JPS6229017B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for measuring the milk solids content of milk using infrared absorption spectroscopy. The main components other than water in milk are fat, protein, lactose, and ash.The sum of components other than water, that is, fat + protein + lactose + ash, is called total milk solids (TMS).
The component obtained by removing fat from total milk solids is called ignored milk solids (SNF). Milk trading in recent countries has shifted from the traditional fat trading to whole milk solids trading, fat and protein trading, or fat and non-fat milk solids trading. For this reason, an apparatus as shown in FIG. 1 has been developed for measuring the total milk solids content or non-fat milk solids content (both are collectively referred to as milk solids content) in milk. This uses an infrared analyzer 10. When infrared rays are transmitted through milk, the fat, protein, and lactose in the milk each have a specific wavelength spectrum in the infrared region (as shown in Figure 2). So, fat is 5.73μm, protein is 6.46μm,
Applying the principle that lactose absorbs 9.6 μm), the concentration of fat, protein, and lactose in milk is measured by the amount of absorption in the spectrum of each wavelength mentioned above. More specifically, the infrared analyzer 10 shown in FIG. The measurement wavelength of the component to be measured (for example, 5.73 μm for fat) and the reference wavelength that is not absorbed by the component to be measured (for example, 5.55 μm for fat)
m), and the measuring wavelength and the reference wavelength are alternately projected onto the milk in the cell 17 by the chopper 16. The light at the measurement wavelength and the reference wavelength that has passed through the milk is received by the photoelectric converter 18, and an unbalanced signal corresponding to the difference in the amount of light received at these two wavelengths is output. The more components to be measured (for example, fat) in milk, the greater the amount of absorption of the measurement wavelength, so an imbalance occurs in proportion to the concentration of the component to be measured. This unbalanced signal is transmitted to the amplifier 19.
The signal is amplified to operate the servo motor 20. The servo motor 20 adjusts the amount of light passing through the optical path 13 to the light shielding plate 2.
1 for adjustment, and stops when the unbalanced signal is no longer output. Therefore, since the amount of movement of the light shielding plate 21 corresponds to the concentration of the component to be measured, this is extracted as an electrical signal by the potentiometer 22. The measurement infrared interference filter 14
A pair of infrared interference filters 15 for measurement are provided for each component of fat, protein, and lactose, and are sequentially switched to sequentially measure the concentrations of fat, protein, and lactose. Note that the reference numeral 23 indicates a motor that drives the chopper 16. In order to determine the total milk solid content or non-fat milk solid content, it is necessary to determine the ash concentration, but as is clear from FIG. 2, there is no ash content spectrum in the infrared region, so it cannot be measured. _Therefore , as shown in FIG.
The fat and protein stored in 2 _p and 32 _l , respectively,
This set value is added to the concentration of lactose, protein, or lactose using an adder 33 to determine the concentration of total milk solids or non-fat milk solids, which is displayed on a display 34. The changeover switch 35 is used to switch between whole milk solid content and non-fat milk solid content. In this way, conventional measurement methods assume that the ash content is always a constant amount and measure the total milk solid content or non-fat milk solid content, but the ash content in milk is complex with the aforementioned fat, protein, and lactose. It is known that the concentration of ash changes in proportion to the respective concentrations of fat, protein, and lactose. Therefore, it is inaccurate to measure total milk solids and non-fat milk solids by setting the ash content to a constant value regardless of changes in the concentration of fat, protein, and lactose, as in the conventional measurement method. As the range becomes wider, measurement errors inevitably become very large. Figure 3 is a schematic diagram to show the difference (bias) between the measurement value by the standard measurement method (official method) based on chemical analysis and the measurement method described above for non-fat milk solid content. It is assumed that the bias in the measured values is zero in the case of milk with a concentration of 8.5%, and the set value of ash content is set to 0.7 (concentration 0.7%). The horizontal axis represents the standard measurement value as the reference value, and the vertical axis represents the deviation of the measured value due to the aforementioned measurement method. As is clear from this figure, when each component is zero, the bias in the measured values using the measurement method described above is
In other words, when measuring distilled water, it is 0.7%, so
An inclined straight line a passing through (0, 8.5) with 0.7 as the intercept
It is represented by. Therefore, in the conventional measuring method using the device shown in Figure 1, the deviation of the measured value of total milk solids or non-fat milk solids can theoretically become zero at only one point, and even if some practical error in the deviation is allowed, Taking into account the dispersion of measured values, the measurement range becomes very narrow. It is an object of the present invention to overcome these drawbacks and provide a method and apparatus for measuring whole milk solids or non-fat milk solids with almost no measurement error over a wide measurement range. As mentioned above, the ash in milk is composed of fat, protein,
It is known that it exists in a state related to lactose and changes in proportion to changes in the amounts of each of these components. That is, the ash content in milk is a general term for an inorganic compound containing various metals and inorganic acid radicals, and Table 1 shows the main composition of the ash content and its content.

