Food or edible material: processes – compositions – and products – Processes – Preparation of product which is dry in final form
Patent
1991-06-12
1993-02-09
Yeung, George
Food or edible material: processes, compositions, and products
Processes
Preparation of product which is dry in final form
34 10, 34 57R, 99286, 99474, 426466, A23F 500, A23N 1200
Patent
active
051851717
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to roasters for particulate food matter, and in particular to a roaster for coffee beans, nuts, or the like.
BACKGROUND OF THE INVENTION
In the past, particulate food matter which is suitable for roasting, for example coffee beans, has traditionally been placed within a rotating drum which is heated and/or has hot air blown through it. The process usually takes 5-30 minutes. For approximately two-thirds of this period the charge heats up uniformly and most of the moisture is lost. During the last five minutes or less the temperature of the coffee causes a rapid change of colour. Drum roasting of beans has several disadvantages including slowness, the buffeting of the beans against the sides of the drum or drum baffles with consequent risk of damage to beans and loss of aroma, and the fact that any machine incorporating rotating parts is susceptible to wear and breakdown. In addition, husks detach and burn within the drum causing flavour change.
On a larger scale, coffee beans have been roasted in a fluidized bed roaster in which hot air is admitted to a fluidizing chamber The air enters the fluidizing chamber in a vertical direction and fluidizes a bed of beans within the chamber. The beans remain suspended in hot air in the chamber or may be circulated in a vortex in the chamber until fully roasted. A substantial vertical air flow is required to maintain the fluidized bed in suspension and the whole of the fluidizing air has to be heated to a roasting temperature (typically 250.degree. C. to 300.degree. C.) which results in energy wastage or expensive heat recovery apparatus. Moreover it is difficult to establish and maintain a fluidized bed and the flow conditions required are critical and vary with bean blend and size. Furthermore, bean density varies during roasting as beans lose moisture and swell and air loses its potency as it heats up. These factors further complicate control of a fluidized bed. Fluidized bed roasters have been used for production rates of upwards of 5 Kgs. per hour and while mechanically simpler and quicker than drum roasters are more costly to manufacture and more difficult and costly to operate.
It is an object of the present invention to provide a roaster which ameliorates at least some the disadvantages of prior art. An object of preferred embodiments of the present invention is to provide a roaster which is mechanically simple, and is of less complicated construction and operation than a fluidized bed roaster. A further object of preferred embodiments of the invention is to provide a roaster suitable for use at a point of sale of roasted beans. Such a roaster would be capable of roasting quantities as small as half to one kilogram and be capable of operation by an unskilled operator.
DISCLOSURE OF THE INVENTION
According to a first aspect, the invention consists in a method for roasting a particulate food matter, said method comprising the steps of: stream entrance; curvilinear path to an altitude above that of the entrance and then allowing the particles to return to the entrance; and particles into the air stream.
In preferred embodiments the air flow adjacent the entrance is in a substantially horizontal direction and the particles of food matter, for example coffee beans, enter the air stream at an angle of not greater than 90.degree.. For preference, the particles enter the air stream from a hopper having a constricted throat and at an angle of 45.degree. or less to the air flow so that the beans have a component of velocity in the air flow direction. The rate of admission of the beans into the air flow is controlled by the constriction in relation to the air flow rate so that beans are enveloped and transported by the air away from the entrance without accumulating in the air flow at the entrance.
The term "horizontal" in this specification is used broadly to indicate a direction more nearly horizontal than vertical.
According to another aspect the present invention consists in roasting apparatus for particulat
REFERENCES:
patent: 2859116 (1958-11-01), Heimbs et al.
patent: 3328172 (1967-06-01), Smith
patent: 3724090 (1973-04-01), Smith, Jr.
patent: 4325191 (1982-04-01), Kumagai et al.
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