Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1998-02-18
1999-08-03
Peselev, Elli
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536122, 53612313, 536127, C07H 100
Patent
active
059327200
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the preparation of solid crystalline sucralose having improved flow characteristics and appearance. Sucralose (4-chloro-4-deoxy-.alpha.-D-galactopyranosyl 1.6-dichloro-1.6-dideoxy-.beta.-D-fructo-furanoside, otherwise known as 4,1', 6'-trichloro4, 1',6'- trideoxyealacto sucrose) is a potent sweetener originally disclosed in GB 1543167. Crystalline sucralose was disclosed in GB 2065646A in the form of orthorhombic needles. It is a problem of crystalline materials of this type. that because the needle-like structure tends to bind together to form mats, thev are thus difficult to transfer from one container to another. It is difficult to produce free-flowing sucralose, even under closely controlled laboratory conditions, and on large scale plant the problem is aggravated by the fact that the subsequent processing equipment such as pumps, centrifuges and drvers tends to fracture the crvstals, thus further harming the flow properties. There is thus a need for pure sucralose having a modified structure with improved flow properties.
The flow behaviour of solids is conventionally assessed in terms of flow speeds and also in terms of the angle of repose of the poured material. In Bulk Solids Handling: An Introduction To Practice And Technology, by C R Woodcock and J S Mason, Leonard Hill, Julv 1987, page 31, the flow behaviour of particulate solids is crudely classified in terms of the angle of repose as follows:
From this it will be seen that a free-flowing material should have an angle of repose not exceeding about 38.degree. and it is an object of the present invention to provide sucralose having an angle of repose tvpically below 40.degree. and preferably within the range of 34 -38.degree.. Flow behaviour for a particulate solid can also be more directly measured by a funnel test in which a sample of the material is timed as it flows through a funnel of known dimensions (as described below with reference to the Examples and in Bulk Solids Handling (ibid)).
We have now found that crystalline sucralose obtained directly from the final crystallisation stage of the synthetic process can be treated by a simple operation using standard equipment to provide considerably enhanced flow characteristics. The nature of the changes taking place in the material appear to be relatively complex and varied. It appears that the treatment removes fines and modifies the size and shape of individual crystals, providing a narrower particle size distribution and crystals of a chunkier, more cubic shape. The treated product may actually have a larger overall particle size, but this is not always the case. In particular, it should be noted that the process is not an agglomeration process in which small particles become stuck together, but more a process of crystal redefinition.
According to the present invention there is provided a method of treating crystalline sucralose to remove fines and to modify the size and shape of individual crystals so as to lower the angle of repose and to increase the flowability, comprising treating the crystalline material in a fluidised bed at ambient temperature with additions of water, followed by drying the crystalline material while it is fluidised. Typically, fluidisation is achieved by an upward current of an appropriate carrier gas, typically air. The process can be carried out in conventional fluidised bed drivers and granulators for example the MP2 (Niro Limited) which consists of four main areas:
The drying air is drawn in by a fan through an inlet filter and heated by passing it over a steam heat exchanger. Temperature control is achieved by mixing hot air from the heat exchanger with ambient air via a valve.
The sucralose is placed in the product container and fluidised in a stream of warm air. The water is sprayed using a top spray two fluid nozzle onto the fluidised bed. The product is therefore modified and dried in one operation.
The water is fed to the nozzle using a peristaltic pump. The exhaust air is passed through a filter to prevent the product leaving the
REFERENCES:
patent: 5498709 (1996-03-01), Navia et al.
Peselev Elli
Tate & Lyle Public Limited Company
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