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TOPIC 3
THE BIOLOGICALLY ACTIVE COMPOUNDS OF FOODS AND THEIR IMPLICATION IN HEALTH
WELLNESS AND PRESERVATION
Besides the main function – to supply the body with necessary nutrients and energy –
foods can also strengthen human organism, decrease the risk of illness. Such are the functional
foods with biologically active compounds.
Compounds of functional foods:
 Dietary fibres
 Vitamins and minerals
 Antioxidants
 The lactic acid bacteria (bifidobacteria)
 Polyunsaturated fatty acids
 Peptides and proteins
 Natural extracts of plants (nutritional herbs, fruits, roots extracts)
 Oligosaccharides ( fructo-oligosaccharides, galacto-oligosaccharides, cyclodextrins)
 Sugar-alcohols
What are dietary fibres? Dietary fibres are carbohydrates (polysaccharides), found in
vegetable products. Dietary fibres in digestive tracts are decomposed by the micro flora of the
colon, not the digestive enzymes.
What is the implication of the dietary fibres for health wellness and preservation? Dietary
fibres fasten intestine movements, help to keep water in body , ease the movement of food in
digestive tract, save from constipation, affects absorption of nutrients, increasing of food volume
causes the feeling of satiety.
There are some of scientific researches which prove that using of dietary fibres decreases
the risk of breast cancer in postmenopausal period. Scientific studies show that increased fibres
consumption, reduces levels of coronary heart disease risk factors, such as cholesterol and
triglycerides. Some studies show that the fibres reduce blood glucose and insulin levels and are
important for diabetes prevention.
What foods contain dietary fibres? Main foods, which have fibres are vegetables, fruits,
coarse bread, whole grain bread, pasta (also known as the "full-grain“), beans, oats. Fibres are also
found other plant products, especially leguminous and some other vegetables (carrots, cabbage,
beets), fruits and berries (black currants, raspberries) nuts. Rich in fibres are brans of wheat, oats
and barley.
What are vitamins? Vitamins are biologically active organic compounds, very important
for the metabolism and the body's vital functions support. They cannot be substituted by any
other compounds. One gets vitamins from foods, some of them (B1, B12) are also synthesized by
intestinal bacteria. If a person is healthy and properly fed, vitamins shortages do not occur or it is
very rare. Demand of vitamins is bigger for young and growing organisms, women during
menstruation and pregnancy, breast-feeding, as well as in stressful situations, hard physical work
and so on.
What is the implication of vitamins for health wellness and preservation? The fatsoluble vitamins (FSV) are vitamins A, E, K, D. There are very small amounts of them found in
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human‘s organism. These vitamins are essential for the metabolism, if there is a lack of them,
specific diseases starts developing. Although vitamin D is assigned as fat-soluble vitamin, it is
considered a hormone. FSV regulates proteins synthesis, helps our body to form the normal bone
and muscle tissue and ensures functioning of the endocrine system.
Water soluble vitamins (WSV) - it's all the B vitamins, vitamin H (biotin), vitamin C and
vitamin P (bioflavonoid). B vitamins are involved in our body's neurophysiologic reactions which
are necessary for normal nervous system, help to absorb glucose, fatty and amino acids. B and P
(PP) vitamins are known as "intellectual vitamins". If missing, memory starts weakening, it
becomes more difficult to memorize things, children may have seizures, developmental disorders
arise. Vitamin H helps to regulate protein synthesis processes in cells. Vitamin C (ascorbic acid),
often called the "king of vitamins“, has a very large effect. It is synthesized by many animals,
including human, organisms. If there is a lack of it for a longer period of time, scurvy develops. In
addition, using products of vitamin C in additioncts, reduces predisposition to cardiac and blood
vessels, stomach, oncological diseases. Vitamin C is the great promoter of the immune system,
according to recent data it is even a kind of "anti-depressant“.
What foods contain vitamins? Vitamin A is found in grain cereals, nuts, vegetable oils,
dairy products. Vitamin E is mainly found in cereals, vegetable oils, nuts. Vitamin K is found in
cereals, dairy products, turnips, beets. Most of vitamin D is in fish oil, vegetable oils, a little – in
leafy vegetables. It works more efficiently if you are exposed to the sun and receive other vitamins
with food. Rich in vitamin H is seafood (algae, sea kale), root crops. Vitamin C is found in all citrus
fruits, especially lemons and grapefruit, and vegetables. B vitamins in larger or smaller amounts
are found in all food products, mainly in cereals, root crops, dairy products.
