Patent Application
20110091620
1. Technical Field
The present invention relates to an apparatus and method for the perforation of the skins or hulls of whole fruits, vegetables, grains or legumes to achieve more efficient infusion and dehydration.
2. Description of Related Art
In recent years, consumer demand has been dramatically increasing for healthy foods in general, and healthy snack foods in particular. Healthy snack foods can, for example, take the form of dehydrated slices or cubes of whole fruits or vegetables. The fruit and vegetable pieces (“pieces”) are typically dehydrated through drying, frying and baking. Two advanced dehydration technologies, as examples, are vacuum drying and vacuum frying as conventional air drying and frying yield snacks with an undesirable appearance and higher oil content than desired.
Infusion of the fruit and vegetable pieces prior to dehydration is essential to the dehydration process to achieve the desired product characteristics. Dehydration without prior infusion results in shrinkage of the pieces and an unacceptable texture for sale to consumers. These issues may be resolved by infusing the fruit and vegetable pieces prior to dehydration. Infusion of the fruit and vegetable pieces with a solution containing mono-, di-, or oligo-saccharides, fruit juices, or vegetable fibers adds solids to the fruit and vegetable pieces, which builds the body structure of the pieces and prevents collapse during dehydration. The resulting product is crunchy, has acceptable oil content and retains the appearance of the original fruit and vegetable pieces.
During infusion, solids are infused into fruit and vegetable pieces by immersing them in a hypertonic solution, i.e., a solution with a higher concentration of solids than in the fruit or vegetable. This concentration difference results in two mutually counter flows—solids from the infusion solution entering the fruit or vegetable tissue (solids infusion) and water traveling out of the fruit or vegetable tissue (osmotic dehydration). Subsequent dehydration removes water remaining in the fruit or vegetable tissues after osmotic dehydration. Many different methods for the infusion and dehydration of fruits and vegetables are known in the art.
Infusion and dehydration of whole fruits and vegetables, as compared to slices or cubes (i.e., pieces), is more difficult due to their skins or hulls. The skin or hull acts as a barrier during infusion and dehydration and extends the processing times. The skin or hull also creates explosion problems when the fruit or vegetable is subjected to high-energy or short-time thermal treatments such as boiling, frying, microwave drying as well as high-vacuum treatment such as vacuum drying. Thus, it is desirable to perforate the skin or hull of the whole fruit or vegetable to more efficiently infuse and dehydrate the fruit or vegetable and reduce the processing time, cost, energy requirement and product explosion. It is also desirable that the fruit or vegetable retain its basic shape after being perforated and during both osmotic dehydration and thermal drying.
The present invention provides an apparatus and method for the perforation of the skins or hulls of foods (“product”) to more efficiently produce a dried, shelf-stable product. More specifically, the present invention involves forming micrometer to millimeter sized holes in the skin or hull of a fruit or vegetable to more efficiently product a whole, dried fruit or vegetable with modified texture, taste and flavor.
In a preferred embodiment, the perforator comprises two parallel and adjacent blade wheels positioned longitudinally within a frame in substantially the same horizontal plane. Each blade wheel comprises a plurality of circular blades with a plurality of teeth around the circumference of the blade mounted on a rotatable shaft. The blade wheels are positioned at a distance from each other such that the blades' teeth contact product passing between the blade wheels and make perforations. In one aspect, a guard is provided for each blade wheel to ensure that no product remains on the blades after perforation.
The perforator may be adjusted for the specific product to be perforated. The shape, size and number of blades and the distance between the blade wheels may be modified with respect to the size and shape of the product and the strength of the product's skin or hull.
A preferred embodiment of the method of the present invention comprises the steps of introducing product into a perforator having at least one blade wheel, perforating the product with the blade wheel, removing the perforated product from the perforator, immersing the perforated product in an infusion solution for the period until desirable amounts of solids are infused, and dehydrating the infused product to a moisture content of less than the critical moisture content that is described in quality control documents or specification. Crystalline sugar solutions are preferred for infusion in order to produce a product with a crunchy texture, while non-crystalline sugar solutions are preferred to obtain a chewy texture.
The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:
With reference to the accompanying drawings, identical reference numerals will be used to identify identical elements throughout all of the drawings. In the absence of an indication to a specific figure, refer to
The present invention involves an apparatus and a method for the perforation of the skins or hulls of foods (“product”) to more efficiently produce a dried, shelf-stable product. As used herein, perforation means forming micrometer to millimeter size holes in the skin or hull of a food without damaging its shape or structure.
The foods used in this invention may be any fruit, vegetable, grain or legume. The product may be fresh or frozen. Examples of fruit that may be used are cranberries, grapes, blueberries, cherries, strawberries, goji berries, Saskatoon berries, olives, and acai. Examples of vegetables that may be used are cherry tomatoes, bell peppers, chili peppers, tomatillos, carrots, and mushrooms. Grains that may be used are corn kernels, sorghums, rices, wheats, barleys, and oats. Legumes that may be used are beans, peas, garbanzos, lentils, and says.
Specifically, the present invention aids in the formation of whole, dried fruits and vegetables with a crunchy texture. Two critical steps in the formation of dried fruits and vegetables are infusion and drying. Perforation of the product facilitates both the infusion and drying processes. The skin or hull of fruits and vegetables is generally resistant to infusion, but perforation creates channels for the penetration of solids and water removal, thus increasing the rate of infusion. Further, perforation evens out the pressure in the product during drying and allows steam or pressurized moisture to escape the product without rupturing the skin or causing blistering. For example, a non-perforated blueberry bursts when subjected to vacuum dehydration. However, perforation of the blueberry's skin prevents bursting and allows the whole blueberry to be dried under vacuum while its shape and structure are maintained.
