FIELD OF THE INVENTION

The present invention relates to a method and system for producing a viscous intermediate fruit product from a precursor fruit product, wherein the intermediate fruit product contains a high proportion of fruit and is suitable for forming into a consumable end fruit product.

BACKGROUND OF THE INVENTION

Increasingly, consumers are concerned about eating healthily. Generally, consumers associate eating healthily with consuming fruit snacks that contain a high proportion of fruit. Such fruit snacks are often perceived as being healthier than fruit snacks that contain additives such as processed or refined sugars, starches, gelatins, gums and preservatives. An example of fruit snacks containing a high proportion of fruit is Sun-Rype™ Products Ltd.'s ("Sun Rype's") "Fruit To Go"™ line of fruit snacks.

In order to produce a consumable end product containing a high proportion of fruit (i.e., the fruit snack), raw materials forming a precursor fruit product can be transformed into an intermediate product having appropriate properties for forming into the end product. In particular, it is helpful if the intermediate product has certain physical properties, such as a sufficient viscosity, suitable for mechanical forming into the end product. There are a number of challenges in manufacturing a product having a high concentration of fruit. Such challenges include:

• cooking the precursor product in slurry form at too high a temperature or moving the slurry through processing equipment at too high a temperature may bum or discolour the slurry, and could consequently negatively affect the flavour, colour, texture, and shape of the resulting end fruit product;

• cooking the slurry increases its Brix level, which consequently increases the slurry's thickness, or viscosity. Increased viscosity makes the slurry prone to clogging the pipes and equipment used during cooking; and

• the increased Brix level, along with the high proportion of fruit content, increases the slurry's stickiness. Increased stickiness makes the slurry prone to sticking to equipment and makes the resulting fruit snack prone to sticking to its wrapping and to consumers' fingers and faces.

These problems can be greatly reduced when cooking a slurry that is not composed of a high proportion of fruit, as the additives typically found in such slurries, such as gelatins, starches, and refined sugars, can be used to create a slurry with a high Brix content at lower cooking temperatures and that is not as sticky or viscous as a slurry containing a high proportion of fruit.

Consequently, there is a need for a method and system for manufacturing a viscous intermediate fruit product suitable for mechanical forming into a consumable end product composed of a high proportion of fruit and formed from a precursor fruit product slurry.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide at least one of a system or method for cooking a slurry composed of a high proportion of fruit that addresses at least one of the problems of the prior art.

According to a first aspect of the invention, there is provided a method of cooking viscous fruit product composed of a high proportion of fruit from a fruit based slurry. By "high proportion of fruit", it is meant that the fruit based slurry can have between about 50% to about 100% fruit material; alternatively about 60% to about 100% fruit material; alternatively about 70% to about 100% fruit material; alternatively about 80% to about 100% fruit material; alternatively about 90% to about 100% fruit material; or alternatively about 100% fruit material. In this application, "fruit" or "fruit material" includes any material derivable from fruit, including isolated pectin, but excludes non-fruit materials such as refined sugars, starches, and oils.

The method comprises heating the slurry in a heat exchanger; and subjecting the slurry to a vacuum in a vacuum chamber, the vacuum removing moisture from the slurry. The viscous fruit product may be composed of 100% fruit.

According to a still further aspect of the invention, the slurry can have an initial Brix level of about 50° Brix and an initial pH of about 3.8. The slurry can flow into the heat exchanger at a rate of about 600 kg/hour and can be heated for a duration of about 30 seconds. The slurry can be heated by the heat exchangers such that the temperature of the slurry in the vacuum chamber can be between about 90 ⁰ C and about 96 ⁰ C, and remains in the vacuum chamber for a duration of about 10 seconds. The pressure in the vacuum chamber can be about -0.55 Bar. The resulting viscous intermediate fruit product has a Brix level of about 84 °Brix to about 88 °Brix.

According to an alternative aspect of the invention, the slurry can be heated by the heat exchangers such that the temperature of the slurry in the vacuum chamber can be between about 105 ⁰ C and about 108 ⁰ C. The pressure in the vacuum chamber can be about -0.3 Bar and can remain in the vacuum chamber for a duration of about 20 seconds. The resulting viscous intermediate fruit product has a Brix level of about 84 °Brix to about 86 °Brix. According to a still further aspect of the invention, there is provided a system for cooking viscous fruit product having a high proportion of fruit from a fruit based slurry. The system comprises a heat exchanger, the heat exchanger heating the slurry to promote evaporation; and a vacuum chamber fluidly coupled to the heat exchanger, the vacuum chamber extracting moisture from the slurry. The viscous fruit product may be composed of 100% fruit.

