A Treatise on Baking

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Shortening

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Chapter VII

SHORTENING

SHORTENING

I. DEFINITION

Shortening refers to the fats or oils used in baked goods, principally to produce a soft velvety crumb, thus improving the eating quality of the finished product. This desirable tender and pleasing eating quality is described by the word “short” and the fats or oils which impart this property are therefore known as shortenings.

II. FATS AND OILS USED AS SHORTENING

Shortenings ordinarily used for baking purposes are edible fats or oils of vegetable or animal origin. The dividing line between these fats and oils is not very definite. In general, shortenings which are fluid at ordinary temperatures are called oils, and those which are solid are called fats. Some fats however, have higher melting points and are harder than others. Thus, we have what are known as hard and soft fats. The usual forms of solid shortenings used at the present time represent various mixtures of hard and soft fats.

III. COMPOSITION OF SHORTENINGS

While the various shortenings commonly used may be quite different in their consistency, melting points and other physical properties, they are very similar in chemical composition. Thus ordinary shortenings when analyzed are found to be mixtures containing some of the following substances in various proportions:

1. STEARIN—a hard fat, naturally of animal origin. Vegetable stearin may be secured by saturating vegetable oils with hydrogen gas as described later under the subject of “Hydrogenated Vegetable Shortenings.”
2. PALMITIN—a fat, secured from both animal and vegetable sources.
3. OLEIN—an oil secured from both animal and vegetable sources.
4. LINOLIN—an oil present in cottonseed oil.

Although the four substances mentioned above are similar in composition, they are not identical, and the actual difference in their composition, while very small, is responsible for the fact that stearin and palmitin are solid fats while olein and linolin are oils. This explains why suitable mixtures of the above constituents, such as the ordinary shortenings, are of soft and plastic consistency.

IV. CLASSIFICATION OF SHORTENINGS

A. ANIMAL FATS

1. Lard and Lard Oil

Lard needs little introduction to bakers. It is well known as an excellent shortening and is used extensively in the manufacture of quality bakery products.

The fat of hogs is separated by a heating process known as rendering. The melted fat is then allowed to cool and solidify under controlled conditions. The resulting product is a pure white fat of pleasing taste and odor, known as lard. There are different types of lard depending on the part of the hog from which the fat is secured, and also on the process of rendering and cooling.

Lard is made up of a mixture of stearin, palmitin and olein. When lard is melted it becomes liquid. If this liquid is allowed to cool slowly, the harder fat or stearin separates out first. At this point, the oil which remains can be strained off and thus separated from the stearin. This oil consists mainly of olein and is termed “lard oil.” It is this lard oil which is claimed to impart the pleasant flavor contributed by lard to bakery products.

For years lard has been used as shortening in bakery products due to its excellent shortening power, purity, whiteness, and pleasing mild taste and odor as well as its excellent keeping qualities. Lard is easily handled in the bakery and because of its desirable consistency, it mixes easily into the dough batch.

2. Leaf Lard

Leaf lard is usually considered as the highest grade, and is obtained from the fat surrounding the kidneys, and rendered at a moderately high temperature. However, much of the high quality lard now produced is secured from other sections of the animal as well.

3. Different Types of Lard Classified According To Manufacturing Method

The main difference between the various types of lard are governed by the method of manufacture, and handling. Two commercial types of lard are as follows:

(a) PRIME STEAM LARD

This lard is usually rendered from fats obtained from all parts of the hog. The fat is first melted by means of steam, and drawn off. If the melted fat is allowed to cool down gradually without stirring, the lard thus secured will have a relatively coarse grain.

If, however, the melted fat is chilled very quickly until it just starts to become solid,—and is then agitated or beaten and allowed to set,—the lard thus secured will be very smooth and not at all granular or grainy.

(b) KETTLE RENDERED LARD

This type of lard is usually made from the “leaf” and back fats. Due to the fact that these fats contain more stearin than other hog fats, this type of lard is usually harder than other types of lard. Kettle rendered lard is heated to a somewhat lower temperature than steam rendered lard and is usually cooled with very little agitation, resulting in a lard which is uniform and somewhat grainy in character.

