Produce dextrins from starch, molasses, glucose and other products widely used in the confectionery industry. Starch is a carbohydrate, its chemical formula (C6Н10О5) n
The starch content of various raw materials shown in Table. 49. The starch obtained from potatoes, corn, and considerably less of the wheat and rice.
Starch is the most easily extracted from potato and much more difficult from the other raw material where the proteins are present. In this case, the grain is soaked by applying chemicals * coarse and fine grinding and other operations.
Table. 49. The average starch content of the raw
|name of raw materials||% Starch||Starch, based on dry substance|
|rice||76,75||75 - 80|
It refers to polysaccharides starch and its calorific value is within 418 kcal.
Physico-chemical properties of starch
Starch consists of amylose and a ratio amilopektina 1: (3,5-4,5). The content of amylopectin and amylose in the starch (in%) given in the Table. 50.
50 Table. The content of amylopectin and amylose in the starch
|Type of starch||Amiloza||Amilopektin|
Starch is insoluble in water, well soluble in 30% salicylic sodium solution. Amylose dissolves in hot water and forms clear solutions. Amylopectin dissolves in water when heated under pressure. In this case, viscous solutions are obtained. In hot water without increased pressure, amylopectin swells. When the starch is brewed with water, a crumbled paste forms, which consists of a colloidal solution of amylose with the swollen particles of amylopectin distributed in it. Iodine stains amylose in blue, amylopectin in red * violet, and starch in intensely blue.
Gelatinization of starch is an irreversible process. The data on the starch gelatinization (Table. 51).
51 Table. Gelatinization temperature of starches
|The name of the starch||Температура клейстеризации в ° С|
|made of corn||68,0|
Starch, when swollen following able to absorb water: potato 37,1%, maize to 35%, wheat and rice 31,63% 26,79%. The heat that develops when swollen, is for potato starch 31,71 feces, wheat and rice 28,79 28,62 cal cal.
The specific heat of absolutely dry starch is 0,2697. To calculate the heat capacity of starch is used the following formula:
where: Cр1 - Heat capacity of conventional starch;
Ср - Specific heat of absolutely dry starch (0,2697);
and - completely dry solids content of the starch.
Теплоемкость товарного крахмала при температуре от 0 20 до ° -0,2765, от 21 42 до ° -0,2978 и от 43 62 до ° - 0,3061.
The size and quantity of starch grains are shown in Table. 52.
52 Table. starch grain size
|Starch||Grain size in mm|
|made of corn||0,02—0,03|
The share of commercial potato starch 1,648, 1,623 maize, wheat and rice 1,629 1,620.
Bulk density of commercial starch: potato 650 kg / zh3,
maize 550 kg / m3.
starch solutions can rotate the plane of polarization of the light beam in a polarimeter. Specific rotation of potato starch + 184,4 ° with variations of up to + 177,19 + 204,3; specific rotation maize starch + 201,5; wheat starch + 202 "4-204,3 and rice starch + 202,5.
Starch saccharification rate is expressed in milligrams of maltose on 1 g starch, it depends on the size of the starch granules. Large starch grains are broken down by enzymes in approximately 2 times weaker than the smaller ones. Saccharification of wheat starch is characterized by the following data (according to MI Knyaginichevu): soft wheat (average) 36,8, firm (middle) 42,3.
The average chemical composition of bone dry starch in% is given in Table. 53.
53 Table. The chemical composition of starch
Starch is very hygroscopic. Soluble potato starch 99% relative humidity over 27 days increases the humidity up to 40,6%, and soluble maize starch at the same relative humidity over 25 days increases the humidity up to 31,7%.
The use of starch
Starch is widely used in the manufacture of confectionery (biscuits, biscuits and cakes, muffins), and in the development of tidal sweets. Consumption of starch flour weight formulations provided in the following amounts: for a long grades of cookies to 7,5%, sugar up to 10%, in semi-finished biscuit and cakes 25-12%, and even the cake with almond 100%.
In the production of flour confectionery products usually used maize and potato starch. Furthermore, in the process of producing these products participate ^ wheat starch, which is in the flour
54 Table. to starch quality requirements
|The organoleptic and physico-chemical parameters||Type of starch||starch Grades|
|Appearance and color||made of corn||-||For any inquiries, We're here to answer you.||White||White||White with gray shade|
|Potato||White with crystal shine||White||-||White||White with gray shade|
|wheaten||White||White||White with gray shade|
|Humidity in% max||made of corn||-||__||13||13||13|
|The ash content of the total dry substance in% max||made of corn||0,2||0,3||0,5|
|Acidity in cm3 0,1N NaOH dry substance, max||made of corn||20||25||30|
|Number of Krapina; 1 sm2 surface starch, max||made of corn||2||5||10|
|The content of free chlorine and inorganic acids||made of corn|
|sulfurous acid content in mg per kg 1 air-dry starch, max||made of corn||100||100||100|
|Impurities other types of starch||made of corn|
Note. All kinds of starch intended for human consumption, the crunch when chewed, strange smell, unusual for starch, and the presence of zinc, lead, copper, tin, arsenic and antimony must not take place.
Starch has the following effect in the dough and finished products:
reduces the content of gluten in the flour, it specifically) is added to the flour with a high gluten content too;
increases test plasticity during processing, so that the product is attached to more fragile;
dextrins formed during baking, give a smooth and shiny surface, especially of long grades of cookies;
welding starch is widely used in the manufacture of gingerbreads to improve their quality.
In the production of soft candies tidal varieties found wide application maize and rice starch as a molding material. Preference should be given rice starch, as it is fine-grained and has a high gelatinization temperature.
It was found (EI Zhuravlevoj) that with decreasing moisture content of starch significantly increased osypaemost forms. Thus, when the starch moisture 5 27%% flaking cells, at a humidity of 12% showered only 3% of cells.
Starch in casting enclosure must meet the following requirements:
1) nonshattering cells;
2) minimum adhesion to the surface of the candy shells;
3) sanitary and hygienic cleanliness.
Requirements for starch
Maize starch is packed in bags weighing up 60 85 kg. Potato, wheat starch and rice packed in sacks 50, 80, 100 kg each. The bags can be flax and jute, but always clean, dry and whole, new and used. The deviation in the gross weight of the bag + 50 g%
In production plants the starch stored in heated rooms at the optimum temperature 15-18 °, t. E., At a temperature closest to the temperature of dough.
If the moisture content of starch is within the normal range, this number increased storage temperature (15-18 °) do not affect the quality of the starch.
Low room temperature does not affect the quality of starch. When storing starch together with flour should be noted that the temperature of the room above 10 ° favors the development insektisidov and microorganisms.
Warn their appearance and reproduction possible cleanliness room and airing it. The relative humidity in storage starch in warehouses is recommended to keep no more than 70%.
B and by a tio n NA, Boorman ME, Solntseva NV, Handbook of starch and syrup production Pishchepromizdat, 1952.
Kravchenko, SF, T p x and y h e c a AA, technical-chemical control of corn-starch production Pishchepromizdat, 1952.
The technology of starch and syrup production, ed. prof. A. C and n i n g and a, Pishchepromizdat, 1950.