WO2013108283A1

WO2013108283A1 - Roasting method and roasting apparatus using such a method

Info

Publication number: WO2013108283A1
Application number: PCT/IT2013/000016
Authority: WO
Inventors: Fernando Mauro NAPOLI; Angelo Napoli
Original assignee: Ing. Napoli & C. Industrie Riunite S.R.L.
Priority date: 2012-01-20
Filing date: 2013-01-18
Publication date: 2013-07-25
Also published as: AU2013210650A1; ITRM20120021A1; EP2804486A1

Abstract

The present invention concerns a roasting method, comprising the following steps: (A) providing a roasting oven of a product, such as coffee, barley or the like, provided with a temperature sensor; (B) providing heat generating means; (C) setting the total duration (t_cycle) of the roasting process; (D) setting roasting or cooking final temperature (T_Final) of said product; (E) providing a temperature ideal curve (I) of said product normalized with respect to said roasting or cooking final temperature (T_Final); (F) carrying out a plurality of detections of said product temperature (T_Product) during said total roasting time interval (t_cycle) by means of said temperature sensor; and (G) for each detection, comparing the detected temperature of said product (Tpr0duct) and the ideal temperature according to said temperature ideal curve (I), such that: if the detected temperature of said product (T_Product) is greater than the temperature obtained by said ideal curve (I), and the temperature difference is greater than a first threshold, then the heat introduced into said product roasting oven, by means of said heat generating means is reduced; and if the detected temperature of said product (T_Product) is lower than the temperature obtained by said ideal curve (I), and the temperature difference is greater than a second threshold, then the heat introduced into said product roasting oven, by means of said heat generating means is increased. The present invention concerns even a roasting apparatus.

Description

ROASTING METHOD AND ROASTING APPARATUS USING SUCH A

METHOD.

The present invention relates to a roasting method and roasting apparatus using such a method.

More specifically, the invention concerns a method and related apparatus studied and realized, in particular, to allow an optimal roasting of coffee, regardless of the number of roastings already carried out.

In the following, the description will be directed to coffee roasting, but it is clear that the same should not be considered limited to this specific use.

As it is well known, for properly roasting the coffee a time which is as close as possible to 15 minutes is needed, in order to avoid that the coffee bean can remain internally raw, if roasted for a shorter time, or may dry out excessively, in case of prolonged or to an excessive temperature roasting, in both cases losing all the organoleptic properties. Other products include various time intervals for their ideal roasting.

Considering now the roasting of coffee, all the roasting apparatuses currently on the market have several problems to perform all the roastings within the same time preset interval, as, at the start, said apparatuses are cold and takes a longer time interval for roasting, while, as after some roastings, said apparatuses are heated and, therefore, are reduced increasingly roasting times.

It is considered that on the apparatuses currently on the market only the temperature to be achieved can be set. The apparatus continues the roasting until it reaches the preset temperature, using, just for the reasons stated above, for each roasting, a time interval that varies continuously.

Said apparatuses according to the prior art, to get as close as possible to the time interval ideal, that is 15 minutes provided for the coffee, or other time intervals for other products to be toasted, need to stabilize the starting temperature for each roasting, i.e. they must stop for a few minutes, cool and have a warm-up. When the pre-heating temperature reaches always the same value, then it is possible to start again a roasting process. In this way, however, al lot of time as well as energy is lost, as a preliminarily cooling phase and a later heating phase are needed.

This process is also required to avoid that the machines currently in production accumulate heat in the body (which is usually made of metal), which would otherwise significantly alter the temperature measurements by the sensor in the product roasting oven.

Other marketed machines do not adopt the cooling system between a roasting and the other, however, they have the drawback that, in carrying out the roasting, continually decreases the roasting average time, due to the heating of the chassis, which helps to provide the roasting oven additional heat in addition to that provided by the electricity or gas energy source.

