JP2797101B2 - Food freshness monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a food freshness that can be used in an extremely wide range of fields from production to distribution and further consumption of foods whose freshness changes in relation to temperature and time. Monitoring method.

[Conventional technology]

For many processed foods, including fresh foods such as fish meat, vegetables, fruits, milk drinks, etc., it is important to maintain and manage the freshness of food at each stage of production, distribution and consumption.

Generally, the freshness of a food depends on its storage temperature and storage period. For example, for fish, transportation time and environmental temperature after being caught by a fishing boat and transporting it to the landing port,
After the landing, the handling environment in the production market, the transportation status to the central wholesale market, the distribution of goods from the consignee to the retailer through the middleman, the temperature in the retailer's showcase, the time history, the consumer's hand The freshness varies depending on the condition of storage in a refrigerator or the like after crossing, the condition of handling or leaving in a kitchen or dining table, and the like. In case of processed food, procurement as raw materials, storage status, individual stagnation status and processing status at the manufacturing site, intermediate products, product storage status,
The freshness varies depending on the storage temperature and the period depending on the temporary storage for shipping and distribution conditions. The same applies to the restaurant industry such as restaurants and school lunches.

The relationship between the storage temperature and the storage period of various foods can be determined empirically, by a sensory test such as gloss, color, and aroma, or by a chemical method such as K value (Note 1).
Furthermore, it is determined by a physical method such as electric resistance and the like, and the relationship of how many days it lasts at what degree Celsius, or the relationship of the allowable temperature time (TTT-Time Temperature Tolerance) is reported.

(Note 1) K value (%) = {(HxR + Hx) / (ATP + ADP + AMP + IMP + HxR-Hx)} x 100 where ATP: adenosine triphosphate ADP: adenosine diphosphate AMP: adenosine monophosphate IPM: inosinic acid HxR: inosine Hx: hypoxanthine However, the temperature and time environment where the individual foods are actually placed are the same, and it is rather rare that the same time elapses. It is normal that the temperature changes with time even in the same place, and that the food does not travel in the same place but travels in a plurality of places with different environments.

For example, a refrigerator in a kitchen has different internal temperatures between summer and winter, and is affected by the frequency of opening and closing, the tightness of doors, the heat load of stored items, the ventilation status depending on the storage state, the microbial contamination environment, and the like. Even in commercial refrigerated warehouses, since the handling of small lots of various types has increased in recent years, the residence time outside the warehouse (front room, elevator, platform, etc.) may become a problem in freshness management.

[Problems to be solved by the invention]

In contrast to the diversification of such food temperature environmental conditions, the determination of food freshness is still a subjective factor, and as a result, application management according to freshness, for example, raw food →
At present, confusion is also seen daily in the application categories according to the freshness of raw materials, such as half-life (tapping, vinegaring, etc.) → heating (boiling, baking → frying).

Conventional freshness management depends on the memory and intuition of the person in charge,
Or, it was performed by sampling check, etc., but as the number of entering and exiting the managed environment becomes more intense as recently, when individual products enter, under what temperature environment and how freshness becomes It is practically difficult to manage whether to go out. Also, even if you can see it directly with your eyes, if it is packed and it can not be checked,
In some cases, it may not be possible to verify the location.

Also, if the temperature is constant, it is reported that the freshness is always maintained as data, but when the temperature changes over time, it is actually inferred in the head from various examples of constant temperature. It is in full swing, with the danger of sometimes going far off.

Also, even if there is a problem with freshness, unless the freshness of incoming and outgoing is always known in the responsible area of each managed environment, the cause can not be tracked and it is always neglected . The end result is that users tend to choose quality only based on the trust of the ultimate supplier.

[Means for solving the problem]

The present invention has been made in order to solve the above-described problems, and a taste, a color, which changes in relation to temperature and time,
For various forms of freshness such as fragrance, touch, etc., follow the changes in the temperature environment at the place where each food is placed for each target food, while modifying it using known relational formulas so as to match. In principle, each freshness is carefully calculated in real time, and the temperature and freshness are constantly monitored so as not to deviate from a predetermined freshness range. In addition, when entering or leaving the environmental area to be managed, if necessary, a label that can be identified as the food concerned is attached, and these controls the freshness quantitatively without relying on conventional intuition and without losing the opportunity. By doing so, the freshness management system was clarified in a practical sense,
It aims to improve the freshness level and solve problems.

