Patent Application
20090047400
1. Technical Field
The present invention relates to an apparatus and a method for the infusion of solutes into food pieces. More specifically, the invention relates to an apparatus and a method for the infusion of food pieces, particularly fruit and vegetable pieces, by hybrid infusion, comprising atmospheric infusion followed by vacuum infusion within a single apparatus.
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 generally take the form of dehydrated slices or cubes of whole fruits or vegetables. The fruit and vegetable pieces (“pieces”) are typically dehydrated via vacuum frying as conventional frying yields snacks with an undesirable appearance and higher oil content than desired.
Infusion of the fruit and vegetable pieces prior to frying 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.
Well known methods exist in the art for infusion of fruit and vegetable pieces. One such method is the continuous or step-wise infusion at atmospheric pressure. Under this method, disclosed in U.S. Pat. No. 5,718,939 to Nugent and U.S. Pat. No. 6,440,483 to Ghaedian et al., fruit and vegetable pieces are treated with water or an aqueous solution to rapture the pieces' cell walls, then with an infusion solution to infuse the pieces with solids. These steps may be performed continuously in a single apparatus or step-wise in a series of apparatuses.
Another well known method in the art is vacuum infusion, disclosed in U.S. Pat. No. 5,747,088 to Fletcher, where the fruit and vegetable pieces are subjected to decreased pressure (less than atmospheric pressure) while in an infusion solution. This method accelerates the mass transfer of solids and water in the pieces and significantly reduces the time required for infusion compared to atmospheric infusion. Vacuum infusion employs two mechanisms—osmotic dehydration followed by infusion of solids. Osmotic dehydration, the evacuation of water and gas from the fruit and vegetable pieces, occurs when the vacuum is first applied and the apparatus is depressurized. When the vacuum is released and the apparatus repressurizes, solids from the infusion solution are taken in by the pieces to fill the spaces left by the evacuated water and gas.
However, applying a vacuum immediately after contact between the fruit and vegetable pieces and the infusion solution damages the cell walls of the product, leading to increased oil absorption during further operations. Thus, it is preferred to subject the fruit and vegetable pieces to reduced pressure after a period of atmospheric infusion to allow the pieces to build structure and prevent damage to the pieces' cell walls when the vacuum is applied. Current technology utilizes either atmospheric or vacuum infusion, but not both methods in conjunction, which would maximize the efficiency of the infusion process. It is desirable to be able to conduct both infusion methods, either in conjunction or alone, within a single apparatus and customize the times to be used for each method and pressure levels for the vacuum infusion period to achieve the desired product characteristics.
Another drawback of current technology for infusion of fruit and vegetable pieces lies in the lack of uniform infusion of all pieces. Most fruit and vegetable pieces float in solution rather than remaining completely submerged in the solution throughout the infusion process. A means for immersing the fruit and vegetable pieces and gently mixing the pieces in the solution is desired to obtain sufficient contact between the pieces and the infusion solution.
Collection issues also arise due to the fruit and vegetable pieces floating in the infusion solution. Current technology uses rotating or vertically standing drums, as disclosed in U.S. Pat. No. 6,457,403 to Wettlaufer et al., U.S. Pat. No. 6,159,527 to Wettlaufer, U.S. Pat. No. 6,479,092 to Wettlaufer, and U.S. Pat. No. 6,440,483 to Ghaedian et al., in which collection is difficult and requires manual intervention, thereby reducing efficiency and increasing time between batches. An apparatus that allows for the collection of the pieces without manual intervention is desired.
Downstream operations are affected by residual infusion solution on the fruit and vegetable pieces after removal from the infusion process. Excess sugar or solutes, still on the pieces from the infusion process, causes sugar buildup in the downstream operations and a resulting infusion solution waste and yield loss. Current technology washes the fruit and vegetable pieces after removal from the infusion solution to reduce sugar buildup downstream, but it would be preferred to eliminate the additional step and accomplish removal of the residual infusion solution as the product is removed from the infusion solution.
