factors
Chemical form of mineral
Highly insoluble forms are poorly absorbed
Food ligands
Depends on what compounds the minerals are bound with
Redox activity of food components
Reductants (e.g. ascorbic acid)
Enhance absorption of iron but no effect on other minerals
Mineral-mineral interactions
High concentration of one mineral in diet may inhibit the absorption of another
Physiological state of consumer
Age
Homeostatic regulation
Mineral Composition in Food
:check:
Animals: Mineral concentration much lower than plant foods
Influenced by dietary intake of animals
Plants: Water and essential mineral uptake from soil
Ultimate nutrient content of plants influenced by fertility of soil, genetics of plant, and the environment
Mineral Determination
:check:
Normally determined by ashing or incineration: Estimates total mineral of foods
Minerals in ash are found in the form of metal oxides, sulfates, phosphates, nitrates, chlorides and other halides
Individual minerals can be determined by atomic absorption spectroscopy
Effect of Processing
Minerals can not be destroyed
Can be removed from foods by leaching or physical separation
Minerals have significant solubility in water
Heating and pH can change the solubility of the minerals
Example: Milk minerals, mainly citrate, potassium, calcium, chloride
Decrease in pH will change calcium and phosphate from colloidal to soluble form
Calcium phosphate is more soluble at low pH
Calcium and phosphate are changed from soluble to colloidal phase when heated.
Milk Calcium
The rest is in the form of calcium phosphate which is encapsulated inside the casein micelles
The casein micelles are stable colloids keeping the calcium phosphate from reacting with the environment
Each casein micelle has a porous structure where all components of the micelle are in slow equilibria with milk serum
Only 20-30% of the calcium (2-3 mM) is soluble
Meat vs Plant Minerals
:check:
Metal Uptake in Canned Food
:check:
Canned foods can take up metal from the container
Acid foods can erode the tins slowly
Some foods are more likely to involve rapid detinning, including spinach, green beans, tomato products, potatoes, carrots, vegetable soups, and certain fruit juices