That is, the present invention uses the formula F (t) = F (0) exp (-kt) or F (∞)-｛F (∞) -F (0)｝ exp
(−kt) k = Aexp (−E / RT) where F (t): freshness of time t F (∞): final freshness t: time elapsed after production F (0): initial freshness A: constant depending on item E: activation energy depending on the item R: gas constant T: product temperature (absolute temperature) A, E is obtained by examining the time change of the freshness in advance for at least two product temperatures and substituting the result into the above equation. And the temperature of the food is determined over time, and is calculated as F (t) = F (0) exp {-A {exp (-E / RT) dt} or F (∞)-{F (∞)}. -F (0) {exp} -A {exp (-E / RT) dt} A method for monitoring the freshness of food, characterized by calculating the freshness of the food at present at the present time. Food temperature and freshness for each food group with the same temperature and time history when food is stored or passed in the course of work The present invention relates to a food management method characterized by providing initial setting conditions relating to a storage location and the like, and managing freshness of the food by obtaining freshness according to the above method until the food disappears from the environment.

In the present invention, the initial setting condition may be given by estimation or measurement, and the freshness may be calculated as relative freshness without giving the initial setting, and may be set later. The display may be printed or displayed on the screen, and any display method may be used as long as it can be displayed.

The relational expression used for the basic arithmetic method of the present invention is:
It must indicate freshness.

Hereinafter, first, a relational expression between temperature and time with respect to freshness will generally be illustrated within a range that can be practically used, and then a method of calculating freshness by following a temperature change every moment will be described.

1. Relationship between temperature and time with respect to freshness and its examples First, for the method of the present invention to be effective, although the concept of "freshness" of food is extremely complicated and varied depending on items and uses, etc. It is necessary for typical foods to be manageable with a typical measure of freshness, with a typical temperature-time relationship, and with practically acceptable accuracy.

For this verification, the following two publicly known materials shall be used. That is, Table 1 shows cited examples of two documents concerning the shelf life of a world-famous food. A in the table
The column shows the storage period of frozen food (shelf life based on storage temperature, that is, allowable temperature time), which is the historical trigger that the standard circulation temperature of frozen food becomes 0 ° F, that is, -18 ° C or less. In addition, it is test data from 1948 to 10 years based on the sensory evaluation of the allowable temperature time of frozen food by the United States Department of Agriculture Western Area Research Laboratory and Pasadena Laboratory, and it is data that this storage period can be used for food ( Kawabata, Haruta, Hosokai "Practical food hygiene", published by Chuo Law). Column B in Table 1 is a representative document that indicates the approximate shelf life of chilled (refrigerated) products in the secondary market.
This is an excerpt from HRAE HENDBOOK (1982 edition, USA) corresponding to column A in Table 1 (this document is also used by the Ministry of Health and Welfare in guidance materials for food stores and the food service industry).

The inventor has attempted to apply the Arrhenius law as a basic relationship between temperature and time. However, freshness of food includes various conceptual events such as the following items (1) to (5).

I. Not based on individual chemical reactions, but based on comprehensive sensory evaluation by humans.

B. There must be fundamental differences between animals, plants, and so on.

C. There is a difference in the state of systematic life and death as a living body.

D. There are differences between individuals.

E. The effect depends on the presence or absence of microbial contamination.

F. Differences in individual local environmental conditions (micrometeorological conditions such as temperature, humidity, carbon dioxide temperature, convection, and radiation).

G. The difference in the purpose of use as food (material) is the difference in freshness evaluation criteria.

Therefore, the present inventor used the following method in order to facilitate a comprehensive explanation.

For example, if the freshness of the food is the first (fresh vegetables and fruits at harvest, fresh fish at catch, fresh meat at slaughter, processed food at the time of manufacture, and foods requiring aging are aged At the end, etc.) it is 100%, and it is assumed that it gradually deteriorates and falls to 0%. That is, it is assumed that the freshness of the food is initially 100, and gradually decreases to 0 according to the Arrhenius rule as in the following equation (1). However, the food temperature is fixed.

F (t) = F (0) exp (−kt): (1) k = Aexp (−E / RT): (2) where F (t): freshness (%) of time t F (0): Initial freshness (%) k: Reaction rate constant A: Constant by item (1 / day) E: Activation energy by item (cal / mol) R: Gas constant = 1.986cal / ゜ K · mol T: Product temperature ( (Absolute temperature ゜ K) To display as starting from 0% and degrading to 100%, replace F (t) with 100-F (t),
The following equation (1) ′ is used instead of equation (1).

