Use of a Modified Starch for Softgel Coating, Suitable for Food, Nutraceutical and Pharmaceutical Products

In the last years, the market of the food and nutraceutical supplements has had a remarkable development in the sales. The research for new products and the optimization of the existing ones have pushed the producers to more and more complex and peculiar formulations. It was born the need to create nutritional complements able to resist to the gastric juices with the setting up of enteric coatings. With these methods the stomach is protected from irritant substances and, at the same time, the full effectiveness of the active principle is assured. Nevertheless to mask unpleasant smell, coming from stomach, of products containing garlic, fish oils, such purpose crashes with the absence, or nearly, of coating products for food and nutraceutical use admitted by the authorities, able to confer such properties to the product.

Inside this wide nutritional field, one of the most appreciated forms, under the commercial point of view, is represented by softgels, which allow to formulate semi-solid and liquid preparations.

The request for enteric coated nutritional products has pushed us to study a biopolymer for coating film water based, constituted by a modified starch, rich in amylose, which we found suitable for soft gelatin.

Literature shows that softgel coatings are made using a coating solution with organic solvent, to avoid that water absorption causes damage to the softgels. The hydrophilic nature of the shell is the matter that mainly interests during the coating process with aqueous dispersion, because a certain amount of water can be absorbed by the shell, causing problems of softening and swelling of the softgels.

They have been therefore prepared softgel of different sizes, and once standardized on dimensions and gelatin shell composition, they have been covered using a laboratory coating pan and a premixed dispersion made with starch and other different excipients. Standard formulations for softgel capsule base have been set up for their influence on the shell characteristics and on the long-term stability of the softgel itself.

The softgel has been standardized in terms of hardness through a measurement device for flexible materials hardness determination. While applying opportune process conditions, particularly referring to core bed temperature, to coating bed rotating speed and to spraying amount, sticking problems between the softgels or adhesion to the coating bed walls have not taken place.

In order to avoid an excessive water absorption of the softgel, we had made an under coating on the softgel with volatile oils, waxes and, more generally, lypophilic material, in order to waterproof the softgel, before proceeding with the real coating.

Moreover the introduction, into the spray suspension, of materials sensitive to pH, concurs to reduce the process times, obtaining however optimal gastro resistance results.

In order to optimize the coating process for each product, new mixtures and parameters are always under development.