Demand for functionality in this sector is growing rapidly, and microencapsulation is a great way to provide it. However, choosing among the variables can be a tricky process. Kristine V Lukasik, PhD, explains
The formulation of functional foods,particularly those in the bakery sector, brings with it numerous technical challenges. The product must be palatable and inviting to the consumer, and properly targeted demographically. It should be differentiated in the marketplace, perhaps by unique label claims for nutrient content or therapeutic value. The novel nutritional ingredients, vitamins and minerals that distinguish these products can present problems, as can the food matrices themselves.
For example, high-fibre baked products are less straightforward to formulate for optimal product quality and extended mould-free shelf life. It can be difficult to dose unstable nutrients, especially water-soluble active ingredients such as vitamin C, at levels that will consistently meet label claims. The controlled release of many functional ingredients and nutrients in vivo may be virtually impossible, and these compounds often contribute undesirable off-flavours to a finished product.
Choosing a micro method
A current and growing method to address many of these issues is microencapsulation of functional ingredients. As formulators become more aware of the properties and functionality that microencapsulates provide, they can begin to utilise these ingredients in their product-development process, thus accelerating their development efforts and reducing their time-to-market.
Microencapsulation is, in the most general terms, the process of coating a material (the substrate) with another material in order to control the behavior of the substrate. This description is deceptively simple, however. Numerous different methods exist for microencapsulation, and the choice of coatings is equally diverse. Spray drying, spray chilling, coacervation, melt extrusion and fluidised bed-type processes are among the most common manufacturing methods in use today. The choice of process depends upon the nature of the ingredient to be encapsulated, as well as the targeted functionality in the final application.
Generally speaking, oil-based substrates (eg, flavours, fish oil) are encapsulated using spray drying, coacervation and melt extrusion. The coatings typically used for these substrates are water-soluble or water-sensitive materials such as starch, sugars, gelatin, polyols or gum arabic. When water solubility is an issue, however, an alternative coating may be selected.
In such an instance, it may actually be preferable to use a fluidised bed technique to apply a lipid barrier coating to an oil substrate. Water-soluble actives are commonly encapsulated by spray chilling or fluidized bed techniques, with the goal of providing a water barrier for taste masking, modified release, improved stability and reduced solubilisation. Lipid encapsulation is most often the best choice for these active ingredients.
Microencapsulated substrates are typically released by the combined effects of temperature and moisture and the application of shear force. The composition, level, quality and method of coating of a substrate largely dictate its release characteristics. For example, coacervates are typically released through abrasion and moisture, though lipid-coated encapsulates are released by elevated temperature. This point offers some explanation for the range of functionality and stability exhibited by the numerous microencapsulated omega-3 products that are currently marketed to manufacturers of bakery products.
Careful manipulation of the coating composition and its application to a substrate can provide modified release profiles or, alternatively, a very stable form that is suitable for fortification. The release of lipid-encapsulated material will occur in vivo by the combined action of lipase enzymes and bile salts when the functional food is consumed.
Fortification and enrichment of bakery products is an emerging area of interest for the industry. To date, though, the bakery trade has embraced encapsulated ingredients for several other key functional benefits. Many of these are particularly important in the formulation of new high-fibre and whole-grain products that have begun to fill store shelves, as well as health-oriented line extensions of existing products.
Chemical Leavening. Encapsulation of sodium bicarbonate is particularly important in such products when high moisture/low pH fruits are mixed in to a batter or dough, as it prevents premature leavening and undesirable colour changes in the fruit. It can also supplement yeast activity in dense multi-grain products. The viable shelf life of refrigerated and frozen batters and doughs can be extended and performance improved, even if products endure abuse during the distribution cycle.
Preservation. Mould control can be achieved in heavily buffered high-protein dough systems with encapsulated ingredients such as sorbate and propionate salts in combination with organic acids. These can be added directly to dry ingredients without the danger of yeast mortality or interference with chemical leavening in the dough. Encapsulation of sorbate can also help control the acid?s reducing effect on flour proteins during dough development. This is especially significant in products such as flatbreads and tortillas, which are popular with consumers on reduced carbohydrate diets.
Encapsulation may be used to more effectively control the chemical reactions of certain dough conditioners (oxidants and reducing agents) with flour proteins in a dough matrix. The reactivity of conditioners such as ascorbic acid, azodicarbonamide and L-cysteine can be delayed from the dough mixing stage to well into or after the proof stage. Pan breads and flat breads are the most common application for such ingredients.
As knowledge in coating materials and technology advances, novel lipids and combinations of lipids with polysaccharides or proteins may confer improved functionality such as modified release and better stability to heat and abrasion. As the interest in ?wellness through food,? and the trend toward healthier products grow, encapsulation will be used for emerging functional ingredients as well as more traditional avenues of fortification. Improvement of encapsulation will certainly extend the range of viable applications in cereal foods and technical innovation in the bakery industry.
Kristine V Lukasik, PhD, is the applications manager at Balchem Corporation, a provider of microencapsulation technologies to a wide range of industries.
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