F (t) = 100− {100−F (0)} exp (−kt): (1) ′ In equation (1), how to obtain the freshness at the “first time”, ie, F (0) Thus, two types of freshness can be considered. In other words, when vegetables are harvested or processed foods are manufactured, the absolute standard for food is 100%. The relative freshness, which is what percentage is compared to the initial value of 100% when it enters, is considered.

If equation (1) is satisfied as a relation of freshness, F (t) is proportional to F (0) from equation (1), so even if the absolute freshness of F (0) is not known, F
(T) can be expressed by a relative freshness such as% of F (0), for example, α% of F (0). Therefore, for example, if the freshness F (t) after t hours is found to be β% as the absolute freshness by analyzing the K value or the like, from the equation (1), F (t) = F (0) × α% ÷ 100% = β% That is, the absolute freshness of F (0) is required to be β ÷ α × 100%. This is only possible if you know the temperature and time history. This means that freshness can be traced back to the past from the results of later analysis. For example, in the same manner, the relative freshness becomes α% with respect to the first, then the β%, and further the γ%. If the analyzed result is δ% in absolute freshness, the initial absolute freshness is δ ÷ (αβγ) × 10 ⁶ %.

The K value (Note 1) for general fish, chicken, pork, etc., is about 60% as the limit of heating and cooking. It is 20% for raw food such as sashimi and usually up to about 10%. Therefore, since the data of the storage period in column A of Table 1 is data from the viewpoint of the edible period, the K value starting from 0% initially corresponds to 60%, and therefore, the freshness starting from 100% initially corresponds to 40%. Consider it as data. Similarly, the data in column B of Table 1 is data recommended as a guide from the viewpoint of market distribution of perishable goods, so that the K value is equivalent to 10%, and the freshness starting from 100% is equivalent to 90%. Try to consider. Then, the relational expressions corresponding to the columns A and B are (1) and (1) ′, respectively, as the following expressions (A) and (B).

40 = 100exp (-kt): (A) 90 = 100exp (-kt): (B) Self-decomposition after death is fast like squid or octopus.
Even with a high K value as high as 25%, there is something that can be eaten normally but with a freshness starting at 100%,
If the K value is normally eaten raw, it can be made to correspond to 90%. Alternatively, if it is the K value of the edible limit to be cooked and eaten, it may be made to correspond to 40%. The interval may be appropriately divided into A, B, C ranks and the like. That is, if the K value is converted to a freshness starting from 100% so as to correspond, without knowing the value as the K value each time,
You will be able to trade fairly.

In Table 2, the storage period t and the absolute temperature T are substituted into the equations (A) and (2) from the data at -12 ° C and -23 ° C in the column A of Table 1 and the constants of A and E are calculated by simultaneous equations. Is obtained first, and then using the obtained constants A and E, the following equation (A) ′ is used to obtain −18 in column A.
The storage days t at ° C. are calculated by estimating the storage days t at the temperature (around 0 ° C.) in column B from the formula (B) ′. That is, t = ln (100/40) / (Aexp (−E / RT)) :( A) ′ t = ln (100/90) / (Aexp (−E / RT)) :( B) ′ Looking at the results in Table A, column A, it can be seen that the days calculated as freshness of 40% according to the Arrhenius rule for the various foods relatively well match the values in the literature in Table A, column A.
In the results of Table B column, the constants obtained from Table A column have two digits difference in the number of storage days, except for peach, raspberry, strawberry, asparagus, brussels sprouts, cauliflower, pumpkin, etc. Nevertheless, it turns out that they match well. The peach is considered to be because the data in column A was peeled and sliced. Raspberries and strawberries are used in jams in Europe and the United States, and since the grains break down and soften over time, this is considered to be the reason for their early use in terms of the texture of the grains. Asparagus, brussels sprouts and cauliflower are breathing as living organisms, so their appearance may be different. Then, it can be dealt with by changing the calculation formula between the frozen state and the non-frozen state. It seems that the pumpkin is thick and protected by it. When peeled, sensory comparison takes about one week at around 10 ° C. By the way, squash is a kind of pumpkin, but its skin is relatively thin and is calculated as it is.

From the above, it can be seen that the calculation of freshness according to the Arrhenius rule as an example is valid for fresh food within an accuracy range that can be practically used.

Next, the fact that moisture and odor can be treated according to the Arrhenius rule will be described.

When the Arrhenius rule is followed, the storage period t is inversely proportional to the reaction rate constant k as shown in the equations (A) and (B), that is, inversely proportional to the constant A and exp (−E / RT).

Table 3 is a table comparing the saturated steam table with exp (-E / RT).

