Sweet goods everlasting

Urban legend has it that Twinkies® can sit on the shelf for 30 years and maintain their eating quality. They have even been entombed in a time capsule as an icon of the 20th century, supposedly in hopes of remaining soft and edible when the capsule is opened. In actuality, “A Twinkie would be considered by most people past its prime in 30 days, with a deterioration of both texture and flavor,” says Troy Boutte, Ph.D., director of innovation, Caravan Ingredients, Lenexa, Kan.

Even so, a 30-day shelf life for a sweet baked product is a pretty remarkable accomplishment. Shelf life extension has improved greatly in the past two years with the introduction extended shelf life (ESL) Ingredients, Boutte says. Caravan’s Cakesoft, which is a combination of enzymes and emulsifiers, can overcome nearly all the shelf life limitations of sweet products.

“The main quality problems that bakers face with regard to extending shelf life of sweet baked goods are staling, mold growth, loss of flavor and resilience, and breakdown of icings, glazes and fillings,” Boutte says.

Slowing the effects of staling

“Sugar, of course, provides sweetness which is desirable. However, sugar is detrimental in the sense that it dissolves in water and increases the “liquid phase” of the dough or batter,” Boutte adds. “Therefore, as the amount of sugar in a formula goes up, the amount of water is generally decreased to maintain proper dough or batter handling. However, water is the main plasticizer in baked goods and even small decreases of two percent can decrease shelf life by several days. This is mainly a problem in yeast raised doughs.”

For batters, very high sugar levels, such as in high ratio cakes, actually provides a benefit with regard to staling. The high sugar level in these cakes results in much delayed, and more limited starch gelatinization. High sugar level actually increases shelf life, since it is the recrystallization of gelatinized starch that causes staling. This is the primary reason why a cake will generally have longer shelf life than breads.

“Aside from mold growth, by far the primary determinant of shelf life is the amount of starch gelatinized during the baking process and subsequently how much of that starch crystallizes during the shelf life,” continues Boutte “The amount of starch gelatinized is determined primarily by how well the starch is coated with fat or emulsifier, and how much water is available. High fat, low water systems, such as cookies, result in less gelatinization and recrystallization of starch, resulting in less post-bake firming. Emulsifiers complex with the starch, and enzymes break down the starch, resulting in starch that has less tendency to recrystallize.”

Novozymes Opticake® Fresh slows the retrogradation of starch molecules in wheat flour without causing a gummy, non-elastic or sticky crumb, says Gary Johnson, regional marketing manager, Novozymes North America, Franklinton, N.C.

Synergistic freshkeeping technologies

Using enzyme and emulsifier technologies together work better than any single ingredient by itself. For instance a cake may have a shelf life for two weeks with either an emulsifier or a hydrocolloid, but with a combination of these ingredients with a freshkeeping enzyme, the life may be extended by to as much as three weeks without breaking down, Johnson notes.

“Lallemand offers products for use in chemically leavened baked sweet goods to keep them softer and more resilient using Novozyme’s cake freshkeeping technology with a starch modifying enzyme,” says Jan van Eijk, Ph.D., research director, Lallemand Baking Solutions, Montreal, Canada. "[This ESL system] may be used with other ingredients to increase the shelf life of sweet goods or improve eating quality.”

Select charts to enlarge.

Cake Donut Firmness

Yeast Raised Donut Firmness

High Ratio Pound Cake Crumb Firmness

High Ratio Pound Cake Crumb Cohesiveness

*NOTE: Three of Novozymes’ charts are firmness curves. The less force it takes to compress the sweet good, the softer it is. The fourth chart shows crumb cohesiveness. Select charts to enlarge.

For bakers, even the shelf life extension by a week can mean considerable savings in the return of stales to the manufacturer, transportation costs, and the good will of the consumer. Bakeries that, in the past, baked and froze sweet treats in anticipation of busy holiday seasons, can now save freezer space by using ESL ingredients and storing holiday fare in refrigerated, or in some cases even ambient conditions.

