KANSAS CITY – Plenty of questions arise when determining what starch to use in a snack. Will the item be crispy, crunchy, creamy or thin? How much should the snack expand? Is it baked? Will it have a coating?
“The type of starch used will affect properties at both the initial bite portion of the eating experience and the oral breakdown of the snack,” said Matt Yurgec, associate, global applications, bakery and snack team for Ingredion, Inc. and based in Bridgewater, N.J. “For instance, the type of starch used can affect how hard the initial bite is and how loud the sound is that the snack makes when it is bitten. The starch selection can also affect whether or not the snack will break down via a shatter like a pretzel or a snap like a hard biscuit.”
Starch selection also will play a role in the dissolving rate of the snack, he said. The cohesiveness of the bolus (a lump of chewed food) and the amount of “toothpack” (food debris that gets stuck in teeth) also may be affected by starches.
“Based on our knowledge of snack texture, adjusting some or all of these attributes will lead to a product being perceived as either crunchy or crispy,” Mr. Yurgec said. “Each of these properties can be tailored to achieve a texture experience that is desired.”
Starches are not easily interchangeable for any given application, said Mel Festejo, chief operating officer for American Key Food Products, Closter, N.J.
“Crispness in texture, for instance, is characteristic of starches with higher levels of amylose,” he said. “Such starches, however, do not lend themselves to much expansion. High-amylopectin starches, on the other hand, contribute to greater expansion, which may not be the target in the formulation of thin snacks.”
Potential sources for starches include rice, tapioca, wheat and corn. Sub-categories appear, too, such as in corn starch.
Dent corn starches may provide a harder, more audible crunch when compared to a waxy starch, which may provide a flinty, light bite in a snack product like a cracker, said Michelle Kozora, technical services manager for Cargill Texturizing Solutions. Amylose in dent starch may contribute to more of a harder texture but still may be crispy, she said. Amylopectin-only starches, like waxy corn, contribute more of a lighter, crispy texture.
Grain Processing Corp., Muscatine, Iowa, offers PURE-COTE modified food starches from corn that have film-forming properties to help provide crispness and crunchiness when added to snack formulations, said Tonya Armstrong, senior applications scientist. In extruded snacks, the PURE-COTE starches add crunchiness and strength to the snack.
In baked crackers, the film-forming properties of Instant PURE-COTE B792 add crispness and crunchiness over a control and an unmodified corn starch, as shown in an experiment at AIB International, Manhattan, Kas. Baked whole grain crackers using a level of Instant PURE-COTE B792 at 3% were significantly crunchier than both control starches. Crackers with Instant PURE-COTE B792 at 4% were even more crunchy.
A study at the University of Nebraska, Lincoln, examined starches sourced from wheat. Specifically, it looked at how modified wheat starches from MGP Ingredients, Atchison, Kas., affected the crispiness of an indirect expanded snack, said Ody Maningat, Ph.D., vice-president of research and development and chief science officer at MGP Ingredients.
Snack pellets were produced by extrusion and then deep fried. Crispiness was increased by the addition of 5% to 10% of oxidized wheat starch (Midsol Adhere) and also by 5% to 10% of cross-linked wheat starch (Midsol 1). Another oxidized starch (Midsol Krisp) and a cross-linked hydroxylpropylated wheat starch (Midsol 46) also increased crispiness but not to the same effect as Midsol Adhere and Midsol 1.
“Wheat-based starches are very compatible with wheat flour-based products because the added wheat starch closely matches in properties to the starch that is endogenous or naturally occurring in the flour,” Dr. Maningat said. “The distinct benefits include similarities in starch size, shape, distribution of sizes and surface properties, which contribute to yielding a finished food product with desired volume, appearance and textural qualities. In addition, the similarities in flavor will not introduce any foreign taste and thus, have additional favorable impact on the food’s sensory attributes.”