Further, some fruit and vegetable pieces are individually quick frozen prior to infusion. Infusion cannot take place when the pieces are frozen. Thus, fruit and vegetable pieces that are individually quick frozen must be tempered, requiring an additional step before infusion may occur. It is desired to combine the steps of tempering and infusion into a single step within an apparatus to decrease the overall time required for the infusion process.
The present invention provides a method and an apparatus for the hybrid infusion of solutes into food pieces, which comprises atmospheric infusion followed by vacuum infusion, within a single apparatus. The pieces are introduced into the apparatus, where they undergo a period of atmospheric infusion to build the pieces' body structures and then a period of vacuum infusion to accelerate the infusion process and decrease the overall time needed for infusion. The time for each phase and level of the pressure during the vacuum phase may be adjusted for a chosen fruit or vegetable to achieve the desired product characteristics.
In one aspect, the apparatus of the present invention comprises a sealable vessel containing a mixing mechanism that provides a means for immersing and gently mixing the pieces while in solution. The mixing mechanism moves upward and downward at a predetermined velocity and periodicity, customized for the specific inputted food piece, to immerse the pieces in solution to ensure sufficient contact for uniform infusion.
In one aspect, the apparatus of the present invention further comprises retaining walls extending the length of, and abutting the longitudinal sides of, an internal conveyor to prevent floating pieces from straying away from directly above the internal conveyor. Alternative embodiments of the invention allow for the side walls of the apparatus to act as retaining walls. As the infusion solution is drained from the apparatus, the retaining walls, along with gravity, ensures that the pieces settle on the internal conveyor for collection, regardless of whether the pieces are completely immersed in the solution or floating in the solution. The internal conveyor then delivers the infused pieces for further operations, removing the need for manual intervention during the collection process.
In one aspect, the method of the present invention allows for removal of the residual solution on the infused food pieces without the additional washing step by draining the infusion solution from the apparatus under vacuum. The pieces are then removed from the apparatus and sugar buildup in downstream operations is decreased.
The invention also allows for the steps of tempering individually quick frozen food pieces and infusion to be accomplished within a single apparatus. The pieces may be tempered while in the apparatus by circulating the infusion solution at a higher temperature to gradually increase the pieces' temperature. As the pieces thaw, infusion begins, which decreases the overall time needed for the infusion process.
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
A preferred embodiment of the method of the invention is shown in
Using the method and apparatus of the present invention, food pieces may undergo atmospheric, vacuum, or hybrid infusion depending on the specific product needs. Hybrid infusion comprises an atmospheric infusion phase and a vacuum infusion phase to achieve the most efficient infusion. The method illustrated in
Prior to infusion, the food pieces may be fresh or individually quick frozen, depending on the desired product characteristics and availability. Examples of fruit pieces which may be used include, but are not limited to, apple pieces, pineapple cubes, sliced mango, sliced papaya, sliced jack fruit, canned Lychee, sliced pear, whole/sliced strawberry, whole blueberry, whole raspberry, and banana pieces. Examples of vegetable pieces which may be used include, but are not limited to, whole green beans, sliced carrots, whole cauliflower heads, whole broccoli heads with florets, sliced sweet potato, taro sticks, and sliced squash. The infusion solution can be custom designed to contain various mono, di, or oligo saccharides, fruit juices, or vegetable fibers to achieve the desired product characteristics.
In a preferred method of using the apparatus of Applicants' invention, the product is initially soaked in the infusion solution at atmospheric pressure, approximately 760 torr (1 atm), for 30 minutes to 4 hours, to allow replacement of a sufficient portion of the product's water content with infusion solutes. The structural integrity of the product is reinforced as it is filled with solids, which avoids collapse during frying in further operations. The infusion solution is maintained at a temperature at or below 50° F., more preferably in the range of 45° F. to 50° F., most preferably at 50° F., and a solute concentration of 43 brix to 45 brix, preferably about 45 brix. Maintaining the temperature at or below 50° F. is preferred to control microbial growth. A microbicide may also be added to the infusion solution to prevent or slow the growth of microbes, thereby allowing higher temperatures as well.
