Learn about cassava (manioc) in food technology

1. Structure of cassava tubers

- Cassava is the core tubers (tubers heart) connecting trunk to tail along the tubers and roots.

- Components: wood chips, bark pulp, meat cassava, cassava core.
Compared with other root vegetables, then cover the kind of peel cassava distinctive and most easily separated.

+) Shell wood

Occupying 0.5 to 3% by weight of tubers. Including cells made of cellulose and hemicellulose, almost no starch. Wood shell is the outermost layer, lumpy, dark brown, containing specific pigments. Keep the bulbs work very durable, without external mechanical impact.

+) Shell pulp

Thicker wood chips, accounting for about 8-20% by weight of tubers. Including cell is composed of cellulose and starch (5-8%). Between the crust is a network of plastic pipes and roots, in pus are more tannins, enzymes and pigments.

+) Meat cassava (tubers intestine)

Who comprise mainly of tubers, including cells made of cellulose and pentozan, inside the starch granules and cytoplasm. Starch content in tubers gut unevenly distributed. Starch grain size 15-80mm Kong. Cassava as to age, the more fibrous.

+) Core cassava

Often located in the center along tubers, roots linking itself to tail.
The core occupies from 0.3 to 1% by weight of tubers. The constituents are mainly cellulose and hemicelluloses.

2. Chemical properties

Fresh cassava roots:
- The percentage of 38-40% dry matter,
- 16-32% starch;
- The quality of protein, fat, fiber, ash in 100g are respectively 0,8-2,5g, 0,2-0,3g, 1,1-1,7g, 0,6-0,9g;
- The quality minerals and vitamins in 100g tubers are 18,8-22,5mg Ca, P 22,5-25,4mg, 0,02mg B1, B2 0,02mg, 0.5 mg PP.

In tubers, concentrations of amino acids is not balanced, excessive arginine but lacks the sulfur-containing amino acid.
Like the majority of grains and tubers, the main component of starch cassava tubers. Also, in cassava also substances: protein, minerals, lipids, fiber and some vitamins B1, B2.

Starch

As an important component of cassava roots, it decided to use their value. Starch granule drums, diameter approximately 35 mircomet.

Starch consists of two components:
- Amylose: 15-25%.
- Amylopectin: 75-85%.
Amylopectin ratio: Amylo in tapioca starch high (80:20), the starch gel viscosity, high adhesion and ability to gel with low degradation.

Cassava
Cassava
Starch content is most concentrated in the close packs, deeper into the flesh layer to close the starch core less.
Starch is a sphere, ovoid or shaped hat, with some low-lying county, with very white color. Should the manufacturing process should eliminate dark shell to not create starch.

Tapioca starch size from 5 to 40μm with large grains of 25-35μm, small particles 5-15μm and the shape, mostly round, smooth surface, a side with conical recess and a knob little in between. Under polarized light, the crosslinking density medium to thick can be clearly seen. The ultrastructural study by X-ray showed tapioca starch crystal structure and form a mixture A, B.

When tapioca starch granules burst, can observe the grooves porous structure of the particle. The amorphous prolonged trench from the surface to the center of the particles forming the pores. It is these pores help water infiltrate help swell the starch, breaking the hydrogen bonds between the molecules in the crystal structure, facilitates the decomposition of enzyme action. Cassava has relatively porous particle structure, linking the molecules in the crystal structure is weak, so it is easy to be destroyed by agents such as acid and enzymes than other starches like corn and rice.

Tapioca starch amylopectin content and the average molecular weight is relatively high, 215.00g / mol compared with 30,500, 130,000, 224,500 and 276,000 respectively in amylose corn, wheat starch, potato starch and starch wax. Amylose content in the range 8-28%, but in general the majority of cassava cultivars with amylose ratio of 16-18%. Cassava has the same properties of starches contain amylosepectin as high viscosity, low tendency to degenerate and high gel strength. Amylosepectin and amylose content in cassava starch related to the stickiness of the cooked tubers and multiple properties in industrial applications.

Temperature gelatinized tapioca starch during 58.5-700C than 56-660C 62-720C in potato and corn starch. The creation of starch derivatives by crosslinking or addition of surface active substances that can change temperature gelatinized. Gelatinized temperature also affects the cooking quality of starch, low gelatinization temperature usually cook low quality flour by private easily broken.

Viscosity is important properties of starch have many applications in the food industry and industries scattered, paper. Cassava has very high viscosity. High viscosity in its present weak link between starch molecules in grain structure. Handling of chemical, physical (heat, treated with steam pressure, more chemicals, change the pH of the environment) as well as the presence of substances such as proteins, lipids, surface active substances face are affecting cassava starch.

