Food or edible material: processes – compositions – and products – Processes – Molding – casting – or shaping
Reexamination Certificate
2001-05-03
2003-08-19
Yeung, George C. (Department: 1761)
Food or edible material: processes, compositions, and products
Processes
Molding, casting, or shaping
C426S533000, C426S650000
Reexamination Certificate
active
06607771
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND ART
It is well known in the food industry that the addition of flavoring ingredients contributes to a major extent to the palatability of consumable edible materials; consequently, it is paramount to ensure the production of food products which are of consistent flavor quality and are thus attractive to consumers. This can be achieved by ensuring proper flavor release. In fact, taste and aroma are greatly influenced by volatile components present in such products. However, because of the volatility of these compounds, it is not easy to ensure that the predetermined critical amounts of each flavor component remains stable during food processing, cooking, baking, during transportation and storage and finally during the preparation of the food product by the consumer himself.
The losses of volatile components from the food products may produce undesirable variations in the taste and aroma of the products as perceived by the consumer. On the other hand, losses of volatile components might occur through the conversion of certain flavor materials into unwanted less desirable or tasteless chemicals by their interaction with reagents present in the environment. Oxygen is an example of this type of reagent as it promotes the conversion of several labile flavor materials of current and critical utilization in the industry.
It is not surprising therefore to observe that, in order to reduce or eliminate the above-mentioned problems associated with volatile and labile flavor components, various attempts have been made to encapsulate such components in certain carbohydrate matrices so as to reduce the volatility or lability of these components. Volatile flavor or fragrance ingredients are thus encapsulated in amorphous solid materials to protect them from evaporation, chemical reactions and physical interactions until needed. Solid formulations facilitate the handling of flavors and fragrances by customers and their cost in use is generally improved.
Another important reason for encapsulating flavors or fragrances is the control of the kinetics of flavor or fragrance release to induce sensory effects through sequential release. Therefore, in view of the growing demand from the industry for delivery systems allowing a controlled release of flavors or fragrances, the improvement of technical preparations of stable free flowing powders containing the flavor or fragrance compositions for the latter flavor or fragrance release is always of paramount importance.
The prior art has therefore developed a number of techniques for producing encapsulated volatile compounds. In essence, the literature in the field of the invention discloses the encapsulation of flavor materials in glass-like polymeric materials.
The understanding of the glassy state and its importance in food products has been considerably extended in recent years. Several methods of creating glass-like states have been reported. The concept of glass transition temperature (Tg) is well described in the literature. It represents the transition temperature from a rubbery liquid state to a glassy solid state; such a transition is characterized by a rapid increase in viscosity over several orders of magnitude and over a rather small temperature range. It is recognized by many experts in the field that, in the glassy state, i.e. at temperatures below Tg, all molecular translation is halted and it is this process which provides such effective entrapping of the volatile flavors and prevention of other chemical events such as oxidation.
Implicit in much of the literature is the converse, namely that at temperatures above Tg, the encapsulation of flavor molecules will be ineffective and hence the importance of creating polymeric encapsulating materials with Tg values above ambient temperature.
The physical state of an encapsulated flavor system can thus be expressed by the difference (T−Tg), T being the temperature surrounding the system, i.e. the extrusion temperature when reference is made to the encapsulation process, and the ambient or storing temperature, namely a temperature typically comprised between 20 and 25° C. when reference is made to the storage of the final product, after the end of the process.
When T is equal to Tg, the surrounding temperature corresponds to the glass transition temperature of the system; when (T−Tg) is negative, the system is in the glassy state and the more the difference is negative, the more viscous is the system. Conversely, in the rubbery state, i.e. when (T−Tg) is positive, the more positive is the difference, the less viscous is the system.
The difference (T−Tg) evolves during the different steps of an encapsulation process and is representative of the changes in the physical state and viscosity of the system.
In the processes described in the prior art, a homogeneous mixture of flavor material and carbohydrate matrix is generally prepared in the first step of the encapsulation process and is then heated in such a way that the temperature of the mixture is greater than the glass transition temperature of the matrix, in order to form a molten mass. More particularly, the system, in the first step of the prior art processes, is such that the difference (T−Tg) is very positive, providing a low viscosity rubbery melt. The molten mass is then extruded through a die.
Following the extrusion step, all the processes described in the prior art comprise an additional step which allows to decrease the difference (T−Tg), in other words to increase the viscosity of the system, in order to render it sufficiently viscous to be able to be shaped to provide the desired particles.
The patent literature in the field of the invention discloses several ways of lowering (T−Tg) after the extrusion step, either by decreasing the temperature T through a cooling step, or by increasing the glass transition temperature Tg through a drying step.
A typical example of extrusion techniques for preparing encapsulated volatile compounds is provided in U.S. Pat. No. 4,707,367 which describes a process for preparing a solid essential oil composition having a high content of essential oil, completely encapsulated within the extruded particulate solids. The process there-described comprises forming a homogeneous mixture combining matrix components and an essential oil flavor and extruding said homogeneous melt into a relatively cool liquid solvent. The cooling step induces the solidification and permits to form a solid extruded material which is further dried and combined with an anticaking agent to produce a stable and relatively non hygroscopic particulate essential oil composition in encapsulated form.
U.S. Pat. No. 2,856,291 also discloses a process for preparing solid flavor compositions which comprises forming a hot, liquid emulsion of a volatile flavoring agent in a melted sugar base, extruding the hot emulsion in the form of a continuous stream and cooling the stream to a plastic condition, thus reducing the difference (T−Tg) to be able to then subdivide the stream into rod shaped elements.
Another way to reduce (T−Tg) is to increase the glass transition temperature Tg. It is well known in the art that the ingress of water into the system can significantly reduce the Tg; a drying step can thus be carried out with the objective of increasing Tg. Said method is used in the wet-granulation. For instance, EP-A2-202409 describes a method for the production of stable, spherical particles of viable micro-organisms which comprises the steps of mixing a culture concentrate with a bulking agent to form a homogeneous wet granulate, extruding the wet granulate through a die to produce filaments having a diameter of approximately the size of the desired spheres and then using a spheroniser device which comprises a plate that rotates at a tangential speed sufficient to cause the filaments to be shaped into discrete spherical particles, and finally drying the particles. Before the drying step, the glass transition temperature of the extruded mass is relatively low
Benczedi Daniel
Bouquerand Pierre-Etienne
Firmenich SA
Winston & Strawn
Yeung George C.
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