JPH02236141A - Judgment of change in contents held in container from liquid to solid - Google Patents

Abstract

PURPOSE:To judge coagulation and fermentation states of a material in a cup by applying a freely attenuating vibration to the sealed cup to analyze a data of a vibration phenomenon automatically. CONSTITUTION:A cup 1 holding contents such as yogurt or the like is placed on a top plate 2 and a torsional vibration is applied to the top plate 2 with a torsional spring 3. Then, the torsional vibration is detected hourly with a sensor 4 to be inputted into a data processor 6 through an amplifier 5. The processor 6 measures a cycle, a frequency and an amplitude of a freely attenuating vibration of the cup to determine a logarithmic attenuation factor of the amplitude and calculates a viscous resistance based on a specified formula. Then, based on an increase or decrease in the frequency and a change in the viscous resistance, a solidification or fluidization state of the contents is judged. This enables judgment of a coagulation and fermentation states of a fermenting material without opening the cup.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention generally relates to a method for determining the state of fluid Φ solid state of the contents contained in a container, and in particular, after filling and sealing a commercially available cup with fermentation raw materials, fermentation Yogurt obtained by A method for determining the coagulation state and fermentation state of fermented raw materials without opening the cup in the production of fermented and coagulated products in cups (hereinafter referred to as the post-sealing fermentation method) such as
non-destructive testing method).

Problems with the Prior Art Conventionally, various methods are known for determining the coagulation state of fermented products.

A typical example of these is a method of detecting (intermittently or continuously) the concentration change of a product (e.g. lactic acid) produced as fermentation progresses as an indicator. Titration of fermented products (e.g. acidity titration)
C. Measuring the pH of the fermented product or measuring the conductivity of the fermented product (
(See Japanese Patent Application Laid-Open No. 63-59838).

Another typical conventional method is a method of determining the state of fermentation by utilizing changes in physical properties due to coagulation. Measure the viscoelasticity of the fermented product using a viscoelasticity measuring device such as the device described in Publication No. The temperature or electrical resistance of the conductor is measured, and the solidification state is determined thereby (see Japanese Patent Laid-Open No. 62-40246, hereinafter referred to as the hot wire method).

Further, from page 178 onwards of "Rheology Measurement Method" (edited by Rheology Committee of the Society of Polymer Science and Technology, 1965, published by Kyoritsu Shuppan), there is a description of dynamic viscoelasticity in the extremely low frequency region.

In particular, on page 182 of the above-mentioned document, the Morrison
An overview of measurement equipment such as the following is introduced. In this measuring device, a frame supporting a coil is suspended in the magnetic field of a permanent magnet using conductive wires, a mirror is provided at the bottom of the frame, and a cylindrical body is fixed below the frame. Immersion into the liquid to be measured. A galvanometer is connected in series to the coil,
By passing a current from an ultra-low frequency oscillator through the circuit configured in this manner, forced torsional vibration is applied to the cylindrical body. The device is placed in an air constant temperature chamber, and temperature-controlled air is circulated. Observe the force waveform reflected from the galvanometer mirror and the displacement waveform reflected from the coil mirror, find their amplitude ratio and phase difference, and calculate the dynamic viscoelasticity of the liquid from them.

The titration method described above requires at least 4 to 5
However, the time required for measurement changes significantly depending on the concentration difference of the substance to be measured (fermented product), and errors occur due to the buffering effect of the fermentation card ("Comprehensive Diary of Dairy Technology", Vol. 1). 64 and 65 (see 1977).

Although the method of measuring pH or conductivity described above has the advantage of being able to perform continuous measurements, it is difficult to maintain the temperature of the sample during measurement. The operation is complicated because it requires calibration and cleaning of the measurement means itself. Therefore, even if the time required for the measurement itself is short, there is a cleaning time between the measurement times, and the measurement required per 1 sample ends up being complicated. There was a problem that it took a long time.