A swelling and solubility of starch are also important properties and also very different between starches. Properties of cassava starch depends heavily on cassava cultivars, habitat conditions, time of harvest, but not related to the particle size and molecular weight of the starch.

The structure of tapioca starch gel durable than many other grains should be applied more in the food industry, especially for those products must be stored for long periods.

Street

Roads in cassava mainly glucose and some maltose, saccharose. Cassava is getting older, the sugar content decreases. During processing, sugar dissolved in water is discharged in water services.

Protein

The content of protein composition in very low tuber should also minimize impact on technological processes. Rate range: 1-1.2%. From outside to inside protein increased a little.

Country

Moisture in fresh cassava roots are very high, accounting for about 70% of the whole tuber. High moisture makes the preservation of fresh roots very difficult. So we have to set the protected mode depending reasonable tubers specific conditions.

Toxins in cassava roots

In addition to the above nutrients in cassava also toxic. The poison contained in cassava research today has been relatively clear and determined. That is HCN. In cassava roots, HCN exist as two glucoside linamarin phazeolunatin and Lotaustralin.

Enzyme System

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In cassava, the polyphenols and enzymes polyphenoloxydaza coa greatly affect the quality of preservation and processing.
Polyphenoloxydaza catalytic oxidation of polyphenols form coincided octoquinon then the insubstantial nature as axitamin phenol to form colored products. Among polyphenoloxydaza have enzymes that oxidize the typical monophenol tirozinnaza oxidation catalytic amino acid corresponding quinones tirozin created. After some transformation of this quinones born dark gray pigment called melanin. These demonstrate one of the causes for the black tapioca meat that often called tapioca flow of latex concentrate nhua.Vi enzymes in pulp shell so sunspots also appear in meat and roots starting from peripheral layers.

When cassava was melting then grinding hard time breaking the cell to release the starch thus obtained starch efficiency low, on the other hand is not white starch.

Also tirozinaza redox enzymes also active as dry matter losses of tubers.
Tannin content in cassava little but the oxidized tannins are substances flobafen hard black dark colored erasers. When processed, tannins also works with iron to form iron tannate gray also. Both of these substances are known to affect the color of the starch if the processing is not fast cell separation and thorough service.

In preserving fresh cassava dry rot and disease often wet rot fungal and bacterial particularly those roots peeling bark and crushed. Also if tubers are serious melting phenomenon also leads to dry rot.

The main nutrients are protein and starch (because there are two important components of cassava tubers have the most economic value).
Percentage of starch and protein but unevenly distributed in different parts of cassava tubers. The general rule: the starch content in the police files most trungnhieu casings, deeper into the meat layer outside the core damage less starch, but increased protein part considering the class.

3. Application of cassava

Cassava has a high nutritional value, such as potato, taro, yam ... But the low protein content but it contains more carbohydrates that supply energy to the body. It's also a good source to provide potassium and fiber.
Cassava help maintain the balance of water content in the blood.

Fiber helps prevent constipation, tends to lower blood cholesterol levels and prevent cardiovascular diseases.
Since cassava contain little protein and fat, so when using cassava in the diet should be supplemented by foods rich in proteins and lipids to the diet is balanced.

Cassava is used to produce starch. Tapioca starch accounted for the bulk and low price should be more widely used in the food industry, such as used in the production of sweeteners or as binding agents for confectionery products, using crystals in manufacturing biscuit dough sweet, not sweet biscuit, cream sandwich with a content of about 5-10% to soft and not sticky buns help in producing bread,  starch is used as a substrate for yeast use in the fermentation process and participate in browning reactions characteristic of the product when baked.

Standard starch used (according to the FAO standard immolation: TC 176-1989)
- Safe and suitable for the user.
- No unusual smells and harmful insects.
- No contamination.
- Indicators physicochemical
- Moisture content 13%
- HCN acid content of less than or equal 10 mg / kg.
- There are no heavy metals.
- The fiber content of less than or equal to 2%.
- Microbiological Criteria:
- Microbial pathogens: no.
- Insect damage: no.
- Only Sensory:
- White powder dry and smooth.
- No unusual taste.
- No contamination.

Cassava is used a lot in food, in addition to processed food from fresh cassava tubers: cassava bread, tea ... Besides cassava, cassava starch production are used, and used very widely in the paper industry, textile, as adhesives, industrial ... Also tapioca dextrin can also be used as feed for cattle.