What are minerals? Minerals same as vitamins are necessary for human nutrition. They
are needed for normal body functions as well as normal physiological processes in the body. The
demand of them increases for a growing organism, people with trauma, blood loss, some diseases,
after heavy work or intense workout.
Minerals are divided into two groups:
1) macroelements - sodium, potassium, calcium, magnesium, phosphorus, chlorine,
sulphur and iron.
2) microelements - tin, zinc, chromium, fluorine, iodine, cobalt, manganese,
molybdenum, selenium, silicon, vanadium, copper.
What is the implication of minerals for health wellness and preservation? Minerals are
required in almost all the body's vital reactions, it is necessary for a various enzymes, vitamins,
hormones metabolism, blood cells production, cells metabolism etc. They are important for the
nervous system, blood clotting, the normal activities of the endocrine glands, heart muscle work.
Getting enough minerals, increases body resistance to infectious diseases.
What foods contain minerals? Minerals are found in almost all foods, so eating various
food satisfies the need of them.
What are antioxidants? It contains vitamins, minerals and other nutrients that protect cells
from the damaging effects of free radicals. The main three antioxidants are betacaroten (vitamin
A), vitamin C and vitamin E. Vitamins are not the only antioxidants that can be found in food,
moreover there are zinc, selenium, quercetin, luteolin, catechin.
What is the implication of antioxidants for health wellness and preservation? Antioxidants
fight against the harmful effect of free radicals and helps to maintain immune system, also helps
to avoid colds, flu and other infections.
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What foods contain antioxidants? They are mostly found in fruits and vegetables, so try to
incorporate them into your diet as much as possible. But not all fruits and vegetables have the
same amount of antioxidants. Most of them are in colorful fruits and vegetables, especially purple,
blue, red, orange and yellow hue.
Beta-carotene and other carotenoids are found in apricots, asparagus, beets, broccoli,
corns, green peppers, carrots, cabbages, mangoes, turnips, nectarines, peaches, grapefruits,
pumpkins, spinaches, sweet potatoes, tangerines, tomatoes, watermelons and persimmons.
Vitamin C is in broccoli, Brussels sprouts, cauliflowers, grapefruits, kiwi, mangoes, nectarines,
oranges, papayas, full-color peppers, sweet potatoes, strawberries and tomatoes. Most of vitamin
E has broccoli, mustards, turnips, mangoes, nuts, papayas, pumpkins, red peppers, spinaches and
sunflower seeds.
What are bifidobacteria? Bifidobacteria, earliery known as Lactobacillus bifidus, are microorganisms which exist mainly in the colon and plays an important role in the digestion of milk
carbohydrates and directly affects the metabolism. Precisely these microorganisms dominate in
the intestines of breast-fed infants; bifidobacteria contains up to 95 per cent of total microflora.
What is the implication of bifidobacteria for health wellness and preservation?
Bifidobacteria inhibit growth of many dangerous viruses and bacteria, act as immunomodulators
(absorbs carcinogens and attack malignant cells), reduces cholesterol levels, produces the B group
vitamins, folinic acid, digestive enzymes, improves the absorption of minerals.
Eating a lot of meat and fat and low-fiber foods, the amount of intestinal bifidobacteria
decreases and the proliferation of pathogenic Clostridium, Bacteroides, which have enzymes that
activate nutrients that cause decay, fermentation, intestinal cells cancerous lesions, starts
increasing.
What foods contain bifidobacteria? Lactobacillus rhamnosus GG is used in yogurt, cheese,
juice, and other dairy products. Str.Thermophilus are found in fermented dairy products, used in
the production of yoghurt and probiotic preparations.
What are polyunsaturated fatty acids? Polyunsaturated fatty acids are organic acids
having one or more double bonds and long carbon chain. These acids are essential for the body's
vital activities. They can be products of both plant and animal origin. Polyunsaturated fatty acids
are divided by the position of the first double bond: omega-3 (linolenic, eicosapentaenoic,
docosahexaenoic, etc.), omega-6 (linoleic, arachidonic, etc.), omega-9 (erucic etc.). The most
important of them are omega-3 and omega-6 fatty acids.
What is the implication of polyunsaturated fatty acids for health wellness and
preservation? Omega-3 and omega-6 fatty acids are important for brain membranes function and
brain activity, for normal functioning of the skin, the body's resistance, blood viscosity and
coagulation (reduces platelet aggregation), blood pressure. Regulation of cellular processes
depends on the dietary intake of omega-3 and omega-6 fatty acids and their ratio and the ratio of
their metabolism products.
Abnormal ratio of omega-3 and omega-6 fatty acids is associated with vascular changes in
the composition of membrane lipids and increased predisposition of atherosclerosis and
inflammatory diseases. Deficiency of essential omega-6 fatty acid affects the growth retardation,
skin lesions, reproductive system damage, fatty liver.
