Improvements in shelf life not only increase consumer satisfaction,
but provide benefits throughout the value chain.
Progress in extended shelf life (ESL) in the bread category has been dramatic during the past two decades because of enzyme technology developed by Novozymes, Franklinton, N.C. Novamyl®, a maltogenic amylase enzyme, not only provided a fresh-keeping solution for bread, but redefined the fresh bread industry. This technology has reportedly saved bakeries $4 billion in stale return costs since its inception.
When the benefits of ESL are factored in all along the value chain-from producer to consumer-the results are astounding. Included among these benefits are improvements in the bread's eating quality and consumer perception of the brand's value; fewer stale returns, resulting in a higher quantity of saleable bread for the baker's customers; longer distribution routes over an expanded geographic market area; and lower distribution and production costs.
ESL solutions not only involve textural issues, such as softness and resiliency, but mold prevention as well. While enzyme technology provides a solution for maintaining textural integrity over an extended period of time, other formulation and processing parameters are critical too. Finished product quality will deteriorate if these factors are not considered.
Ultimately, the texture of bread should be soft, but resilient. If bread is soft and not resilient, it will not spring back in the mouth, which is an indication of gumminess. “Resilience equals crumb elasticity,” says Jan Van Eijk, Ph.D., research director, Lallemand Baking Solutions, Montreal. “Softness is how much force it takes to suppress the crumb. If the force pushes back some, that's resilience.”
Fresh keeping delays the effects of staling. “A major effect of staling is the increase in crumb firmness and the loss of fresh crumb springiness or elasticity over time,” says Todd Forman, staff scientist, Novozymes. “These changes in texture are due to changes in configuration of the flour's highly branched amylopectin starch molecules, either due to retrogradation/recrystallization, or perhaps to an increase in the number of complexes formed with the gluten protein in flour.”
Certain ingredients, such as enzymes and emulsifiers, interact with the starch molecule, and in so doing, control the change in its configuration. Amylase enzymes modify the size and structure of the starch molecule, Forman notes. Mono and diglycerides, an emulsifier and crumb softener, complexes with the amylose fraction of the starch molecule during baking, Van Eijk adds. While both methods often are used, the enzymatic approach is more effective on its own. As enzymatic activity differs from one type to another, it is important to choose wisely. Fungal amylases are generally heat labile and will thus become inactive before the starch in dough is available, which occurs above gelatinization temperatures greater than 140°F. While fungal amylase is effectively used as a flour supplement or dough improver, it's not particularly effective as a shelf -life extender.
Bacterial amylases were the first enzymes used to extend shelf life. Unlike the fungal amylases, bacterial amylases are thermostable and can therefore withstand heat. “Depending on the internal temperature of the baked product, upwards of 10 percent of the initial dosage of bacterial amylase could remain active when the bread leaves the oven,” Forman explains. “This means as the bread cools, the enzyme is still working slowly and could be reinvigorated when the bread is reheated during toasting.”
“This extended activity is particularly problematic due to the way the enzyme modifies the amylopectin molecule. It is rather aggressive, working deep within the molecule creating large branched dextrins. The amylopectin molecules become so broken down that the strength of the amylopectin structure is reduced and the inherent, fresh crumb springiness is destroyed. The resultant bread will be quite soft, but even a slight overdose could cause a very soft crumb to become sticky and gummy in texture,” Forman adds.
About 17 years ago, Novozymes patented a maltogenic amylase that forms the basis for most enzymatic shelf-life extenders used today. Instead of breaking down amylopectin as bacterial amylase does, this maltogenic amylase leaves amylopectin primarily intact, and instead generates small sugar molecules from the ends of the starch molecules. As a result, starch granules stay softer and more resilient longer, plus starch retrogradation is reduced, Forman notes.
Still, for the enzyme to be most effective, bakers may have to change the baking profile of their ovens to ensure the enzyme is most active during the baking process, as the starch can only be modified after it gelatinizes, Forman adds. Apart from the quality improvements derived from enzyme use, the labeling of enzymes is at the discretion of the baker, as enzymes are considered processing aids. Even if labeled, enzymes are reasonably well received by consumers and provide a clean label, notes Bernie Bruinsma, Ph.D., vice president, technology, Innovative Cereal Systems, Wilsonville, Ore.
Even if the rate of staling is not decreased, certain ingredients can help bread stay softer for a longer period of time, notes Troy Boutte, Ph.D., director, Innovation Center, Caravan Ingredients, Lenexa, Kan. For instance, hydrated monoglycerides or powdered distilled monoglycerides will increase initial softness, but do not change the rate of staling. Some strengthening emulsifiers, such as sodium stearoyl lactylate (SSL) and ethoxylated monoglycerides, provide additional softness.
Dough conditioners that produce higher volume loaves also can enhance bread freshness. A loaf with a higher volume is more diluted with air, which enhances its softness, Van Eijk notes. Although these ingredients will not affect the rate of staling, the bread will be softer to begin with.
