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Transcript
NUTRITIONAL VALUE OF FOODS
A characteristic of all living organisms is the intake of nutritional substances, nutrients, necessary for their life.
Nutrients include proteins, fats, carbohydrates, minerals and vitamins. A fundamental function of human body is
to metabolise the food constituents into energy. Energy metabolism is customarily expressed in terms of the
calorie, which is a heat unit of energy. By convention a large calorie equivalent to the kilocalorie (kcal or Cal) is
adopted in measuring energy. The only sources of calories are proteins, fats, carbohydrates and alcohol. They
have a different calorific value: 1 g of pure protein will yield 4 calories, 1 g of pure fat will yield 9 calories, 1 g
of pure carbohydrate will yield 4 calories and 1 gram of pure alcohol will yeld 7 calories. It results that the
calorific value of foods largely depends on the fats they contain. In addition to their calorific value, foods have a
biological value in that they provide human body with the fundamental substances necessary to its development.
These substances are the proteins. Protein-rich foods come from animal or plant origin. Proteins are needed for
the growth and repair of tissues. Lack of protein affects physical growth and mental development. The following
table shows the distribution of nutrients in foods:
NUTRIENTS
FOODS
Proteins
Proteins are organic compounds that in the diet serve primarily to
build and maintain cells. They are responsible for muscle
contraction, digestion, immune system and carry vital substances
throughout the body. They are derived from food and in particular
from meat, fish, poultry, eggs, milk, dairy, cheese, cereals (wheat,
barley, rye, corn, millet, etc), legumes (peas, beans, lentils, broad
beans ).
Fats
Dietary fat is a compound that is derived from both plant and animal
sources. As a nutrient it helps support cell walls, provides a
concentrated source of energy, insulates and protects vital organs
and aids in the metabolism of vitamins. Fats may be saturated and
unsaturated. Saturated fats are found in meats, dairy products and
tropical oils. Unsaturated fat is found primarily in vegetable oils and
fish, as well as in margarine.
Carbohydrates
Carbohydrates are the most abundant substances found in nature.
They form the connective tissue of cells and are a primary source of
energy. A large part of the human diet consists in carbohydrates in
the form of starches which are found in the grains, the legumes, the
tubers and sugars which are found in plants and fruits. Bread, flour,
pasta, rice, sugar, honey, fruit, legumes, and potatoes contain
carbohydrates.
Minerals
Minerals are necessary to the structural composition of human body.
They affect the development of bones and teeth, energy metabolism,
the nervous system. The most important ones which must be
supplied in the diet are:
calcium, which is provided by milk, dairy products, cheese, yolk,
roots, vegetables; phosphorus which is found in milk, dairy
products, cheese, yolk, meat, fish, potatoes, carrots; iron in yolk,
legumes, spinach; iodine in seafish (cod, cod oil, lobster, herring,
oyster).
Vitamins
Vitamins are organic compounds whose function is to enhance
nutrients’ metabolism. They are distributed in milk and dairy
products, meat, fish, eggs, legumes, bread and pasta, citrus fruits
(oranges, lemons, tangerines), fruit and vegetables (cauliflower,
chicory, endive, lettuce, spinach, courgette, apples, pears, peaches,
apricots, plums).
The following diagram sums up nutrients specific roles:
Fats
Carbohydrates
Energy-giving foods
Proteins
Minerals
Body-building foods
Vitamins
Body-protecting foods
The value of minerals and vitamins
It is essential to know some basic facts regarding the benefits our body draws from minerals and vitamins. A
proper knowledge of this helps both caterers and customers to be more discerning when choosing food.