This roasting time reduction deteriorates the quality of coffee or other products, because, in order to obtain a good roasting, each product has, as mentioned, its ideal cooking times.

Always in order to reduce the drawbacks mentioned above, some devices provide for an ON / OFF system of connection and disconnection of the electrical resistance or gas, whenever the temperature within the oven reaches the temperature set on a thermostat. However, this solution is not able to immediately stop the increase of the actual temperature to align it to the real one.

Furthermore, it is noted that for properly roasting food products, such as coffee, it would be appropriate that the temperature would follow a curve, i.e. a locus of points, function of time. In general such locus of points is a curve which typically has a parabolic shape, with a high slope at the beginning, which flattens in the final portion.

A problem is, therefore, to drive the heat generating means (e.g. the resistance) so that the temperature of the product follows said curve as accurately as possible.

In light of the above, it is, therefore, object of the present invention, to propose an apparatus capable to perform the roasting of coffee without interruption and without the need to stabilize the temperature at the start, reducing the time between one roasting and the subsequent one .

A further object of the present invention is also that the apparatus may be capable of driving the heat generating means of the roasting oven, so that the product is roasted according to the profile of ideal roasting.

These and other results are obtained according to the invention with a roasting method, which allows to roast always in the same desired time interval and at the desired temperature.

It is therefore specific object of the invention a roasting method, comprising the following steps: (A) providing a roasting oven of a product, such as coffee, barley or the like, provided with a temperature sensor; (B) providing heat generating means; (C) setting the total duration of the roasting process; (D) setting roasting or cooking final temperature of said product; (E) providing a temperature ideal curve (I) of said product normalized with respect to said roasting or cooking final temperature; (F) carrying out a plurality of detections of said product temperature during said total roasting time interval by means of said temperature sensor; and (G) for each detection, comparing the detected temperature of said product and the ideal temperature according to said temperature ideal curve, such that: if the detected temperature of said product is greater than the temperature obtained by said ideal curve, and the temperature difference is greater than a first threshold, then the heat introduced into said product roasting oven, by means of said heat generating means is reduced; and if the detected temperature of said product is lower than the temperature obtained by said ideal curve, and the temperature difference is greater than a second threshold, then the heat introduced into said product roasting oven, by means of said heat generating means is increased.

Always according to the invention, said first and/or said second threshold could be adjustable.

Still according to the invention, said step (G) could comprises the following substeps: dividing said ideal curve into a number N of time intervals, preferably of the same duration, indicated with the index n, with n = 1 ... N, so that said time segments identify N time instants, indicated with to ... t_n ... t with n = 0 ... N and -N equal to said total duration of the roasting process; approximating said ideal curve with a broken curve, obtained by joining the points of said ideal curve corresponding to the abscissae of said time instants, indicated with t₀ ... t_n ... t_N with n = 0 ... N; detecting, for each detection instant t of the temperature of said product, with t₀ < t <t , the actual passed time at the time t from the start of the roasting cycle, as a percentage of the cycle time, according to the equation: t_Passed(%) =—— -100; identifying which of the n time segments said detection instant t belongs, by the following equation:

; calculating the slope and the intercept of the straight line passing through the points of the ideal straight line corresponding to extremes instants of the interval t_n-i, t_n of said segment nsegment determined in the preceding step, given by the pairs of points (t_n- , T_n-i) and (t_n, T_n), where T_n is the temperature of said normalized ideal curve (I) at time t_n according to the system of equations:

T - T

Slope = 'n-1

'„ - „->

Intercept

with n comprised between 1 and N; calculating the value of the ideal temperature Ti (t) on said broken curve in each time instant t; and calculating the difference AT between said product temperature at each detection instant t of said product temperature, detected by said temperature sensor, and the ideal temperature at time t on said broken curve (Γ), given by Ti (t), after it has been multiplied by said final temperature, AT = T_Ptoducl(t) - T_r(t) - T_Final ; such that: if AT > 0 and if \AT\ is greater than said first temperature threshold, then the power supplied by said heat generating means is set equal to zero; and if AT < 0 and if [AT is greater than said second temperature threshold, then the power supplied by heat generating means is set equal to the maximum.