What food contains polyunsaturated fatty acids? Essential fatty acids are found in plant
(mainly linoleic) and animal (mainly linolenic) foods. Linoleic acid is the main component of most
vegetable oils (sunflower, soybean, maize). Alpha-linolenic acid is found in linseed, rapeseed,
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soybean oil, green-leaf plants. Not all vegetable fats are equally valuable. The more linoleic
(omega-6) and linolenic (omega-3) fatty acids they have, the more valuable they are. Marine fish
and other marine oils have a long carbon chain containing polyunsaturated fatty acids
(eicosapentaenoic and docosahexaenoic). The highest amounts of omega-3 fatty acids are found in
northern sea fish. The amount of omega-3 fatty acids in fish is different and depends on the type
and origin (e.g., grown in farms and wild).
What are peptides and proteins? Peptides are short polymers of amino acids (compounds chains) connected by peptide bonds (-CO-NH-). Peptides and polypeptides are known as
incomplete proteins. Peptides and polypeptides are then combined into a proteins. Each protein
has its own unique amino acid composition arrangements. The most important peptides and
proteins are whey proteins, milk peptides (casomorphin, lactopherrines), soy protein (soy
globulin).
What is the implication of peptides and proteins for health wellness and preservation?
Peptides and proteins are characterized by the broad physiological function in the human body:
they improve the absorption of minerals, regulate the stomach and intestinal activity, lower blood
pressure, act as immunomodulators and anti-thrombotics, helps to prevent tooth decay, promote
the development of useful intestinal microflora, regulates protein metabolism. Whey proteins are
important for nutrition, because they have balanced amino acids composition. Whey protein
concentrate (WPC) and whey protein isolate (WPI) has anticancerogenic and immune system
enhancing properties. Some milk peptides (casomorphin, lactopherrines) perform the function of
the digestive tract adjustment. Soy protein (soya globulin) reduces risk of cardiovascular disease,
total cholesterol and low-density cholesterol levels.
What foods contain peptides and proteins? Peptides and proteins are found in milk and
dairy products, meat, fish, eggs, legumes and others.
What are natural extracts of plants? An extract is a substance made by extracting a part of
a raw material, often by using a solvent such as ethanol, ether or water. Accordingly, there are
types os extracts: essential spirit and aqueous extracts.
By consistency extracts are divided into liquid (e.g., essence), thick liquid (water content
not more than 25%) and the powder (water content not more than 5%). Concentrated fragrances,
healing substances and other valuable active substances which were in raw materials remain in
extract.
Chemical compounds in plants which have healing properties are called active
components. Plants may have few or many active components. They accumulate in whole plant or
only in some of its parts: roots, leaves, bark, flowers, fruits, seeds. Their quantity and quality
depends on the plant species, habitats, collection time, drying and storage conditions. The main
active components of plant extracts are bioflavonoids, saponins, phenolic compounds, vitamins
and minerals, essential oils, chlorophyll, polysaccharides, glycosides, terpenes, tannins.
What is the implication of natural extracts of plants for health wellness and
preservation? One of the best investigated plant active compound is anthocyanins. Anthocyanins
are natural pigments of the flavonoid family, which are plants metabolites with antioxidant
properties. Flavonoids may protect from damage caused by cholesterol in blood cells. Phenolic
compounds have antioxidant, anti-tumor and antiradianion effect, protects the body from colds
and inflammations. Essential oils are used to treat respiratory tract. Tanning substances are used
in oral or intestinal mucositis treatment, diarrhea, skin diseases and poisoning treatment.
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What foods contain natural extracts of plants? At present foreign countries most
commonly use these plants: ginger, cinnamon, cardamom, licorice, mint, ginseng, gumbo or ladies
fingers, Ginkgo biloba, aloe, stevia (in USA, Lithuania has banned it), it was also started using rare
Chinese, Indian plants and mushrooms. Flavonoids are found in vegetables, fruit and beverages
(tea, wine, fruit juice). A small amount of saponins are in beans, garlic, onion, and other plants.
Essential oils are mainly found in lamiaceae umbrella and asteraceae family plants. Tanning
materials are in oak bark and wood, cinquefoil, meadow smartweed, bird cherries, blueberries and
other plants.
What are oligosaccharides? Oligosaccharides are complex carbohydrates consisting of 210 monosaccharide molecules. The simplest form of complex carbohydrates is disaccharides. They
consist of two identical or different monosaccharide molecules. In nature there is not many selfexisting disaccharides. The most common disaccharides are: maltose, cellobiose, lactose, sucrose,
trehalose. Much more often in nature occur disaccharide fragments, forming part of many plants
and bacterial origin glycosides.
