Foods and beverages: apparatus – Electric – radiant or vibrational treating means
Reexamination Certificate
2000-02-04
2001-11-20
Yeung, George C. (Department: 1761)
Foods and beverages: apparatus
Electric, radiant or vibrational treating means
C099S353000, C099SDIG014, C425S174200
Reexamination Certificate
active
06318248
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to improved processes for the preparation of puffed cereal cakes or other products, such as rice cakes. The invention also relates to improved puffed cereal cakes, and to an apparatus suitable for use in the method of the invention. Rice is the most commonly, but not the only advantageously used cereal. Consequently, when the expression “rice” appears herein, the term is understood to be used in the illustrative rather than the limiting sense.
Rice cakes are commercially available products formed from puffed rice grains that are bonded together without a binding matrix. The rice cakes have low density, and low moisture content, and are typically the size and shape of a cookie or rusk. Similar puffed (also known as expanded) cereal cakes can be made with other cereal grains such as wheat, millet, buckwheat, barley or corn.
Rice cakes are currently made by a process comprising the steps of: (i) providing a mold comprising a plurality of mold elements including a reciprocally movable piston element for compressing rice grains inside the mold; (ii) introducing a predetermined quantity of unpuffed (i.e. plain parboiled or non-parboiled) rice into the mold, the average moisture content of this rice being typically about 16% by weight; (iii) compressing the rice grains in the mold to about 6 MPa (60 bar) pressure; (iv) heating the rice grains in the mold to a temperature of 230-280° C.; (v) moving the piston element to expand the mold by a predetermined amount, whereupon the heated rice grains expand and bond together to form the rice cake, followed by (vi) removing the finished rice cake from the mold.
A first drawback of the above method is that it requires a pressure mold that can provide high pressures and temperatures, together with precisely controlled expansion of the mold in the puffing step. This involves considerable technical complexity. Various alternative mold designs are described, for example, in WO92/08375, WO90/08477, and EP-A-0359740.
A second drawback of the above-described existing methods of forming rice cakes is that the high temperature mold surfaces required to heat the rice quickly to the puffing temperature result in rapid build-up of carbon deposits on the mold. This necessitates frequent down time (typically 5-10 minutes every hour) for mold cleaning.
A further drawback of the above-described method is that each compression, heating, expansion and product removal cycle takes at least 6 seconds, and usually 10-12 seconds. The relatively lengthy heating and expansion cycle needed to produce each rice cake reduces the process throughput and increases the cost of the products.
A further drawback of the above-described existing methods of forming rice cakes is that the edible inclusions that can be incorporated into or onto the rice cakes are very limited. Most edible materials, such as vitamins or chocolate, are degraded by the high temperatures used to form rice cakes. In fact, existing rice cakes generally only contain rice and salt, with flavoring agents optionally applied to the surface of the rice cake after it has been formed. This contributes to the limited consumer acceptance of existing rice cakes.
Finally, the high pressure expansion used to form rice cakes according to the prior art means that only a limited range of rice cake shapes is available. In particular, the top and bottom faces of the rice cakes obtained by this method are substantially parallel and flat, i.e. free from patterns or shapes in relief.
In view of the above and other shortcomings of prior art methods and apparatus, it is an object of the present invention to provide an improved process for the preparation of puffed cereal cakes, in particular puffed rice cakes.
Another object of the present invention is to provide a process for the preparation of puffed cereal cakes that is faster than existing methods.
It is a further object of the present invention to provide a process for the preparation of puffed cereal cakes that requires less equipment down-time than existing methods.
Yet another object of the present invention is to provide a process for the preparation of puffed cereal cakes that permits the inclusion of heat-sensitive edible materials into the puffed cereal cakes obtained by the method.
It is a still further object of the present invention to provide a process for the preparation of puffed cereal cakes having top and/or bottom surfaces that are patterned or shaped in relief.
A further object of the invention is to provide puffed cereal cakes, in particular puffed rice cakes, having incorporated therein heat-sensitive edible substances.
One more object of the present invention is to provide puffed cereal cakes, in particular, puffed rice cakes, having a top and/or a bottom surface that is patterned or shaped in relief.
Finally, it is an object of the present invention to provide an improved apparatus for the preparation of a puffed cereal cake, specifically adapted for use in a process according to the present invention or for the production of a rice cake according to the present invention.
In a first aspect, the present invention provides a process for the preparation of a puffed cereal cake comprising the steps of: providing a mold comprising a plurality of mold elements including a reciprocally movable piston element for compressing material inside said mold; introducing a predetermined quantity of unpuffed cereal grains into said mold; compressing the cereal grains in the mold; applying ultrasonic energy to the cereal grains in the mold; moving said piston element to expand the mold by a predetermined amount while applying said ultrasonic energy to the cereal grains to cause expansion and bonding of the cereal grains to form the puffed cereal cake; and removing the puffed cereal cake from the mold.
It has been found that the application of ultrasonic energy to heat the cereal grains during the heating and expansion steps results in a number of technical advantages. First, the time required to heat the cereal grains to their puffing temperature of 210° C.-280° C. is reduced, because the ultrasonic energy heats the cereal grains directly.
A further advantage of the application of ultrasonic energy is that the expansion and bonding of the cereal grains is accelerated. This means that the cycle of compression, heating and expanding the cereal grains can all be completed in less than 5 seconds, and preferably in 2.0 seconds or less. This compares with at least 6-8 seconds needed in the absence of ultrasonic energy.
Yet another advantage of the application of ultrasonic energy is greatly reduced carbonization of the mold. This is partly because of the reduced dwell time of the heated cereal grains in the mold, and partly because the ultrasonic apparatus is self-cleaning. The reduced carbonization of the mold results in reduced down-time and faster throughput.
Yet another advantage of the application of ultrasonic energy is that the ultrasound reduces sticking of the finished cereal cakes to the mold.
The starting material for this process can be brown or milled, parboiled or non-parboiled rice, preferably having a moisture content of 16-28% w/w.
It will be noted that the process according to the first aspect of the present invention retains certain disadvantages of the prior art, including the need for a high pressure expansion step and the need for high temperatures to puff the cereal grains. This means that shaped puffed cereal cakes, and/or puffed cereal cakes having heat-sensitive edible inclusions cannot readily be made by the process according to the first aspect of the present invention. In addition, a high pressure mold is required, as described above for the prior art methods. The mold should be capable of rapid, controlled expansion in order to take advantage of the faster puffing time provided by this aspect of the invention.
Accordingly, in a second aspect, the present invention provides a process for the preparation of a puffed cereal cake, comprising the steps of: providing a mold comprising a plura
Mars Incorporated
McAndrews Held & Malloy Ltd.
Yeung George C.
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