In cake production, ESL ingredients can save costs by reducing the amount of sugar and eggs needed in a formula to maintain cohesiveness. Bakers may be able to rebalance their formulas to attain the same level of eating quality with lower levels of these expensive and high calorie ingredients

Products that have improved softness, moistness and cohesiveness provide for consumers increased satisfaction, and ultimately drives brand loyalty and return business, Johnson says. “There is a benefit in improving eating quality within the current level of shelf life in addition to extending the shelf life,” Johnson adds. “When you flatten the firmness curve, the cake is softer on day four, or eight, or 12.”

“Shelf life extenders, in combination with emulsifiers, hydrocolloids, proper formulation and proper processing can virtually eliminate the staling-related issues of firmness, dryness, loss of flavor and resilience. However, the best systems that have been introduced in the last two years, are being used primarily in extreme cases or in more premium products where they are considered affordable,” Boutte says.

Inhibiting mold

Shelf life extenders do not combat the development of mold on sweet goods. The development of mold inhibitors has not kept pace with other shelf life developments. Most mold inhibitors carry with them off-flavors that are undesirable and Boutte finds that improved antimicrobials are needed. However, Caravan has kept a refrigerated bread made with Fridge Soft, which prevents staling in bread up to one year with very good eating qualities, Boutte notes.

“Yeast raised sweet goods (sweet bread, yeast raised donuts, cinnamon rolls, etc. with usually less than 25 bakers’ percentage of sugar) have similar shelf life issues as regular bread with respect to changes in flavor, texture and mold growth (although not as fast as regular bread because high sugar levels inhibit mold growth),” van Eijk says.

“Chemically leavened sweet goods (cakes, cake donuts, cake muffins, etc) stale as a result of changes in texture (becoming firmer, less resilient [brittle], less moist) and mold growth. Chemically leavened sweet goods have a long mold-free shelf life because of high sugar levels and the use of more effective (at higher pH) preservatives like potassium sorbate,” van Eijk says.

Easy delivery

Emulisifiers and enzymes are added to mixes by using tableted or dry powdered blends, at three percent per flour weight of the formula, typically. Depending on the blend, these additions may be considered processing aids, and may not need to be labeled, but bakers should always check with their suppliers to make sure they are in compliance. Most ESL systems do not require specialized equipment or handling procedures. Manufacturers, such as Caravan, strive to make their ingredients “drop in” simple, with no changes necessary on the part of the baker.

And, while some ESL ingredients can add to the cost of some baked goods, depending on the formulation, the benefits to the baker are improved sales, fewer returns and increased flexibility. These benefits may vastly outweigh the cost of the ingredient. In fact, Caravan’s Boutte advises all bakers review their formulations in light of the recent development of improved ESL ingredients. An addition of an ESL component to a hot dog bun formula, for example, not only improved the shelf life of the product, but increased the flexibility of the bun hinge, resulting in an overall upgrade in the quality of the product.

An alternative

The California Dried Plum Board advises that the addition of dried plums can help extend the shelf life of bakery items. Dried plums have 7.5 percent fiber that attracts moisture, and 15 percent sorbitol that binds the moisture in baked goods and helps extend their shelf life. And sorbitol is only 60 percent as sweet as sucrose. In addition, reducing sugars glucose and fructose contribute to moisture retention and sweetness, without over-sweetening the product. Dried plums can be used in yeast-leavened baked products, dual-textured cookies, muffins, bars and doughnuts and is available as purees, powders and juice concentrates.

Prune juice concentrates appear to inhibit mold growth at nine to 12 percent use levels, giving from three to 4 ½ days of additional shelf life without molding, according to a study published by AIB International, entitled Prunes in Bakery Products, 1990.

Another alternative to ESL ingredients are packaging materials that help improve shelf life. In a recent announcement, Biopak, Hong Kong, introduced a water-based spray coated fiber tray that improved the shelf life of baked goods and other food products. The trays are biodegradable and approved for use by the FDA and the Canadian Food Inspection Agency (CFIA).

While shelf stability of 30 years may be far into the future, bakery scientists are busy working to improve the shorter-term quality of sweet goods. Bakers are well advised to check into these new developments. If you haven’t given your formulations a review in the past couple of years, it may be well worth the effort to do so.