Moisture is an important consideration as well. “If the bread is losing moisture, it's not only going to be firmer, but the firming rate also is going to increase,” Van Eijk says. On the other hand, too much moisture can affect the bread's stability, causing it to “keyhole,” Van Eijk adds. When a loaf keyholes, its volume tends to be lower and the excess moisture that penetrates the hard and brittle crust causes the loaf to weaken and cave in at certain locations. Under these circumstances, loaves cannot be stacked on top of one another because of their instability.
“Water is very important as too little results in dryness and too much leads to excessive starch gelatinization and ultimately increased staling,” Boutte says. “Actual moisture retention is generally not the major problem with regard to eating quality of bakery products. It is well known that stale bread contains the same amount of water as fresh bread if packaged properly. However, as a result of starch recrystallization, the water in the stale bread is in a different physical form, which negatively impacts eating quality. Therefore, bakery scientists generally talk about the perception of moistness rather than absolute moisture retention.”
Moisture retention does play a crucial role in the baking process. “Probably the single most important factor related to moisture retention is the bake time and temperature,” Boutte says. “The goal is to reach proper internal temperature as quickly as possible while still achieving proper set to avoid collapse of the product. Any additional baking after these two parameters are met simply results in drying of the product. Improper baking can easily result in the loss of two days of shelf life.”
Bread products on average tend toward underbaking, which leaves the inside of the product overly soft and possibly gummy, Bruinsma notes. On the other hand, smaller dough pieces, such as buns, tend to be overbaked, and therefore drier.
How long a product is cooled and at what temperature also becomes an issue for moisture retention, Bruinsma adds. If a product is cooled excessively long before it is packaged, it will lose moisture to the air, but probably the biggest issue is using the correct packaging.
Controlling bread freshness is perhaps easier than inhibiting mold growth, Forman notes. Higher levels of mold inhibitors may be needed, which in turn may require higher levels of yeast.
Fresh keeping benefits everyone along the value chain, from producer to consumer. When bakers started using Novamyl, the rate of stale returns dropped in half, from about 15 percent to about 8 percent, notes Gary Johnson, regional marketing manager, Novozymes. “One of the most expensive things a bakery does is recover their stales,” adds Brian Stevenson, principle, B. Stevenson Associates LLC, Weatherby Lake, Mo. Costs factored into stale return rates include those involved in producing the product, from ingredients and packaging to utilities and labor, plus the distribution and labor costs involved in hauling product back to the bakery.
Stevenson worked in senior management for a major baking company while it researched possibilities for ESL. During that time, ingredient technology, particularly that involving the use of the maltogenic amylase Novamyl, revolutionized fresh bread sales by providing a solution for longer fresh keeping. Longer fresh keeping has enabled bakeries to reduce their volume of production in order to sell the same amount of units. For example, if a bakery can reduce its stale return rates from 15 percent to 8 percent, it won't have to produce one million units in order to sell 850,000, but can instead produce 904,000 units to sell the same amount, Stevenson notes.
“Fresh keeping has allowed bakers to look at distribution differently,” Stevenson says. “The distribution system is very expensive in the baking industry. About 40 cents of every sales dollar is in sales, delivery and administration. Bread with a longer shelf life does not have to be produced as often, giving bakeries another potential cost savings in having fewer changeovers. Longer runs provide a greater opportunity for consistency of product, Stevenson notes. ESL enables bakers to get excess capacity out of their bakeries, and allows them to do a better job of production forecasting.
Not only has savings from ESL been measured monetarily, but in environmental impact as well. For example, if a normal dosage of Novamyl reduces overall production volume by 5 percent, for every million loaves of bread produced, the amount of CO2 emitted into the environment will be reduced by 36 metric tons, according to a life cycle assessment on the enzyme. Savings also are passed along to bakeries' customers and the end user. Stores can keep shelves full without having to stock them as often. And, consumers perceive more value from a loaf of bread that stays fresher longer, resulting in less waste,Stevenson notes.
Fresh-keeping enzyme technology and its ability to improve shelf life quality has given bakers an opportunity to invest more in brand building, Johnson notes. “Consistent, high-quality products are a prerequisite for sustaining leading brands in every industry,” Johnson adds. “And, the bread industry is no exception.”
Bakeries interested in managing quality by monitoring texture analytically often rely on an instrument called a texture analyzer. Without proper analysis, texture may be judged subjectively and problems typically become apparent through consumer complaints.
Many bakers, particularly those running large, multi-shift operations, didn't want to incur training costs for line operators to learn how to use a measuring device during production runs. As such, training costs became a real barrier to using texture analyzers in production facilities, notes Marc Johnson, president, Texture Technologies Corp., Hamilton, Mass. “Training costs are actually higher than instrument costs, “ Johnson adds.
Companies, such as Texture Technologies, responded to this issue by developing a programmable texture analyzer that requires no training. Line operators respond to a set of pop-up questions about the product being produced at the time. The instrument is electronically connected to the corporate network and thus provides instant feedback, letting the operator know whether he's running within specification.