This article was published in the March 2022 issue of Pet Food Processing. Read it and other articles from this issue in our March digital edition.
Although not an essential nutrient for dog and cat nutrition, starches are an essential aspect of formulation and processing. Product attributes and processing methods determine which type of starch ingredient is best for each application.
Higher levels of resistant starch could benefit colonic health in pets, but there are currently process limitations for achieving this. (Source: ©DECADE3D – STOCK.ADOBE.COM)
Starch molecules are gelatinized, or broken down, when subjected to water and heat. This gelatinization makes the starch digestible and contributes to texture, structure and expansion of the final product. This makes selecting the right starch for the right application essential for processors.
Derived from plant-based foods, starches are polysaccharides containing two types of glucose molecules: amylose and amylopectin. Different starch ingredients contain different ratios of amylose and amylopectin, and that ratio determines each ingredient’s functionality, according to Patrick Luchsinger, marketing manager, nutrition and pet food, Ingredion Incorporated, Westchester, Ill.
“For example, tapioca starch typically has 17% amylose and 83% amylopectin, which helps to provide extended stability and freeze/thaw stability in canned pet loaves,” Luchsinger said. “Conversely, pea starch typically has 35% amylose and 65% amylopectin, which helps provide firmness and structure in canned loaf type products.”
“Starches can provide a host of functional benefits, including help with water binding, viscosity, freeze/thaw stability, purge control and texture,” said Conor Sullivan, senior technical services specialist, Cargill, Minneapolis. “For example, a starch can help with the texture and structure development of a wet extruded pet treat, resulting in improved chew time.”
“When starch contents are inadequate, extrusion may fail,” said Patrick Luchsinger, marketing manager, nutrition and pet food at Ingredion Incorporated.
Pulses, tubers and cereal ingredients all contain starch. Some of the most common starch ingredients used in pet food formulations come from corn, potato, tapioca, rice and peas, but researchers are looking at new ways to incorporate starch through ancient grains and other pulse ingredients.
According to Sullivan, there are two main categories of starch ingredients used in pet food and treat formulations — native starches and modified starches — and each lends itself to different processing functionalities and product demands.
Native starches come from botanical sources, including from corn, tapioca and potato. Depending on the starch, these ingredients offer different characteristics for viscosity and gelling, but pose limitations for heat, acid and shear stability, Sullivan said.
Enter modified starches. Modified starches have been chemically enhanced to improve processing functionality and formulation, including for shelf-life stability, texture, tolerance to heat, acid and shear, and freeze/thaw stability. They are ideal for wet pet food products or dry extruded treats, Sullivan explained, due to the high heat, acid and shear stability requirements of extrusion and retort processes.
“There are many types of starches and choosing the one that will give you the results you want can be challenging as there are many bases and starch technologies to choose from, including cross linked, substituted, pre-gelatinized, acid-thinned, dextrinized, enzyme converted, OSA modified and physical,” Luchsinger said.
For dry pet food applications, starches can be used to achieve kibble expansion, density and texture, as well as help bind other ingredients in the formula. Injection molded treats or extruded …….