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Edible oils and fats
olive oil

Introduction

Function of fats and oils

Oils and fats can be used in the preparation of certain dishes or they can be used for deep-frying, frying or braising. The following is a short summary of their uses:
Oils

  • For frying and braising.  With the exception of a few very aromatic types of oil such as hazel nut, almond and sesame oils, most types of oil can be used for frying and braising.
  • For deep-frying.  The most neutral oils such as arachide, corn, sunflower and salad oil are suitable for deep-frying.  Aromatic oils are too expensive and have too strong a flavour.  Deep-frying in oil is especially suitable for dishes that are eaten cold such as beignets, doughnuts and the like.
  • As components of dressings and home made mayonnaise. Both neutral oils and oils with a more distinct flavour can be used such as nut or olive oil.
  • As flavouring.  Aromatic oils such as sesame, nut and virgin olive oils are ideal for Chinese dishes, nut tarts and pasta dishes in giving them extra flavour.
  • As basis for flavoured oil.  Oils with a neutral flavour are excellent oils for the preparation of flavoured oils such as chilli, paprika, garlic or shellfish oil. The desired flavour can be made by adding for example Spanish peppers, finely chopped paprika or shellfish carcasses to oil and allowing the oil to absorb the flavours.

Fats can also be used in various ways for example:

  • For frying and braising. All types of fats can be used for frying and braising meat and poultry: for frying fish some fats are less suitable for example beef, pork and goose fat. The flavour of these fats is too strong for the delicate flavour of fish

goosefat

Fats and fat products
A distinction is made between frying and braising fats and frying and braising products.
Frying and braising fats are fat rich products of fat that are suitable for frying and braising. Examples are margarine (products) with a high fat content and lard.
Frying and braising products ‘are similar to edible fat commodities’ with a fat content of ± 95%.

  • For deep-frying.  Certain fats are made especially suitable for frying for longer periods at high temperatures.  These deep-fryer fats are made for health reasons, mostly from vegetable fats, although they can be made completely or partly from animal fats.
  • For spreading on toast and bread.  Margarine (products) are suitable for this but in some cases also lard and goose fat.  Margarine can be used as an alternative for herb butter.
  • As a component of sauces.  Margarine is an ideal alternative for butter in sauces, which have a roux basis: other fats are less suitable because of their flavour.  For thickening a warm sauce ‘monter’ with cold butter, margarine is not suitable, as the rich, full flavour of the butter would be missed.  For this reason, other fats are also unsuitable.
  • As a component of pastry. Margarine is again in this case the most obvious alternative to butter, but in some cases (mostly foreign) pastry and tarts, lard or kidney fat (beef) is used adding an extra flavour to savoury dishes.

The nutritional value of fats and oils

Fat is an important nutrient in oils and fats.  Oils and fats also contain a small amount of carbohydrate and proteins and therefore are very important to our diet, especially in the form of energy.  In the following chart it can be seen that edible oils and fats have a fat content of at least 80%.  Fat if also an important carrier of the soluble (in fat) vitamins A, D, E and K. As well as vitamins fat contains essential fatty acids.  Fatty acids are important as building bricks in the body and are absorbed into the body via food.  On top of the nutritional value of fats, it adds important flavour to food.

Nutrients
The law dictates that the vitamins A and D are added to certain products such as margarine and halvarine – these vitamins are natural in butter.  Other nutrients found in fats are not so important.  Some margarine products contain small percentages of proteins and/or carbohydrates such as dry milk components, gelatine or starch.  There are some fat materials that contain natural salt.

Calories
Fats are an important energy source however too many calories are unhealthy.  For this reason industry has introduced margarines and other fat materials with a fat content lower than 80%, such as halvarine (half margarine) which is 39-41% fat.  These products contain therefore fewer calories.

