Encapsulation Technologies Protect Key Ingredients

Encapsulation technologies protect key ingredients and deliver them at just the right moment.

By Kantha Shelke, Ingredients Editor

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As consumers increasingly turn to foods as sources of health, processors are trying to cram in as many healthful ingredients as possible. Unfortunately, vitamins, minerals and other nutritive ingredients are not known for their pleasant tastes. But precision microencapsulation technologies can mask the taste or color of nutrients, mitigate nutrient loss during processing and generally help processors create foods with added value.

Kraft Foods, Northfield, Ill., is exploring nutrient microencapsulation technologies through NanoteK, a consortium of researchers from 15 universities and government labs recently created to explore improvements for the food industry. "The widespread use of such technology is all but inevitable in the next few years," says Manuel Marquez-Sanchez, head of the consortium.

Encapsulation involves the incorporation of ingredients, enzymes, cells or other materials into small capsules for delivery of the contents at the appropriate time. By creating a barrier between reactive components, encapsulation protects oxygen-sensitive flavor and color compounds during processing and storage so consumers can enjoy the results at a later time and for a longer time. The process also protects these and other highly reactive materials from interacting with other ingredients to form non-nutritive complexes and compounds with undesirable color or flavor.

Thanks to two techniques — coacervation and microencapsulation — the Oh! Mama provides 100 percent of a pregnant woman's daily iron requirement, plus DHA and 14 vitamins and minerals.

Encapsulation protects nutrients such as iron and vitamin C through processing and storage until the foods are consumed. It turns fragile, volatile and easy-to-spoil liquid ingredients that require controlled storage conditions into stable, easy-flowing powdered solids that can survive the rigors of processing and packaging and be viable even with ambient storage. Conversion of liquids into solid powders also helps simplify processing, often by converting batch production into continuous manufacturing.

The market for encapsulated ingredients could be huge, based on market research estimates. The Freedonia Group (www.freedoniagroup.com), Cleveland, predicts the market for functional foods containing medically beneficial nutrients will exceed $40 billion in 2008. Chemical Market Reporter estimates the demand for encapsulation technologies is growing at around 10 percent annually, driven both by increasing fortification with health ingredients and consumer demand for novel products.

A capsule history

Encapsulation technology, developed three decades ago, largely involves enveloping or entrapping a liquid, solid or sometimes even a gas -- which may be called the core material, internal phase, actives, fill or payload -- in an enclosing material commonly referred to as the carrier, shell, wall, capsule or membrane.

Entrapment in the early days entailed impermeable materials and relied on mechanical means to crush and deliver the contained ingredients for flavor, aroma, leavening ... or enzymatic activity, as in the case of pectin esterase for juice clarification, rennet for milk coagulation or invertase for sucrose inversion.
The commercial production of yogurt, for example, was brought about by the encapsulation and immobilization of lactic acid bacteria (lactobacillus lactis) so they could survive pasteurization but take part in fermentation. Now, even more sophisticated techniques in DanActive from Dannon also protect these beneficial bacteria from degradation in the stomach so they can provide probiotic effects in the lower intestine.

The coating may be made from sugars, proteins, gums, natural and modified polysaccharides, synthetic polymers and even fats -- whatever it takes to protect the core material from the environment, moisture and heat. Encapsulated materials can range from 0.5 to 250 microns in diameter; the particle size and the size distribution may be easily adjusted to the application. A wide distribution range allows for delivery of the core materials over a prolonged period, and a narrow range allows for more rapid and precise delivery.

The core materials typically are released from a microcapsule one of four ways: mechanical capsule rupture, capsule wall dissolution, capsule wall melting or diffusion through the wall.

For a long while, encapsulation was regarded as expensive and too specific for the food industry. In the past decade, cost-effective preparation and increased production volumes contributed to the affordability of encapsulated ingredients, making them increasingly valuable to food processors.

Encapsulation methods

Ingredients may be encapsulated by various physical and chemical techniques including: spray drying, spray cooling, extrusion coating, fluidized bed coating, inclusion complexation, lipid entrapment, coacervation and centrifugal extrusion.

Elements essential and common to all methods are:
  • Coating around the material to contain it with integrity.

  • Ensuring protection from undesirable conditions.

  • Delivering it unchanged at the appropriate stage.

  • Understanding the basics and suitability of the method to the food product application is essential to developing products that deliver what they promise.
Spray drying is probably the most economical and most widely used method, especially for flavors. Solutions of carrier materials such as modified starch, maltodextrin or gums are homogenized with the core material and atomized; the hot air evaporates the solvent and the carrier dries entrapping volatile material. This technique is particularly useful for heat-labile flavors, but the disadvantage is the resulting encapsulated material needs to be agglomerated to render it soluble. Thus a mixture of citral and gum arabic may be subjected to high air velocity at 300-400°C to effectively entrap the lemon flavor without degradation.

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