Method for detecting pH value of malt syrup

Abstract

The invention provides a method for detecting the pH value of malt syrup, and relates to the technical field of malt syrup detection. The method comprises the following steps: accurately weighing a malt syrup sample and preparing a 30% aqueous solution; manually stirring, and uniformly stirring on a magnetic stirrer to destroy hydrogen bonds among water molecules; vertically inserting the calibrated PH electrode into the sample, wherein the top end of the electrode is 0.5 cm higher than the rotor; rapidly measuring and recording stable readings; and repeatedly determining under the same condition to verify the precision. Compared with a traditional national standard method, the method can effectively eliminate errors caused by diluted water quality, electrode aging and manual operation differences, is higher in measurement speed and better in repeatability, and can meet the strict requirement of the beer industry on the accuracy of the pH value + / -0.3 of the malt syrup.

Description

Technical Field

[0001] The present invention relates to the technical field of maltose syrup detection, and particularly relates to a method for detecting the pH value of maltose syrup. Background Art

[0002] With the continuous improvement of the requirements for raw material quality control in food processing and beverage production, the pH value of maltose syrup has become an important indicator for evaluating its quality and production stability. Especially in the field of beer production, pH has a crucial impact on fermentation efficiency, flavor stability, and the taste of the final product. At present, the detection range of the pH value of maltose syrup specified in the national standard of China (GB / T 20804-2007) is 4.0 - 7.0. However, with the rise of the craft beer and high-end beer markets, many beer manufacturers have put forward higher requirements for the control accuracy of the raw material pH, and the pH needs to be controlled within a range of ±0.3 or even a narrower fluctuation range to ensure the consistency between product batches and the taste stability.

[0003] The current national standard detection method usually dilutes the maltose syrup sample into a 30% aqueous solution and then directly uses a pH meter for determination. However, this method has the following problems in practical applications: 1. Dilution medium difference: Diluting with distilled water from different batches or water qualities is likely to introduce additional ion interference and affect the electrode response sensitivity; 2. Electrode aging lag: During long-term use or repeated measurements of the pH electrode, the sensitive glass sphere is more likely to generate ion polarization and aging, resulting in slow or inaccurate endpoint recognition; 3. Large operation fluctuations: It is difficult to strictly reproduce the manual stirring intensity and time, and the differences in viscosity and dispersibility in the sample will also cause measurement errors; 4. Slow measurement speed: The time-consuming processes of waiting for the electrode to stabilize and manual recording make it difficult to meet the production requirements of large-scale and rapid detection.

[0004] Therefore, it is necessary to develop a new pH value determination method that can overcome the above influencing factors and improve the detection speed and repeatability accuracy to meet the strict requirements for maltose syrup pH control in the beer industry and other high-end applications. Summary of the Invention

[0005] A method for detecting the pH value of maltose syrup includes the following steps: S1: Sample pretreatment, mixing the maltose syrup sample to be measured evenly; S2: Weighing the sample, weighing m grams of the sample into a beaker using an electronic balance with a precision of 0.01 grams, where m is 15 - 30 grams; S3: Diluting and dissolving, adding M grams of distilled water to the sample to make the mass concentration of the mixed aqueous solution 30%, where M is calculated according to the formula: ; S4: For the first stirring, use a glass rod or a plastic rod to stir the diluted sample until it is homogeneous; S5: Place the stirring rotor, put the evenly stirred sample solution on a magnetic stirrer, and place a magnetic rotor in it; S6: Insert the pH electrode, adjust the electrode height so that its bottom is at least 0.5 cm higher than the surface of the rotor; S7: For dynamic stirring detection, start the magnetic stirrer and adjust the rotation speed to a stable state without generating vortices and bubbles, and at the same time turn on the pH meter for real-time measurement; S8: Record the result. When the reading of the pH meter is stable, read and record the data. The absolute difference between the results of two repeated detections does not exceed ±0.2 pH units.

[0006] Further, the distilled water in step S3 is deionized water or ultrapure water, and the conductivity ≤ 2 μS / cm.

[0007] Further, the pH electrode in S6 is a combined glass electrode, which is calibrated with pH 4.0 and pH 6.86 standard buffer solutions before use.

[0008] Further, the rotation speed of the magnetic stirrer in step S7 is controlled within the range of 200 - 400 rpm.

