The use of starch in the process of canning food

Canning preserves food for up to several years by achieving a temperature sufficient to destroy or inactivate food poisoning or spoilage microbes. Starch is most commonly used to thicken, stabilize and enhance the mouthfeel of canned foods such as puddings, pie fillings, soups, sauces and gravies. It is also used to provide viscosity at the time of filling for controlled metering of suspended particulates and for control of splashing.

Canning is a process that includes heating, filling, and sealing the container to preserve food. The required time and temperature for sterilization depend on the food, container, and equipment. The coldest part of the food is heated to at least 120°C for 20 minutes and at least 145°C for a few seconds. Reducing the time it takes to heat the food can prevent quality loss during retorting.

If you wait to thicken the food, it will be heated more evenly. But if there are chunks in the food, it needs to be thickened before filling the cans so they don’t move around too much. You can use fill-viscosity starches to control the thickness during filling and heating.

A fill-viscosity starch thickens in the make-up kettle, but breaks down quickly in the retort. They are most typically used where no residual viscosity is needed, such as in chicken noodle soup. Light to moderately crosslinked starches are used to thicken many canned foods, but when delayed thickening is needed a highly crosslinked starch, usually waxy maize starch, is favored.

Canning starches will contain various levels of monosubstitution depending on the stability and desired texture of the food. Fill-viscosity starches are typically waxy maize or potato starches with or without monosubstitution or acid thinning, both of which enhance breakdown. These give high initial viscosity for suspension of particulates during filling, but then break down to provide good heat penetration.

Other canned foods have other specific requirements. Vegetable soups often contain only a lightly crosslinked fill-viscosity starch which breaks down to form a light broth in the final product. Cream-style canned corn is improved by the use of a highly-stabilized, lightly crosslinked waxy maize starch. This starch prevents curdling by coating soluble protein which is denatured early in retorting. More highly crosslinked products are required for short texture in acidic foods like lemon or cherry pie fillings. Retorted cheese sauces are often thickened with a highly crosslinked and stabilized dent corn starch for the short cuttable texture it provides.

Unmodified dent corn starch is sometimes added to gravies to enhance the opacity for a homemade appearance. Unmodified waxy maize starch is added to provide gloss and slight cohesiveness in products such as dips.

Aseptic processing is a method of preserving certain foods, like dairy products, without damaging their flavor. It involves putting sterilized food into sterilized packaging in a sterile environment. This process quickly heats and cools the food, which kills microbes while keeping the food’s quality intact.

Aseptically processed cheese sauce, for example, is often thickened using a highly crosslinked and stabilized waxy maize starch to achieve a smooth and flowable texture. Alternatively, a blend of highly crosslinked and stabilized dent and waxy maize starches is used to create a smooth and short cuttable texture.

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