Starch selection is critical to the expansion of a sheeted snack, such as a fabricated potato chip or a cracker, Mr. Yurgec said.
“Starch affects the rheology of the dough, which will affect the ability of the dough to expand during baking,” he said. “During baking, gas is released via moisture evaporation and chemical leavening. If the dough is able to stretch or expand as the gas is released, it will be more likely to be retained in the cell structure of the final product.”
Waxy corn-based starches have been shown to impart crispy texture properties and also induce expansion in a snack, Mr. Yurgec said.
“Because of the lack of amylose, waxy corn-based ingredients deliver a longer texture of the dough, which greatly improves the ability of the snack to expand during baking,” he said. “Waxy corn-based starches tend to be more crispy, less hard and (have a) more dissolvable texture.”
Dr. Maningat said that for direct expanded snacks like corn curls, the addition of 10% modified wheat starch (Midsol Adhere or Midsol 1) tends to decrease radial expansion while increasing crispiness.
Tapioca starch has a high level of amylopectin, which gives it expansion potential for snacks, Mr. Festejo said.
“On the other hand, its amylose is not that low such that it is known to yield crisp texture to snacks using tapioca starch or cassava flour,” he said.
In baked snacks pre-gelatinized starches typically are used for texture, Mr. Yurgec said.
“Because there is a low level of available moisture and relatively mild heating conditions of baking (compared to frying), a pre-gelatinized starch is required to impart functionality,” he said. “As far as texture, starch-based texturizers offer the ability to manipulate the texture properties of a baked snack to be closer to fried snacks for attributes such as duration of sound, volume and dissolvability.”
Fried snacks benefit from the film-forming properties of oil, which also acts as a carrier for seasonings or coatings used for the snack, Mr. Festejo said.
“Baked snacks do not have oil as an ingredient in the way it is with fried snacks,” he said. “Thus, amounts of seasoning used will be generally greater with baked snacks. A good alternative for the film-forming and adhesiveness of seasonings or coatings in baked snacks is the use of pre-gelatinized starch, which helps with their film-forming characteristics.”
Ms. Kozora of Cargill said, “Starches are great ingredients to aid in developing texture in baked snacks and can provide crispy and crunchy textures without frying. In some cases, the starch granules are breaking, and the broken granules contribute to the resulting crispy texture. Crackers and cracker-like coatings are great spaces for starch as they can help with dough binding and then can be baked to offer great crispy textures.”
Snack coatings may adhere seasonings to snacks or may add flavor to snacks, Ms. Armstrong said. Coatings have been shown to provide better adhesion and distribution of the seasoning/particulate on the snack.
“A more evenly coated snack will provide a better flavor release of the seasoning on the snack,” she said. “A snack with a good adhesive coating system will save the snack manufacturer money with lower seasoning or particulate loss on a production line.”
Coatings also may affect texture.
“A water-based coating containing one of the PURE-COTE modified food starches can provide a slight increase in crispness or crunchiness once the coating is dried on the snack,” she said. “Snack coatings with starches such as PURE-COTE need to be dried in order for them to provide adhesion of the seasoning and not make the snack soggy. Typical oil-based coatings will add flavor with the seasoning but should not affect the initial texture of the snack product.”
During the Institute of Food Technologists’ annual meeting and food exposition in Chicago in July, Grain Processing Corp. featured winners from Iowa State University of an ingredient application challenge. A coconut curry chicken rice cup appetizer, the grand prize winner, featured PURE-GEL B994 modified food starch in the coconut curry chicken sauce. PURE-GEL B994 was added to improve heat, acid, shear and freezer stability of the sauce.
Ms. Armstrong said a chickpea fry snack with sriracha sauce was a “crowd favorite.” It featured Instant PURE-COTE B792 modified food starch that provided crispness in the chickpea fry. INSCOSITY B658 modified food starch was added to the sriracha sauce to provide viscosity, stability and sheen in a cold processed sauce.