When the food pieces are individually quick frozen prior to being infused, the product must be tempered before infusion can occur. Applicants' apparatus allows for both tempering and infusing the product within the apparatus, thus eliminating the need for a separate piece of equipment to perform this operation. Referring to
Fresh product does not require tempering prior to infusion. Upon immersion in the infusion solution, the product begins to take in solids. Thus, the time required to infuse by soaking at atmospheric pressure for fresh product is considerably less than that for an individually quick frozen product.
In a preferred method, the food pieces are first infused at atmospheric pressure, by soaking in the infusion solution at atmospheric pressure, for 30 minutes to 4 hours. Examples of the typical length of the atmospheric pressure phase for different fruits and vegetables undergoing hybrid infusion are about as follows: apple (fresh)—30 minutes; pineapple (individually quick frozen)—101 minutes; green bean (individually quick frozen)—60 minutes; and carrot (individually quick frozen)—60 minutes. These times can vary depending on the specific product and the desired end product attributes.
After the infusion phase at atmospheric pressure, the apparatus is depressurized through a vacuum port to a predetermined level, preferably in the range of 50 to 600 torr, more preferably in 100 to 500 torr, and most preferably in 200 to 400 torr, as needed and customized for the product being infused. Examples of the vacuum pressure typically used for various fruit and vegetable pieces under the hybrid infusion method are as follows: apple (fresh)—200 torr; pineapple (individually quick frozen)—400 torr; green bean (individually quick frozen)—400 torr; and carrot (individually quick frozen)—200 torr. These pressures are, however, provided for the purpose of illustration and are not limitations. The vacuum may be maintained for 5 minutes to 1 hour. Again, the residence time and pressures involved in the step can vary significantly depending on the product and desired end product.
In a preferred embodiment of the invention, pulses of vacuum are used to further accelerate the solute intake. A pulse of vacuum comprises depressurizing the apparatus for a short period of time and then repressurizing. Each pulse of vacuum is typically maintained for 2 minutes. Applying at least one pulse, and up to three pulses, of vacuum results in the most efficient product infusion.
In the hybrid infusion method, vacuum infusion is preferably performed after a time of infusion at atmospheric pressure in order to protect the product's cell walls. Applying vacuum before the product has been infused to some degree damages the cell walls of the product, leading to increased oil absorption during farther processing. Therefore, strengthening the product from solute build-up during the atmospheric phase and then subjecting the product to vacuum infusion allows for a stronger product in a shorter overall time. A period of vacuum infusion following the atmospheric infusion phase is preferred in order to infuse the product with solids more efficiently. Upon the depressurization, gas contained between the cell walls of the product is evacuated. When the vacuum is released, repressurization causes the product to take in solids from the infusion solution to fill the spaces gas previously occupied.
Once infusion is complete, the infusion solution is drained from the apparatus. A vacuum may be applied during draining, preferably after the bulk of the solution has been removed and the product has settled onto the U-shaped conveyor. In a preferred embodiment, the pressure of the apparatus is lowered, for example, to about 400-600 torr, through a vacuum port for a brief period of time, for example, about 2-5 minutes. This brief period of gentle vacuum allows for the removal of any excess solution on the surface of the product, resulting in decreased sugar buildup in the downstream dehydration operations. The product is then removed from the apparatus for downstream operations.
