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 the 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 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 treats demand starch contents that will hold up during processing without falling apart or creating an undesirable texture, Luchsinger noted.
“Using a native starch in a dry extrusion pet food process will typically yield disappointing results,” Sullivan said. “Most native corn starches won’t stand up to the high heat. Instead, we advise customers to use a modified starch with a higher heat tolerance and branch substitutions, a combination that provides the process tolerance needed to help with forming and gelling in a dry extruded application. ”
“A starch can help with the texture and structure development of a wet extruded pet treat, resulting in improved chew time,” said Conor Sullivan, senior technical services specialist at Cargill.
For wet, gravy-style pet foods, starches can be incorporated to stabilize viscosity in shearing or retort processes. They can also be used in high-viscosity applications, to achieve transparency or a glossy appearance, and to stabilize freeze / thaw of the product.
Moving the needle
Processors looking for starch ingredients with simple label names and grain-free attributes have an expanding range of options to choose from, without compromising functionality. In some cases, emerging starch ingredients can even offer improved functionality, particularly for sensory attributes.
“As new process techniques are invented, these starches become even better in both functionality and visual / sensory attributes,” Luchsinger said. “For example, Ingredion’s recently introduced NOVATION Lumina functional starches provide superior visual and color properties than traditional physically modified starches. New functional native starch ingredients from waxy cassava have also recently become available. These products have improved functionalities in both pet treat and wet food applications. ”
Luchsinger suggested tapioca starch as a clean-label, grain-free option for canned, loaf-style wet pet foods. Ingredion’s NOVATION® 3300 functional tapioca starch ingredient, which can be listed simply as “tapioca starch” on a pet food label, can provide firmness and structure to this type of product and prevent water and fat separation during cooking.
Cargill’s SimPure portfolio of label-friendly texturizing solutions is designed to replace modified starches with clean-label alternatives. For pet food applications, the company offers SimPure starches to stabilize viscosity and add sheen to gravy-style products, Sullivan said.
“As an added benefit, the SimPure starches also function as single system viscosifiers, allowing pet food makers to add peas or other particulates to the cooked gravy and be assured that the starch will continue to keep everything in suspension, through pumping and retort, without breaking down, ”Sullivan added.
The company recently added SimPure tapioca starch to the list, which caters to both clean-label and grain-free formulations alongside its potato starch ingredients.
Ingredient suppliers are digging in to better understand how starches can be used to improve quality and nutrition. Manufacturers looking to create products with specific attributes and claims should seek out this supplier expertise to ensure the right starch ingredients are being used in the right applications.
“The key is finding a starch that matches your processing methods and desired functionalities,” Sullivan said. “Working with your ingredient supplier can save hours of development time.”
Read more about product development, ingredients and formulation.