Modified starch

Modified starch

Modified starch is a food additive which is prepared by treating starch or starch granules, causing the starch to be partially degraded. Modified starch is used as a thickening agent, stabilizer, or an emulsifier. Apart from food products, modified starch is also found in pharmaceuticals, paper and many other applications.

Starches are modified for a number of reasons. Starches may be modified to increase their stability against excessive heat, acid, shear, time and cooling or freezing; to change their texture; to decrease the viscosity, or to lengthen or shorten gelatinization time.

A modified starch may be an instant starch which thickens and gels without heat, or a cook-up starch which must be cooked like regular starch.

Acid-treated starch (E1401), usually simply called "modified starch", is prepared by treating starch or starch granules with inorganic acids, breaking down the starch molecule and thus reducing the viscosity.

Other treatments may produce modified starch with different E numbers, such as alkaline-modified starch (E1402), bleached starch (E1403), oxidized starch (E1404), enzyme-treated starch (INS: 1405), acetylated starch (E1420), and acetylated oxidized starch (E1451).

Pre-gelatinized starch is used to thicken instant desserts, allowing the food to thicken with the addition of cold water or milk. Similarly, cheese sauce granules (such as in Macaroni and Cheese or lasagna) or gravy granules may be thickened with boiling water without the product going lumpy. Commercial pizza toppings containing modified starch will thicken when heated in the oven, keeping them on top of the pizza, and then become runny when cooled.

A suitably-modified starch is used, quite successfully (with respect to the taste), as a fat substitute for low-fat versions of traditionally fatty foods, e.g., reduced-fat hard salami having about 1/3rd the usual fat content. For such uses, it is an alternative to the product Olestra.

Modified starch is added to frozen products to prevent them from dripping when defrosted. Modified starch, bonded with phosphate, allows the starch to absorb more water and keeps the ingredients together. Modified starch acts as an emulsifier for French dressing by enveloping oil droplets and suspending them in the water. Acid-treated starch forms the shell of jelly beans. Oxidized starch increases the stickiness of batter.

Genetically modified starch

Modified starch should not be confused with genetically modified starch, which refers to starch from genetically engineered plants, which have been genetically modified to produce novel carbohydrates which might not naturally occur in the plant species being harvested. The modification in this sense refers to the genetic engineering of the plant DNA, and not the later processing or treatment of the starch or starch granules.

Genetically modified starch is of interest in the manufacture of biodegradable polymers and noncellulose feedstock in the paper industry, as well as the creation of new food additives.

See also

• Dextrin (E1400)
• Starch gelatinization
• Retrogradation (starch)
• Resistant starch
• glucose syrup
• glucose

References

• GCSE Food Technology for OCR, Jenny Ridgwell. 2001.
• Revise for OCR GCSE Food Technology, Alison Winson. 2003.
• Degradable Polymers, Recycling, and Plastics Waste Management. S Huang, Ann-Christine Albertsson. 1995.
• Modified Starch, Ridgwell Press, 2002