[0009] Further, the data stability in step S8 is defined as the fluctuation of the pH meter reading ≤ 0.05 pH units within 30 seconds.

[0010] Compared with the prior art, the present invention has the following advantages: 1. Use an electronic balance with a resolution of 0.01 g to accurately weigh the sample, strictly control the sample quality, and eliminate the artificial weighing error; prepare a 30% aqueous solution according to the mass ratio of 1:1.5, accurately, to avoid the ion strength fluctuation caused by inconsistent dilution water consumption or water quality differences.

[0011] 3. After preparing the solution, use a magnetic stirrer to continuously stir evenly, and the rotation speed can be adjusted to the state of "no vortex, no bubble", so that the viscous substances in the sample are fully dispersed, avoiding the intensity and time fluctuations brought by manual stirring; during the stirring process, the intermolecular hydrogen bonds are broken, accelerating the balance between water molecules and sample ions, and achieving faster electrode response and stable reading.

[0012] 3. Vertically insert the pH electrode probe into the solution, and the top of the electrode is 0.5 cm higher than the top of the rotor, preventing the rotor from directly hitting the sensitive glass bulb, reducing the mechanical damage and polarization lag of the electrode; by pre-calibrating (using pH 4.00 and 6.86 buffer solutions) and completing the measurement in a short time, the influence of electrode aging and drift on the measurement result is reduced.

[0013] Two independent determinations are required to be carried out under the same conditions, and the absolute difference between the two readings is limited to not more than 3% of the arithmetic mean to verify the precision and stability of the method; through a strict quality control process, the test results are both fast and highly reproducible, meeting the industry application requirements of ±0.3 pH units. Detailed implementation manners

[0014] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein, and is not a limitation on the scope of protection, applicability, or examples set forth in the claims. Changes can be made to the functions and arrangements of the elements discussed without departing from the scope of protection of the content of this specification. Each example can omit, substitute, or add various processes or components as needed. For example, the described method can be performed in an order different from the described order, and each step can be added, omitted, or combined. Additionally, the features described relative to some examples can also be combined in other examples.

[0015] As used herein, the term "comprising" and its variants denote open terms, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" and "an embodiment" mean "at least one embodiment". The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc. can refer to different or the same objects. Other definitions, whether explicit or implicit, may be included below. Unless explicitly specified in the context, the definition of a term is consistent throughout the specification.

[0016] Embodiment A method for detecting the pH value of maltose syrup, comprising the following steps: S1: Sample pretreatment, mixing the maltose syrup sample to be tested evenly; S2: Weigh the sample, weigh m grams of the sample into a beaker using an electronic balance with a precision of 0.01 grams, where m is 15 - 30 grams; S3: Dilute and dissolve, add M grams of distilled water to the sample to make the mass concentration of the mixed aqueous solution 30%, where M is calculated according to the formula: ; S4: First stirring, stir the diluted sample evenly using a glass rod or a plastic rod; S5: Place the stirring rotor, place the evenly stirred sample solution on a magnetic stirrer and put in a magnetic rotor; S6: Insert the pH electrode and adjust its height so that the bottom is at least 0.5 cm above the rotor surface; S7: Dynamic stirring detection. Start the magnetic stirrer and adjust the rotation speed to a stable state without vortices and bubbles. At the same time, turn on the pH meter for real-time measurement; S8: Record the results. When the indication of the pH meter is stable, read and record the data. The absolute difference between the results of two repeated detections does not exceed ±0.2 pH units.

[0017] Further, the distilled water in step S3 is deionized water or ultrapure water with a conductivity ≤ 2 μS / cm.

[0018] Further, the pH electrode in S6 is a combined glass electrode, which is calibrated with pH 4.0 and pH 6.86 standard buffer solutions before use.

[0019] Further, the rotation speed of the magnetic stirrer in step S7 is controlled within the range of 200 - 400 rpm.

[0020] Further, the data stability in step S8 is defined as the fluctuation of the pH meter indication ≤ 0.05 pH units within 30 seconds.

[0021] Select 8 groups of samples for detection according to the above steps, and at the same time conduct national standard method detection. The results of the two methods are compared with the user's usage effect in a comparative experiment. The results are shown in Table 1. These 8 groups of samples are all used in the beer product manufacturing industry, and the user's usage effect is the feedback result during the actual use by the customers.