4. Beef Fats

By a process of melting, pressing and filtering, beef fat or tallow, can be separated into hard fat known as oleo-stearin, and soft fats or oils known as “oleo.”

The oleo oils whidh are pressed out of the beef fat are used extensively in the manufacture of oleomargarine. The oleo stearin is used in the preparation of Compound shortenings.

5. Butter

Butter is the fat of milk separated from milk or cream by churning and contains also a small amount of other milk constituents. The U. S. standards for butter state that it must contain not less than 80 % of milk fat. The remainder of butter is made up largely of water, together with a very small amount of casein (milk protein), salt, milk sugar and certain substances which impart the delightful characteristic flavor to butter which is found in no other fat.

Salted butter may contain various amounts of salt ranging from about 1/2% about 6%.

In products where appreciable amounts of butter are used, the salt content of the butter should be taken into consideration, and any necessary adjustment on account of this should be made. In yeast raised sweet doughs, butter which is rolled into the dough should first be washed with cold water to remove the salt present.

Because of its composition and low melting point butter is very easily digested and like other edible fats is a concentrated fuel food for the human bodfr. Furthermore, butter is one of the richest sources of vitamin A, an essential food factor which is necessary for normal growth, teeth and bone development.

Butter is used mainly in cakes and pastries, because of the excellent flavor and food value which it imparts to the finished product.

B. VEGETABLE SHORTENING

1. Vegetable Oils

Certain vegetable oils, principally those pressed from corn, cocoanut and cotton-seed have been used to some extent for baking purposes. For such use, these oils are refined, bleached and deodorized.

Vegetable oils are not used to any extent in pastries due to the fact that a solid fat is more desirable for such purposes. While these oils as such can be used for shortening purposes in breadmaking, they are more likely to become rancid and are not so easily handled as solid fats. This fact was recognized years ago and therefore vegetable oils were frequently blended with harder fats so as to form a solid soft fat mixture known as compound. In later years a process of treating such oils with hydrogen so as to produce an ideal solid vegetable shortening was discovered.

Compounds and hydrogenated shortenings are described in the paragraphs which follow.

Highly refined cottonseed oil or corn oil, however, is used to a considerable extent in the frying of doughnuts and similar products because of the “fact that they can be heated to a higher temperature than lard without smoking, and yield a fried product which is dry and free from greasiness.

2. Hydrogenated Vegetable Shortenings

Some years ago it was discovered that if hydrogen gas were circulated through the ordinary vegetable oils at a high temperature and under certain other necessary controlled conditions, they would gradually be changed into a solid fat. This change is due to the fact that the olein and linolin which are the principal constituents of such oil, absorb the hydrogen and are thereby converted into the solid fat, stearin. The longer the hydrogen is passed through the oil, the more will be absorbed and the harder and whiter, the resultant fat will become; because a greater amount of the fluid olein and linolin is thus converted into vegetable stearin. This process is used extensively today in converting oils into solid fats and is known as the “Hydrogenation of oils.” The hardness of any hydrogenated oil can be governed by the extent to which it is hydrogenated. The complete hydrogenation of a vegetable oil would change it into a fat which would be far too hard for satisfactory use as a shortening agent. Therefore in order to secure a product having the proper degree of hardness or consistency such as that of lard,—vegetable oils are only partially hydrogenated, so that only enough of the linolin and olein are hardened thus producing a shortening of the desirable plasticity. It can be easily seen that the discovery of the hydrogenation of oils was very valuable for it meant that oils could be readily converted into solid or semi-solid shortenings. There are many brands of excellent hydrogenated fats extensively used in practically all types of bakery products today and the value of this class of shortenings is well known to the bakery industry.