Advantageously, according to the invention, the supplied power could vary according any function when said temperature difference AT is between said first and said second threshold.

Further according to the invention, said first threshold could be equal to 0 °C, said second threshold could be equal to 10 °C and the power supplied by said heat generating means varies as follows: if AT is greater than said first threshold, then the power supplied by the resistance is set equal to zero; if AT is lower than 0 °C and the modulus of the temperature difference \AT\ is greater than said second threshold, then the power supplied by the resistance is set equal to 100%; if AT is lower than 0 °C and the modulus of the temperature difference \AT\ is lower than said second threshold, then the power supplied by the resistance, varies linearly in inverse proportion AT .

Always according to the invention, said function could provide that if said temperature difference = 0, then the power supplied to the resistance is set equal to a fraction of the maximum power, preferably equal to 50% of maximum power.

Still according to the invention, the number of said time intervals N is equal to 5 and said total duration of the roasting process tc_ycie is about

15 minutes.

Further according to the invention, said step (E) provides the selection of a temperature ideal curve (I) according to a plurality of preset curves.

It is further object of the invention a roasting apparatus comprising an oven for roasting a product, such as coffee, barley and the like, a temperature sensor, located within said roasting oven, adapted to detect the roasting or cooking temperature of said product, heat generating means, and a control logic unit, preferably programmable, operatively connected with said temperature sensor and with said heat generating means, said apparatus being characterized in that said control logic unit is adapted to run the roasting method above described. Always according to the invention, said apparatus could comprise interface means, such as a display and a keyboard, or a touch-on-screen display, operatively connected with said control logic unit.

Still according to the invention, said apparatus could comprise means for mixing said product arranged within said roasting oven.

Further according to the invention, said heat generating means could be electric or gas.

The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the enclosed figure, which shows a chart where an ideal cooking curve and the ideal approximate curve of the temperature of the product, for the execution of the method according to the present invention, are shown.

An roasting apparatus, particularly for roasting coffee, comprises, in general, a product roasting oven, which in this case is coffee, a temperature sensor or thermometer, placed inside the roasting oven in the product itself, so as to detect the temperature of the product during the cooking steps, means for mixing coffee beans, arranged inside said roasting oven, and cooking heat generating means, which are typically electrical or gas.

Said apparatus also includes a programmable control logic unit, provided with interface means, such as a display and a keyboard, or a touch-on-screen display.

Said control logic unit is operatively connected with said temperature sensor, with said cooking heat generating means and with said interface means.

By the interface means the total roasting time interval can be set, i.e. the time of the cooking cycle, that, in the case of coffee, based on empirical data and experiences, is generally 15 minutes, the maximum target roasting temperature and/or the final temperature, at the end of the cooking cycle, the product to be roasted and the detection time intervals of the temperature, typically about 1 second.

In this way, the apparatus, by a suitable method executed by said logic control unit, instantaneously calculates the remaining time necessary to reach the desired temperature instant-by-instant, and modulates the amount of heat to be supplied, so that the roasting takes place in the time preset, that in the present case, as mentioned, is 15 minutes, but which can be specifically set for other products, such as, in addition to coffee, barley and the like.

In other words, the control logic unit determines, also on the basis of data or of preinstalled curves, chosen even according to the type of product to be roasted, the ideal curve of the roasting temperature within said coffee roasting oven, such as that shown in the figure, identified by the letter I, to perform the ideal cooking, driving the heat generation means.

The reduction and the increase of the quantity of heat to be introduced into the product roasting oven does not take place simply as a result of the comparison of the detected temperature and the ideal one according to the ideal curve in the detection instants, just to avoid that the product temperature may exceed, due to the thermal not null resistance of the oven, that of the ideal curve, compromising the quality of the roasting.