[0022] Table 1 According to the comparative test data, the difference between the pH value of malt syrup measured by the method of the present invention and the detection result of the national standard method is between -0.31 and -0.32. This is because when using the national standard method, the liquid junction of the combined electrode is close to the sensitive glass bulb, and the salt bridge solution leaking out from the liquid junction will first accumulate around the sensitive bulb, changing the ion concentration around it. Therefore, the pH value measured by the national standard method cannot truly reflect the electromotive force value of the electrode.

[0023] In addition, when using the national standard method, in the aqueous solution of the sample placed for a long time, hydrogen bonds will be generated between water molecules, thus reducing the ionization degree of water. While the method of the present invention effectively destroys the hydrogen bonds between water molecules by using a magnetic stirrer, restoring the ionization degree of water, thereby improving the measurement accuracy and speed.

[0024] Therefore, although the pH measurement results using the national standard method are judged to be qualified in some cases, they cannot fully meet the strict requirements of the beer industry for a pH accuracy of ±0.3 in practical applications. The method provided by the present invention can more accurately measure the true pH value of malt syrup, meet the needs of customers, and ensure the high requirements for pH accuracy in the beer manufacturing industry.

[0025] Those skilled in the art should understand that various changes and modifications can be made to the above-disclosed embodiments without departing from the essence of the invention. Therefore, the protection scope of the present invention should be defined by the appended claims.

[0026] It should be noted that not all steps and units in the above processes are necessary, and some steps or units can be ignored according to actual needs. The execution order of each step is not fixed and can be determined according to needs. The device structures described in the above embodiments can be physical structures or logical structures, that is, some units may be implemented by the same physical entity, or some units may be implemented by multiple physical entities respectively, or some components in multiple independent devices may be jointly implemented.

[0027] The specific embodiments described above illustrate exemplary embodiments, but do not represent all embodiments that can be implemented or fall within the scope of protection of the claims. The term "exemplary" used throughout this specification means "serving as an example, instance, or illustration", and does not mean "preferred" or "advantageous" compared to other embodiments. For the purpose of providing an understanding of the described technology, the specific embodiments include specific details. However, these technologies can be implemented without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described embodiments.

[0028] The above description of the present disclosure is provided to enable any ordinary skilled person in the art to implement or use the present disclosure. Various modifications to the present disclosure are obvious to those of ordinary skill in the art, and the general principles defined herein can also be applied to other variations without departing from the scope of protection of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is consistent with the broadest scope that conforms to the principles and novel features disclosed herein.

Claims

1. A method for detecting the pH value of malt syrup, characterized in that, It includes the following steps: S1: Sample pretreatment, mixing the malt syrup sample to be measured evenly; S2: Weigh the sample, weigh m grams of the sample into a beaker using an electronic balance with a precision of 0.01 grams, where m is 15 to 30 grams; S3: Dilute and dissolve, add M grams of distilled water to the sample to make the mass concentration of the mixed aqueous solution 30%, where M is calculated according to the formula: ； S4: First stirring, stir the diluted sample evenly with a glass rod or plastic rod; S5: Place the stirring rotor, place the evenly stirred sample solution on a magnetic stirrer and put in a magnetic rotor; S6: Insert the pH electrode, adjust the electrode height so that its bottom is at least 0.5 cm higher than the rotor surface; S7: Dynamic stirring detection, start the magnetic stirrer and adjust the rotation speed to a stable state without generating vortices and bubbles, and at the same time turn on the pH meter for real-time measurement; S8: Record the results, read and record the data when the pH meter reading is stable, and the absolute difference between the results of two repeated detections does not exceed ±0.2 pH units.

2. The detection method of the pH value of maltose syrup according to claim 1, characterized in that: The distilled water mentioned in step S3 is deionized water or ultrapure water, and the conductivity ≤ 2 μS / cm.

3. The detection method of the pH value of maltose syrup according to claim 1, characterized in that: The pH electrode mentioned in S6 is a combined glass electrode, which is calibrated with pH 4.0 and pH 6.86 standard buffer solutions before use.

4. The detection method of the pH value of maltose syrup according to claim 1, characterized in that: The rotation speed of the magnetic stirrer in step S7 is controlled within the range of 200 to 400 rpm.

5. The detection method of the pH value of maltose syrup according to claim 1, wherein: The data stability mentioned in step S8 is defined as the pH meter reading fluctuating ≤ 0.05 pH units within 30 seconds.

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