When E is 10656 cal / mol, it is in agreement from 0 ° C to 30 ° C (an error of about 20% occurs at 100 ° C). This means that if the relative humidity is constant, the relative humidity is α% between 0 ° C. and 30 ° C., and the saturated steam pressure is p.
There is room for evaporation by p (1−α), that is, evaporation occurs in proportion to the saturated water vapor pressure. Therefore, it is possible to estimate the amount of water evaporation by approximating the temperature and humidity by the Arrhenius rule. With the same concept, volatile components such as odor can be calculated. The magnitude of the amount of volatilization at the same temperature depends on the magnitude of the constant A. By subtracting the amount of volatilization every moment,
The amount of the remaining volatile components is determined. However, if the surface is relatively dry and it enters a humid environment, it will absorb moisture until equilibrium, so the condition is that it is under a somewhat low humidity environment. The same is true.

The meaning of the above term is that if the Arrhenius constant E relating to freshness is exactly 10656 cal / mol, then the food will evaporate momentarily and the water lost will correspond to the amount of freshness deterioration that is deteriorating. Become. Therefore, if you measure the water content,
When it is not necessary to consider the imbalance between the water in the center and the water in the surface layer (for example, a thin type, a water that permeates the surface faster than the evaporation rate, or a water in the surface) , Etc.), the freshness can be calculated theoretically.

When the moisture% at time t is represented by W (t), initial moisture W (0), and final moisture W (∞), the Arrhenius constant is set to Aw, Ew = 10656 cal / mol instead of A and E, and If the humidity (r%) is constant, W (t) = W (∞) + (W (0) −W (∞)) · exp (−Aw · (100−r) · exp (−Ew / RT) ) · T) or W (t) −W (∞) = (W (0) −W (∞)) · exp (−Aw · (100−r) · exp (−Ew / RT) · t): (3) Taking the ratio with the expression (1) obtained by substituting the expression (2) results in the following expression (C).

F (t) / (W (t) -W (∞)) = F (0) / (W (0) -W (∞)) × exp (−A · exp (−E / RT) ·) t} exp (−Aw · (100−r) · exp (−Ew / RT) · t): (C) That is, the calculation of the Arrhenius rule based on the constants A and E and the calculation using the constants Aw and Ew are performed in parallel. If you go, freshness starting from 100% and moisture can be matched.

Microbial contamination naturally affects freshness, including the K value. However, if the calculated freshness value differs from the measured freshness value (sampling value) due to individual differences or individual local environment variations, microbial contamination will occur. The suspicion of this could be an indirect check.

II. Calculation of Freshness Following Temperature Change The calculation of freshness when the temperature changes is as follows: If the absolute temperature of the product temperature is T when obeying the Arrhenius law, equation (1)
The following equations (4) and (4) 'correspond to equation (1)'.

F (t) = F (0) exp {-A {exp (-E / RT) dt}: (4) F (t) = 100- {100-F (0)} exp {-A} exp (- E / RT) dt｝: (4) ′ That is, equation (4) is a general form of freshness starting from 100%. The expression (4) ′ is obtained by expressing the K value as K (t) instead of F (t). K (t) = 100− {100−K (0)} exp {−A} exp (−E / RT) dt｝: (4) ″ is a general form of the K value. For moisture, the following formula is general instead of the formula (3).

W (t) −W (∞) = (W (0) −W (∞) exp (−Aw · ∫ (100−r (t)) · exp (−Ew / RT) · dt): (3) ′ Aw: Arrhenius constant of water evaporation due to food, shape, etc. Ew: Same as above r (t): Relative humidity at time t Therefore, if equations (4) and (3) ′ are calculated in parallel, freshness And moisture.

In general, if the deterioration rate v of the freshness is expressed by the following equation with the food temperature as θ, Freshness deterioration amount v (θ) Δt from time t to time t + Δt
Is subtracted from the freshness at time t, F (t + Δt) = F (t) −v (θ) Δt: (5) ′, and F (t + Δt) is replaced with a new F (t),
Thereafter, if the calculation of the expression (5) ′ is repeated from time to time using the product temperature θ at that time, the freshness F (t) at the time t is approximately obtained.

Even if the relationship of various temperatures to the degradation rate is given as a table, if the above equation (5) is obtained by interpolation or extrapolation, freshness can be calculated for any relationship, not limited to the Arrhenius law. Become. That is, it is possible if the relationship between the temperature and the time is known for the target temperature range.

