The baking process involves a series of steps: weighing, mixing, fermentation (possibly), forming, heating, cooking, packaging and delivery. Certain ingredients are involved at all stages, while it is desirable for others to participate only at certain points. In order to accomplish this, a stage-dependent mechanism is needed. Encapsulation provides one way to add "time release" action to critical ingredients.
Flavors have been encapsulated for several decades. Of the three top bakery food flavors — vanilla, cinnamon and chocolate — the first two are somewhat volatile and partially disappear ("go up the flue") in the oven. Vanilla, either natural or artificial, was one of the first encapsulated ingredients offered to bakers, particularly to cookie manufacturers. Volatility is greatly reduced. Even with the added cost of the encapsulating agent and process, the overall ingredient cost to achieve the same final flavor impact is also decreased.
Cinnamon tends to inhibit yeast somewhat, so cinnamon bread usually requires a bit more yeast than the same formula without the spice. Encapsulation prevents this inhibition and, at the same time, decreases volatility. So, in addition to the better flavor yield, there is also a processing advantage during fermentation and proofing.
Other herbal flavors are used in specialty breads and tortillas. Garlic, onion and the like are gaining popularity in these applications. By using an encapsulated concentrate of the essential oils, the baker can actually decrease the weight of material required for the desired flavor impact as well as avoiding the losses during baking.
Fortification with vitamins and minerals involves certain losses, generally on the order of 20% for added vitamins. Therefore, a slight "overdosing" is routinely practiced to obtain the desired final level of vitamins in enriched bread. Encapsulation limits the loss caused by heat and fermentation, so the added level can be more precisely like the final target level. Vitamin C, better known to bakers as ascorbic acid, is used as an oxidizing agent in many bromate replacers, yet use of it for this function means that little survives to enrich the finished product. To achieve actual enrichment with vitamin C requires isolating it from the action of yeast, and encapsulation can accomplish this.
Proper chemical leavening of layer cakes, for example, depends on the reaction of the acidifying agent with sodium bicarbonate, which takes place when enough moisture and heat are present. This reaction begins almost as soon as the batter is mixed, and if the batter sits for a while before panning and baking, some of the leavening action may be lost.This is particularly noticeable in pancake and waffle batters in restaurants, where the batter is mixed and then used sporadically over a long period of time. Bakery blends, in which the sodium bicarbonate is isolated from the acidulant by encapsulation, avoid this problem.
Mold growth can be a problem for many bakery foods, particularly specialty breads, which have a rather high moisture content, and flour tortillas. The inclusion of calcium propionate in the dough serves to inhibit mold. The propionate migrates to the surface during baking by a process called steam distillation and exerts its protective effect. Fumaric acid and sorbic acid are much more effective mycostats, but adding either of them to the dough also inhibits yeast action — a very undesir- able effect. The answer is to encapsulate these mold inhibitors, so they are released only during baking. This has been particularly effective with flour tortillas.
Several different encapsulating materials have been tried over the years, but hard fats remain the leading contender for two reasons. First, the "release temperature," or melting point, is easily adjusted, and second, they are relatively inexpensive. With the advent of the trans fat labeling rules, bakers are becoming more sensitive to that aspect of their ingredients, and companies using fat for encapsulation are moving towards no-trans coatings. Given the small amount of fat incorporated with these materials, the concern seems misplaced, but sometimes perception outweighs objective analysis.
While not an application of encapsulation in the strict sense, powdered shortenings and emulsifiers fit the general usage picture of fat-coated active ingredients. For example, a "hard" monoglyceride (one whose iodine value is less than 3) is reacted with soy lecithin, stabilized in the alpha crystal form necessary for anti-staling action and solidified into microspheres. In this form, it can be added to bread doughs in place of hydrated monoglycerides or plastic mono- and diglycerides for extending shelf life. A similar product combines emulsifiers and nonfat dry milk to make a powdered cake shortening that is functional in "oil" cakes — items that use liquid vegetable oil rather than plastic shortening in their formulations. This is recommended for making "no-trans" layer cakes as well as providing the extra shelf life obtained by using a liquid fat in the cake.