Formulators of baked grain-based foods such as breads, muffins, and even cookies, are increasing the whole grain and fiber contents of formulations to help Americans better achieve their recommended daily intakes. Many are using less refined flours, ancient grains and fiber ingredients, all of which can increase products’ susceptibility to staling, also known as drying out.
Staling has always been one of the earliest signs of deterioration in baked goods. In chemistry books, this is referred to as retrogradation, and it is an irreversible process that not only liberates water but also collapses starch molecules into insoluble moieties.
Without protective measures in place, a bakery-fresh loaf of bread will lose its desirable tender crumb and aroma in a few days. Most neighborhood and in-store bakeries avoid artificial preservatives and ingredients, as are an increasing number of commercial bakeries. This is where egg products enter the picture.
Not only do egg products provide a wide variety of nutrients, including high-quality protein, trans-fatty acid free mono- and poly-unsaturated fats, vitamins, minerals, and other highly bioavailable nutrients with recognized health and wellness benefits, they are able to assist with maintaining quality through a baked good’s expected shelf life. And the best part is that they do this while being very simply listed as egg, egg white or egg yolk on ingredient statements.
The process of retrogradation begins in the oven, when the starch chains located inside of the starch granules swell with moisture when heated. As the grain-based product starts to cool, the swollen starch chains lose their moisture content. Over time, moisture migrates to dryer regions of the product and then eventually evaporates into the surrounding atmosphere. Loss of moisture causes the starch chains in the swollen granules to collapse, and the crumb degrades, resulting in a firm texture and dry mouthfeel, eventually rendering the baked good inedible.
Here’s where egg products can help, specifically the all-natural emulsifier lecithin that is concentrated in the yolk. Emulsifiers, which are molecules that have one end that dissolves in water and one end that dissolves in oil, are thought to interfere with the collapse of the swollen starch molecules by lodging in the spaces between the highly branched starch chains, thus preventing their collapse. This retards the onset and rate of firming that occurs with age.
And here’s an added bonus. Egg yolks have a beautiful yellow-orange hue, as they are a concentrated source of the carotenoid xanthophylls. This pigment provides richness in terms of color when added to grain-based foods…and rich color contributes to perceived quality and freshness. For example, the egg yolks in Dunkin’ Donuts’ new Egg Bagels provide a desirable yellow hue, while contributing to a moist, soft, chewy inside.
Egg proteins, in particular those found in whites, can also assist with extending the shelf life of baked goods through foam formation. Foams entrap air, giving baked goods volume and springiness, attributes that suggest freshness. And when it comes to providing structure to baked goods, egg proteins accomplish this by the chemical process known as coagulation, which is the transformation of liquid egg into a semi-solid or solid matrix.
Essentially the same chemistry supports the functions of aeration and coagulation, with the former entrapping air and the latter binding water. Through a series of reactions, millions of egg protein molecules aggregate to form an insoluble three-dimensional network. As the proteins aggregate together, they entrap air—as in the case of a foam—and moisture—as in the case of a gel, as well as interact with gluten, thereby essentially building the baked good. In essence, they create cells where the cellular wall is composed of proteins and the cell contents are air or moisture.
Egg products, through their ability to retain moisture, slow down the staling process. This science has proven to be very useful in providing extended shelf life to gluten-free bread, as bread relies heavily on gluten for structure and palatability. Egg proteins can mimic gluten.
There are many other ways egg products can assist with preventing staling. For example, an egg wash applied to the surface prior to baking can seal in moisture. Further, eggs are a natural source of antioxidants, which may minimize oxidation of lipids during storage.
To learn more about how egg products can assist with extending the shelf life of baked goods, please view “Baked Goods: Extending Shelf Life.” This video, as well as the 11 others, can assist you with understanding the 20-plus functional benefits of egg products while earning free continuing education credits.