Operation process and precautions
In general, pure milk
pH
Value in
6.4-6.8
Between, it is weakly acidic,
pH
Value can accurately reflect the freshness of milk, reliable
pH
Value measurement is important for quality control of fresh milk.
pH
Why it's important, online testing
pH
The value is mainly considered from the perspective of the freshness of milk and other media contamination in the production process. Freshness is also focused on the acidity change of the product, which will seriously affect the stability of your later products. If the product is reinforced,
pH
The value is the key basis for whether the product is released. It is the quickest way to verify the sterilization effect of your product and whether the product is contaminated.
At the same time, dairy manufacturing can rely on
pH
Value to ensure that the milk does not clump. This critical point is
pH4.3-4.6
Milk
pH
The value cannot be lower than this value anyway. This is the so-called milk protein isoelectric point, which means when
pH
When the value is in this range, the milk protein molecules have the least repulsive force and are prone to precipitation, so the protein beverage
pH
Need to
pH
Adjusted to the isoelectric point, but
pH
Generally not higher than
6.8
,
pH
High is not conducive to product quality, and when
pH
Above
6.8
In the sterilization process, the protein and the reducing sugar are prone to Maillard reaction, and the color of the product is browned.
Milk
pH
Values ​​are not easy to measure. They usually contain fat, protein, sulfides, and many other substances, all of which interfere with electrode measurements and make measurement errors. In addition, in the milk
pH
During the measurement process, the milk itself or the precipitated protein contaminates the liquid junction of the electrode, causing
pH
Changes in electrode calibration values ​​(zero and slope). They can also be very thick, very thin, very sticky or very hard, but we have to measure them and get fast and accurate results, so it is difficult to implement. However, if the electrodes are chosen correctly and used properly, your measurements are accurate and reliable. normal
pH
The electrode will not be able to withstand such a high pollution measurement environment, which will cause measurement errors due to poor relinearity of the electrode measurement. Anleiss
S3221
Glass composite
pH
The electrode adopts Swiss imported ceramic liquid junction and long-life reference system. It has large glass electrode contact area, is not easy to block, and can withstand high pollution. It is very suitable for measuring milk.
pH
value.
Normal milk has a certain conductivity, and the change in conductivity increases or decreases as the temperature of the milk increases or decreases. The adulterated milk can be separated into electrolytes or non-electrolytes by using a conductivity meter to test adulterated milk. The conductivity of the electrolyte is significantly increased when the electrolyte is incorporated into the electrolyte. The more the amount of the mixture is, the more the change is. The conductivity of the non-electrolyte is reduced. Therefore, the conductivity of milk is measured by a conductivity meter. According to the change of conductivity, it is possible to determine whether the milk is adulterated, and provides a direction for further quantitative analysis of adulterants. The Anlerich high-precision conductivity electrode is suitable for the measurement of conductivity in this study.
An Lillius used in this experiment
pH510
Host matching
S3221
Glass composite
pH
Electrode and
T2132
Temperature electrode for pure milk of two brands of Bright and Erie
pH
Values ​​were measured using Anleris
CD510
Conductivity meter combination
E2224T
The glass conductivity electrode measures the conductivity values ​​of the above two brands.
pH510
type
PH
Measuring pure milk
pH
Value operation
1
Preparing machine
pH510
Host matching
S3221
Glass composite
pH
Electrodes for precision
pH
measuring
,
Regular use in the laboratory
;
Can be used in turbid liquid or colloidal solutions
,
Such as milk, jam, water-based paints, cosmetics, soil solutions, sewage and sludge. with
T2132
Temperature electrode, ready for sample.
2
Connect the power supply. Place the universal electrode holder.
3
Use standard
pH
The buffer solution is routinely calibrated to the instrument.
4
will
pH
The electrode is washed with pure water and dried, immersed in the solution to be tested, placed agitated and then placed still, etc.
LCD
Display stable measurements and
The reading when the icon is measured
pH
value.
Note Regular calibration:
1.
press
CAL
Key, the instrument enters calibration mode,
LCD
Blinking in the lower right corner
6.86 pH
, prompt
pH6.86
Buffer solution
1
Point calibration.
2.