Benefits
calcium
builds strong bones and teeth
copper
essential for red blood cell formation
iodine
zinc
important for thyroid gland function. Lack of iodine
leads to hair loss and dry and wrinkled skin
transports oxygen throughout the body
essential for nerves and muscles, helps cell
metabolism
strengthens bones
maintains fluid balance; important for muscles and
nerves
controls blood sugar and activate enzymes
Vitamin A
vital for healthy skin, eyes, bones, hair and teeth
Vitamin B1 (thiamine)
Vitamin D
releases energy from carbohydrates, assists
functioning of the heart, liver and nevous system
releases energy from foods, necessary for healthy
skin and eyes
plays a vital role in protein and fat metabolism;
regulates the central nervous system
necessary for healthy nervous system; forms red
blood cells.
important for maintenance of bones, teeth, collagen
and blood vessels. It helps heal wounds and mend
fractures, and aids in resisting bacteria infections.
important for bone and teeth development
Vitamin E
helps protect red blood cells
iron
magnesium
phosphorous
potassium
Vitamin B2 (riboflavin)
Vitamin B6 (pyridoxine)
Vitamin b12 (cobalamin)
Vitamin C
Sources
almonds, broccoli, cheese, milk, whole
grains, yogurt
cabbage, kidney, nuts, poultry, whole
grains
salt, sea salt, seafood
dark green vegetables, lean meat, soya
almonds, egg yolk, nuts, sea salt,
spinach, whole grains
cheese, egg yolk, fish, meat, whole grains
bananas, citrus fruits, green vegetables,
potatoes, whole grains
beans, eggs, fish, onion, whole grain
apricots, dark green vegetables, carrots,
kidney, liver
green vegetables, wheatgerm, wholegrain
cereals
cheese, eggs, green vegetables, kidney
liver, milk, poultry
brewers’ yeast, meats, nuts, whole grains
eggs, fish, liver, meat, soybeans
citrus fruits, cabbage, broccoli, tomatoes,
potatoes
sunlight, egg yolk, fish-liver oil, milk and
milk products
eggs, green vegetables, margarine,
peanuts, vegetable oils, wheat germs,
whole grains
FOOD GROUPS
Foods can be classified into several groups:
1. Milk and Dairy products (milk, yoghurt, ice cream, milk shake, cheese, butter). Milk has a high nutritional
value. It is rich in calcium, and phosphorus and contains vitamin A, riboflavin (vitamin B2) and carbohydrate
(lactose).
2. Meat, Fish, Poultry and Eggs. This group includes a variety of meats (beef, veal, lamb, pork), fish and
shellfish, poultry and eggs. The main nutrients are proteins, fats, minerals and vitamins (Thiamine, riboflavin,
niacin, B vitamins). Beef liver is an excellent source of iron and vitamin A.
3. Legumes (peas, chickpeas, beans, broadbeans, lentils, soya seeds) and cereals (wheat, barley, maize/corn,
millet, oats, rice, rye, sorghum). Cereals are very rich in starch and carbohydrates.
4. Bread, Pasta and Starchy Food. This group includes white and brown bread, bread-sticks, flour, brown and
wild rice, couscous, barley, millet, cornmeal, polenta, cornflakes, branflakes, biscuits, cakes, crackers,
spaghetti, noodles, pies, potatoes and chestnuts. They provide proteins, carbohydrates, vitamins and iron. The
whole grain products contribute significant quantities of fibre, vitamins and minerals. Bread contributes
complex carbohydrates. Apart the ordinary sliced white bread and the varieties for sandwiches and toast,
bread includes whole-grain bread, crackers, oatmeal, rye, semolina bread, cornbread, English muffins, bagels,
Swedish-style crispbreads, bread shells for pizza. Pasta is a good nutritious food: it contains very little fat and
is loaded with complex carbohydrates which are a main source of energy.
5. Citrus Fruits (oranges, lemons, mandarins/tangerins, grapefruit, limes) and Tomatoes. They all supply large
amount of vitamin C. The juice and grated peel of lemons and limes add fat free flavour to foods. Tomatoes
contribute appreciable quantities of iron, calcium and potassium.
6. Fruits and Vegetables. Fruits are rich in minerals and vitamins. Grapes, peaches, plums, apples and pears are
high in fibre. Other fruits such as apricots, figs, prunes, dates, and raisins are good sources of iron and
potassium. Vegetables are also an important source of minerals, vitamins and cellulose. Beans, peas and
broccoli supply large amounts of calcium and iron. Orange-yellow vegetables (carrots, squash, sweet
potatoes) are good sources of beta-carotene.