The apparatus carries out, for each detection, the comparison between the ideal temperature, given by curve I, and drives the resistance based on one or more adjustment coefficients or thresholds, and the actual temperature measured.

These coefficients or adaptation thresholds can be fixed or variable. In this way, the product temperature is never (excessively) over the ideal temperature, thereby respecting, with good approximation, ideal temperatures and times and especially without compromising or damaging the product.

The operation of the apparatus of roasting described above is according to the following method.

With reference to the figure, an ideal roasting curve can be observed, which is settable with respect to the profile (shape of the curve, possibly distinct for different types of food to be roasted), in the time interval of the overall cooking and final temperature of cooking. An objective of the method according to the invention is to roast the coffee making as far as a possible optimal cooking, avoiding, at the same time, the risk that the product can burn.

As a first step of the roasting method , the form of the reset roasting normalized ideal curve is considered. This ideal curve I is normalized with respect to the roasting or cooking final temperature Tnnai. which is fixed or presettable. Said curve is stored in the memory of the roasting apparatus and it can be obtained in an empirical way, and in any case is known to the skilled person, on the basis of roasting experiences. Said ideal curve I is then divided into time intervals, preferably of the same duration, the number of which is indicated with the index n, with n = 1 ... N. As it can be seen, in the preferred embodiment of the method according to the present invention N=5.

The time segments identify N time instants, indicated by t₀...t_n...tN with n = 1 ... N and tN equal to the cycle time tc_ycie- The cycle time tc_ycie, i.e. the total duration of the roasting process, can be set by the user. In this case, the ideal curve I does not change its shape, it varies the proportion among the different ordinates: the N intervals then proportionally lengthen, and then the entire curve. For example, for roasting coffee is used, as said above, a tc_ycie = 15 minutes.

However, according to specific environmental requirements (humidity degree, external temperature, season, etc.) or of the product (differences between mixtures of coffee to be roasted, etc.), tc_ycie can be changed by the user, i.e. increased or decreased.

As a result of the above, the ideal curve I is approximated with a broken curve Γ, obtained simply by joining the points of the curve I corresponding to the abscissae of temporal segments, i.e. to...tN.

During roasting continuous detections of the temperature T of the product are carried out, typically every second, and usually with time intervals very lower than t_n-t_n-i .

Therefore, in the second step of the specified method, when a detection is made at any instant t, of course with to < t <†N (t can exceed tN, in which case the curve is extended and the final temperature is assumed constant) the actual passed time at time t since the start of the roasting cycle is detected, i.e. from t₀, as a percentage of the cycle time, according to the following equation: tpassed(%) ~ ~ ^ ^

^Cicie

In the third step, it is identified to which of the n time segments (5 in this case) the detection instant t belongs, using the following equation:

which of course provides the integer given by n, as number of the time interval to which t belongs.

In a fourth step, once the time interval n to which the detection instant t belongs has been found, the slope and intercept of the straight line passing through the points on the line ideal I are calculated, corresponding to the extremes instants of the time interval t_{n -}i, t_n, given by the pairs of points (t_n-i, T_n-i) and (t_n, T_n), where T_n is the temperature (normalized) on the ideal curve at the instant t_n, i.e.:

T - T

Slope =

Intercept = 7

Γ„_,— ^ ⁿ-t_t with n varying between 1 and N.

With this straight line, the value of the ideal temperature (always a normalized percentage with respect to the final temperature of the roasting or cooking cycle Tpinai) on the broken curve I' is calculated, which is an approximation of the ideal curve I, at time t for detecting the temperature of the product, indicated with T>(t).