Fat content
Since 1996 the following groups apply to the sale of products within this product group:
Margarine with a fat content of 80 – 90%
¾ Margarine with a fat content of 60 – 62%
Half full margarine / halvarine / minarine with a fat content of 39 – 41%
Products with X fat with a fat content between 10 – 39% fat, 42 – 60% fat or 63 – 80% fat

Fatty acids
For health reasons products are brought onto the market with a favourable fatty acid composition.  The composition of fatty acids influences the cholesterol levels in the blood.  Fats are built of saturated and unsaturated fatty acids.  Unsaturated fatty acids are divided in (single) or monounsaturated fatty acids (mfa) and (multiple) or polyunsaturated fatty acids (pfa).
Of the last group linoleic acid is the most common.
Saturated fatty acids can increase the cholesterol level in the body whereas unsaturated fatty acids, especially the polyunsaturated fatty acids, can reduce cholesterol levels. It is very important when preparing dishes for people with cholesterol restricted diets, to use vegetable fat products rich in polyunsaturated fatty acids.
Animal products (meat, meat cuts, animal fats, eggs and dairy products) contain cholesterol and have a high content of saturated fatty acids.  Vegetable products do not contain cholesterol however there are a few vegetable fats for example coconut and palm oil which do contain many saturated fatty acids.
Unsaturated fatty acids are found in vegetable fats and fish.  The relationship between single and multiple unsaturated fatty acids can vary greatly.  Olive oil, arachide oil and avocados contain more monounsaturated fatty acids than polyunsaturated fatty acids. In all other vegetable oils is the proportion of polyunsaturated fatty acids (including linoleic acid), the greatest.

Type of fat

Fat content

saturated

unsaturated

unsaturated

Edible oils
Almond oil
Arachide oil
Grape seed oil
Hazel nut oil
Corn oil
Olive oil
Rape seed oil
Safflower oil
Sesame oil
Salad oil
Soya oil
Wheat germ oil
Walnut oil
Sunflower oil

 

100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%

 

8,3 g
14 g
11 g
10 g
14 g
14 g
5.5 g
10,6 g
14 g
15 g
15g
18,2 g
8 g
11 g

Monounsaturated
68.2 g
54 g
16 g
70 g
26 g
77 g
64 g
14,3 g
42 g
23 g
23 g
18,2 g
22,2 g
25 g

Polyunsaturated
22,8 g
31 g
72 g
20 g
60 g
  9 g
30,5 g
75,1 g
44 g
62 g
62 g
63,6 g
69,8 g
64 g

Fats

 

 

 

 

1. Animal Fats
Beef fat
Lard
Melted beef fat
Melted pork fat
Goose fat

 

100%

100%
100%
100%

 

44 g

44 g
41 g
74 g

 

48 g

48 g
48 g
21 g

 

3 g

3 g
9 g
5 g

2. Deep fryer fats
Deep fryer fat
Deep fryer fat

 

99%
100%

 

29 g
27 g

 

49 g
18 g

 

21 g
55 g

3. Margarine products
Margarine
Diet margarine
Half margarine
Diet half margarine

 

80%
80%
40%
40%

 

21 g
17 g
9 g
9 g

 

22 g
17 g
18 g
7 g

 

37 g
46 g
12 g
24 g

4. Vegetable fats
(Tropical oils)
Coconut fat (oil)
Palm fat (oil)
Palm seed fat (oil)

 

100%
100%
100%

 

91 g
50 g
82 g

 

7 g
38.5 g
15,5

 

2 g
11.5 g
2,5 g

5. Butter
Salted cream butter
Unsalted cream butter

 

84,2%
82,5%

 

54,2 g
54,1 g

 

26,2 g
26 g

 

3 g
2,4 g

Notes:  Per 100 gram: the numbers have been rounded off

    • The numbers are the average of an number of similar products with a favourable fatty acid composition
    • Butter is not discussed in this chapter any further but has been included in this chart for clarification in comparing it with other fats and oil