As for the product temperature, the transient temperature generally varies depending on the position of the food such as the surface and the center. However, since the temperature of the product cannot be measured in total from the nature of the food, it is necessary to estimate the product temperature at the target position to be managed from the surrounding environmental temperature and the sampled product temperature value. The target position referred to here is the average product temperature, the surface product temperature (the temperature rises immediately in a high temperature environment, that is, easily deteriorates), and the central product temperature (the coldest environment in a low temperature environment, that is, the product easily deteriorates). , A position according to the purpose of use (for example, in the K value analysis of fish, the back muscle is sampled), and the like.

For example, calculation of the average temperature every moment is approximately obtained as follows. First, the heat transfer during no phase change such as freezing and thawing (thawing) is caused by the average temperature of the food P θP
And the following equations (6) to (9).

From equations (6) and (7), Δθp = Uap · Ap (θA (t) −θP (t)) Δt / Wp · Cp: (8) Then, new θP (t) = previous θP (t) + Δθp : (9) where, ΔQ (t) / Δt: the amount of heat transferred per unit time from environment A to food P from time t to t + Δt (Kcal / H) θA (t): environment A at time t temperature (℃) θp (t): temperature of the food P at time t (℃) Uap: 2 kinds of overall heat transfer coefficient ^{(Kcal / (m 2 · H} · ℃)) deicing time and at the time of freeze-Ap: food Area surrounding p (m ² ) Wp: Weight of food P (K ^- g) Cp: Specific heat of food p (Kcal / (Kg · ° C)) Two types, non-freezing and freezing, and freezing / thawing (thawing) )), The latent heat is received during the phase change, and the product temperature does not change during this period (θp (t) = freezing temperature).
The equation changes as in the following equations (10) and (11).

New w '= previous w' + Δw '<Wp: (11) where, L: latent heat (kcal / kg) w': weight of phase change (kg) Q ': heat received by phase change and (9) Equation (11) indicates that while the inequality of Equation (11) holds, a new θp (t) = freezing temperature: (12) In the case of following the Arrhenius law, for example, the K value and the moisture (the volatile component can also be applied mutatis mutandis) are each at time t Is expressed as K (t) and water is expressed as W (t). Assuming that T = 273 + θp (t) ゜ K, the equation (4) ″ and the equation (3) ′ are differentiated, and ΔK (t) = (100−K (t)) · A · exp (−E / RT) · Δt: (13) New K (t) = previous K (t) + ΔK (t): (14) ΔW (t) = − (W (t) −W (∞)) · Aw · (100−r (t)) · exp (−Ew / RT) · Δt: (15) New W (t) = previous W (t) + ΔW (t): (16)
Is obtained.

However, ΔK (t):% change in K value from time t to t + Δt ΔW (t):% change in moisture from time t to t + Δt W (∞): Final moisture% The surrounding environment is not constant For example, convection from above, heat conduction from the floor side, radiation from front and back by heat source and cold heat source, heat conduction from left and right by contacting with objects, etc. May be received. If the boundary surrounding P is divided into n places, P
Is the heat balance surrounding at each boundary (= i) instead of equation (6)
Divided into Also, instead of equation (7), May be used. Formulas (17) and (18) can also be applied mutatis mutandis when dividing the interior of the food to determine the product temperature for each part.

〔Example〕

FIG. 1 is a block diagram of an apparatus for implementing a method for managing food freshness according to an allowable temperature time according to the present invention.

In this figure, reference numeral 1 denotes a personal computer for calculating and managing the product temperature and freshness. The personal computer 1 includes a CRT 2, a keyboard 3 and a printer 4.
Is connected. In addition, personal computer 1
Is connected to a 6-point temperature indicator recorder 5,
The point type temperature indicating recorder 5 is connected to six thermocouples 6... 6 each of which is installed in the freezer 7, the refrigerator 8 and the air conditioning room 9.

Further, a bar code printer 11 and a bar code reader 12 are connected to the personal computer 1 via an expansion board 10, and the bar code printer 11 receives a command from the personal computer 1 for a product name, date of manufacture, admission ( Or entry) a sign that can be specified for management of time, storage location, etc., a freshness value at the time of entry (or at the time of entry) is printed,
The barcode reader 12 is used for reading when entering, moving in the hall, identifying at the time of entry, identifying at the time of sampling analysis,
Reference numeral 13 denotes a portable radiation thermometer, which measures an initial product temperature in a non-contact manner and inputs the initial condition to the personal computer 1 through a keyboard 3.

Reference numeral 14 denotes a portable thermo-hygrometer, reference numeral 15 denotes an electronic balance type infrared moisture meter, and reference numeral 16 denotes a freshness measuring device for measuring a K value of animal meat.

