SE1051332A1

SE1051332A1 - Device and method for moisturizing edible products

Info

Publication number: SE1051332A1
Application number: SE1051332A
Authority: SE
Inventors: Kurt Spirig
Original assignee: Revent Int Ab
Priority date: 2010-12-16
Filing date: 2010-12-16
Publication date: 2012-06-17
Also published as: EP2651228A4; WO2012082060A1; SE535844C2; EP2651228A1

Abstract

lO ABSTRACT The invention relates to an arrangement (1) and a method for Cooling freshlybaked bread under a negative pressure, WhiCh arrangement includes avaCuum Chamber (2) WhiCh is adapted for reCeiving freshly baked bread forthe Cooling thereof; a vaCuum sourCe (3), suCh as a vaCuum pump, WhiCh isConneCted to the vaCuum Chamber (2) for exhausting ﬂuid from the vaCuumChamber (2) and Creating a negative pressure inside it. The arrangement alsoinCludes a steam generator (4) for produCing steam under a negativepressure, WhiCh steam is essentially free from air, Wherein the steamgenerator (4) is loCated in ConneCtion to the vaCuum Chamber (2), suCh thatgenerated steam may be introduCed into the Chamber substantially Withoutsimultaneous introduCtion of air. (Fig. 2)

Description

lO ARRANGEMENT AND METHOD FOR REHYDRATING EDIBLE PRODUCTS TECHNICAL FIELD The invention relates to an arrangement and a method for Cooling Warmedible products such as freshly baked bread or recently cooked food.Especially, the invention relates to an arrangement where edible productsare cooled in a chamber under sub atmospheric pressure and eventuallyrehydrated in the same chamber.

BACKGROUND In the conventional bread baking industry freshly baked breads are allowedto cool on racks somewhere close to the ovens. This is however a timeconsuming and ineff1cient way of cooling bread. An effective way of coolingthe bread more rapidly is to use vacuum. Today vacuum cooling of bread iswidely used. Apart from the fact that vacuum cooling saves time and place, itis also beneficial in view of the properties obtained by the vacuum cooledbread. For example, vacuum cooled bread stays fresher for a longer timethan a conventional rack cooled bread.

By lowering the pressure, the boiling point of water is also lowered. A watercontaining product that is subjected to a negative pressure will lose part ofits water content to the surrounding medium. As a consequence of thatsteam is evaporated from the product, the product will be cooled. In acooling from 98°C to 28°C as much as 5-6% of the total weight of theproduct is lost due to the evaporated water.

For a bread product this may typically imply that the water content in thebread after the vacuum cooling is as low as about 8% in the crust of thebread, while the water content is about 47% in the central crumb of thebread and about 45% in the outer crumb. The relatively high water contentin the crumb of the bread helps to keep the bread fresh for a long time, andthe relatively low water content in the crust of the bread will keep theproduct crispy for a longer time and it will also help the bread product topreserve its shape for a longer time. A similar effect is achieved in pre-bakedproducts.

For some products this is however not advantageous. In products likesponge cakes, ﬂan cases, swiss roll breads, sliced breads, such as e.g. toastbreads, rye bread or wheat bread, it is instead desired to keep the watercontent as high as possible. lO For these kinds of breads methods of rehydrating the bread have beenelaborated, in Which Water or steam is sprayed onto the bread during thevacuum cooling or after the vacuum cooling has been concluded.

A problem With these conventional rehydration processes is that it is difficultcontrol the degree of rehydration and that it is likely that most of the steamWill stay on the surface of the bread and not penetrate into the crumb of thebread.

Therefore, there is a need of an improved rehydration process that offersbetter possibilities of rehydrating the bread.

SUMMARY An object of the invention is to provide an improved arrangement for coolingfreshly baked bread.

According to a first aspect the invention relates to an arrangement for coolingfreshly baked bread under a negative pressure, Which arrangement includes:a vacuum chamber Which is adapted for receiving freshly baked bread forthe cooling thereof; a vacuum source, such as a vacuum pump, Which isconnected to the vacuum chamber for exhausting ﬂuid from the vacuumchamber and creating a negative pressure inside it. Further, thearrangement also includes a steam generator for producing steam under anegative pressure, Which steam is essentially free from air, Wherein thesteam generator is located in connection to the vacuum chamber, such thatgenerated steam may be introduced into the chamber substantially Withoutsimultaneous introduction of air.