    Purchasing fats and oils

    Purchasing of oils and fats varies from company to company. Normally in a professional kitchen one type of oil or fat will be totally insufficient.  Just how many different types will depend on the dishes being prepared, the company formula and the budget available.  In a snack bar it is perhaps possible to work with one type of fat for buttering rolls and one type of fat for deep-frying.
    However in a top class restaurant five types of oil and five different types of fat may sometimes be too few.  In the kitchen of an old folk’s home or a hospital, it will be very important to take special note of the fatty acid composition of the oils and fats. In the kitchen of a café or a highway restaurant, expensive walnut oil will not be used normally in salad dressings but more likely a cheaper, neutral salad oil.
    When purchasing oils and fats attention must be paid to the following:

    1. The types of oils and fats that are available for purchasing
    2. The physical condition of them
    3. The quality hallmarks of the various types of oils and fats
    4. The price of the various types

    1. The types of oils and fats that are available for purchasing                                                 
    Types of oils
    Oils are in general vegetable with the exception of fish oil.  Fish oil originates from small sea fish such as herring or sardines.  Vegetable oils are made from:
          - Seeds, such as sunflower seeds, grape seeds and sesame seeds

    • Nuts, such as walnuts, almonds and arachide oil
    • Fruit such as olives and avocado oil
    • Germs such as corn and wheat-germ oil
    • Sometimes even from oil retaining pulses such as soya oil

    walnut oil

    Oils can be removed from the product in two different ways: through pressing or extraction.  Sometimes a combination of both techniques is used.

    Types of fats
    As mentioned above fats can be both animal and vegetable from origin.  Combinations of both animal and vegetable can be found too, such as in certain deep-frying fats.

    Animal fats
    Animal fat is found in the fat tissues of slaughtered animals.  In Holland this is normally beef and pork, but in other parts of the world use is made of the fat tissues of chickens and geese too. The fat layer is found normally just under the skin and around the organs.  Animal fat is available in two forms: raw and melted.  Raw fat such as fresh pork fat is excellent in the preparation of pâtés and terrines, both as a basis ingredient of the farce and as a lining for the dish.
    Melted types of fat are lard of melted pork fat, the melted stomach or kidney fat of beef and goose fat that is melted fat from under the skin of fattened geese.
    Allowing fresh fat to melt slowly whereby the connective tissue is left behind in the pan produces melted fat.  The melted fat is poured into waxed pots or pressed in blocks.  Goose fat is usually tinned.

    lard

    Frying and braising products
    Frying and braising products are made from a mixture of fats and/or oils.  The composition differs per make.

    Margarines
    Margarines or margarine products are made normally from vegetable oils, fats and acidified milk that has had the cream fats removed.  There are also types of margarine that contain a percentage of fish oil.  For use in margarine products, it is first hardened so that it is firm and able to be kneaded.

    margarine

    Deep frying fat
    Deep frying fats are made like other frying and braising products with a mixture of different oils and/or fats.  The composition differs from make to make.

    2.         The physical condition of oils and fats

    In the beginning of this chapter the important differences in the physical condition of oils and fats was mentioned:

    • Oils are liquid
    • Fats are solid

    By a change in the temperature, the physical condition can be changed: oils harden and solid fats become liquid.

    3.         The quality hallmarks of the various types of oils and fats

    Edible oils and fats and margarine (products) must adhere to the legal requirements as set down in the Food Standards Agency with regard to the Production of Margarine, Fats and Oils.  These rules take special account of:

    • The composition with regard to the fat content, vitamin content and the additives
    • The quality with regard to the (non) presence of dangerous materials
    • The labelling of the products – the details concerning the fat content in particular

    Olive oil is the only oil that is marketed in various qualities.  The class of oil must be clearly shown on the etiquette.  In 1992 a new classification was introduced for all countries in the European Community.  Acidity, aroma, flavour and colour are deciding factors for the classification in a certain quality class.  The following classes of olive oil are recognised:

    • Extra virgin oil.  This oil is produced from the first pressing or ‘huile extra vierge’.  It is not purified and un-refined olive oil, Extra virgin olive oil could, in fact, have another name – perfect virgin olive oil, because this is precisely what it is: virgin olive oil with no flaws whatsoever. By law the acidity of extra virgin olive oil is never more than 0.8 per cent.  What does this mean? Flavour. First there is an aromatic fragrance, then a sweetness not marred by acidity, and then an abundant taste of fruit.
    • Virgin oil.  This is similar to the above oil with an acidity of maximal 2 per cent.
    • Olive oil.  This category includes oils that are refined and which have some oil from the above categories added to increase the flavour.  The acidity of this type of oil must not be higher than 1.5 or 2 gram per 100 grams of oil.  The flavour, aroma and colour must be acceptable.

    There is yet another un-classified olive oil, which is made from the remains of the olives and/or olive skins from pressed  olives of the first pressing.  After refining this oil has often colouring and other olive oil added to improve it.

    4.         The price of the various types of oils and fats

    The price of oils and fats is dependent on the purity of the product.  The purer the oil and fats are, the better the quality and the more expensive the products.

    The treatment of oils and fats in the kitchen

    There are various phases of handling oils and fats:

    1. The delivery to the kitchen
    2. The storage
    3. The preparation

    1.         The delivery to the kitchen

    When an order arrives at the kitchen of oil or fat, the physical condition of the products should be checked.  The information on the packaging should be inspected. This includes the name or type of oil or fat, the net contents, the use by date, the names or E numbers and perhaps any additives such as anti-oxidants, flavour and aroma additives. In some cases it is important to check the fatty acid composition.

    2.         The storage

    In general terms oils and fats reduce in quality if they are exposed to air and light too long.  If the temperature of the storage area is too high, this is again unfavourable. For these reasons, oils and fats must be stored in closed bottles or containers in a cool, dark place.  The best storage area for margarine and similar products is in the fridge or cool cell.  It is also advisable to store some aromatic oils such as hazelnut and walnut oils in the fridge after opening.  If this is not done oxygen can turn the fatty acids rancid.  Since this type of oil has a limited storage life, it is advisable to note the date of opening on the outside of the bottle (perhaps on the etiquette).   The storage life of most oils is between six to twelve months.  Opened bottles and tins have a shorter storage life.  Especially virgin olive oil and other aromatic oils, it is good practice to use up opened bottles in a relatively short time.  Keep the bottles away from direct light to avoid deterioration.  For this reason some companies prefer to buy aromatic oils not in bottles but in tins. Tin does not allow light to penetrate through and protects the product from the dangerous effects of light.
    The storage time of margarine products, including the half-full, diet versions and the secondary frying and braising products is roughly three months, unless stated otherwise on the sell or use by date on the etiquette. It is therefore not advisable to lay down a large stock that will take longer than six weeks to use.
    Like many other products it is advisable to use oils and fats in the order that they are delivered; use first the old stock before starting on the new stock.

    3.         Preparation

    Oils and fats can be heated to a certain temperature.  If the temperature is increased further, a chemical process begins to break down the oils, emitting a gas and various by-products, some of which contribute off- flavours to the oil. It can also be a health danger. The temperature at which this breaking down process begins is called the smoking point.
    When an oil or fat is heated so much that white damp begins to rise from it, this is a sign that the smoking point has been reached.  This means that the oil is over-heated.  This should be avoided at all costs. Fats that have reached their smoking point are damaged and have no further use. They need to be discarded.
    Each type of fat has a different smoking point.  The smoking point of margarine is around 120º C and derivative products made from margarine around 150º C. These products can accept a higher temperature since they contain very little liquid.  The smoking point of deep frying oils is around 190 - 205º C, depending on the origin of the fat, animal or vegetable and the possible existence of an emulsifier.  The smoking points of oils vary from around 200 to 225º C.