7. Other Ingredients (butter, margarine, oils, sugars, fats. They generally are added to food during preparation.
They supply a large amount of calories and make food more tasty. Products with high levels of unsaturated
fat include olive oil, peanut oil, canola oil, sunflower oil.
Nowdays more and more restaurant customers are becoming cautious of their dietary requirements. A small
number of people are likely to be particularly interested in, for example, the calorie content of specific menu
items or in vegetarian items.
In order to meet normal nutritional needs it is recommended that caterers offer a variety of foods daily, including
fruits, vegetables, grain products, dairy products, meats, poultry, fish, and eggs. The greater the variety of foods
eaten, the less likely is a deficiency or excess of any single nutrient to develop.
Let’s now examine the nutritive value (calories, proteins, etc.) of some foods from various groups:
q.ty
cal
prot
fat
carb
calc
iron
vit-a
thi
rib
BREAD
GROUP
brown apple
roll
pie
1/26g
1/135g
85
345
2g
3
2g
15
14g
51
20mg
11
.5mg
.9
T
40
.10mg .15
.06mg .11
FRUIT &
VEGETABLE
banana carrots
1/120g
100
1
T
26
10
.8
230
.06
.07
1/72g
30
1
T
7
27
.5
7,930
.04
.04
MILK &
DAIRY
skim
ice
milk cream
244g 130g
85
270
8
5
T
14
12
32
302
176
.1
.1
500
540
.09
.05
.37
.33
MEAT & FISH
beef
steak
85g
330
20
27
0
9
2.5
50
.05
.15
FATS & SWEETS
salmon
butter
candy
85
120
17
5
0
167
.7
60
.03
.16
1tbsp
100
T
12
T
3
T
430
T
T
28g
115
1
3
22
42
.4
T
.01
.05
Source: Home and Garden Bulletin No. 72; available from Supt. of Documents, U. S. Government Printing Office, Washington, DC 20402
In devising the pyramid, the US Department of Agricolture (USDA) wanted to visually represent the amount of
food in each of the five food groups that contribute to a healthy daily diet: 6 to 11 servings of grains; 3 to 5
servings of vegetables; 2 to 4 fruit servings; 2 to 3 servings of meat; 2 to 3 servings of milk products; spare
consumption of fats and sweets. The pyramid enables us to choose a balanced diet by matching foods and
choosing from different groups in the limits of the relative number of servings allowed. We can improve our
eating habits modifying our everyday food intake according to these recommendations:
 Choose more foods that are high in fibre, including whole-grain cereals, rolls, breads;
 Eat more vegetables and fruit;
 Limit intake of milk and dairy products as well as meat, fish, poultry and eggs to the essential number of
servings prescribed a day;
 Reduce fat food and sweets as sugars, fats and alcohol are rich in calories.
Foods having a high fat content
sausages, cakes, biscuits, crisps, pastries,
chocolate, sauces, fried foods, milk, butter,
cheese, margarine, lard, egg yolk, nuts, cod,
halibut, tuna, salmon, herring
Sugar-containing snacks
cakes, biscuits, pastries, scones, buns, pies,
sponges, tarts, croissants, trifles, cornets, icecreams, preserves, jams, creams, chocolate, Swiss
rolls.
Healthy Eating
A growing trend towards healthier foods is being introduced in catering operations. Many menus offered by both
hotel- and stand-alone restaurants highlight those dishes which have been specially prepared for vegetarians or
for customers who love healthy eating. The switch to a more healthy style of eating started about 15 years ago
and was supported by the variety of low-fat food products available at supermarkets.