According to a second aspect the invention relates to a method of coolingfreshly baked bread under a negative pressure, Which method includes thesteps of placing freshly baked bread in a vacuum chamber for the coolingthereof; eXhausting ﬂuid from the vacuum chamber by means of a vacuumsource and creating a negative pressure inside the vacuum chamber. In afurther step, steam is introduced into the chamber, Wherein the steam isproduced under a negative pressure such that that the introduced steam issubstantially free from air When it is introduced into the chamber.

With the arrangement and the method according to the invention the steamWill be absorbed by the bread to a much higher degree than in aconventional re-hydrating process following a vacuum cooling. Further, themethod and arrangement is easily adapted to different types products andspecif1cations.

Preferred embodiments of the invention and its advantages will be apparentfrom the detailed description and the dependent claims.

SHORT DESCRIPTION OF THE DRAWINGS The invention, and further objects and advantages of it, is best understood from the following description with reference to the appended drawings, ofwhich: Fig. 1 is a schematic illustration of a first embodiment of the arrangementaccording to the invention; Fig. 2 is a schematic illustration of a second embodiment of thearrangement according to the invention; and Fig. 3 is a schematic illustration of the method according to the invention.DETAILED DESCRIPTION The invention relates to an arrangement for cooling freshly baked breadunder negative pressure and below the arrangement will be described withreference to figures 1 and 2.

The arrangement 1 shown in figure 1 includes a vacuum chamber 2 which isadapted for receiving freshly baked bread. Preferably the vacuum chamberhas racks for receiving standard baking plates. In the figure, nine pieces ofbread products 20 are distributed on three baking plates 21 which may belocated on racks inside the vacuum chamber, or individually mounted intracks on the inside walls of the chamber 2.

In one embodiment of the invention, the vacuum chamber 2 may alsofunction as an oven, such that the baking of the bread and the cooling of thebread may be performed in the same chamber. In order for the vacuumchamber to also function as an oven some adaptations need to be made to it.Firstly it must be constructed to withstand high temperature and further itneeds to be completed with adequate heating elements. These adaptationsare however obvious to a person skilled in the art and are therefore nottreated in detail in this description, especially since the invention concernsthe vacuum chamber, regardless of if it also involves an oven.

In order to create a negative pressure inside the vacuum chamber 2 avacuum source 3, e.g. in the form of a vacuum pump, is arranged inconnection to the vacuum chamber. The vacuum source 3 is used both foreXhausting ﬂuid from the vacuum chamber 2 and for creating the negativepressure inside it. Even though the term vacuum is used in this application, there will be no absolute vacuum inside the vacuum chamber. In absoluteterms the pressure inside will preferably be kept between 10 and 100 mBar.

An advantageous feature of the arrangement according to the invention isthat it includes a steam generator 4 for producing steam to be introducedinto the vacuum chamber. Further, the steam is produced under a negativepressure, such that the steam may be essentially free from air when it entersthe vacuum chamber 2. When the steam enters the vacuum chamber whenthere is still a negative pressure inside the chamber, the steam will be ableto penetrate deeper into the bread.

Conventionally, when vacuum cooled bread has been rehydrated this hasbeen done after the cooling has been concluded and after or simultaneouslyas the negative pressure inside the vacuum chamber has been released.Therefore, in conventional arrangements for rehydrating vacuum cooledbread, almost all of the steam or water gets stuck at the outer parts of thecrust, whereas the crumb is unaffected by the steam. Instead the negativepressure that has been established in the crumb of the bread will bebalanced by the air, which will penetrate into the crumb more easily thanthe steam.

In the arrangement according to the invention the steam generator 4 islocated in connection to the vacuum chamber 2, such that generated steammay be introduced into the chamber without simultaneous introduction ofair. This may be achieved in two general manners, which are individuallyrepresented in figure 1 and figure 2, respectively.

In the first embodiment of the arrangement according to the invention,which is shown in figure 1, the steam generator 4 is arranged in a separatechamber, in which the steam is produced under a negative pressure andsubsequently introduced into the vacuum chamber 2 in which the bread 20is being cooled. In this embodiment the steam generator is connected tovacuum source. Possibly, the same vacuum source 3 that creates thevacuum in the vacuum chamber 2 is connected to the steam generator 4.This is the case in the embodiment shown in figure 1, where the vacuumsource 3 is connected to the vacuum chamber 2 via first vacuum valve 6 andto the steam generator 4 via a second vacuum valve 7. Further, the steamgenerator 4 is connected to the vacuum chamber via a steam valve 9.