What is the implication of oligosaccharides for health wellness and preservation?
Oligosaccharides play an important role in the human intestine. They create favourable conditions
to the development of intestinal microflora, feed the good probiotic bacteria and promote their
growth. Recently, studies have shown that oligosaccharides can be directly remove dangerous
bacteria or viruses from the body. In the intestine, oligosaccharide molecule binds to the microbe
membrane protein in order to keep germs closer to ourselves and not allowing them to enter the
intestinal wall. Thus dangerous viruses and bacteria together with the oligosaccharides are
removed from the intestines. Oligosaccharides can also connect and remove from the body
malignant enterotoxica E. coli bacteria, which are attached to the intestinal wall and causes
diarrhea.
What foods contain oligosaccharides? In nature, oligosaccharides are found in artichokes,
chicories, leeks, onions, asparagus and alo in mothers' milk.
What are sugar-alcohols ? The chemical structure of sugar alcohols is a hybrid between a
sugar molecule and an alcohol molecule, hence the name, but they are neither one nor the other.
Sugarį-alcohols are also known as polyols. The most widely they are consumed in sugar-free and
reduced-sugar foods. The main saccharides-alcohols, which are found in foods, are sorbitol, xylitol,
erythritol, isomalt, lactitol, maltitol, mannitol. The sweetness of sugar-alcohols varies from 25% to
100% compared with table sugar (sucrose).
What is the implication of sugar-alcohols for health wellness and preservation? Although
included in most sugar-free products, sugar alcohols do have a caloric value. This value is generally
half that of sugar and is very low on the glycemic index, which is great for controlling blood sugar
levels. Sugar-alcohols also do not ferment in the mouth when coming into contact with oral
bacteria, which is another plus for dealing with oral health.
What foods contain sugar-alcohols? Sugar-alcohols are naturally found in most of fruits
and vegetables. They can also be found in sweets, gum, ice cream, baked goods and fruit spreads.
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PRACTICAL ACTIVITIES
THE BIOLOGICALLY ACTIVE COMPOUNDS OF FOOD
AND THEIR IMPLICATION IN HEALTH
General objective of the work: Many fruits and vegetables contain vitamin C, but cooking destroys
the vitamin, so raw citrus fruits and their juices are the main source of ascorbic acid for most
people. The object of this lab work is to highlight vitamin C content in the various juice and to
determine the differences preparation of different juice.
Objectives:
 determination the amount of vitamin C in different juice
 determination of the influence of juice preparation methods in the amount of vitamin C.
Problem questions:
What is the vitamin C?
What kind of role do vitamin C in human body?
What fruit or vegetable have most amount of vitamin C?
What kind of juice have the most amount of vitamin C?
How much vitamin C should be consumed per day?
Identification the amount of vitamin C in juice
Introduction:
This method determines the vitamin C concentration in a solution by a redox titration using iodine.
Vitamin C, more properly called ascorbic acid, is an essential antioxidant needed by the human
body. Vitamin C, or ascorbic acid, is a water soluble antioxidant that plays a vital role in protecting
the body from infection and disease. It is not synthesised by the human body and therefore must
be acquired from dietary sources – primarily fruits and vegetables. As the iodine is added during
the titration, the ascorbic acid is oxidised to dehydroascorbic acid, while the iodine is reduced to
iodide ions.
ascorbic acid + I2 → 2 I− + dehydroascorbic acid
Due to this reaction, the iodine formed is immediately reduced to iodide as long as there is any
ascorbic acid present. Once all the ascorbic acid has been oxidised, the excess iodine is free to
react with the starch indicator, forming the blue-black starch-iodine complex. This is the endpoint
of the titration.
Equipment and materials:
 burette and stand
 100 mL or 200 mL volumetric flask
 20 mL pipette
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 10 mL and 100 mL measuring cylinders





250 mL conical flasks
distilled water,
various juice of tropical fruits, or orange juice of different producers,
Iodine solution: (0.005 mol L−1).,
Starch indicator solution: (0.5%).
Procedure
 Firstly prepare two mixtures:

Iodine solution: (0.005 mol L−1). Weigh 2 g of potassium iodide into a 100 mL beaker.