Wash the electrode with pure water and dry it, immersing
pH6.864
In the buffer solution, stand still after agitation to wait for the reading to stabilize. When the instrument is locked
6.86 pH
Time
LCD
Will show stability
Icon, press now
ENTER
Key to calibrate the instrument, display after successful calibration
End
Icon, number
1
The point calibration ends.
3.
If proceeding
3
Point calibration, please change
pH4.003
,
pH9.182
Buffer repeat
2
step,
5
The point calibration mode operates the same as above, but the calibration solution and calibration sequence can be selected at will.
Experimental result
The picture below shows famous brands
1
And well-known brands
2
And contrasting pure water pictures
Test Data
Analysis: From the above experimental results, we can see the two brands of Guangming and Yili used in this study.
pH
Values ​​are in
6.61
with
6.67
, relatively close, and all in
6.4-6.8
Within the scope of this standard.
Precautions
pH
The protective bottle at the front end of the electrode has an appropriate amount of electrode soaking solution, and the electrode tip is immersed therein to maintain the activation of the glass bulb and the liquid junction.
2.
The electrode plug must be kept highly clean and dry. If it is contaminated, it can be cleaned and dried with medical cotton 蘸 anhydrous alcohol to prevent short circuit at the two ends of the electrode plug, otherwise the measurement will be invalid.
3.
The electrode protection bottle has an appropriate amount of electrode soaking solution, and the electrode tip is immersed therein to keep the glass bulb moist and the liquid junction unobstructed. When measuring, loosen the cap, pull out the electrode, and wash it with deionized water to use. After use, insert the electrode and tighten the cap. If the solution in the protective bottle is found to be turbid and moldy, the protective bottle should be washed in time and replaced with a new one.
4.
The electrode life cycle is about one year, and new electrodes should be replaced in time after aging.
CD510
Conductivity meter measures the conductivity of pure milk
1.
Connect the power supply.
2.
will
E2224T
After the conductivity electrode finds the position of the bayonet, it is slowly rotated and inserted, and the socket nut is tightened.
3.
Install the universal electrode holder.
4.
Set the conductivity constant
K
.
5.
Select the conductivity standard solution as needed (default
CH
), set the reference temperature (default
25.0
°C
), temperature coefficient (default
2.00
)and
TDS
And conductivity conversion factor (default
0.71
).
General calibration:
(to
"1408 μS/cm"
Calibration as an example)
Rinse the electrode with pure water and dry it, then rinse with a small amount of calibration solution. Dip the electrode into the calibration solution, stand still after agitation and wait for the reading to stabilize.
2.
press
CAL
Key, the instrument enters calibration mode when the instrument is locked
1408 μS/cm
Time
LCD
Will display the symbol
At this time, press
ENTER
Key to calibrate the instrument, after successful calibration
LCD
display
End
Icon to return to measurement mode.
If you want to proceed
2-4
Point calibration (note that the concentration of the calibration solution is from low to high), please repeat the above steps until
Some calibrations are completed.
Test chart
Test Data
Analysis: From the above experimental results, it can be seen that the conductivity values ​​of the two brands of Guangming and Yili used in this study are respectively
4.29
Ms/cm
with
4.22
Ms/cm
, also relatively close. By consulting the relevant literature and regulations, it is judged that the pure milk of the above two brands is a reliable product through these two conductivity values, and there is no adulteration, and it can be safely consumed.
Precautions
1.
Keep the conductivity electrode clean. Rinse the electrode with pure water and dry it before measuring. It is best to rinse the electrode with the solution to be tested. After the conductivity electrode is immersed in the solution, it should be stirred a few times and then placed still to eliminate the bubble interference and make the measured value. Fast and stable. Rinse the electrode with pure water after use.
2.
The surface of the electrode should not be wiped. It can only be washed and shaken in water to avoid damaging the electrode sensing layer. The hot organic water containing detergent can be used to clean the organic components on the electrode, or it can be washed with alcohol.
3.
Immersed if the electrode is found to be ineffective
10%
Nitric acid solution or
10%
Hydrochloric acid solution
2min
Rinse with pure water and measure again. If there is no improvement, you may need to replace the new conductivity electrode.
Hydrogel Film,Film Tpu Flexible Hd,Hydrogel Vs Glass,Tpu Film
Shenzhen TUOLI Electronic Technology Co., Ltd. , https://www.hydrogelprotector.com