The vacuum chamber may comprise either an auger, the auger extracting the slurry from the vacuum chamber when rotated, or a positive displacement pump, the pump pumping the slurry from the vacuum chamber when operating. Beneficially, the auger allows higher pressures to be used in the vacuum chamber, consequently allowing temperatures in the heat exchanger to be reduced, thereby mitigating the unpleasant effects that relatively high temperatures can have on the slurry (e.g.: caramelization).

The system may further comprise a holding tank fluidly coupled to the heat exchanger, the tank holding the slurry prior to feeding it to the heat exchanger.

Additionally, the system may have mass flow pumps for metering the flow of the slurry; the pumps are disposed intermediate the holding tank and the heat exchanger and fluidly coupled thereto. The system can also have a three-way valve following and fluidly coupled to the vacuum chamber, the three-way valve operable to divert excess slurry out of the system. A booster pump can be disposed downstream of the vacuum chamber.

Advantagously, the system and method can be used in a continuous, as opposed to a batch, process for cooking viscous fruit product. In other words, the combination of the heat exchangers and the vacuum chamber allow the system and method to cook viscous fruit product without interruption, which allows for a viscous fruit product of a consistent quality to be created. This is in contrast to a batch process, wherein due in part to the long residence time of the viscous fruit product in the processing line equipment and due to changes in processing conditions between batches, the quality of the cooked viscous fruit product between batches may not be consistent.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:

Figure 1 is a schematic view of a system for manufacturing a viscous intermediate fruit product ("kitchen") from a precursor fruit product slurry, wherein the intermediate fruit product is suitable for forming into a consumable end product having a high proportion of fruit.

Figure 2 is top plan view of the kitchen.

Figure 3 is a side elevation view of a portion of the kitchen.

Figure 4 is a front elevation view of the portion of the kitchen.

Figure 5 is a flow chart depicting steps of an exemplary method for manufacturing the intermediate fruit product.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring generally to Figures 1 - 4, and according to a first embodiment, a system 100 ("kitchen") is provided for manufacturing an intermediate fruit product from a precursor fruit product. The precursor fruit product is in a slurry form (hereinafter referred to as "slurry"), and the intermediate fruit product is viscous and has other physical properties suitable for mechanical forming into a consumable end fruit product.

The slurry can be made of a variety of ingredients, and its composition will vary depending on the desired properties of the end product. In this first embodiment, the slurry is made exclusively of fruit product and is 100% fruit. Generally, the slurry can contain various concentrations of fruit puree concentrates, such as apple, pear, or strawberry puree concentrate, various juice concentrates, pectin, and ascorbic acid. These ingredients are mixed together in a mixing tank (not shown) such that the resulting slurry is roughly 50 °Brix and has a pH of roughly 3.8. Following mixing, the resulting slurry is transferred to a holding tank 1 to await further processing.

From the holding tank 1 , the slurry is pumped out of the tank 1 so that the cooking process can begin. In this exemplary embodiment, such pumping is accomplished by two mass infeed pumps 3, 4. Suitable mass infeed pumps 3, 4 are positive displacement pumps. The flow rate of the pumps 3, 4 can be monitored and controlled using a flowmeter. In this exemplary embodiment, the flow rate of the slurry through each pump 3, 4 is approximately 600 kg/hour. Each pump 3, 4 feeds the slurry into one of two scrape surface heat exchangers 13, 19 from the holding tank 1 via mass infeed pipes; the heat exchangers 13, 19 may be operated in "bottom-up" mode. The temperature in the heat exchangers 13, 19 will vary with the residence time of the slurry in the exchangers 13, 19. The residence time of the slurry within the heat exchangers 13, 19 is about 30 seconds.