Preferred embodiments of the invention are shown in
The shafts 122, 132 are connected to a motor (not shown) that supplies power to rotate the blade wheels 120, 130. The blade wheels 120, 130 rotate in opposing directions. Referring to
In one embodiment, shown in
In an alternate embodiment, shown in
In a preferred embodiment, two guards, one for each blade wheel, are used to ensure that no product remains on the blades 140 after perforation. Referring to
The size, shape and number of the blades 140 forming the blade wheels 120, 130 may be modified with respect to the size and shape of the product and the strength of the product's skin or hull. First, the shape of the blades 140 may be changed to adjust the size of the perforation. Product with a thin, weak skin or hull only requires a small hole to sufficiently promote infusion and drying, while product with a thicker, tougher skin or hull requires a larger perforation to achieve the same result. For example, the skin of blueberries is thin, so a 0.5 to 2 millimeter hole is sufficient. The preferred size of holes for blueberries is 1 millimeter. In contrast, cranberries have a thick, tough hull and require a 1 millimeter to 0.25 inch hole. The preferred size of holes for cranberries is 2 millimeter. Referring to
Second, the number of blades 140 mounted on the shafts 122, 132 may be modified according to the size of the product to be perforated. When the product to be perforated is large, such as strawberries, the number of blades needed is less than when the product is small, such as blueberries. For example, 4 blades mounted per 1 inch is preferred for the perforation of strawberries while 8 blades mounted per 1 inch from each other is preferred for the perforation of blueberries.
Further, the horizontal distance between the shafts 122, 132 and thereby blade wheels 120, 130 may be adjusted to accommodate products of different sizes and control the depth of the perforations. Smaller product, such as blueberries, requires the blade wheels to be in closer proximity to perforate the product than larger product like strawberries. Also, products with a thick skin or hull or a tough internal structure, such as cranberries, require a deeper penetration to achieve efficient infusion. Thus, the horizontal distance between the blade wheels 120, 130 may be decreased so that the blades' teeth penetrate deep into the product. In a preferred embodiment, the shafts 122, 132 are supported by the end walls 104 in slots 124, 134, respectively. The shafts 122, 132 may be moved horizontally within the slots 124, 134, thus increasing or decreasing the horizontal distance between the blade wheels 120, 130. A locking mechanism (not shown) is used to keep the shafts 122, 132 in position.
The perforator 100 is preferably used as part of a continuous process. A conveyor may be used to deliver the product from an earlier processing step to the opening 112. The product then passes between the rotating blade wheels 120, 130 where it is perforated. The product exits the perforator 100 through the opening 114, where a conveyor may be used to deliver the perforated product for further processing, such as infusion and drying.
An alternate embodiment of the invention is shown in
The double blade wheel embodiment shown in
Another alternate embodiment of the invention is shown in
A preferred embodiment of the method of the present invention comprises the steps of introducing product into a perforator having at least one blade wheel 120, perforating the product with the blade wheel 120, removing the perforated product from the perforator, immersing the perforated product in an infusion solution, and dehydrating the infused product. The single blade wheel perforator 500 or the double blade wheel perforator 100 may be used. The perforator forms 0.5 micrometer to 0.25 inch sized holes in the skin or hull of the product during the perforating step.
The perforated product remains immersed in the infusion solution for at least 10 minutes. Crystalline sugar solutions are preferred for infusion to create a crunchy texture, while liquid sugar solutions are preferred to create a chewy texture. Examples of crystalline sugars that may be used are sucrose, glucose, maltose, fructose, lactose or any sugar in a crystalline or powder form at room temperature. Examples of liquid sugars that may be used are high fructose corn syrup and high-maltose rice syrup.
Dehydration of the product may be accomplished by a vacuum dryer, vacuum microwave, fluidized bed dryer, convectional air dryer, or puffing dryer. The product is dehydrated to a moisture content of less than 10% to obtain a shelf-stable product. If a half-product, or intermediate moisture food, is desired, a moisture content of less than 40% is sufficient.
The perforator 100 was set up to perforate cranberries. Blades 140 with pointed teeth 142, such as that shown in
100 grams of frozen cranberries were introduced into the perforator 100 via the opening 112. The cranberries proceeded through the blade wheels 120, 130 where they were perforated. The product then exited the perforator 100 via the opening 114.
100 grams of perforated cranberries and 100 grams of non-perforated cranberries (control) were immerged into separate vessels, each containing 1 kilogram of 40% (w/w) sucrose solution. With slow agitation at room temperature, the infusion solution was sampled and their sugar content (Brix) and cranberry juice color (absorbance or OD at 510 nm) were monitored over a 72-hour period. The Brix was measured using a digital reflectometer and absorbance (or OD) was determined by a spectrophotometer at 510 nm.
Referring to
Still referring to
It can be seen that the perforated cranberries absorbed more sucrose and, consequently, the concentration of the infusion solution of the perforated cranberries was lower than that of the non-perforated cranberries. The infusion solution with perforated cranberries was much stronger in red color than that of the infusion solution of the non-perforated cranberries as shown by the higher absorbance of the perforated cranberries' infusion solution. Thus, perforation of the cranberries greatly increased the rate of infusion.
The above described invention discloses a method and preferred embodiments of an apparatus for the perforation of the skins or hulls of food pieces. Although the invention has been particularly shown and described, the disclosure is not intended to limit the scope of the invention. It will be understood by those skilled in the art that various changes in form and conditions may be made therein without departing from the spirit and scope of the invention.