    Deep-frying
    Oils for deep-frying cannot continually be used.  Heating at high temperatures causes the oil to deteriorate because of free fatty acids, which arise in the oil.  For this reason oils and frying fats must be sieved after each use and after several uses, replaced by fresh oil.  The regularity of changing oils is dependent on the way in which the oil is used.  The quality will deteriorate quicker if the oil is only used occasionally than when it is used regularly.  If it is heated to too high a temperature, this will also affect the quality and life span. Oils and fats that need to be replaced are recognisable by the following points:

    • A dark colour and /or visible deposits on the bottom and sides of the of frying pan
    • A strong smell from the oil
    • A lot of foam forming around the food when it is dropped into the oil
    • A syrupy consistency
    • Nowadays there are testing strips for checking the percentage of free fatty acids in frying fats and oils.

    Golden rules for deep-frying
    The better the oil or fat is treated, the longer it will last.  Care should be paid to the following points:

    • Sieve the oil or fat regularly, especially after frying coated products. Loose breadcrumbs can easily burn and give the oil an unappetising flavour.
    • Never add fresh oil or fat to used oil or fat: this reduces the life of the total amount
    • Never deep-fry too many products at the same time. If too much food is added at the same time, the fat will cool down too much. At that point, the food will absorb unnecessarily too much fat.  It will also have negative consequences for the shelf life of the fat. Oils and fats absorb the flavour of the food being cooked.  For this reason oil or fat that has had fish cooked in it cannot be used for frying other food types.

    The production of oils and fats

    The preparation of margarine

    The production of margarine is quite complicated.  In short, refined oils or fats in the so-called   ‘oil phase’ are hardened and mixed with milk that has had the cream removed, the so-called ‘water phase’. To achieve this, an emulsifier is added to the oil phase, as without a binding material, the oil and water phases cannot remain fused.
    Before fusing, additional ingredients are added to the both the oil phase and the water phase. For the oil phase these are emulsifiers, the vitamins A and D, flavour and aroma materials and colouring to give margarine a butter look.  To the water or milk phase, lactic acid bacteria are added for acidity.  Sometimes salt and the preservation material citric acid are added.
    Mixing takes place in a large machine, the rotator, which does not only mix and knead the ingredients but also cools them whereby the fats solidify and the mass becomes firm. By the time this process is complete, the margarine is ready for packaging in foil or tubs.

    Production of oils and fats
    For the production of oils and fats there are various methods: cold or warm pressing or the extraction method.

    Pressing
    This technique is divided into two groups: the cold and the warm pressing.

    • In cold pressing the basis materials are crushed or milled and then pressed. Relatively speaking this method produces little oil, but when produced is of the best quality. Cold pressed oil contains no pollutants and can be sold after being centrifuged without any complicated processing.  Most oils with a definite flavour such as almond, olive, walnut and sesame oils are produced in this manner.
    • Warm pressing is carried out a temperature of 80º C and under high pressure. This type of production produces more oil but due to the high temperature an amount of the original flavour and aroma is lost and it is possible that unwanted particles can appear in the oil. The oil needs to be refined and cleaned of all materials that can have a negative effect on the colour, flavour and shelf life of the oil. During the refining process, depending on the origin of the oil, slime will be removed, acid removed, it will be bleached and deodorised. The result of the refining process is clear oil, which has no smell and flavour.  To some edible oils colouring and /or anti oxidants are added to extend its shelf life. Cold pressed olive oil can be added to refined olive oil to improve the flavour. Almost all neutral oils are refined, produced through warm pressing. Apart from edible oils, they are also used as basis ingredients for other fats such as margarine and some deep frying fats.

    Extraction method

    In this method, treating the crushed or milled basis materials with a solution, usually hexane produces the oil. This solution extracts the oil from the mass whereby a mixture of oil and solution is produced.  This mixture is then heated in distillery kettles until the solution has evaporated. The solution falls as condensation and can be used again. The oil that is produced in this way is further refined as above.