C. COMPOUNDS

“Compounds,” as the name signifies represent that group of shortenings made by compounding or blending a vegetable oil with a hard fat in proper proportions so as to give a resulting product of a desirable consistency such as that of lard. Thus cottonseed oil, corn oil or other vegetable oil blended with vegetable or animal stearin, in a suitable manner forms a compound shortening, which is white, odorless and of plastic consistency.

The animal stearin used in the manufacture of compounds is usually oleo-stearin or the hard fat secured from tallow. Today this is often replaced by vegetable stearin secured by hydrogenating vegetable oil as previously described.

D. OLEOMARGARINE

Oleomargarine is well known as “artificial butter” or butter substitute. It is usually made of refined oleo oil churned in with some pure butter, neutral lard, and milk. Sometimes vegetable oils, such as cottonseed oil are also used. Cocoanut oil is often used in the preparation of various kinds of so-called “nut butter or nut margarine.” Oleomargarine is pure and wholesome. Its shortening power is excellent and its flavor resembles that of butter.

V. EFFECT OF SHORTENING ON BAKERY PRODUCTS

A. IMPROVED EATING QUALITIES

Shortening is used in bread, sweet doughs, cookies, crackers, cakes and pastries primarily for the purpose of imparting desirable tender eating or chewing qualities known as “shortness’ to the finished product. The kind of shortening, amount used and manner of incorporation in the dough depends of course on the nature of the finished baked goods, i. e. whether bread, cake or pastry.

B. IMPROVED APPEARANCE OF BAKERY PRODUCTS

The proper use of shortening, not only imparts richness to the finished bakery products but also improves their appearance. The smooth pleasing crust of bread, the soft velvety crumb of bread and cakes, and the much desired “flakiness” of pastries are due in large measure to the shortening used. In a bread dough, the shortening acts as an internal lubricant making the dough more pliable and tending to prevent stickiness and to reduce the amount of dusting flour required. Thus the grain, texture, color character of crust and “slicing” qualities as well as the volume and symmetry of the finished loaf are enhanced by the physical action of the shortening.

C. ENHANCED KEEPING QUALITY OF BAKERY PRODUCTS

The shortening or fat which is uniformly distributed throughout the dough batch coats each tiny particle of dough thus imparting a long lasting softness to the crumb. This means that the finished product will retain its appearance of freshness for a longer period of time. Some authorities claim that shortening lessens the loss of moisture from the baked goods and in this manner assists in keeping them fresh.

D. FOOD VALUE CONTRIBUTED BY SHORTENING

The edible fats and oils used as shortenings represent the most concentrated fuel furnishing food known, and supply heat to the body. One pound of fat furnishes about 4100 Calories. While fats are completely digested, they are digested and assimilated slower than carbohydrates or proteins and yield heat to the body gradually, thus contributing “staying power” to any meal. The oils and fats ordinarily used as shortening agents digest readily inasmuch as they melt either at the normal temperature of the body or below.

VI. POINTS ABOUT SHORTENING OF INTEREST TO THE BAKER

A. SHORTENING POWER AND THE FACTORS CONTROLLING IT

In the use of any shortening, naturally one of the first points which the baker considers is its actual “shortening” power. Now in this connection it must be remembered that shortening does not dissolve in the water of the dough, but is merely mixed mechanically into the rest of the dough. The action of shortening in bakery products is therefore physical and not chemical. It merely acts as an internal lubricant making the dough softer and smoother and when it is baked, the characteristic “shortness” becomes apparent.

In bread making where only two or three pounds of shortening are used to every 100 pounds of flour,—there is probably little difference in the actual “shortening” effect produced by several different types of good solid shortening when employed in the same amount and in the same way. However, it is well known that the actual degree of “shortness” secured is dependent not only on the amount of shortening used, but also on the manner in which it is incorporated in the dough batch. In order to obtain the best results from a given amount of shortening in a bread dough it is necessary for it to be thoroughly and uniformly distributed throughout the . entire mass of dough.