Next, a procedure of managing the freshness of food by the above-described apparatus based on the allowable temperature time will be described with reference to FIG.

First, a sign is read or ST1 for setting initial conditions. Here, the signs indicate the type of food, the time of entry into the managed location,
It is intended to be able to identify foods by storage location. This sign will be used later for verification when entering from the managed location, when moving inside the venue, when correcting past data or food data in the existing venue based on the results of sampling analysis, or afterwards. This is used when problem tracking is performed. For example, if food is entered on a pallet basis, a unique sign (for example, a bar code indicating the unique address attached to the center digit of the pallet) should be attached to the pallet, and the unique sign should correspond to the food on the pallet. Then, freshness management is performed until the food disappears even if the food is divided little by little. If the handling unit is a cardboard case, a label is attached to the cardboard case. The above may be combined. Heat balance data includes overall heat transfer coefficient, heat transfer area,
Freshness data such as weight and specific heat are stored in advance in principle using constants A and E according to the Arrhenius rule.

Next, after ST2 where the sign is written if necessary, the portable radiation thermometer 13 measures the surface temperature at the time of entering the food (used for calculation as the initial product temperature) ST3. Then, while considering the allowable freshness error, the freshness management calculation is performed with priority given to those having a high freshness deterioration rate such as food at high temperature, so that it is determined whether or not it is time to calculate the food. . If YES, measure the ambient temperature, humidity, product temperature, etc., ST5, calculate the product temperature (the elapsed time from the previous time to this time Δt
→ heat balance ΔQp → product temperature change Δθp → current product temperature θp = previous product temperature θp + Δθp) and calculate ST7, and freshness is calculated (previous and current product temperature average → freshness deterioration rate V of that temperature → freshness deterioration ΔF) = −V · Δt → the freshness F of this time = the freshness F + of the previous time
ΔF) ST8. If the evaporating moisture is calculated every moment and made to correspond to the analysis value of moisture%, the equation (15), (16)
The calculation of the formula is calculated in parallel with ST8. If ST4 is NO, the process returns to ST4 after ST6 after performing other calculation processing. After the above ST8, it is determined whether or not it is outside the target freshness range. In the case of NO in ST9, the process proceeds to ST6 unless there is an instruction to move in and out of the hall. Warn if YES
ST10. ST11 is for moving food inside or out of the hall, changing the correspondence between signs and storage locations when moving inside the hall, calculating the remaining quantity when dividing out of the hall, and performing the following work on the food to enter I do. That is, ST12 which measures the surface temperature at the time of participation, and ST13 which writes or prints a sign if necessary.

ST14 inputs sampling data obtained by sampling freshness or temperature inside and outside the site, statistically processes this data, and corrects heat balance data and freshness data as necessary.
I do. Then, it is determined whether or not all the foods are off-site, in ST16, in the case of YES, the process ends, and in the case of NO, the process returns to ST6.

Next, in order to monitor many foods with high accuracy, the calculation timing is changed in accordance with the deterioration speed of each food, that is, the one with fast freshness deterioration, that is, the one with high product temperature is degraded in short time intervals. A method of calculating a slower product, that is, a product having a lower product temperature, at a longer time interval will be described with reference to FIG.

First, the current temperature θ at each environment i point (i = 1, 2,... N)
i (t) is measured and ST21, then the calculation result tp for each management target
0, tp1, θp (tp1), ΔFp, αp (θp), ΔθMAX ・ P
ST22 (p = 1, 2, 3,... M).

However, tp0: the previous calculation time of the management target target part p tp1: the latest calculation time of the management target target part p θp (tp1): the product temperature (° C.) of the management target target part P at the same time ΔFp: the management target Freshness deterioration (%) of target portion P from time tp0 to tp1 αP (θp): Temperature gradient of freshness deterioration rate at temperature θp of target portion p to be managed (% · sec ⁻¹ · ° C. ⁻¹ ) ΔθMAX p: θi (t) related to the target site P to be managed
Temperature rise (° C.) ΔθMAX · p = MAX {θi (t) −θi (t−T)} where θi (t)> θp Next, the next calculation time tp2 for each management target is ST23 (P = 1, 2,... M).

 tp2 = tp1 + EP / {ΔFp / (tp1-tpo) + Mp} where, Ep: allowable freshness error (%) of the target part p to be managed Mp: αp (θp) · ΔθMAX · p However, it is set to zero when the temperature drops.

