STARCH Determination of total, resistant, damaged and gelatinized starch and maltodextrins starch granules, as resistant starch, as damaged Introduction starch or gelatinized starch. The physiological Starch is a natural vegetable polysaccharide. It state of the starch in a food and/or feed product serves as a storage form of glucose, and thus strongly affects the energy, in plants. Therefore starch is an important constituent in seeds and grains (corn, wheat, rice), tubers (potato) and root vegetables (e.g. tapioca or cassava). But it is also present in immature fruits as bananas. The main starch crops are cereals, potatoes, and tapioca.

In plant material, starch is present as small white digestibility of the starch by human and animal and granules insoluble in cold water. Both shape and therefore its energy value. size of the starch granules are characteristic to its botanical source. Depending upon the botanical Damaged starch origin, starch granule sizes range from less than 1 μm up to 50-60 μm.

Damaged starch granules hydrate rapidly and are susceptible to amylolytic hydrolysis and, therefore Starches of different botanical origin contribute significant to water absorption of a a = potato, b = tapioca, c = corn dough. The level of damaged starch in flours determines amongst others the baking capability Chemical structure and of the flour and is therefore an important quality physiological forms of starch parameter for flours. From a chemical viewpoint, starch is a homopolymer of glucose. It consists of long linear unbranched chains of 14-α-D-glucose units Gelatinized starch (amylose) and/or long α-16 branched chains of Due to process conditions as heat, pressure and 14-α linked D-glucose units (amylopectin). The moisture (e.g. extrusion, drum, drying), starch repeating unit in starch is the disaccharide granules can gelatinize. Gelatinized starch is maltose. accessible for digestive enzymatic hydrolyses, native granular starches are more or less Starch inaccessible for those enzyme activities. For this reason, pet food contains significant levels Starch can be present in raw materials, semi gelatinized starch. finished products, food, feed, and pet food in different physiological forms, being as native

2012-04-18 PI Starch

resistance. Above DE 20, the Resistant starch European Union's CN code calls In the enzymatic maltodextrin By definition resistant starch is it glucose syrup, at DE 10 or determination the total content of the total amount of starch, and lower the customs CN code maltodextrins, starch and malto- the products of starch nomenclature classifies oligosaccharides are quantified, degradation that resists maltodextrins as dextrins. excluding the free glucose. digestion in the small intestine of healthy people. (EURESTA, Analytical For the quantitative 1991). It enters the large determination of resistant starch intestine where it is partially or methods in food a specific enzymatic analytical method is available wholly fermented. Resistant Different analytical methods are (AOAC 2002.02). Specific starch is nowadays considered available for the different digestive enzymes and as dietary fibre. physiological forms of the starch. physiological conditions are

applied in this protocol, Maltodextrin The enzymatic starch approximately mimicking the determination according ISO Maltodextrin is produced by digestive tract. 15914 is applied for the partial hydrolysis of starch. determination of the total (native Maltodextrins are classified by Damaged starch is enzymatically + damaged/gelatinized + DE (dextrose equivalent) and determined by the AACC 76-31 resistant) starch content. The have a DE between 3 to 20. The protocol and the determination of method is very specific and higher the DE value, the shorter the gelatinized starch content is selective for starch. Other non- the glucose chains, the higher based on the same protocol. the sweetness, the higher the starch polysaccharides/ solubility and the lower heat oligosaccharides/monosaccharai des do not interfere.

Overview Methods

Total starch Resistant starch Damaged/gelatinized starch Maltodextrins Analytical ISO 15914 AOAC 2002.02 AACC 76-31 Own method protocol Principle enzymatic enzymatic enzymatic enzymatic Statistics LOQ = 0.4 % LOQ = 0.5 % LOQ = 0.3% LOQ = 0.4 % Range 0.4 – 100 % Range 1 – 75 % Flour Range 0.4 – 100 % RSDr < 2 % RSDr < 2 % - range 0.3 – 20 % RSDr < 2 % RSDR < 5 % RSDR < 4 % - RSDr = 0.9 % RSDR < 5 % Recovery > 98 ±2 % - RSDR < 4 % Recovery > 98 ±2 % Petfood - Range 10 – 35 % - RSDr = 2.2 % - RSDR = 3.9 %

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