Foodservice Technology: A Textbook for Bachelors. "Technology of public catering products" - Textbook Handbook of a public catering technologist read

The textbook sets out the theoretical foundations of the technology for the production of products at public catering enterprises (the technological process of preparing culinary products, regulatory documentation, methods of culinary processing of products, etc.). The technology of preparation and the rules for serving the main products are described. modern enterprises nutrition. Particular attention is paid to quality requirements. The material is presented in a strictly scientific and at the same time accessible form. The textbook includes a variety of practical tasks for future specialists - technologists and managers who will have to meet the needs of people in good and high-quality nutrition. The book is addressed to university students studying in the direction of "Product technology and organization of public catering", and their teachers.

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Rice. 1.3. Starch grain structure:

1 - the structure of amylose; 2 - the structure of amylopectin; 3 - starch grains of raw potatoes; 4 - starch grains of boiled potatoes; 5 - starch grains in raw dough; 6 - starch grains after baking

When heated from 55 to 80 ° C, starch grains absorb a large amount of water, increase in volume several times, lose their crystalline structure, and, consequently, anisotropy. The starch suspension turns into a paste. The process of its formation is called gelatinization. Thus, gelatinization is the destruction of the native structure of the starch grain, accompanied by swelling.

The temperature at which the anisotropy of most grains is destroyed is called the temperature gelatinization... The gelatinization temperature of different types of starch is not the same. So, the gelatinization of potato starch occurs at 55-65 ° C, wheat - at 60-80, corn - at 60-71 °, rice - at 70-80 ° C.

The process of gelatinization of starch grains is carried out in stages:

* at 55-70 ° C, the grains increase in volume several times, lose optical anisotropy, but still retain their layered structure; a cavity ("bubble") is formed in the center of the starch grain; a suspension of grains in water turns into a paste - a low-concentrated sol of amylose, in which swollen grains are distributed (the first stage of gelatinization);

* when heated above 70 ° C in the presence of a significant amount of water, starch grains increase in volume tens of times, the layered structure disappears, the viscosity of the system increases significantly (the second stage of gelatinization); at this stage, the amount of soluble amylose increases; its solution partly remains in the grain, and partly diffuses into the environment.

With prolonged heating with excess water, starch bubbles burst, and the viscosity of the paste decreases. An example of this in culinary practice is the liquefaction of jelly as a result of excessive heating.

The starch of tuberous plants (potatoes, Jerusalem artichoke) gives transparent pastes of a jelly-like consistency, and cereals (corn, rice, wheat, etc.) - opaque, milky white, pasty consistency.

The consistency of the paste depends on the amount of starch: when its content is from 2 to 5%, the paste turns out to be liquid (liquid jelly, sauces, mashed soups); at 6-8% - thick (thick jelly). An even thicker paste forms inside potato cells, in cereals, pasta dishes.

The viscosity of the paste is influenced not only by the starch concentration, but also by the presence of various nutrients (sugars, mineral elements, acids, proteins, etc.). So, sucrose increases the viscosity of the system, salt reduces, proteins have a stabilizing effect on starch pastes.

When starch-containing products are cooled, the amount of soluble amylose in them decreases as a result of retrogradation (precipitation). At the same time, aging of starch jellies (syneresis) occurs, and the products become stale. The aging rate depends on the type of products, their humidity and storage temperature. The higher the humidity of the dish, culinary product, the more intensively the amount of water-soluble substances in it decreases. Aging occurs most rapidly in millet porridge, slower in semolina and buckwheat. An increase in temperature slows down the retrogradation process, therefore, dishes from cereals and pasta, which are stored on bain-marie with a temperature of 70-80 ° C, have good organoleptic characteristics for 4 hours.

Starch hydrolysis. Starch polysaccharides are capable of breaking down to the molecules of their constituent sugars. This process is called hydrolysis, as it goes with the addition of water. Distinguish between enzymatic and acid hydrolysis.

The enzymes that break down starch are called amylases. There are two types of them:

α-amylase, which causes partial degradation of starch polysaccharide chains with the formation of low molecular weight compounds - dextrins; with prolonged hydrolysis, the formation of maltose and glucose is possible;

β-amylase, which breaks down starch to maltose.

Enzymatic hydrolysis of starch occurs when making yeast dough and baking products from it, boiling potatoes, etc. Wheat flour usually contains β-amylase; maltose, formed under its influence, is a breeding ground for yeast. In flour from sprouted grain, α-amylase predominates, the dextrins formed under its influence give the products stickiness and unpleasant taste.

The degree of hydrolysis of starch under the action)

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