【table】

[Table] As is clear from this table, it is known that the concentrations of some of the salts in the composition vary over a considerable range. It has also been found that the composition of ash in milk is as follows. In other words, sodium and potassium exist in milk as cations, while calcium, magnesium, phosphorus, and citric acid are partially dissolved in milk and the rest exists in the form of colloids. Table 2 shows the distribution of calcium, magnesium, phosphorus, and citric acid dissolved in milk and colloidal amounts.

[Table] Most of the colloidal amount forms bonds and complexes with casein, which makes up the majority of proteins. Furthermore, in normal milk, the amount of these dissolved substances and the amount of colloidal substances are kept in an almost equilibrium state at the ratio shown in Table 2. As described above, there is a close relationship between ash and protein, and the concentration of protein greatly influences the concentration of ash. Furthermore, fat exists in milk as an emulsion in the form of particles with an average size of 2 to 5 μm, and the surfaces of these fat globules are covered with an adsorption layer called a fat globule membrane. Fat globule membranes are adsorption layers mainly composed of complexes such as proteins and phospholipids. In this way, fat contains phosphorus from phospholipids, and other ash is also adsorbed. Therefore, the concentration of fat greatly influences the concentration of ash. Furthermore, the influence of lactose on ash content is noticeable, for example, in mastitis milk, where chlorine and sodium increase as lactose decreases. From this point of view, it is more accurate to treat the amount of ash as the sum of functions of the concentrations of fat, protein, and lactose. Therefore, instead of determining the ash content as a constant value as in the conventional measurement method, measurement errors will be reduced if the milk solids content is determined by treating it as the sum of three quantities that vary depending on the amount of each of the three components. ,
In addition, as shown in Figure 3, with the conventional measurement method, as the measurement range widens, the error increases due to the ash content being set at a constant value, but since the ash content is also treated as a variable, the measurement range can be expanded. However, the error will not increase. From this point of view, the measurement method according to the present invention uses infrared absorption spectra to determine the fat and fat content in milk.
The concentrations of protein and lactose are measured, and the ash concentration is calculated as the sum of functions proportional to each of the measured concentrations of fat, protein, and lactose by a predetermined coefficient, and the ash concentration obtained in this way is calculated as the sum of functions. The concentration of total milk solids or non-fat milk solids is determined by adding to the concentration of fat, protein, lactose or protein, lactose. That is, F is the fat concentration, P is the protein concentration, L is the lactose concentration, α is the proportional coefficient (constant) of ash to fat, β is the proportional coefficient (constant) of ash to protein, and δ is the proportional coefficient of ash to lactose ( constant)
Then, calculate the ash concentration as αF + βP + δL, and let T be the total milk solids content and S be the non-fat milk solids content.
T and S are determined as T=F+P+L+αF+βP+δL S=P+L+αF+βP+δL. FIG. 4 shows an embodiment of the measuring device according to the invention. In the same figure, an infrared analyzer 10 has the same configuration as the conventional measuring device shown in FIG. 1, so a description thereof will be omitted. 41 _f , 41 _p , and 41 _l are memory devices for storing the concentrations of _fat , _protein , and _lactose output from the potentiometer 22, respectively; The set setting devices 43 _f , 43 _p , 43 _l are the memory devices 41 _f , 41 _p ,