Then, S which rearranges the next operation time tp2 in the earlier order
T24. That is, P = 1, 2,... M from ST23, and only j from ST27.

Next, the earliest next calculation time when sorting has been completed in ST24
The target of tp2, that is, the management target (this is assumed to be j) is skipped to the freshness calculation routine as shown in FIG. 1, and the freshness is calculated and returned ST25, and it is determined whether or not the next cycle T of the timing check has come. In ST26, in the case of YES, it is determined whether or not there is a management target. In the case of YES, the process proceeds to ST21, and in the case of NO, the process ends. When ST26 is NO, the next calculation time tj2 of the management target J is calculated as follows in ST27.

tj2 = ti1 + Ej / {ΔFj / (tj1-tj0)} Using the foods shown in Table 2, the constants A and E of the foods shown in Table 2 are also used as they are, and the freshness calculation is performed according to the Arrhenius law. The results of the experiment performed will be described. However, as for mackerel, the data in column A does not specify polyfatty fish and fish species.
(= 46086) and the calculation using the numerical value of E (= 7072) were also used.

Table 1 shows the storage period based on the sensory determination as described above, so that the freshness should be evaluated basically using the same criteria. However, that was 30 years ago, which is virtually impossible, and sensory evaluation makes verification difficult. Therefore, as a measurable measure of freshness, a K value was selected for animal meat and moisture was selected for plant meat. Expressions (13) and (14) were used for the K value as an expression used for calculating the freshness at every moment. For the water content, equations (15) and (16) should be used originally, but here, the constants of A and E are used as is for the water content, and the approximate value is adjusted by the final water content W (∞). I decided to take the method.

That is, as shown in Table 3, E and Ew (= 10656cal
(mol / mol), the difference in the amount of evaporation is large at high temperatures and small at low temperatures (including the freezing side not shown in the table). Humidity is tested for various temperatures (room temperature, chilled temperature, refrigeration temperature) under the environmental conditions of 50-60% average humidity (except for temporary transient conditions such as at the beginning of relocation, and usually evaporation side). I do. Then, the final moisture value W (∞) in the equation (15) is approximately determined by performing a preliminary experiment at the same room temperature and humidity for the same time based on the case where the test is left at the highest temperature in the room for the longest time. . That is, the following equation (19) for obtaining the final moisture value W (∞) derived from the equation (3): W (∞) = (W (t) −W (0) × Jw) ÷ (1-J
w): (19) However, instead of Jw = exp (−Aw · (100−r) · exp (−Ew / RT) · t), the pseudo final moisture value W · (∞) is calculated by the following (20).
Formula, W · (∞) = (W (t) −W (0) × J) ÷ (1−
J): (20) where J = exp (A−exp (−E / RT) · t), and the experimental initial moisture value W (0) and the experimental final moisture value W (t)
Is determined in advance using

When the initial moisture at the time of harvest is Ws, the freshness F (t) after t hours and the initial freshness value F (0) are as follows: F (t) = {Ws−W (t)} /｝ Ws−W · ( ∞)｝ × 100 F (0) = {Ws−W (0)} / {Ws−W · (∞)} × 100: (21), the same form as equation (4) can be obtained. That is, the moisture% and the freshness% correspond approximately one to one.
Even in the same manner, octopus, squid, and the like whose K value does not start from 0% can correspond to freshness of 100% to 0%, which is easy to understand in general use. Also, when expressed in relative freshness based on the initial value, the following equation is obtained by using W (0) instead of Ws.

F (t) = {W (0) -W (t)} / {W (0) -W
・ (∞)｝ × 100: (21) ′ Items to be tested are 1. mackerel, 2.
Strawberry, 3. Beef loin, 4. Pork loin, 5. Chicken fillet, 6.
Eight items were selected: asparagus, 7.peace, and 8.spinach. K value is 1.3.4.5., Moisture is 2.6.7.8.
The initial and final values of the start and the sampling values in the middle were analyzed.

As a method for measuring the K value, there are a simple column method belonging to the separation analysis method, an enzyme method belonging to the coexistence analysis method, a colorimetric method, a biosensor, and the like. In this experiment, inosine and hypoxanthine, which are simplified enzyme methods, were used. Were measured using a test paper (freshness measurement kit and freshness test paper manufactured by Environmental Analysis Center Co., Ltd.). In the analysis, 3 to 5 were used for the fleshy part, and the mackerel in 1. was used for the back muscle part.

The moisture was measured by a commercially available infrared moisture analyzer (FD-220, manufactured by Kett Chemical Laboratory Co., Ltd .; drying end point automatically detected moisture% display type).