The use of a broken curve I' to approximate an ideal curve I is for practical simplicity of the operator. In fact, in case of it is necessary to insert such ideal curve I through the use of a keypad or interface means in general, with the proposed method, the operator will be able to set a curve

I', by inserting only 5 numbers. These numbers, among other things, may be recorded or printed as an indication on the package of the product to be roasted, communicated by phone, etc..

In the fifth step of the roasting method according to the invention, the difference between the temperature of the product at the time instant t is calculated, given by Tp_roduct (t), detected by the temperature sensor within the product, and the ideal temperature at time t on the broken curve Γ, Ti(t), after it has been multiplied by the final temperature set, i.e. obtaining an absolute value and not as a result of normalization:

T = ^TProduc,( - Tr( - T_Final

At this point the sixth step provides that, if the temperature of said product Tproduct is greater than the temperature obtained by the broken curve Γ (with a preferred embodiment in which the temperature difference is greater than a first threshold), then the heat introduced in said product roasting oven, by means of said heat generating means is decreased; while, if the temperature detected of said product T_Pr0duct is less than the temperature obtained by the broken curve Γ (with a preferred embodiment in which the temperature difference is greater than a second threshold), then the heat introduced into said product roasting oven, by means of said heat generating means is increased.

In particular, in one embodiment of the method according to the invention, said first threshold is equal to 0 °C, while said second threshold is equal to 10 °C and the function is as follows:

- If Δ > 0 (first threshold), then the power supplied by the resistance is set equal to zero;

- If AT < 0 and \AT\ > 10 °C (second threshold), then the power supplied by the resistance is set equal to 00%;

- If AT < 0 and \AT\ < 10 °C (second threshold) then the power supplied by the resistance, varies linearly in inverse proportion AT .

Moreover, in a further embodiment, the above mentioned function provides that AT= 0, then the power supplied to the resistance is set equal to 50% of maximum power. This in order to compensate the heat losses and to allow the product to get closer to the desired temperature in a gradual way. In any case, other functions may be provided.

The heat generating means receive the command from said control logic unit to supply more or less heat, by modulating the percentages of operation, from 0% to 100%, of supplying output power, according to the greater or lesser need to accelerate or reduce the roasting time.

An advantage of the present invention is that the apparatus, although starting with any roasting oven temperature, high or low, can carry out an excellent roasting, as the apparatus will modulate the amount of heat to reach the desired temperature in the optimal time set, which, as mentioned above, in the case of coffee is 15 minutes.

The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that modifications and/or changes can be introduced by those skilled in the art without departing from the relevant scope as defined in the enclosed claims.

Claims

1. Roasting method, comprising the following steps:

(A) providing a roasting oven of a product, such as coffee, barley or the like, provided with a temperature sensor;

(B) providing heat generating means;

(C) setting the total duration (tc_ycie) of the roasting process;

(D) setting roasting or cooking final temperature (T_Fi_nai) of said product;

(E) providing a temperature ideal curve (I) of said product normalized with respect to said roasting or cooking final temperature

(TFinai);

(F) carrying out a plurality of detections of said product temperature ( product) during said total roasting time interval (t_CyCie) by means of said temperature sensor; and

(G) for each detection, comparing the detected temperature of said product (Tproduct) and the ideal temperature according to said temperature ideal curve (I), such that:

- if the detected temperature of said product (Tp_roduct) is greater than the temperature obtained by said ideal curve (I), and the temperature difference is greater than a first threshold, then the heat introduced into said product roasting oven, by means of said heat generating means is reduced; and

- if the detected temperature of said product (T_Pr0Ciuct) is lower than the temperature obtained by said ideal curve (I), and the temperature difference is greater than a second threshold, then the heat introduced into said product roasting oven, by means of said heat generating means is increased.

2. Method according to claim 1 , characterized in that said first and/or said second threshold are adjustable.

3. Method according to anyone of the preceding claims, characterized in that said step (G) comprises the following substeps:

- dividing said ideal curve (I) into a number N of time intervals, preferably of the same duration, indicated with the index n, with n = 1 ... N, so that said time segments identify N time instants, indicated with to ... t_n ... tN with n = 0 ... N and tn equal to said total duration of the roasting process

(tcycle)!