The fat, protein, and lactose concentrations F, P, and L stored in 41 _l are multiplied by the coefficients α, β, and δ set in setters 42 _f , 42 _p , and 42 _l , respectively, to obtain αF,
A multiplier 44 outputs βP and δL, an adder 44 outputs F+P+L+αF+βP+δL when the switch 45 is closed, and an adder outputs P+L+αF+βP+δL when the switch 45 is opened, and 46 is a display. According to this device, the infrared rays from the light source 11 are applied to the milk in the cell 17 to measure the concentration of fat, protein, and lactose, which are stored in the memory devices 41 _f , 41 _p , and 41 _l. , multipliers 43 _f , 43 _p , 43 _l by each coefficient α, β, δ to the concentration of lactose
This function sum αF + βP + δL is added to the concentration of fat, protein, lactose or protein and lactose in the adder 44 as the ash concentration, and the result is displayed on the display 46.
Displays the concentration of total milk solids or non-fat milk solids. In addition, in the above explanation, ash content was treated as a sum of functions of three components: fat, protein, and lactose.
The milk solids content may be determined by treating it as a function sum of only two of these components, not necessarily the three components. Even if only two components are used, it is possible to obtain a much more accurate measurement value of the milk solid content compared to the conventional method where the amount is always treated as a constant amount. As explained above, according to the present invention, in order to obtain the total milk solid content or non-fat milk solid content in milk, ash content is calculated as the sum of functions of fat, protein, and lactose, or all of them. Since the amount of ash is treated as an amount that changes in response to changes in the amounts of each component of fat, protein, and lactose, it is possible to reduce errors when treating ash as a constant amount as in conventional measurement methods. Also, the measurement range can be expanded.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a conventional measuring device for measuring total milk solids content or non-fat milk solid content in milk, Figure 2 is an infrared absorption spectrum diagram of milk, and Figure 3 is a measurement using a conventional measurement method. FIG. 4 is a schematic diagram showing the deviation of the value from the reference value according to the standard measurement method, and FIG. 4 is a block diagram showing the measuring device according to the present invention. 10...Infrared analyzer, 11...Light source, 14...
...Infrared interference filter for measurement, 15...Infrared interference filter for reference, 16...Chiyotsupa, 17...
Cell, 18... Photoelectric converter, 20... Servo motor, 21... Light shielding plate, 22... Potentiometer, 41 _f , 41 _p , 41 _l ... Memory device, 42 _f , 4
2 _p , 42 _l ... setting device, 43 _f , 43 _p , 43 _l ...
Multiplier, 44... Adder, 45... Changeover switch, 46... Display.

Claims (1)

[Claims] 1. The concentration of fat, protein, and lactose in milk is measured by infrared absorption spectrum, and the concentration of one or all of fat, protein, and lactose is multiplied by a predetermined coefficient, and the concentration of fat, protein, and lactose is multiplied by a predetermined coefficient. , to the sum of the concentrations of protein and lactose, or to the sum of the concentrations of the protein and lactose,
A method for measuring milk solids in milk using infrared rays, characterized in that the concentration of milk solids in milk is determined by adding the sums of the multiplication values. 2. An infrared analyzer that measures the concentration of fat, protein, and lactose in milk using an infrared absorption spectrum; a multiplier for multiplication; and an adder for calculating the concentration of milk solids by adding the sum of the multiplication values from each multiplier to the sum of the concentrations of fat, protein, and lactose, or to the sum of the concentrations of protein and lactose. A device for measuring milk solids in milk using infrared rays.