Gelatin and gelatin derivatives are used to encapsulate the products of several industries. Examples are described in U.S. Pat. No. 5,074,102, issued to Simpson et al, and include the encapsulation of medicinal compounds such as drugs and vitamins; employment of gelatin encapsulation in food packaging, such as for powdered instant coffee or spices; in candy manufacturing; in fertilization of ornamental plants and/or indoor plants; in packaging of sensitive seeds in combination with protective agents and/or fertilizers; and in the packing of single dyestuffs or mixtures of various drugs.
In each of the above-recited manufacturing and production processes, a certain amount of the encapsulating material is lost as waste. Frequently, this amount approaches 50% or more of the total starting material, depending on the arrangement of production employed. When considering that the cost of the encapsulating material in the United States averages approximately $3.10 per pound ($6.82 per kilo) as of September, 1997, it is clear that the economic consequences of such waste can be significant. As a result, manufacturers have attempted to off-set poor production efficiency by recycling the waste material for reuse. Such attempts, however, have not been met with a great deal of success.
Prior art methods of gelatin recovery and purification suffer from a variety of shortcomings to be discussed in further detail below. Before these shortcomings can be fully appreciated, however, the composition of the encapsulation waste material itself should be further understood. In general, waste material of encapsulation processes are comprised of a variable number of components added to a gelatin base. Among them are solvents (usually water); softening agents and oil coatings (when desired); and, contaminants in the form of residual active ingredients, i.e. the substance being encapsulated. In addition, colorings and preservatives may also be added. Thus, it can be observed that successful recycling involves not only the recovery of gelatin from surrounding oils, but also the removal of the remaining components of the waste in order to achieve a relatively pure, reusable product.
Extraction has been the principle method for accomplishing removal of oils, actives and the like in the pharmaceutical industry. While several solvents have been used in the prior art in an effort to accomplish separation, each suffer from a variety of shortcomings not the least of which is the necessity of ultimately removing yet another component, i.e. the solvent itself, from the recycled materials. To date, the most popular and widely used solvents used to separate gelatin from oils and actives are chlorinated solvents such as, for example, 1,1,1, -trichloroethane with naphtha. The use of chlorinated solvents, however, is accompanied by high costs, disposal problems, and most importantly, environmental concerns. Attempts have been made to use other solvents including isopropyl alcohol, methyl isobutyl ketone, toluene, hexane, heptane, acetone, and acetone/water mixtures, but the resulting yields are insufficient and/or the separation is poor. Furthermore, some of these chemicals are relatively expensive and present similar environmental, disposal, and safety concerns as the chlorinated solvents. None of them have been found to separate oils and actives with a high degree of efficiency.
U.S. Pat. No. 5,288,408, issued to Schmidt et al, discloses a method of recycling gelatin-based encapsulation waste material, and more specifically, to a process for the recovery and purification of gelatin and softening agents therefrom. In the preferred embodiment, deionized water is added to the waste material thereby forming an aqueous solution of gelatin and glycerin dispersed within the remaining oil and residual active-ingredient components of the waste material. Extraction methods are employed under specific conditions to effect separation of the lower aqueous phase from the upper oil phase. The lower phase is hot filtered to remove any remaining traces of oil or other contaminants and the filtrate is then charged to a concentration vessel adapted for vacuum distillation. The water solvent is thus removed under specific thermal and atmospheric conditions until the desired concentration of gelatin and glycerine is achieved. A pure, concentrated aqueous gelatin-glycerin solution results which may be stored or further prepared for immediate reuse. Although this process lends itself to the removal of dyes and active ingredients with additional chemical reactions and processing, such dyes, active ingredients, and glycerin are not removed in situ.
It would, therefore, be desirable to provide a method for recycling gelatin-based encapsulation waste material that removes dyes, active ingredients, and glycerin in situ without the need for any additional processing.