In addition to their assured consistent availability and quality, speciality starches can improve processing, produce high quality products and offer substantial savings. Fred Heinze and Himanshu Shah report.
Traditional emulsion stabilisers and encapsulation agents present manufacturers with a number of problems. Gum Arabic, for example, has a history of uncertain supply, fluctuating prices, variable quality and consistency and performance. Other issues associated with its use include the longer hydration time required and higher energy costs to form stable emulsions due to its limited emulsification efficacy.
Developments in speciality starch technology offer effective alternatives to gum Arabic and other encapsulants (eg animal derived gelatine or casein) to stabilise emulsions and encapsulate active ingredients such as flavours, lipids (oils and waxes) and vitamins for food, beverage, nutrition and pharmaceutical applications.
Starch is hydrophilic in its native form and therefore, does not have any affinity towards hydrophobic substances such as fats and oils. National Starch has applied its natural polymer expertise to adapt the molecular structures of starch to develop a range of amphiphilic, fat-loving starches which form and stabilise oil-in-water emulsions.
Encapsulation is most frequently combined with the transformation of functional ingredients, which are often present in liquid form, into free-flowing powders. These ingredients include flavours (citrus oils, extracts and nature-identicals), neutral oils, natural colouring agents (oleoresins, carotenoids), vitamins (eg vitamins A and E), PUFA's polyunsaturated fatty acids), pharmaceutical actives, spices, herbal extracts, enzymes, fragrances and minerals including mineral oils and silicones. The natural film-forming properties of starch make it an excellent to encapsulate those actives which are not hydrophobic in nature.
To encapsulate actives which are hydrophobic in nature requires starches with dual functionality such as excellent film-forming along with superior emulsifying properties. Amphiphilic starches do possess this dual functionality and are widely used in flavour, fragrance and pharmaceutical industries to encapsulate hydrophobic actives. These starches are capable of forming very fine oil-in-water emulsions and stabilise for the time needed to encapsulate and recover by means of various mechanical drying techniques.
Encapsulation reduces losses during storage and processing as it protects the functional ingredients against oxidation, hydrolysis, evaporation and incompatibilities with other potentially reactive substances. Encapsulation can also if required mask the taste, flavour and odour of the product and allow for improved complete instantaneous or controlled release of the active ingredients.
Of the numerous encapsulation processes including coacervation, film-coating and spray-chilling spray-drying is the best known and most economical method.
National Starch has developed a range of speciality starches Hi-Cap 100, Capsul, Capsul TA and N-Lok for use in the encapsulation of a variety of ingredients. Starches offer a range of advantages over other encapsulating agents:
* Controlled amphiphilic structure excellent emulsification and encapsulation performance.
* Low viscosity at high solids provides faster spray-drying rates and lower energy consumption.
* Low surface oil and excellent oxidation resistance ensures excellent flavour/taste preservation and stabilisation of sensitive ingredients.
* Excellent emulsification and stabilisation power prevents coalescence, agglomeration or separation.
* High microbiological purity.
* Dependable source of supply and consistent quality.
Products that can be encapsulated with starch-based encapsulating agents include a wide range of flavours as well as vitamins, fats, oils and fragrances.
Many flavours, such as orange and lemon oils, deteriorate rapidly when exposed to oxygen. During spray-drying and in storage, these substances will oxidise and develop and aoff' taste. It is important that the encapsulating agent is capable of forming very fine emulsions and impermeable films to protect the active ingredient from evaporation and oxidation. N-Lok, a waxy maize-based starch, has been developed to provide the flavour industry with a product characterised by low viscosity, good emulsion qualities and enhanced oxidation barrier properties. It is able to carry and protect the flavour oil essential for the encapsulation of premium oils up to typically 20 per cent load levels.
Recently developed Hi-Cap 100 is specially designed to be capable of encapsulating considerably higher levels of active ingredients up to 40 per cent without suffering the prohibitive losses during processing typical of other carriers such as gum Arabic.
Whereas the oxidation resistance of the traditional encapsulating agents deteriorates at higher oil loads, the polymer structure of Hi-Cap 100 has been designed to provide excellent oil retention even at double the conventional load of about 20 per cent. The oxidation resistance was determined after aging the spray-dried powders in a closed container for two weeks at 50ºC, steam distilling the flavour oil and measuring the level of carvone present in distilled oil by gas chromatography.
National Starch has also developed an amphiphilic starch based on tapioca. Called Capsul TA, it is similar to Capsul which has been used in the industry for a long time. The first pure tapioca-based encapsulant, Capsul TA offers a clean flavour and taste profile for use with volatile flavour oils, neutral oils, vitamins and herbal extracts where natural flavours need to be preserved.
Beverage emulsions are oil-in-water emulsions that are typically made in a concentrated form and then diluted into finished products (beverages). The emulsion in both its concentrated and diluted form must have very good long-term stability. Poor stability of an emulsion will result in either ringing or sediment in the final beverage. Normally, in carbonated and non-carbonated beverages, amphiphilic starch or gum Arabic are used to stabilise emulsions. These emulsions are further stabilised by adding approved weighting agents such as EG, SAIB or Dammar Gum into either flavour oil, vegetable oil or terpene.
Amphiphilic starches such as OSA-type (octenyl succinate) starches Purity Gum 2000 and Purity Gum 1773 offer many advantages over gum Arabic in the stabilisation of flavour, vitamin and nutrient emulsions and cloud emulsions. More often these types of emulsions need to be stored in a refrigerator to protect the flavour and top-notes. Purity Gum 2000 is suitable when emulsions need refrigeration for an extended period of time up to 24 months.
From the array of emulsification and encapsulation agents to choose from, speciality starches provide an economical alternative to conventional systems. In addition to improving the quality of the final product, the starches promise manufacturers simpler yet more cost-effective processing.
Fred Heinze is Business Manager, Healthcare with National Starch Europe and Himanshu Shah is Technical Service Supervisor, Encapsulation and Delivery Systems, National Starch, Manchester, UK. www.foodstarch.com or www.nationalstarch.com
