A primer on preservatives: 2
Staling as about more than bad taste. Ensure food safety and quality by using the correct additives.
Baked goods, like all other foods, must be safe when consumed. At the same time, they need to deliver excellent taste and texture. Over the many years of producing such foods, the baking industry has relied on a multitude of ingredients to ensure safety and good quality.
My last column discussed the safety of baked goods, including microbiological contamination as well as the danger of chemical contamination with natural toxins, such as mycotoxins. Preservatives do not necessarily mean that they function as antimicrobials alone. They can usually be grouped into: antimicrobials (which are described above and act against bacteria), moulds or yeasts; and antioxidants, which slow the oxidation of fats and lipids (a process that, in turn, leads to rancidity. Natural and synthetic antioxidants can be used to prevent rancidity of processed grains as well. Grain products such as oat flakes, oat flour and bran as well as wheat germ contain high amount of lipids which oxidize quickly due to inherent enzymes or exposure to oxygen. Application of heat can stabilize (deactivate the oxidizing enzymes) but added antioxidants will further extend their shelf life by preventing spoilage due to exposure to atmospheric oxygen.
This column will discuss staling of baked goods. Bakers also must contend with staling of baked goods, particularly bread products. Staling of bread is a complex issue and has been extensively investigated. Crust staling results in a soft and leathery appearance and loss of aroma as well as the development of bitter taste. Crumb staling, on the other hand, is more concerning and results in harder, tougher and crumblier appearance and feel.
These processes are accelerated when the bread is stored at refrigeration temperatures and quite reversible when it is exposed to heat. We may want to store bread at low temperatures to slow microbial growth but this practice will result in accelerated staling.
More and more large manufacturers are moving towards centralizing their production of bread and other baked goods. As a result their distribution expands to greater geographical areas and the products taking longer to reach the consumer. For this reason the longer shelf life is paramount otherwise the economic impact will be quite substantial. Shelf life extension of baked goods by prevention of staling can be achieved by the inclusion of various ingredients, improving production processes and packaging.
Ingredients used in the normal formulation of these products can be optimized and thus reduce the staling effect. Optimizing the use of common ingredients such as water, fat, oxidizing agents, gluten and others will result in softer crumb, which in turn will delay the staling process. In addition anti-staling agents are readily available for this purpose. Several ingredients are available that can be added to formulations in order to prevent staling and extend the shelf life of baked goods. For example, emulsifiers and surfactants result in crumb softening by forming complexes with the gelatinizing starch and thus prolong the shelf life of baked goods by retarding the staling process. Mono and diglycerides and sodium stearoyl – 2 – lactylate (SSL) are effective crumb softeners. Many emulsifiers are available to be used for different functional effects in the production of baked goods. Most of these emulsifiers are synthetic chemicals.
Mono and diglycerides may also be classified as natural since they are found naturally in fats and oils. However, modified ones such as ethoxylated mono and diglycerides, will not be considered natural.
Lecithin, a naturally occurring compound, was one of the first emulsifiers to be used extensively in the baking industry. The use of lecithin may be revisited as the demand for natural ingredients is increasing and consumers are looking for food products that are more natural and organic. Additional anti-staling ingredients such as enzymes are very effective in preventing staling and extending the shelf life of many baked goods. A number of anti-staling enzymes are available in the market and approaching the suppliers of such ingredients will help you. These enzymes act by breaking down the gelatinizing starch during the baking process and therefore need to be active at the baking temperatures
In attempting to use these ingredients, either to preserve quality or ensure safety of food products, we need to make sure they are permitted for use in foods in Canada and any other country to which we are planning to export the finished products.
Processing parameters and conditions such as mixing and fermentation will influence the structure of the crumb and if optimized will result in the delay of the onset of stailing.
A factor of the onset of staling is also the migration of water from the crumb to the crust. The use of packaging material that will reduce the moisture loss of the bread will result in less staling and a longer shelf life.
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