The above-described method using a card tension meter or tensipressor has a problem in that it is difficult to determine the coagulation state when the change in hardness of the test object is small (such as in the case of yogurt).

The above-mentioned hot wire method was originally adapted for continuous online measurement by being attached to a fermentation tank, and the device size is large, making it unsuitable for application to cups of fermented and coagulated products. There was a problem in that the means itself required cleaning, making the operation complicated.

The above-mentioned method of Morrison et al. also had the problem of requiring cleaning of the measuring means itself, making the operation complicated.

Furthermore, all of the conventional methods described above require direct access to the fermented product during the fermentation process, and cannot perform measurements with the fermentation container sealed, that is, non-destructive testing. Therefore, sampling inspection is required in the post-sealing fermentation method. Destructive inspection is essential, which reduces product yield.

In addition, a common problem with some of the above methods is that the time required for one measurement increases due to the complexity of operations, and it is necessary to measure a large number of samples within a limited time. In some cases, it is necessary to process in parallel using multiple inspection devices, which reduces equipment costs. The problem is compounded by increased measurement costs, especially if the measurement equipment is expensive.

Furthermore, when the rate of change of the judgment target is fast. By the time a determination is made, the state of the sample has already changed further, and there is a risk that the measurement results will become meaningless.

Additionally, if there are variations in the time required for measurement, managing the sampling test for a large number of samples becomes more complex, and in effect the method of fermenting the raw material and then sealing it (
(hereinafter referred to as the post-fermentation sealing method).

In the production of fermented or coagulated products such as yogurt, the presence of viable bacteria in the fermented product may be important.

Generally, in the production of food bag products, it is necessary to prevent contamination of the product with germs as much as possible from the viewpoint of food preservation and food hygiene.

The easiest way to eliminate contamination of products with bacteria is to sterilize or sterilize the product after dispensing and packing (sealing) the product in containers, but for products such as yogurt where the presence of live bacteria is desired, This method is not applicable.

Therefore, products such as yogurt are prepared by preparing sterilized or aseptically treated raw materials, inoculating raw materials with pure cultured fermentation bacteria, fermentation, checking the coagulation state, and dispensing and packaging (sealing) fermented products into containers. Either all operations are carried out in a sterile environment (post-fermentation sealing method), or preparation of sterilized or sterilized raw materials, inoculation of raw materials with one or more pure cultures of fermentation bacteria, or raw materials inoculated with fermentation bacteria. Dispense into containers and pack (seal) in a sterile environment, and then ferment. It is desirable to either test the coagulation state (fermentation method after sealing). The former method has the disadvantage of requiring additional costs to maintain a sterile environment.

In addition, the palatability of fermented and coagulated products such as yogurt varies greatly depending on the fermentation and coagulation state of the product.
Homogenization of the product is important. Further, since fermentation and coagulation proceed at an accelerated rate, it is desirable to be able to make a quick determination.

The above-mentioned fermentation method after sealing can reduce the cost of maintaining a sterile environment, but since there was no way to determine the fermentation state and coagulation state without opening the bag (non-destructively), it was difficult to determine the fermentation state and coagulation state. In order to do this, it was necessary to conduct a pouring inspection (sampling inspection/destructive inspection). Products that are opened during pouring inspection are discarded, resulting in poor product yield. Furthermore, since the temperature distribution and air volume distribution within the fermentation chamber are uneven, subtle differences occur in the fermentation state of the raw materials in each container, and a large number of pouring inspections are generally required to homogenize the product.

From the viewpoint of homogenizing the product, the post-fermentation sealing method is easy, but it has the problem of increasing the cost of maintaining a sterile environment as described above.

Therefore, in the post-sealing fermentation method, it is desirable to be able to quickly determine the coagulation state and fermentation state (non-destructive testing) without opening the container.