Weigh 1.3 g of iodine and add it into the same beaker. Add a few mL of distilled water and
swirl for a few minutes until iodine is dissolved. Transfer iodine solution to a 1 L volumetric
flask, making sure to rinse all traces of solution into the volumetric flask using distilled
water. Make the solution up to the 1 L mark with distilled water. Note: The concentration
of the prepared iodine solution can be more accurately determined by titration with a
standard solution of ascorbic acid or a standard solution of potassium thiosulfate using a
starch indicator. This should be done if possible as iodine solutions can be unstable.

Starch indicator solution: (0.5%). Weigh 0.25 g of soluble starch and add it to 50 mL of
near boiling water in a 100 mL conical flask. Stir to dissolve and cool before using.

Sample Preparation
For fresh fruit juice: Strain the juice through cheesecloth to remove seeds and pulp which may
block pipettes.
For packaged fruit juice: This may also need to be strained through cheesecloth if it contains a lot
of pulp or seeds.
For fruits and vegetables: Cut a 100 g sample into small pieces and grind in a mortar and pestle.
Add 10 mL portions of distilled water several times while grinding the sample, each time decanting
off the liquid extract into a 100 mL volumetric flask. Finally, strain the ground fruit/vegetable pulp
through cheesecloth, rinsing the pulp with a few 10 mL portions of water and collecting all filtrate
and washings in the volumetric flask. Make the extracted solution up to 100 mL with distilled
water.
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
Titration
1. Pipette a 20 mL aliquot of the sample solution into a 250 mL conical flask and add about 150 mL
of distilled water and 1 mL of starch indicator solution (figure 1).
2. Titrate the sample with 0.005 mol L−1 iodine solution. The endpoint of the titration is identified
as the first permanent trace of a dark blue-black color due to the starch-iodine complex (figure
2).
3. Repeat the titration with further aliquots of sample solution until you obtain concordant results
(titres agreeing within 0.1 mL)
Burette containing iodine solution
Conical flask
Vitamin C sample solution
Fig. 1. Determination of Vitamin C Concentration by Titration
Fig. 2. Left photo: before endpoint, added iodine reacts with ascorbic acid leaving the
solution colorless. Centre photo: At the titration endpoint all the ascorbic acid has reacted and the
excess iodine reacts with the starch indicator to give a pale blue color. Right photo: If addition of
iodine is continued after the endpoint, further iodine-starch complex is formed. NB: in each of
these images a flask showing the pale blue color of the endpoint is shown for comparison.
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Interpretation of the results
Identification of the endpoint in this titration is significantly affected by the coloration of the
sample solution used. If the solutions are colorless or are pale in color, there is no problem
identifying the endpoint. For strongly colored juices there can be a problem with the endpoint and
it is advised to carry out a “rough” titration in order to become familiar with any distinct color
change which occurs at the endpoint, (it may just be a darkening of the color) This will also help by
establishing an approximate volume of iodine solution required.
Commercial fruit juice. Left flask: before the endpoint, the colour of the solution reflects the pale
yellow colour of the fruit juice. Centre flask: At the titration endpoint all the ascorbic acid has
reacted and any excess iodine reacts with the starch indicator to form a dark blue-black complex.
In this case the result is a darkening of the solution’s colour from yellow to brown-grey. Right
flask: This illustrates the effect of adding just a mL or two more of iodine solution after the
endpoint is reached, resulting in the formation of further iodine-starch complex.
Freshly squeezed orange juice. Left flask: before the endpoint, the colour of the solution reflects
the bright orange colour of fresh orange juice and is unaffected by addition of iodine. Centre flask:
Once all the ascorbic acid has been oxidised, a slight excess of added iodine complexes with the
starch indicator, giving the solution a green colour in this case. This is the endpoint of the titration.
Right flask: If further iodine solution were to be added, the solution’s green colour would become
darker as shown.
Calculations
Calculate the ml of titrant used for each flask. Take the measurements you obtained and average
them.
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Average volume = total volume / number of trials
Determine how much titrant was required for your Standard. If you needed an average of 10.00 ml
of iodine solution to react 0.250 grams of vitamin C, then you can determine how much vitamin C
was in a sample. For example, if you needed 6.00 ml to react your juice (a made-up value - don't
worry if you get something totally different):
10.00 ml iodine solution / 0.250 g Vit C = 6.00 ml iodine solution / X ml Vit C
40.00 X = 6.00
X = 0.15 g Vit C in that sample
Keep in mind the volume of your sample, so you can make other calculations, such as grams per
liter. For a 25 ml juice sample, for example:
0.15 g / 25 ml = 0.15 g / 0.025 L = 6.00 g/L of vitamin C in that sample
This project has been funded with support from the European Commission. This presentation
(communication) reflects the views only of the author(s), and the National Agency and
Commission cannot be held responsible for any use which may be made of the information
contained therein.
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