The steam generator 4 comprises a heating element 1 1 and at least onewater nozzle 5 directed towards said heating element 11. In the shownembodiment the heating element 11 consists of a heating spiral. Other typesof heating elements are however also possible. An important feature of theinvention is that a negative pressure may be established inside the steam generator 4 before the steam is produced. Hence, in a first step of the steamproducing process, the second vacuum valve 7 is opened in order to create anegative inside the steam generator 4 by means of the vacuum source 3. Inthe following step, after closure of the second vacuum valve 7, steam isproduced by spraying water from the nozzles 5 onto the heating element 11,whereupon the steam valve 8 is opened such that the steam will be suckedinto the vacuum chamber 2.

In the second embodiment, which is shown in figure 2, the steps of formingthe steam are somewhat different with respect to the first embodiment. Inthis embodiment the steam valve between the steam generator 4 and thevacuum chamber 2 may be omitted. Instead there is a direct contact betweenthe steam generator 4 and the vacuum chamber 2. In a not shown specificembodiment the steam generator 4 is even an integrated part of the vacuumchamber 2. Either way, the connection between the steam generator 4 andthe vacuum chamber 2 will make sure that the pressure will be the same inboth chambers. Hence, when water is sprayed onto the heating element 11the produced steam will directly ﬂow into the vacuum chamber and into thebread product 20.

Further, in a not shown embodiment of the invention, steam or hot watermay be introduced directly into the vacuum chamber 2 from nozzlesarranged inside the vacuum chamber 2.

In all of these embodiments the rehydration may be pressure controlled,such that the steam introduction into the vacuum chamber may beinterrupted at a product specific pressure. Hence, it will be possible tocontrol the relative water content in both the crust structure and the crumbof the bread.

Also, as a further step, steam may be introduced during the vacuum coolingprocess in order to reduce the loss of water and to improve the formation of asofter crust.

The degree of moisture in the bread does not only have an impact on thefinal product. In addition, it is also of importance for the subsequent processsteps. For example the formation of cracks in the crust will be reduced oreven totally eliminated if the steam pressure is controlled to not sink below acertain value. By cutting the surface of the bread product a lower weight lossin the crumb may be attained. This means that the packed product will havea higher weight, which is an advantage in most aspects.

In the following, the method according to the invention will be described withreference to the schematic stepwise illustration shown in figure 3. In this lO illustration necessary inventive steps are provided in closed rectangles, Whileadvantageous but not necessary method steps are provided in dashedrectangles.

In a first step (A) freshly baked bread products are provided into the vacuumchamber. In a second step (B) a negative pressure is established inside thevacuum chamber, in order to cool the bread products by evaporation ofWater from them. Further, in an optional step (C) the core temperature of thebread product may be monitored by means of a temperature sensor 12, i.e. athermometer, that is provided into core of the bread product, or Whereapplicable, one of the bread products 20. Preferably, the humidity inside thevacuum chamber 2 is monitored in another optional step (D) by means of ahumidity sensor 13, i.e. a hygrometer, and preferably the pressure inside thevacuum chamber 2 is monitored in yet another optional step (E) by means ofa pressure sensor 14.

By means of these three sensors the cooling process may be monitored andcontrolled throughout the Whole cooling process and individually adapted tothe type of product that is being cooled and to the desired properties of thecooled bread products.

The pressure and the humidity may be controlled jointly or separately, andthese values Will of course inﬂuence the core temperature of the breadproduct. The actual controlling of the parameters is of course something thatis individually performed for each type of product and is based on theoreticaland empirical parameters. In a specific embodiment of the invention, boththe monitoring and the controlling of the processing parameters is performedautomatically by means of a processing unit that is programmed to keep thepressure, humidity and core temperature Within threshold values.

When, the core temperature of the bread has reached below a certainthreshold value or When the bread product 20 has been cooled for apredetermined amount of time, steam Will be introduced into the vacuumchamber 2 in an inventive method step (F).

The first vacuum valve 6 should preferably be held closed as the steam isintroduced into the vacuum chamber 2, such that the steam is absorbed bythe bread product 20 and does not escape from the chamber 2 through saidfirst valve 6. Further, the pressure may be controlled to a certainpredetermined value before steam is introduced into the vacuum chamber 2.Preferably, steam is introduced into the chamber until a certainpredetermined threshold parameter is reached. This predeterminedthreshold parameter may be the monitored pressure value, the monitored lO humidity value, the monitored core temperature value, or any feasiblecombination of these parameters.