An apparatus for the atmospheric, vacuum, or hybrid infusion of food pieces in accordance with one embodiment of the invention is shown in
In two different preferred embodiments of the invention, as shown in
The internal U-shaped conveyor 300 has opposed raised ends 302, 304 that form a trough 306 between the raised ends 302, 304. The U-shaped conveyor 300 is preferably made of meshed material, but may also be comprised of plastic or stainless steel roller chains positioned side by side, stainless steel woven mesh, plastic interlocking belting, or any other material that allows fluid to freely pass through the conveyor 300. The U-shaped conveyor 300 is supported and conducted by rollers. As an example, six rollers 308, 310, 312, 314, 316, 318 are shown in the drawings; however, fewer or additional rollers may be required in order to maintain the desired shape of the conveyor 300. The number of rollers and their placement will be known to those skilled in the art. The food pieces are deposited from the retractable inlet conveyor 200 onto the moving U-shaped conveyor 300 at receiving raised end 302. The pieces then proceed down the incline 320 of the U-shaped conveyor 300 to form a product bed in the trough area 306. The U-shaped conveyor 300 stops once the product has been spread out on the trough 306 and before it exits the U-shaped conveyor 300 at the discharging raised end 304.
After the desired amount of product has been introduced into the vessel 100, the retractable inlet conveyor 200 is removed from the vessel 100. The entrance door 116 is then tightly closed so that the vessel 100 is sealed from the external environment, thereby allowing for depressurization of the vessel. Other possible methods for introducing food pieces into the vessel 100 are, for example, by stationary inlet conveyor or rotary airlock.
Referring to
In an alternate embodiment of the invention, as shown in
In a preferred embodiment, the food pieces are subjected to atmospheric and vacuum infusion phases. The infusion solution 402 during the total residence of the product in the apparatus is maintained in the range of about 45° F. to 50° F., preferably at about 50° F., and a solute concentration of about 43 brix to 45 brix, preferably about 45 brix is also maintained. Maintenance of the desired temperature and concentration is accomplished by circulating the infusion solution 402 through an external system 408 that is in fluid communication with the vessel 100 by the inlet fluid port 404 and the outlet or exit fluid port 406, as shown in two different embodiments of the invention in
Draining and replacement of the fluid through the external system 408 is possible while the vessel 100 is at atmospheric pressure or under vacuum. Although not shown in the figures, a preferred embodiment of Applicants' apparatus uses a distribution pipe to route the inlet port 404 to a position above the trough 306 and the product bed for distribution of solution onto the top of the product bed by, for example, spray balls or spray nozzles. This introduction of the solution above the product bed assists with the agitation of the product bed, helps with product immersion, and provides a convenient means for cleaning the mixing mechanism. Thus, the preferred embodiment places the inlet port 404 above the trough 306.
Throughout the atmospheric and vacuum infusion phases, a mixing mechanism 500, positioned directly above the trough 306, is intermittingly lowered into the product bed. In a preferred embodiment, the mixing mechanism is a rectangular slab, but may be modified by those skilled in the art. By way of example, the rectangular slab of the mixing mechanism 500 may be constructed of constructed of stainless steel, TEFLON™ (polytetrafluoroethylene), ultra-high molecular weight polyethylene (UHMW), nylon, or other suitable materials known in the art. As shown in
The retaining walls 700, 702, preferably constructed of stainless steel, abut with and are aligned longitudinally with the elongated sides of the U-shaped conveyor 300 and extend its entire length above the solution fill line in a preferred embodiment of the invention, as shown in
When infusion is complete, the infusion solution 402 is drained from the vessel 100 through the outlet fluid port 406. As the infusion solution 402 drains, gravity causes the infused food pieces, floating or immersed in the solution, to settle on the trough 306 of the U-shaped conveyor 300. The retaining walls 700, 702 further ensure that the product will settle on the trough 306 as the product has no other direction to go. In a preferred embodiment, once the pieces have settled onto the trough 306, a brief period of vacuum is applied to remove any excess solution from the surface of the product.
Returning to
In two preferred embodiments of the invention, as shown in
The hybrid infusion of food pieces in the apparatus of the proposed invention allows for the removal of 10.0-15.0% of the moisture content of the pieces and the addition of 10.0-15.0% of solids. The following tables exemplify the results obtained under the process conditions as set forth above.
The apparatus may be easily cleaned in-place using methodologies well developed in the food industry.
The above described invention discloses a method and preferred embodiments of an apparatus for the hybrid infusion 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.