The test must be simple, and it is also important to reduce the cost of equipment for the test.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the problem by filling a cup. The coagulation state of sealed fermentation raw materials can be inspected without opening the packaging or taking fermentation raw materials as samples, and the cups subjected to the inspection can also be used as products after fermentation is complete.
The object of the present invention is to provide a method that allows rapid non-destructive testing.

As a result of research to solve the problems of the prior art described above, the present inventors applied damped free vibration to a cup filled with fermentation raw materials and sealed, and automatically analyzed the phenomenon data of the free damped vibration. , the solidification state of the raw material in the cup. We have discovered that it is possible to determine the state of fermentation, and have arrived at the present invention.

Specifically, the present inventors charged fermentation raw materials. When a sealed cup is subjected to damped free vibration, it is assumed that there is a change in the unique index representing the vibration phenomenon of the cup between the state in which the fermentation raw material has not solidified and the state in which solidification has progressed. By measuring the change, it is possible to determine the coagulation state of the fermented raw material.Therefore, we came up with the idea that it is possible to determine the fermentation state from the coagulation state, and as a result of repeated research, we established a method.

Generally, when the object to be inspected has viscous damping, free vibration can be expressed by the equation of motion of a torsional vibration system as shown in the following equation. (Mechanical Engineering Handbook. Revised 4th edition, 3
(ed., p. 34; 1960, Japan Society of Mechanical Engineers) dt" dt [where, θ: Torsion angle from the equilibrium position (rad),';
ln-c/I, C: viscous damping coefficient (Kg-S-cm), I: moment of inertia (Kg-S"c+a), P"-k/I (natural circular frequency of the system). k: Spring constant (Kg-cm/rad)
] In particular, the solution in the case of damped oscillation is θ= A e ” ” cos (4t + a), (Since A and a are constants, the period of oscillation becomes independent of amplitude and time, The following equation is obtained.

T = 2 r / J' lower 1:;7 [T: period 1 Also, the amplitude of one period T is from e -m t to e -m
(r + 1 1, and the rate of decrease becomes a constant value of eT. The natural logarithm of this rate of decrease, nT-2rn/
, r 100 = 11- is defined as the logarithmic attenuation rate δ.

The above viscous damping coefficient C is the damping speed (torsion angular velocity)
Since it is a constant when proportional to , in a fluid,
It can be seen as a viscous drag coefficient.

Therefore, to summarize the above relational expression, δ - nT ・・・・・・・・・・・・・・・・・・
...(1) δ-2πn/f lower 7: T-cho...
... (2) 2 n = c / I ・
・・・(3)P″-k/I・・・・・・・・・・・・・・・
・・・・・・・・・(4) Therefore, in a torsion-based damped free vibration device with a known spring constant k,
By measuring and calculating the period T) and the logarithmic decay rate δ, n. From equation (2), P. From equation (4), ■,
Therefore, C can be found sequentially from equation (3). In addition, the damped free frequency P and logarithmic damping rate δ were measured. By calculation, it can be seen that n can be found from equation (2), and C can be found from equations (3) and (4).

To summarize the above relational expressions, C is as follows (5) ~ (
7) It is expressed by the following equation.

cm2δ k 4x+δ) ---(5)2kδ Also, moment of inertia! is a factor normally used when handling rigid bodies, but in cases where the contents of the cup change from a liquid to a solidified body as fermentation progresses,
The change in state of the contents affects the overall moment of inertia between the contents and the cup. In other words, when the content is liquid, the content does not behave as a torsional vibrator, but provides viscous damping to the cup, which behaves as a torsional vibrator, and as the content solidifies, the content gradually changes from the cup. As the cup approaches an integrated rigid body, the above-mentioned viscous damping gradually decreases and the moment of inertia of the cup gradually increases. This change is utilized in the present invention to determine the coagulation state of the contents. This is exemplified by the fact that the damped free frequency P decreases (ie, increases by 1 from equation (4) above) as solidification progresses in the examples described below.

The above-mentioned method is also applicable to linear vibration, and this case will be described later.