The vacuum cooling process is completed by the introduction of fresh airinto the vacuum Chamber 2 via the air valve 8. As the steam is introducedinto the vacuum chamber the pressure will increase as function of howmuch steam that is introduced, which of course is product dependent andcontrollable such that the bread product 20 attains the desired watercontent. There is however still a negative pressure inside the vacuumchamber after that the steam introduction is completed. This negativepressure is levelled out by the introduction of fresh air into the vacuumchamber 2.

An advantage of introducing the steam into the vacuum chamber 2 beforethe pressure is levelled out is that the steam will be absorbed by the bread toa much higher degree.

Above, the invention has been described with reference to specificembodiments. It is, however, obvious to a person skilled in the art that otherembodiments may be used to achieve the same result within the scope of theinvention. Hence, the invention is not limited by these embodiments; instead itis only limited by the appended claims.

Claims

1. An arrangement (1) for Cooling freshly baked bread under a negativepressure, WhiCh arrangement includes: - a vaCuum Chamber (2) WhiCh is adapted for reCeiving freshly bakedbread for the Cooling thereof; - a vaCuum sourCe (3), suCh as a vaCuum pump, WhiCh is ConneCted tothe vaCuum Chamber (2) for exhausting ﬂuid from the vaCuum Chamber (2)and Creating a negative pressure inside it; characterised in that the arrangement also inCludes a steam generator (4)for produCing steam under a negative pressure, WhiCh steam is essentiallyfree from air, Wherein the steam generator (4) is loCated in ConneCtion to thevaCuum Chamber (2), suCh that generated steam may be introduCed into theChamber substantially Without simultaneous introduCtion of air.

2. The arrangement (1) aCCording to Claim 1, Wherein the steam generator(4) Comprises a heating element (11) and at least one Water nozzle (5)direCted towards said heating element (11).

3. The arrangement (1) aCCording to Claim 2, Wherein the heating element(11) Consists of a heating spiral.

4. The arrangement (1) aCCording to any of the preCeding Claims, Whereinthe heating element (11) and the Water nozzle (5) are arranged in a separateChamber, WhiCh is ConneCted both to a vaCuum sourCe and to the vaCuumChamber (2).

5. The arrangement (1) aCCording to any of the Claims 1 to 3, Wherein theheating element (11) and the Water nozzle (5) are arranged inside thevaCuum Chamber (2).

6. The arrangement (1) aCCording to any of the preCeding Claims, furtherComprising a temperature sensor (12) for monitoring the temperature in theCore of the bread produCt (20).

7. The arrangement (1) aCCording to any of the preCeding Claims, furtherComprising a humidity sensor (13) for monitoring the relative humidity insidethe vaCuum Chamber (2).

8. The arrangement (1) aCCording to any of the preCeding Claims, furtherComprising a pressure sensor (14) for monitoring the pressure inside thevaCuum Chamber (2).

9. The arrangement (1) according to any of the claims 6-8, furthercomprising a control unit for controlling the introduction of steam into thevacuum chamber (2) in dependence of given parameter, the given parameterbeing one of the following: the temperature in the core of the bread product(20), the relative humidity inside the vacuum chamber (2), the pressureinside the vacuum chamber (2), or a combination thereof.

10. A method of cooling freshly baked bread under a negative pressure,Which method includes the steps of: - placing freshly baked bread in a vacuum chamber (2) for the coolingthereof; - eXhausting ﬂuid from the vacuum chamber (2) by means of a vacuumsource (3) and creating a negative pressure inside the vacuum chamber (2);characterised by a step of introducing steam into the chamber (2), Whereinthe steam is produced under a negative pressure such that that theintroduced steam is substantially free from air When it is introduced into thechamber (2).

11. The method according to claim 10, Which method further involves thestep of keeping the connection to the vacuum source (3) closed as steam isbeing introduced into the chamber (2).

12. The method according to any of the claims 10-11, further comprising astep of monitoring the temperature in the core of the bread product (20).

13. The method according to any of the claims 10-12, further comprising astep of monitoring the relative humidity inside the vacuum chamber (2).

14. The method according to any of the claims 10-13, further comprising astep of monitoring the pressure inside the vacuum chamber (2).

15. The arrangement (1) according to any of the claims 12-14, furthercomprising a step of controlling the introduction of steam into the vacuumchamber (2) in dependence of given parameter, the given parameter beingone of the following: the temperature in the core of the bread product (20),the relative humidity inside the vacuum chamber (2), the pressure inside thevacuum chamber (2), or a combination thereof.