Healthy eating refers to a well balanced diet providing adequate amounts of the various nutrients. Since nutrients
are present in each group of foods, a healthy diet menu is obtained by choosing a variety of items from different
groups. Healthful low-fat meals may be interesting, satisfying and tasty. They are dishes whose fat has been
replaced with robust flavours and savoury ingredients. Major changes which have occurred in the preparation of
healthy eating range from appetisers to desserts and place emphasis on the following:
 more vegetables which are naturally low in fat and offer a wealth of vitamins, minerals and fibre;
 more fruits which have nutritional benefits similar to vegetables;
 whole grains and pasta which are naturally lean sources of essential complex carbohydrates. Rice, macaroni,
spaghetti and noodles have increased in popularity.
 wholemeal bread which contains more vitamins, minerals and fibre.
 beans, peas and lentils which are a low-fat protein source.
 low-fat dairy products;
 skinless grilled or roast chicken;
 grilled lean meat;
 fish and shellfish which are low in fat and high in protein;
 “lean” sauces which have become a flavour booster to low-fat foods, especially grilled fish, vegetables and
shellfish;
 seasonings, zesty ingredients, assorted fresh and dried herbs and spices, snack foods (pretzels, rice cakes,
vegetable soup, chicken noodle soup, whole-grain crackers, breadsticks, wafer-style cookies).
These types of menus cut back on foods that are high in fat. The new password seems to be “Low in fat, high in
flavour”.
Here follows an example of the healthy breakfast menu offered by Sheraton Park Towers Hotel, London:
Adjectives describing food
Spicy, peppery, rich, creamy, fattening, strong, mild
Opposites:
raw
hot
light
sweet
tasty
juicy
fresh
soft-tender
salty
crisp-y
undercooked
Phrases describing dishes
It’s….
It’s a sort of……….
It contains……
It’s made of…………
It’s cooked in…….
It’s filled with…..
It’s flavoured with……
It’s served with…..
It’s stuffed with…….
It’s sprinkled with……
It’s grilled …
It’s seasoned with…….
It comes with …….
It takes 20 minutes cooking time
cooked
cold
heavy
bitter-sour
tasteless
dry
stale
hard
insipid
flabby
overcooked
1. Match the items on the left with the appropriate completion on the right
1. Milk, yoghurt and cheese
2.
3.
4.
5.
a) are found in the grains, the legumes and the
tubers
b) are calcium rich foods
c) are a valuable source of vitamin C
d) affect the development of bones and teeth
e) are rich in carbohydrates, protein, fiber, vitamins
and minerals
f) are needed for the body’s energy
g) meet the body’s need for minerals, vitamins and
cellulose
h) are a model of low fat, high fiber diet
Bread and pasta
Grains and grain products
Vegetables
Citrus fruits
6. Carbohydrates
7. Minerals
8. Starches
1
2
3
4
5
6
7
8
2. Check the food items of this dish and say which nutrients it contains.
Food items:
turkey breast tenderloins (1 pound)
chopped onion (1/4 cup)
bread crumb (1/2 cup)
spaghetti (16 ounces)
cherry tomatoes
2 tablespoons oil
Nutrients:
....................................................
....................................................
....................................................
....................................................
....................................................
....................................................
3. Write the names and the nutrients associated with the following food items:
name:
..............................
name:
..............................
nutrients:
..............................
..............................
nutrients:
..............................
..............................
name:
..............................
name:
..............................
nutrients:
..............................
..............................
nutrients:
..............................
..............................
name:
..............................
name:
..............................
nutrients:
..............................
..............................
nutrients:
..............................
..............................
name:
..............................
name:
..............................
nutrients:
..............................
..............................
nutrients:
..............................
..............................
4. Refer to the description on the left column and cross the correct box on the right.
This yellow-skinned edible fruit is rich in
carbohydrates and is a source of vitamins A
and C and the minerals potassium and
phosphorus.
lemon 
banana 
Their color ranges from various shades of red
to yellow or green. They supply appreciable
quantities of carbohydrates, calcium and
vitamin A.
apples 
cherries 
Small, soft round fruits, red or black when ripe. cherries 
They have a low caloric power, and contribute oranges 
carbohydrates, calcium and vitamin-A.
A juicy citrus fruit which supplies large
lemon 
amount of vitamin C.
kaki 
A small green vegetable usually cooked when
eaten. It’s rich in calcium
courgette 
lettuce 
A vegetable whose edible flower stalks contain
minerals (calcium, iron) and vitamins.
cauliflower 
fennel 
5. Label the following legumes:
1 ...........................
2 ............................