When the slurry exits the heat exchangers 13, 19, it is sucked into a vacuum chamber 22. The purpose of the vacuum chamber 22 is to remove moisture from the slurry so as to elevate the Brix content of the slurry. The vacuum chamber 22 in the depicted exemplary embodiment is set to produce a vacuum of -0.55 Bar. The heat exchangers 13, 19 heat the slurry such that the temperature measured in the vacuum chamber 22 is between 90 ⁰ C and 96 ⁰ C. The vacuum of -0.55 Bar is sufficient to draw the slurry into the vacuum chamber 22 from the heat exchangers 13, 19 without employing any kind of additional pump or motor. The residence time of the slurry through the vacuum chamber 22 is minimal (on the order of about 10 seconds) in that the slurry enters the vacuum chamber 22, falls through the vacuum chamber 22, and is then forthwith extracted from the vacuum chamber 22 via a discharge auger 23. The discharge auger 23 is powered by a motor 21 that rotates the auger 23 at a frequency such that the slurry is removed from the vacuum chamber 22 approximately as fast as it enters the vacuum chamber 22. The flow rate of the slurry as it leaves the vacuum chamber 22 is approximately 11.5 kg/min when each heat exchanger 13, 19 is feeding slurry to it at a rate of 600 kg/hr, for a total rate of 1 ,200 kg/hr.

Generally, it is advantageous to use the highest vacuum level possible in the vacuum chamber 22 so long as the slurry can be successfully extracted from the vacuum chamber 22. A higher vacuum level allows more moisture to be extracted from the slurry at any given temperature, and consequently allows the temperature used in the heat exchangers 13, 19 and vacuum chamber 22 to be reduced, thus obviating problems, such as discolouration, burning, and undesirable changes in flavour and texture that result from overcooking the slurry.

Schematically represented in Figure 1 are a condenser 26 and a vacuum source 28. The condenser 26 accepts evaporated moisture from the vacuum chamber 22 and condenses it into liquid water for disposal. The vacuum source 28 generates the vacuum used in the vacuum chamber 22.

Following the vacuum chamber 22, the creation of a viscous fruit product suitable for shaping into fruit snacks is complete; such a viscous product is considered an intermediate product, as the viscous product will still have to be mechanically formed into a suitable end product. The viscous fruit product can, for example, be formed into slabs for cutting into strips, extruded and cut into elongated rope- like products or smaller bite-sized pieces, or used to form a bar shaped end product. The intermediate fruit product has a Brix level of approximately 84 - 88 °Brix. Overall, the viscous fruit product is not too sticky, is not too chewy, has good flavour and colour, and is not burnt nor caramel tasting. Optionally, following and fluidly coupled to the auger 23 can be a three-way valve 40 that is coupled to a booster pump 41 and a drain 39. In the event that the pressure in the piping of the kitchen 100 increases to a level such that it becomes desirable to vent the viscous fruit product to prevent damage to the piping, the three-way valve 40 can be set to divert the viscous fruit product out through the drain 39, thus alleviating pressure in the piping. Optionally, the three-way valve 40 can also be used to vent the viscous fruit product if the Brix level of the fruit product has not yet reached a desired level, so as to aid in ensuring that only fruit product of the desired Brix level is conveyed downstream of the three-way valve 40.

Following the vacuum chamber 22 the viscous fruit product can be conveyed directly to the booster pump 41. The booster pump 41 propels the viscous fruit product downstream where, for example, it may undergo further processing. The booster pump 41 can be a positive displacement pump that pumps at about 690 kg/hr. In the depicted embodiment wherein the auger 23 is used to extract slurry from the vacuum chamber 22, the booster pump 41 is configured to pump at a rate such that the back pressure exerted on the auger 23 by the slurry is less than 2 Bar. If the back pressure is greater than 2 Bar, the auger 23 may be incapable of extracting slurry from the vacuum chamber 22 and the flow of the slurry through the kitchen 100 will cease.

While the above text describes the operation of one embodiment of the kitchen 100 in steady-state, prior to entering steady-state operation certain start-up steps that transition the kitchen 100 from a non-operational state to steady-state should be followed. These steps include:

l. Heat the vacuum chamber 22, discharge auger 23, booster pump

41 and associated pipeworks to a temperature of about 95°C. These items can be heated using, for example, steam jacketing. 2. Set the three-way valve 40 to divert all slurry out to the drain 39. This allows the auger 23 to discharge slurry from the vacuum chamber 22 without being subjected to any back pressure.

3. Pre-heat the heat exchangers 13, 19 to about 85 ⁰ C. 4. Pump slurry from the holding tank 1 to the heat exchangers 13, 19 using the mass infeed pumps 3, 4 at a rate of approximately 630 kg/hour.

5. Operate the auger 23 at approximately 725 kgs/hr and the booster pump 41 at approximately 905 kgs/hr, and slowly and repeatedly apply and remove the vacuum of -0.55 Bar to the vacuum chamber

22 until the auger is primed. As the auger 23 is not subject to any back pressure, the slurry will prime the auger 23, which will allow it to extract slurry from the vacuum chamber 22 when the kitchen 100 is operating in steady-state. If the auger 23 is not primed, cavitation will occur and the slurry will not properly discharge from the vacuum chamber 22.

