|High-volume bakeries can use a variety of preservatives and preservative delivery systems to ward off mold and bacteria growth. |
Many people find that sitting in a warm, moist sauna is a great way to relax and unwind. Likewise, most molds and bacteria find that sitting in a warm moist loaf of bread or package of tortillas is a great way to thrive and multiply.
A combination of ambient temperatures, pH levels in the range of 6.5 to 7.5, and water activity in the range of 0.75 to 0.98, provide the perfect environment for tainted bakery foods. Mold and rope bacteria represent two common culprits in bakery food spoilage, and their presence in bakery foods turns off customers and creates a major economic impact on wholesale bakeries.
To prevent mold and bacteria growth, high-volume bakers must implement a series of quality assurance measures that begins with a solid HACCP program and ends with the ideal preservative and preservative delivery system.
Eliminating mold, bacteria
To control spoilage microbes in a plant environment, high-volume bakers should first install a HACCP plan. A solid HACCP program promotes thorough cleaning of production equipment, and monitors plant moisture, temperature, and air flow to minimize conditions for mold growth. Wholesale bakeries also must carefully scrutinize raw materials and rework, which are potential sources of contamination.
The next step in mold prevention is formulating products with pH and water activity levels that minimize microbial growth. Most chemical preservatives used in bakery foods increase in effectiveness as product pH is lowered because more of the organic acids, which are the active components of the preservative, disassociate at lower pH levels. Simply reducing the pH of a corn tortilla from 5.2 to 5.0 can add about 12 days to a product's shelf life.
Bakeries also must monitor a bakery food's water activity to determine the ideal way to prevent mold and bacteria growth. Higher water activity promotes microbial growth, and bakery foods vary in water activity levels depending on the product. Cookies and crackers generally have a water activity level of 0.20 to 0.30, and breads and rolls' water activity level typically hovers in the range of 0.96 to 0.98.
The final step to inhibiting mold and bacteria growth is selecting the ideal preservative and preservative delivery system to optimize shelf life, cost effectiveness and consumer acceptance.
Calcium and sodium propionate inhibit a broad spectrum of mold and rope bacteria while increasing the shelf life of bakery foods. Compared to other preservative options, propionates minimally impact yeast, making them the ingredient of choice for yeast-raised products and tortillas. However, calcium propionate, which is most effective at a pH of 5.5 or lower, may adversely affect baking powder. As a result, sodium propionates are more frequently used in chemically leavened products.
"In breads and rolls the common usage level for calcium propionate is between 4 and 6 ozs. per hundredweight of flour," one preservative supplier says. "Purity levels of commercial propionates vary considerably so always check with the supplier for actual content."
To minimize the inhibitory effect of calcium propionate, bakers can choose to add this preservative to the dough at the mixing stage rather than the preferment stage.
Spurred by a paper from American Institute of Baking detailing some of the benefits of liquid calcium propionate, this once little-used preservative delivery system is receiving more attention from the wholesale baking industry.
Liquid calcium propionate provides a 1:1 replacement for dry calcium propionate. "A liquid product eliminates dust in the bakery, thus improving the employee environment," one preservative supplier states. "A liquid system can also streamline operations to eliminate weighing and addition errors."
Although both liquid and dry calcium propionate are derivatives of the same compound, they possess different attributes. Liquid propionate has a slightly acid pH compared to dry calcium propionate's alkaline pH.
According to the American Institute of Baking study on sponge and brew dough methods, liquid propionates reduce proof times, increase gas production, improve finished bread volume and produce breads with a more closed, even grain compared to dry calcium propionate. These studies also showed that adding liquid propionate to the sponge or brew side of the dough has a stimulating effect on yeast and allows as much as a 25% reduction in yeast content.
An automated liquid preservative system injects liquid calcium propionate into a water line for ideal dispersion and effectiveness. For older, less automated bakeries, setting up a liquid propionate system requires the installation of an application pump to inject the preservative into the water line. For highly-automated plants controlled by PLCs, the only installation requirement should be the reprogramming of the system.
"A large bakery will see tremendous economic benefits by installing a bulk tank and receiving bulk deliveries," a liquid preservative supplier says. "This eliminates the costs associated with packaging into smaller containers and frees up valuable warehouse space and eliminates handling."
Besides liquid and dry calcium propionate, bakers also can opt to use encapsulated preservative systems. This delivery system offers certain advantages to chemically leavened bakery foods that are typically formulated to be more neutral, but require a lower pH to enhance preservative effectiveness. Lowering the pH of these products negatively impacts the dough. Chemical leavening also will react with acid to use up the leavening in the mixer and produce translucent areas of gelatinized starch. To prevent these negative reactions, bakers can employ various encapsulated preservatives.
"An encapsulated preservative won't release until the end of the bake cycle, leaving the preservative action available through the life of the product," notes one supplier of encapsulated preservatives
Sorbic acid, which is soluble in fats and oils, and potassium sorbate, which is soluble in water, prove effective against a broad range of bacteria and molds. However, sorbates inhibit yeast fermentation, causing them to mainly be used as a spray-application after baking. Other applications include pie fillings. In fruit fillings, sorbates are used at 0.03% to 0.1% of the total batch weight. The preservatives are most effective at pH levels between 5.5 to 6.5. Sorbates also are applied to product packaging to prevent surface mold. Sorbates have a neutral effect on flavor and aroma.
Besides spray and package applications, sorbates also can be encapsulated. "Typically sorbic acid is not used in yeastraised products because of its inhibitory effect on yeast," one preservative supplier says. "However, by using an encapsulated sorbic acid, bakers have the benefit of having a powerful preservative or the option to use both sorbic acid and calcium-propionate. These two preservatives work synergisticallyto provide a longer shelf life."
Other preservative options
Benzoates, which are only effective at a pH of 4.5 or lower, also perform ideally in fruit fillings. Methyl and propyl parabens are effective throughout a wide range of pH levels, and provide protection against yeast and molds in bakery foods. Many natural ingredients also effectively control microbial growth in bakery foods. Natural preservatives include prune and raisin juice concentrates, vinegar, and certain spices such as cinnamon and cloves. These natural ingredients are used when bakeries want to produce organic products or exhibit a clean ingredient statement. Although natural preservatives are more label-friendly, they may not be as cost effective as chemical preservatives. Their higher usage levels also may negatively impact finished product quality.
The evolution of ingredients in the baking industry has always brought significant change to bakery operations. In the past, bakeries have debated the switch from shortening to oil, and sugar to high fructose corn syrup. Today, bakers may have to take a serious look at their preservative delivery systems and consider all of the options. When evaluating preservative selection and delivery, wholesale bakeries must juggle maximum shelf life, consumer acceptance, cost effectiveness and plant efficiency.