3 ............................
4 ............................
6. Insert the following food items in the correct column:
spinach, sugar, rye, corn flakes, peas, cod, yolk, yogurt, butter, lamb,
noodles, tomatoes, peaches, strawberries, lentils, ice cream,
milkshake, potatoes, chicken, sole, tuna, rice, chestnuts, butter,
grapefruit, cake, veal, liver, bread sticks, broccoli, eggs.
Milk &
Dairy
Meat-FishPoultry
Legumes &
Cereals
Bread &
Pasta
Fruit
Vegetables
Reading Passage
Nutritional Value of Beans
When separating the “haves” from the “have-nots” on the playing field of nutrition, beans line
up as all-stars. Beans are grouped in the U.S. Department of Agriculture’s Food Guide
Pyramid with high protein foods such as meat, eggs, poultry and fish and with vitamin-rich
vegetables. The double dose of nutrition packed into beans makes them perfect in the daily
diet. They are high in complex carbohydrates, protein and dietary fiber, low in fat and sodium,
and completely cholesterol-free. As little as a half-cup of beans added to your daily diet can
be very helpful in reaching important nutrition goals.
Protein is an essential nutrient that our bodies need daily for sound bones, muscles, healthy
cartilage, blood, skin and the proper working of lymph glands. A constant supply of protein
keeps your body working at peak efficiency. Beans, an excellent sourse of protein, are an
ideal alternative to animal proteins. As members of the vegetal group, beans are chock-full of
vitamins and minerals. Beans are rich natural sources of the B-complex vitamins - thiamin,
pyridoxine, niacin and folc acid. These vitamins trigger the processes that release energy from
carbohydrate foods, help absorb and metabolize proteins, help in the formation of red blood
cells, and keep the digestive and nervous systems healthy. In addition to being high in protein,
vitamins and minerals, beans are loaded with complex carbohydrates - a natural, healthy
source of energy just right for today’s active lifestyles Gram for gram, complex carbohydrates
provide half the calories of fat. They are absorbed more slowly than simple carbohydrates,
such as table sugar and candy, so beans satisfy hunger for longer periods of time. Beans are
also one of the best sources of dietary fiber, containing both insoluble and soluble fiber.
Insoluble fiber, generally thought of as “roughage” that moves quickly through the digestive
system, is important in our diets because it helps promote a healthy digestive tract and can
reduce the risk of some types of cancer. During digestion, soluble fiber forms a gel-like
substance which helps the body handle fats, cholesterol and carbohydrates. Soluble fiber plays
a role in helping to lower blood cholesterol levels, one of the main risk factors for the
development of cardiovascular disease. Since fiber-rich foods are filling, beans also are
helpful in weight control.
Beans should be added gradually to the diet with a goal of one half-cup serving per day.
Consumption should be increased over a four-to eight-week period, even if it’s a bite or two
per day. Adding beans to soup or salad is a good way to gradually increase consumption. It is
also important to drink plenty of liquids as you can increase your bean intake because fluids
aid in the digestion of beans. The key is to continue eating beans once the body’s system is
adjusted to them.
7. Refer to Nutritional Value of Beans and answer the following questions:
1. Which foods are beans grouped with in the USDA Food Guide Pyramid?
2. Which food items are high protein foods?
3. Which nutrients do beans have?
4. Which parts of our body does protein affect?
5. Which functions do bean vitamins perform?
6. What do bean carbohydrates provide?
7. Why is insoluble fiber important in our diet?
8. How is soluble fiber helpful to our body?
9. What should your bean daily serving be like?
10. Which way can you follow to increase bean consumption in the diet?
8. Refer to Nutritional Value of Beans and give the Italian equivalents to the following
phrases:
1. They are high in... low in...
2. As little as a half-cup of beans
3. ... keeps your body working at peak efficiency
4. beans are chock-full of...
5. In addition to being...
6. dietary fiber
7. ...helps the body handle fats
8. to lower blood cholesterol level
9. Fiber-rich foods are filling
10. over a four-to eight-week period
11. you can increase your bean intake
12. once the body’s system is adjusted to them