- approximating said ideal curve (I) with a broken curve (Γ), obtained by joining the points of said ideal curve (I) corresponding to the abscissae of said time instants, indicated with to ... t_n ... t_N, with n = 0 ... N;

- detecting, for each detection instant t of the temperature of said product (Tproduct), with to < t <t_N, the actual passed time at the time t from the start of the roasting cycle, as a percentage of the cycle time, according to the equation: tpassed(%) ⁼ ~ ^ 00

- identifying which of the n time segments said detection instant t belongs, by the following equation:

5 - calculating the slope and the intercept of the straight line passing through the points of the ideal straight line (I) corresponding to extremes instants of the interval t„-i , t_n of said segment n_Segment determined in the preceding step, given by the pairs of points (t_n-i , T_n-i) and (t_n, T_n), where T_n is the temperature of said normalized ideal curve (I) at time t_n according to o the system of equations:

T - T.

Slope = ' n-1

Intercept = T„__l -^-^t„__] with n comprised between 1 and N;

- calculating the value of the ideal temperature TY(t) on said broken curve (Γ) in each time instant t; and

5 - calculating the difference AT between said product temperature at each detection instant t of said product temperature (Tp_r0duct), detected by said temperature sensor, and the ideal temperature at time t on said broken curve (Γ), given by TY(t), after it has been multiplied by said final temperature (T_Fina,), AT = Τ_ηοΛια (t) - T_{, (t ) · T_Final ;

such that:

- if Δ > 0 and if \AT\ is greater than said first temperature threshold, then the power supplied by said heat generating means is set equal to zero; and

- if Δ < 0 and if |Δ | is greater than said second temperature threshold, then the power supplied by heat generating means is set equal to the maximum.

4. Method according to claim 3, characterized in that the supplied power varies according any function when said temperature difference AT is between said first and said second threshold.

5. Method according to claim 4, characterized in that said first threshold is equal to 0 °C, said second threshold is equal to 10 °C and the power supplied by said heat generating means varies as follows:

- if Δ is greater than said first threshold, then the power supplied by the resistance is set equal to zero;

- if Δ is lower than 0 °C and the modulus of the temperature difference |Δ | is greater than said second threshold, then the power supplied by the resistance is set equal to 100%;

- if Δ is lower than 0 °C and the modulus of the temperature difference |Δ | is lower than said second threshold, then the power supplied by the resistance, varies linearly in inverse proportion Δ .

6. Method according to claim 5, characterized in that said function provides that if said temperature difference = 0, then the power supplied to the resistance is set equal to a fraction of the maximum power, preferably equal to 50% of maximum power.

7. Method according to anyone of the preceding claims, characterized in that the number of said time intervals N is equal to 5 and said total duration of the roasting process tc_ycie is about 15 minutes.

8. Method according to anyone of the preceding claims, characterized in that said step (E) provides the selection of a temperature ideal curve (I) according to a plurality of preset curves.

9. Roasting apparatus comprising

an oven for roasting a product, such as coffee, barley and the like, a temperature sensor, located within said roasting oven, adapted to detect the roasting or cooking temperature of said product,

heat generating means, and

a control logic unit, preferably programmable, operatively connected with said temperature sensor and with said heat generating means,

said apparatus being characterized in that said control logic unit is adapted to run the roasting method according to claims 1-8.

10. Apparatus according to claim 9, characterized in that it comprises interface means, such as a display and a keyboard, or a touch- on-screen display, operatively connected with said control logic unit.

11. Apparatus according to anyone of claims 9 or 10, characterized in that it comprises means for mixing said product arranged within said roasting oven.

12. Apparatus according to anyone of claims 9 - 11 , characterized in that said heat generating means are electric or gas.