According to the invention: a) damped free oscillation of said container while the contents therein solidify or fluidize; b) period T1 or damped free frequency P1 and amplitude of damped free oscillations of said container. C) calculating the logarithmic attenuation rate δ of the amplitude, d)
Calculate the viscous drag coefficient C from the relational expression: δwnT δ-2rn/l11:17 2n "c/m P"=k/m (where k: spring constant of the vibrating device, m: moment of inertia or mass ) e) measuring and calculating the increase/decrease in the damped free frequency P and/or the viscous drag coefficient C over time during the assimilation or fluidization process of the contents of the container; f) the damped free frequency P The solidification or fluidization state is determined based on the increase/decrease in and/or the change in the viscous resistance coefficient C.

Although the outline of the present invention has been described above, it is presumed that the inertia of the motion of the fluid in the container acts more strongly in linear vibration than in torsional vibration, and for the purpose of concrete application of the present invention, the former Since this seems to be more suitable, an example using a torsionally damped free vibration system will be described in detail below.

Embodiment FIG. 1 shows an outline of a torsion-based damped free vibration device having a data analysis means used in this embodiment.

2 is a cup that stores the contents, 2 is a base plate on which the cup is placed, and 3 is a torsion spring that gives torsional vibration to the base plate, and the thrust load on the spring from above is applied by appropriate means. excluded. 4 is a sensor for measuring the torsion angle (amplitude) θ, period T, and damped free frequency P; 5 is an amplifier that amplifies the signal from the sensor 4; and 6 is a sensor that converts the signal from the amplifier 5 into a digital signal. ．． This is a data processing device for analysis.

The torsion spring 3 can be a coil spring, a torsion bar spring, a torsion plate spring, etc., and its spring constant k (the moment required for twisting a unit angle) is 3. 9 1 (K
g-cm/rad). The torsion angle θ of the spring is
In order to minimize the physical damage (disturbance) to the solidification of the product, it was made possible to change it arbitrarily within the range of 0 to ±9''.

Moment of inertia of the base plate 2 itself ■. is the device-specific load for torsional vibration, which is 0.0 0 2 5
4 (Kg-S"cm). If the moment of inertia of this platform is too large, the proportion of the entire moment of inertia acting on the torsional spring will increase, and the change in the damped free frequency P will become minute. In addition, the moment of inertia of the cup itself is extremely small compared to the moment of inertia of the base plate, so it is ignored.In other words, the moments of inertia of the base plate and cup should be as small as possible.

? 5 can be set to 0 by adjusting the zero point and span.
It was adjusted to give a voltage output of ~±9V.

The sensor 4 converts the amplitude (twist angle) into a voltage and outputs it, and this output voltage is amplified in the amplifier 5 to about 5V, which is the input level to the computer in the data processing device 6. The amplified signal is converted into a digital signal by the AD converter of the data processing device 6 and input to the computer. The computer differentiates the voltage signal input over time to detect the local maximum point, that is, the peak of the vibration waveform. The height of this peak from the equilibrium reference point is the vibration a,
Next swing II a. The natural logarithm Qn (aa/
aa++) is the logarithmic decay rate δ. Further, the period T is the time from one peak to the next peak.

Inspection 1 of the coagulation state in the cup-fermented yogurt manufacturing process was performed using the above-mentioned apparatus.

The composition of the yogurt formula is shown in Table 1.

Table 1 Condition Skimmed milk powder 10.51 White sugar 9.00 Milk Gelatin 0.15 Agar 0.15 Pour the entire amount of the above yogurt preparation into a tank with a volume of 15 (H2), heat sterilize it, and then cool it to a fermentation temperature of 42°C. Add symbiotic starters of Lactobacillus pulgaricus and Streptococcus thermophilus to the above tank, stir, and transfer 70g to a 90cc yogurt cup.
Approximately 100 cups of unfermented yogurt, each weighed and filled
0 pieces were prepared.