6. Following priming of the auger 23, set the three-way valve 40 to divert slurry to the booster pump 41 instead of the drain 39.

7. Increase the temperature of the heat exchangers 13, 19 to their steady-state value such that the temperature of the slurry within the vacuum chamber 22 is between about 90 - 96°C.

8. Sample the slurry exiting the kitchen 100 for Brix. When the slurry has reached a Brix content of 84 - 88 °Brix, the kitchen 100 can be transitioned entirely to steady-state. Alternative Embodiments

Alternatively, and according to a second embodiment, instead of using the auger 23, a pump (not shown), such as a positive displacement pump, can be used to pump the slurry from the vacuum chamber 22. As the inlet of this pump is considerably smaller than the auger 23 surface area inside the vacuum chamber, it is not able to extract slurry from the vacuum chamber 22 at the same volume as the auger 23, and the vacuum chamber 22 is consequently operated at a lower vacuum pressure when used in conjunction with the pump as opposed to the auger 23. Operating the chamber 22 at a lower pressure allows the product to free fall into the pump inlet. As opposed to the -0.55 Bar vacuum that is possible when the auger 23 is used, a vacuum no larger than -0.3 Bar, for example, should be used if the pump is used to extract slurry from the vacuum chamber 22. The residence time of the slurry within the vacuum chamber 22 in this alternative embodiment is about 20 seconds. Consequently, with a lower vacuum, a higher slurry temperature is needed in the vacuum chamber 22 in order to extract the desired amount of water. At a vacuum of -0.3 Bar, the heat exchangers 13, 19 can be heated such that the temperature measured in the vacuum chamber is between 105 - 108 ⁰ C. The resulting viscous intermediate fruit product of this alternative embodiment has a Brix level of about 84 °Brix to about 86 °Brix. Aside from using the pump instead of the auger 23 to remove the slurry from the vacuum chamber 22 and the associated changes in process parameters, this alternative embodiment is much the same as the embodiment utilizing the auger 23, as described above.

As a consequence of using a vacuum of -0.3 Bar as opposed to a vacuum of - 0.55 Bar when utilizing the auger 23, the viscous fruit product that results from this alternative embodiment has a higher moisture content than that of the viscous fruit product produced using the embodiment having the auger 23. Consequently, during mechanical forming of the viscous fruit product, more drying of the viscous fruit product formed as a product of this alternative embodiment may be required than the viscous fruit product formed as a result of the embodiment utilizing the auger 23 and a vacuum of -0.55 Bar.

Figure 5 graphically depicts some of the steps involved in producing the intermediate fruit product as described with respect to the above embodiments.

As with the first embodiment of the kitchen 100, the above text relating to the second embodiment describes the operation of the second embodiment in steady-state operation. Prior to entering steady-state operation certain start-up steps that transition the kitchen 100 from non-operational to operating in steady- state should be followed. These steps include:

1. Heat the vacuum chamber 22, discharge auger 23, booster pump 41 and associated pipeworks to a temperature of about 95 ⁰ C These items can be pre-heated using, for example, steam jacketing.

2. Pre-heat the heat exchangers 13, 19 to about 107 ⁰ C.

3. Pump slurry from the holding tank 1 to the heat exchangers 13, 19 using the mass infeed pumps 3, 4 at a rate of 600 kg/hour. When the slurry enters the vacuum chamber 22, operate the pump that pumps slurry from the chamber at approximately 575 kgs/hr.

4. Increase the temperature of the heat exchangers 13, 19 to their steady-state temperature such that the temperature in the vacuum chamber is between about 106 - 108 ⁰ C.

5. Apply the vacuum of -0.3 Bar to the vacuum chamber 22. 6. When the level of slurry in the vacuum chamber 22 is approximately 6 inches deep, increase the frequency of the pump that pumps slurry from the chamber 22 to about 850 kgs/hr.

7. Sample the slurry exiting the kitchen 100 for Brix level. When the slurry has a Brix content of 84 - 86° Brix, the kitchen 100 can be transitioned entirely to steady-state.

While a particular embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention and are intended to be included herein. It will be clear to any person skilled in the art that modifications of and adjustments to this invention, not shown, are possible without departing from the spirit of the invention as demonstrated through the exemplary embodiment.