April 18, 2014 – The topic of emerging and applied clean label starches is comprehensive and involved. Starch is a natural carbohydrate polymer packed into a granule. Its shape, size and morphology depend on the plant species. Starch granules contain both linear and branched starch polymers that swell with heat and water during gelatinization, and retrograde or recrystallize upon cooling.
Chemically modified starches provide benefits, such as improved food processing and shelflife stability under acidic conditions, and extreme temperature and shear and during storage. Functional characteristics of chemically modified starch include altered viscosity development, improved film-forming properties, selected aestheic properties, and retrogradation control of amylose and amylopectin.
“However,” explained Sakharam Patil, President, S.K. Patil and Associates, “consumer desire for foods with simple, non-chemical-sounding ingredients has created excellent opportunities for non-chemically modified starches.” Clean label, modified starches can be produced without chemicals, by physical or enzyme modification, yet possess properties similar to chemically modified starches. Clean label starch modifications include heat moisture treatment (HMT), annealing (ANN), dry roasting, spray-drying and enzyme modifications.
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HMT and ANN are physical modifications that change the physicochemical properties of starch without destroying its granular structure. In HMT, starch is heated to temperatures above gelatinization temperature but with insufficient moisture to
gelatinize. Regardless of the starch origin, HMT promotes an increase in the gelatinization transition temperature; a widening of the gelatinization temperature range; decreases in granular swelling and amylose leaching; and increases in thermal stability. HMT induced changes in starch structure and properties vary with starch source and amylose content.
During ANN, starch is exposed to excess water for an extended period of time at temperatures above the glass transition but below gelatinization temperature, explained Patil. ANN specifically changes the physicochemical properties of starch by improving its crystalline perfection and facilitating interactions between the starch chains, resulting in controlled swelling, gelatinization and enhanced stability.
Enzyme-modified starches are another clean label solution. Modern biotechnology has provided several commercial enzymes for clean label starch modification. “Enzyme modification of starches eliminates undesirable byproducts and improves starch purity, producing consistently high-quality products at potentially low cost,” stated Patil.
Major starch-modifying enzymes include endoamylases, which attack starch randomly and reduce viscosity rapidly. Exoamylases attack the glucose polymer chain from the reducing end group and successively remove glucose or maltose units from the starch polymer. Debranching enzymes, like isoamylase, exclusively hydrolyze a -1,6 glycosidic bonds that specifically degrade amylopectin, leaving long linear polysaccharides.
Transferases, such as amylomaltase and cyclodextrin glycosyltransferase, cleave a -1,4 glycosidic bonds and transfer part of the donor molecule to a glycosidic acceptor, forming a new glycosidic bond. Slowly digestible starches (SDS) and resistant starches (RS) result from these new bonds and are in demand because of their fiber-like behavior, both functionally and nutritionally.
Corn, pea and lentil starches are sources of SDS and RS when heat and enzyme treated. SDS also provides sustained or slow energy release, modulating the glucose release in the blood stream, thereby providing the low- or slow-glycemic effects to manage diabetes. Amylomaltases have a similar type of reaction but result in linear starches, while cyclodextrin glycosyltransferase gives a cyclic product. Starch treated with amylomaltases have thermoreversible gelling characteristics and can be dissolved numerous times upon heating, a behavior very similar to gelatin.
The choice of which clean label modified starch to use depends on formulation, processing conditions and shelf-stability. Sources can include waxy, regular maize, potato, tapioca, rice, pea and wheat starches. Applications for clean label modified starches include a wide variety of foods. Examples include a pregelatinized native pea starch that provides pulpiness in tomato sauce and a gelatin-replacing, enzyme-modified potato starch, as a vegan alternative in jelly-type confectioneries.
Enzyme-modified starches can replace fat in cakes and dairy products, to reduce fat up to 30%, while amylomaltase-treated starches enhance creaminess in yogurts.
Sakharam K. Patil, President, S.K. Patil and Associates,Inc, 219-922-1033, sakharam@skpatilassociates.com, www.skpatilassociates.com
April 18, 2014, Global Food Forums — The summary above is an excerpt from the “2013 Clean Label Conference Report.”
