Health and nutrition expert Neil Forbes of UK based chemicals and technical materials manufacturer Cornelius discusses trends in solubilisation. * Why is solubility important?*
Solubility describes the amount of a substance that will dissolve with another to form a homogeneous mixture of substances. It is often convenient to create a solution to improve compatibility, aesthetics and bioavailability. Generally, a useful rule of thumb is “like dissolves like”. In other words, materials are most likely to be soluble in other materials that are similar, particularly in terms of a property called polarity. Oils and fats tend to be non polar whereas water and alcohols are described as polar. Polar materials dissolve in other polar materials, but not in non polar materials.
Unfortunately, the choice of materials available to the formulator and the requirements of bottled water products, means this rule of thumb cannot always be conveniently applied and lack of solubility can cause problems such as grittiness, cloudiness and instability. Solubility, however, can be improved by heating or using an alternative solvent, or by using surfactants, emulsifiers and encapsulation to create nano-sized dispersions that resemble solutions. * Tackling solubility*
Bottled water products already successfully utilise a variety of soluble materials from solids, such as citric acid, to gasses, such as carbon dioxide. However, if insoluble solids or liquids are to be added problems with clarity or stability can ensue. Examples include essential oils (a common component of flavours), oil soluble vitamins such as vitamins A or E, or largely insoluble materials (coenzyme Q10). However, more recent advances mean that solubility problems can now be overcome without compromising on the product appearance or stability.
Modern approaches to tackling solubility problems include the synthesis of variants with different solubility properties, encapsulation (either on a molecular basis, or in micelles, microemulsions and other nano structures) and the use of very finely dispersed, nanosized solids. * Nanosize dispersions *
US based Watson Foods has recently developed a form of vitamin E called Clear-E that forms a micellar dispersion in water. It uses a very finely dispersed form of vitamin E supported on a matrix and, while the vitamin E is not truly solubilised, it gives every impression of being so. Clear, stable beverages can be produced using Clear-E that do not give problems with stability or ring formation.
*Liquid encapsulation *
Adumim Food Ingredients of Israel has developed a flexible approach to solubilising oils, and oil soluble materials, in water. The company’s Nutralease technology allows many materials that are currently difficult to use in clear beverages (examples include beta carotene, vitamin A, vitamin D, vitamin E and phytosterols) to be used in beverages such as bottled water without causing stability problems or affecting clarity. Nutralease uses a patent-pending nanosized liquid encapsulation system that is also finding application in the pharmaceutical world to improve bioavailability.
A simple test mixing beta carotene as the material to be solubilised in water, shows Nutralease beta carotene is easily stirred in without the need for high shear mixing, and a perfectly clear solution of beta carotene results (the orange colour comes from the beta carotene itself, and is not influenced by the use of Nutralease technology). In comparison, a conventional cold water soluble (CWS) beta carotene leads to the formation of a very cloudy liquid. * Molecular encapsulation *
Another approach to altering a material’s solubility is molecular encapsulation. Slovenian company Valens has developed and patented Q10 Vital, which uses cyclodextrin as a molecular carrier for coenzyme Q10, a material that is insoluble in water. Cyclodextrin, however, is soluble in water and encapsulates the molecules of coenzyme Q10 allowing a solution in water to be formed. This means that CoQ10 can be used in beverages like bottled water simply by stirring into the formulation. * Future trends*
With the appearance of the new technologies described here we can expect the arrival of numerous new products, especially in the bottled water industry. The recent surge in interest in functional drinks means initial interest might focus on new product formats using nutraceuticals, but future trends are likely to include the launch of products with improved bioavailability, due to improved absorption of more soluble forms of nutrients. We can also expect to see crossover to and from developments in the pharmaceutical world, where bioavailability is a key concern.
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