These cups were placed in a fermentation chamber maintained at 42°C and fermented. In order to distinguish between cups placed in different positions in the fermentation chamber, the cup placed in the center of the fermentation chamber is designated as b, c, d, e, and the cups placed around a1 are designated as b, c, d, and e.
A number of cups selected from among the cups placed at different positions are taken out over time, subjected to damped free vibration using the previous device, and the period T and logarithmic damping rate δ are measured, and from these measured values. Calculate the damped free frequency P, and further calculate the above (7
) The viscous resistance coefficient C was calculated from the formula. Note that the twist angle (swing angle) in the equation was ±5°.

Table 2 and FIG. 2 show the viscous drag coefficient C(
However, data on the value of cxlO') and the damped free frequency P are shown. Note that a cup adjacent to cup a was also taken out and the acidity, pH, and card tensile a of the contents were measured at the same time, and the results are shown in correspondence with the damped free vibration analysis data for cup 7'a. Also, points A and B in FIG. 2 are shown in the notes.

1.00 59 3B. 4 1110
0.165 02.00 51
38.4 5.697 0.257 0
2.50 58 38.4 5.180
0.401 02.75 5
38.5 5.010 0.514 03
．． 00 8 38.5 4.906
0.561 93.25 601
38.8 4.758 0.632
10.93.50 1343 38.
6 4.687 0.666 14.53.
75 662 35.9 4.564
0.728 15.54.00 847
36.1 4.509 0.759
17-04.50 588 35.6
4.373 0.825 19.05. OQ
356 35.9 4.253
0.881 17.15.50 130
36.2 4.175 0.929
20.56.00 349 35
．． 8 4.097 0.960 17.2
Generally, the following is known about the milk coagulation process of lactic acid fermentation.

As the lactic acid bacteria proliferate, the milk preparation becomes acidic, and calcium and phosphorus are liberated and dissolved from the casein particles. p
At pH 5.2 to 5.3, calcium particles become unstable and begin to precipitate, and at pH 4.6 to 4.7, they reach their isoelectric point and completely precipitate. In addition, the casein particles coagulate and coprecipitate with the denatured whey protein, solidifying into a three-dimensional network structure that envelops the whey containing soluble milk components.

Considering the above findings and looking at the above results, we find the following.

First, looking at the viscous drag coefficient C, it rapidly increases and reaches its maximum value at point A in FIG. 2, and the pH at this time is 4.687, which is approximately the isoelectric point. Also,
It can be seen that the rapid increase in the viscosity resistance coefficient C increases the viscosity of the emulsion to the isoelectric point at which casein particles cause precipitation and aggregation. After reaching its maximum value at the isoelectric point, the viscous drag coefficient C gradually decreases, and as fermentation progresses, the highly viscous liquid progresses through the completion of the skeleton of the network structure, progresses to the completion of the detailed network structure, and becomes fluid as a liquid. It can be seen that it loses its properties and changes into an elastic body (gel) with no viscous resistance.

Furthermore, when looking at the damped free frequency P, it decreases rapidly at point B in FIG. 2, but it maintains a substantially constant value before and after that point. The decrease in P is P
The relationship ``-k/I means an increase in the moment of inertia.This means that the formation of the three-dimensional network structure at point B spreads over the entire cup, and the solidified material adheres to the cup. It is understood that the moment of inertia of the solidified contents is added to the moment of inertia of the cup and the base plate.The acidity at point B is 0.728, which corresponds to the general acidity at the end of fermentation of 0.7.

As mentioned above, it can be seen that the maximum value of the viscous drag coefficient corresponds to the isoelectric point, and the point of decrease of the damped free frequency P corresponds to the change in physical properties due to coagulation of the milk preparation. Therefore, by detecting at least one of these change points, the coagulation state can be determined. The completion state of fermentation can be determined.