Usually the shortening is added gradually and in small amounts to the bread dough just after it has been formed in the mixer. Today some bakers are emulsifying their shortening by the use of a machine called an homogenizer, prior to incorporation in the dough batch. This of course enhances the effectiveness of the shortening by insuring perfect distribution of the fat particles throughout the entire mass of dough.

For yeast raised sweet dough products a much greater shortness is desired and this is secured by the use of considerably larger amounts of shortening which is completely and uniformly incorporated into the dough by first creaming it with sugar and salt, before being mixed in with the rest of the dough batch ingredients used.

For certain sweet dough products known as “rolled in” doughs, still greater “shortness” and greater “flakiness” is secured by rolling butter or other shortening into the regular sweet dough before it is made up into its different forms and baked.

B. PURITY OF SHORTENING—COLOR AND FLAVOR

Because of its importance in baked goods, the shortening used should be a highly refined product, pure and free from any objectionable taste or odor. With the exception of butter and certain shortenings used for cake baking¹, most high grade shortenings are practically colorless.

C. CONSISTENCY

The solid shortenings used in baked goods should be of such a consistency that they can mix readily and perfectly into the dough batch. While such shortenings should have sufficient body to permit ease of handling in the bake-shop, they should not be hard or lumpy, and should melt at a temperature not higher than that of the body.

For sweet doughs, cakes and pastries the “creaming” properties and ease and completeness with which the shortening may be rolled into a dough, determine to a large extent its effectiveness as a shortening agent.

D. KEEPING QUALITIES OF SHORTENING—RANCIDITY EXPLAINED

The ability of any shortening to retain its freshness and sweetness is of utmost importance in the manufacture of quality baked goods, for if any fat or oil becomes slightly rancid and is used, it will impart to the finished product a disagreeable taste and odor which is even more objectionable to the consumer than ordinary staleness.

Today the baker is fortunate in being able to secure solid shortenings which are quite resistant to the development of rancidity provided they are stored in a dry, cool, dark place, in containers which are tightly covered.

If the causes for rancidity in oils and fats are understood, the importance of the careful selection of shortening and the proper storage of the same can be better appreciated.

On standing for a period of time, exposed to air and light, the ordinary edible fats and oils have a tendency to become rancid. This is evidenced by the development of an objectionable odor and gummy consistency in the shortening and is due to the fact that these fats and oils absorb oxygen from the air resulting in the formation of certain oxidation products which possess an objectionable taste and odor.

Shortening in this condition is obviously unfit for baking purposes. As explained previously, shortenings ordinarily used contain various proportions of the solid fat substances known as stearin and palmitin together with the fluid constituents, olein and linolin. Now pure stearin and pure palmitin alone are too hard for satisfactory use as shortening; however, it is significant to note that both stearin and palmitin are very stable and will not become rancid or gummy on standing. This is due to the fact that neither of these solid fat substances will absorb oxygen from the air, and because of this stearin and palmitin are said to be “saturated” fats.

On the other hand, the other two substances present in shortenings namely, the oils, olein and linolin will absorb oxygen from the air and are therefore said to be “unsaturated.”

Hence, the greater the amount of stearin or palmitin contained in any shortening, the harder it is, and the less liable it is to go rancid on standing. For instance: lard contains more stearin and less olein than cottonseed oil. Therefore lard will not become rancid as readily as cottonseed oil. As previously explained, by hydrogenating cottonseed oil, some of the olein and linolin are thereby converted to stearin.

Thus the solid shortenings produced by the hydrogenation of vegetable oils are much less likely to become rancid on standing than the oils if permitted to remain in their original natural fluid state.

In addition to the development of rancidity in shortenings resulting from the process of oxidation as described above, butter may go bad on standing due to certain bacterial action which results in the liberation of butyric acid and other acids which give it a disagreeable taste, making its use in baked goods impossible.

E. STORAGE OF SHORTENING

Light, warmth, air and moisture favor the development of rancidity in fats and oils. Therefore, shortening, in storage, should be kept tightly covered, in a cool, dark, dry place.