Modified starch is formed from natural starch as a result of physical, enzymatic and chemical changes.Thanks to these processes, it can be used in a variety of ways, not only in the food industry.Modified starch is a safe food additive that improves the characteristics of products, but its presence is not always necessary, and is used by producers as a filler.
Natural starch and modified starch
Starch is a carbohydrate composed of glucose molecules that form two fractions of linear amylose and branched amylopectin.The proportions of both fractions in the starch coming from a given plant depend on its properties and the possibility of use in industry.Starch is a natural substance found in almost all plants and widely used in industrial production, not only food.Starches of the highest economic importance constituting over 99% of the world’s production come from maize, wheat, manioc and potatoes.Potato starch is considered to be the purest and best species.
Natural starches extracted directly from the plant and untreated are used in industry, however, they are not very resistant to physical conditions in modern food processing technology.Modified starches have been used in the food industry since the 1940s.Starch modifications allow to give it new features and improve functional properties, which affects the quality of end products with the addition of starch.Modified starch in food gives it a suitable texture, compacts it, in loose products prevents its clumping, and also allows the preparation of instant dishes, eg jelly, which just pour boiling water and stir.
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Modified starch and genetically modified food
It should be noted that modified starch has nothing to do with GMOs and genetic modifications, and changes in its properties are made through physical, enzymatic and chemical methods.Different types of modified starches are safe food additives, which in the composition of products can be found under the designations E1400 to E1500.The methods of their production are specified in the recommendations of the FAO / WHO Expert Committee on Food Additives and they are used in industry on the basis of Polish and European standards.
Modified starches are safe food additives, however, when selecting a food product, one should pay attention to the full composition and rationally assess whether the product will not harm the health in the long term.Often, foods containing modified starch also contain large amounts of salt, monosodium glutamate and unhealthy hardened vegetable fats, e.g. palm oil.There are also products in which starch is unnecessary, and the manufacturer adds it, for example, to increase the mass of the product or adjust the density to consumer preferences, which concerns some natural yoghurts or cold meats.
Methods of starch modification
Starch undergoes three basic types of modifications that allow it to be used more efficiently in industrial production and provide better properties for the finished product.
Physical modifications – natural starch is subjected to high temperature heating, preliminary gelatinization and then drying on drying rolls.The crystalline structure of the starch disappears during the process.Thanks to this treatment, the starch gains its ability to dissolve in cold water or milk, and dissolves faster in hot water.Physically modified starch in the light of food law is not an additive to food, but a foodstuff like natural starch.
Enzymatic modifications – they result in the hydrolysis of starch or the breakdown into compounds of lower molecular weight.This is the main direction of starch processing, which results in maltodextrins and syrups.Starch decomposes into other chemical compounds, therefore enzymatic methods are not modifications in the strict sense of the word.
Chemical modifications – during chemical modifications the hydroxyl groups (-OH) present in the starch rings are replaced with other chemical substituents.Starch is modified in the processes of oxidation, esterification and etherification.The structure of starch macromolecules is changed, which has a very large impact on its physicochemical properties.
Properties of modified starch
The modified starches obtained as a result of transformations differ significantly in their properties from natural starch.Rheological properties obtained in starch modification processes that are used on a large scale in industry are:
- binding very large amounts of water with dissolved substances,
- wide viscosity range,
- varying gelatinizing temperature from room temperature to above 100 ° C,
- creating gels of various kinds,
- not to recover the process of retrogradation (precipitation of starch molecules from the resulting structure),
- clarity and transparency of pastes and gels,
- absorbing various compounds, e.g. flavors, fragrances, alcohols,
- the ability to stabilize emulsions and suspensions,
- the ability to create flexible membranes.
The use of modified starch in the food industry
Depending on the modifications made, starches differ in their specific features and are used differently in food processing.Also, the different botanical origin of starch and the intensity of the process used result in the production of a very wide range of starch derivatives with different properties.They are divided into general categories that determine the best possible use of individual types of modified starches.
Oxidized starch – the gels created by them have a low viscosity, high hardness and stability over time.They are used for the production of puddings, custard creams, whipped cream and powdered cake mixes.They are a component of confectionery bodies and confectionery, for example in soft candies.They can also be used for coating, sprinkling and coating products, because they adhere well to the coating of the product, and after roasting and cooling are crunchy.
Acid starches – their use in the technological process allows the introduction of large amounts of starch into the product without the difficulties of mixing and pumping.After cooling, they form a concise and elastic gel.Thanks to this, acid starches are used as a component of confectionery bodies and fillings and as a partial substitute for wheat flour in confectionery cakes.
The starch esters – the most widely used in the food industry are acetylated starches that do not undergo retrogradation, exhibit high stability and clarity of the gruel and lower gelatinization temperature.They are used in the production of traditional and instant noodles.
Monostarch monophosphates are good emulsion stabilizers, e.g. vinegar oil systems, as well as thickeners resistant to freezing and thawing.They are used to thicken soups, sauces and dressings.
Cross-linked starches – in food processing they are most often used.Cross-linked starches are resistant to temperature changes, mechanical processing and the pH of the manufactured and finished product.They are mainly used as a thickener in many products, such as sausages and cold cuts.
Agglomerated and instant starches are physically modified starches that dissolve perfectly even in cold water and milk.They are usually used for cold-made dairy desserts, jelly, sauces, dairy drinks and curd.They allow immediate dissolution of jelly or soup after boiling with boiling water.Modifying starch by forming complexes with fat allows it to be used as a fat substitute in ice cream.
Other applications of modified starch
The properties of modified starch also use other industries, not only food.Thanks to the huge possibilities of changing the characteristics of starch, the list of its applications is over 1000 and is still expanding.The most popular trends in the use of modified starch include the production of high quality paper, corrugated board, biodegradable plastics, adhesives, production of superabsorbents used in agriculture to improve soil quality, production of dressing materials and disposable diapers, microcapsules used in medicine and cosmetics, production of explosives.
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