In addition, damped free vibration analysis was performed on the other cups b, c, d, and e and the cups adjacent or close to them in the same way as for cup a. The time to find the point of decrease is ±l for the time of points A and B for cup a, respectively.
0 minutes, and the physical... Since there was no significant difference in chemical properties, it was found that the temperature distribution and air volume distribution within the fermentation chamber used were sufficient to ensure virtually uniform fermentation.

Furthermore, as can be seen by comparing the viscous drag coefficient and damped free angular frequency according to the present invention with the card tension value, which is the conventional method for measuring gelation, the card tension value shows a slow increasing curve (the (Figure 2), no clear change point from liquid to solidified could be found.

In addition, in the above embodiment, a damped free vibration device of a torsional vibration system was used, but as described above, a linear vibration system (either vertical or horizontal direction is fine) that linearly vibrates in the direction of the central axis of the cup was used. gives similar results. In this case, the torsion angle θ is the displacement X, and the angular velocity dθ/dt is the velocity d.
x/dt, the moment of inertia ■ is the mass m, and the torsion spring constant (Kg cm/rad) is the linear displacement spring constant (Kg
/cm), the viscous damping coefficient of torsional angular displacement (Kg-S-
CII1) as the viscous damping coefficient for linear displacement (Kg-S
/cm).

In this case, the mass of the base plate to which the cup is fixed is set as mass m instead of the moment of inertia 1, or the total mass of the cup and the base plate is set as mass m. It is clear that the latter is preferable.

In the above embodiments, the method for determining the coagulation state of fermented and coagulated products in cups has been described, but the present invention is generally applicable to any product that changes over time from liquid to coagulated or solid. It can also be applied to determining the state of change in products that change from solid to liquid over time.

Effect of the invention The effects of the present invention are as follows.

(1) Coagulation state of fermented and coagulated products in cups. The completion state of fermentation can be determined non-destructively.

(2) Judgment can be made in a relatively short time (about 1 minute).

(3) Since non-destructive testing can be performed, the product to be tested can be shipped as a finished product, and the product yield can be greatly improved.

(4) It can provide a quality control factory in the post-sealing fermentation method and expand its application field.

(5) The inspection device is relatively simple, and the device cost and inspection cost can be reduced.

(6) Not only fermented and coagulated products in cups, but also
A method for determining whether a frozen layer of a desired thickness has been formed in a mold in the production of frozen confectionery having a laminated structure, and a heating pot. It can also be applied to detecting the molten state of solids contained in crucibles, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the configuration of an apparatus implementing the present invention, and FIG. 2 is a graph showing actual measured values by the method of the present invention. Explanation of symbols 1 Two cups of fermented product, 2: Base plate, 3: Torsion spring,
4: Sensor, 5: Amplifier, 6: Data processing device, F+g, 1 Applicant: Food Industry Online Sensor Technology Research AssociationFig. 2 Procedural amendment (formality) l. Display of incident 2. Name of the invention 3. Person making the amendment Name or name related to the case 4. Agent address: 1999 Patent Application No. 57351 Method for determining the fluid Φ solid state of the contents contained in a container

Claims (1)

[Scope of Claims] [1] A method for determining the solidification or fluidization state of contents during solidification or fluidization after filling the contents into a container, comprising: a) when the contents are solidified or fluidized; b) measuring the period T or the damped free frequency P and the amplitude of the damped free vibration of the container without opening the cup; c) the amplitude d) Relational expression: δ=nT δ=2πn/√(P^2-n^2) 2n=c/m P^2=k/m From, the viscous drag coefficient c (where k: spring constant of the vibrating device, m: moment of inertia or mass) e) Calculate the damped free frequency P and/or the viscous drag coefficient c according to the solidification or flow of the contents of the container. f) determining the solidification or fluidization state based on the increase/decrease change in the damped free frequency P and/or the change in the viscous drag coefficient c. A method for determining the state of change between fluid and solid in the contents contained in a container.