Nine test groups of I to IX are provided for each of 1 to 8 and a freezer (-14 to -17 ° C, average -15 ° C, humidity 45 to 75%, average 60)
%), Refrigerator (0-4 ℃, average 2 ℃, humidity 40-85%, average 55%), air-conditioning room (17-25 ℃, average 22 ℃, humidity 40-55)
%, An average of 50%), the experiment was carried out for a full two days in which each test plot was fixed or moved almost at regular time (every 16 hours).

Each test section for each item is 3-7g (mackerel cuts back meat into sword, strawberry is divided into two, beef, pork and poultry is cut into stalks, asparagus and spinach are in the center) Cut, 7 pieces) 2 bare test pieces with small heat capacity
For the analysis of the progress at the 32nd hour (of course, the analysis results on the way are not used for correcting the freshness calculation in this case) The second is for the final value analysis 約 about 48 hours later, and the drip flows out Are placed in aluminum foil containers one by one so as not to mix with other test pieces. In addition, a bar code label indicating the experiment number is attached to each aluminum foil container (total of 144 containers) via cellophane tape. Each of the test pieces for 32 hours and 48 hours is put in a styrofoam box in a freezer and cooled by dry ice while waiting for the K value and the water content to be measured one by one.

Table 4 shows heat balance constants used in calculating the product temperature every moment. The surface area was determined in advance by determining the relationship between the weight and the surface area depending on the shape, and was roughly calculated from the weight.
The overall heat transfer coefficient was obtained from the temperature rise in the frozen state for the air-conditioning room and the refrigerator and the temperature decrease in the unfrozen state for the freezer using the constants in Table 4 in the preliminary test.
As a result, the difference in storage location is greater than the difference in items,
Overall heat transfer coefficient was found to be varied to ^{4~18Kcal / (m 2 · hr ·} ℃). Therefore, the storage position of each test section (the two test pieces were at the same position) for each item was determined, and the heat balance was calculated using the numerical value of the overall heat transfer coefficient obtained in the preliminary test at that position.

The results obtained are shown in Table 5. It can be seen that the calculated values correspond to the analyzed actual values in all of the outlines of Table 5.

By the way, the "relative freshness" using the formula (21) 'was measured for strawberries in the third test plot which was kept at 22 ° C for 2 days.
% (F (2 days) = (90.6-86.3) / (90.6-43.8) · 10
0 = 9.2% On the other hand, if F (0) = 0 in equation (4) and t = 2 days with the same constants A and E, the calculated value is 7.1%. When calculated in the same manner, the measured “relative freshness” versus the calculated “relative freshness” are asparagus 16.5%: 20.9% and piece 20%: 15.7, respectively.
%, Spinach 9.7%: 15.7%. Although there is an error of about 5% (even if the number of days increases, this is considered from the viewpoint of variation), the error is approximately the same.

[Effect of the Invention] Since the present invention is configured as described above, the freshness of the food having various temperature and time histories in the environment to be managed can be calculated and managed by a calculation method based on the difference, so that the food can be extremely easily and accurately processed. You can see the freshness.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus for carrying out an embodiment of the present invention, and FIGS. 2 and 3 are flowcharts showing work procedures. 1 Personal computer 5 Temperature recorder 6 Thermocouple 7 Freezer 8 Refrigerator 9 Air conditioning room

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) A23L 1/00 A23L 3/00

Claims (2)

(57) [Claims] 1. The freshness of a food is calculated by the formula F (t) = F (0) exp (-kt) or F (∞)-｛F (∞) -F (0)｝ exp (-kt) k = Aexp ( −E / RT) where F (t): freshness of time t F (∞): final freshness t: time elapsed after production F (0): initial freshness A: constant by item E: activation energy by item R : Gas constant T: Expressed as product temperature (absolute temperature), A and E are obtained by examining the time change of the freshness in advance for at least two product temperatures and substituting the results into the above formula, The temperature is determined with time, and is calculated as F (t) = F (0) exp {-A {exp (-E / RT) dt} or F (∞)-{F (∞) -F (0)} exp} -A {exp (-E / RT) dt} A method for monitoring the freshness of food, characterized by calculating the freshness of the food at the present time by calculating according to the formula 2. When foods are stored in an environment to be managed or passed in the course of work, initial setting conditions relating to product temperature, freshness, storage location, etc. are given to each food group having the same temperature and time history, 2. A food management method, wherein freshness of a food is managed by obtaining freshness according to the method according to claim 1 until the food disappears from the environment.