Method for testing acidity of vinegar culture
阅读说明：本技术 一种醋醅酸度化验方法 (Method for testing acidity of vinegar culture ) 是由 郭霞 张慧如 田慧芳 于 2021-09-09 设计创作，主要内容包括：本发明具体涉及一种醋醅酸度化验方法,属于醋醅酸度化验技术领域,所要解决的技术问题是提供一种可以更加直观的判断发酵是否完成的醋醅酸度化验方法,采用的技术方案为：(1)、取醋酸发酵的醋醅,挤出汁液；(2)、取其挤出液1mL于烧杯中,加入50mL中性水,用0.1M的NaOH滴定至pH计显示值为8.2,记录NaOH用量,计算醋醅酸度；本发明可以更加直观的显现出醋酸发酵是否完成,对生产有更加准确直观的指导作用。(The invention particularly relates to a vinegar culture acidity testing method, belongs to the technical field of vinegar culture acidity testing, and aims to provide a vinegar culture acidity testing method capable of judging whether fermentation is finished or not more intuitively, wherein the technical scheme is as follows: (1) taking vinegar grains fermented by acetic acid, and extruding juice; (2) putting 1mL of the extrusion liquid into a beaker, adding 50mL of neutral water, titrating with 0.1M NaOH until the pH value displayed by a pH meter is 8.2, recording the using amount of the NaOH, and calculating the acidity of the vinegar grains; the invention can more intuitively show whether the acetic fermentation is finished or not, and has more accurate and intuitive guiding function for production.)
1. The vinegar culture acidity testing method is characterized by comprising the following steps:
(1) taking vinegar grains fermented by acetic acid, and extruding juice;
(2) and putting 1mL of the extrusion liquid into a beaker, adding 50mL of neutral water, titrating with 0.1M NaOH until the pH value displayed by the pH meter is 8.2, recording the using amount of the NaOH, and calculating the acidity of the vinegar grains.
2. The method for testing acidity of fermented vinegar according to claim 1, wherein in step (1), 100g of acetic acid-fermented vinegar is taken, and the vinegar is placed in a buckwheat branding machine for squeezing to obtain juice, wherein the volume of the squeezed juice is 30 mL.
3. The method for assaying acidity of fermented grains of vinegar according to claim 1 or 2, wherein in step (2), a beaker having a volume of 100mL is selected.
4. The method for assaying acidity of fermented vinegar according to claim 1 or 2, wherein in the step (2), the acidity is calculated by:
b＝{[(V1-V2)*c*0.06]/[V3*(10/100)]}*100
in the formula:
b-total acid content in sample (in terms of acetic acid), g/100 mL;
V1titration of the test sample diluent depleted in volume, mL, of sodium hydroxide standard titrant;
V2-titration of the reagent blank sample to consume the volume of sodium hydroxide standard titration solution, mL;
V3-aspirating the volume of the test sample, mL;
c, concentration of sodium hydroxide standard titration solution, mol/L;
0.06-mass of acetic acid equivalent to 1.00mL of sodium hydroxide standard solution [ c (sodium hydroxide) ═ 1.000mol/L ], g.
Technical Field
The invention belongs to the technical field of acidity test of vinegar culture, and particularly relates to a method for testing acidity of vinegar culture.
Background
In the process of brewing vinegar, the acidity of the fermented grains of vinegar needs to be tested to judge whether the fermentation is finished. The existing vinegar culture assay method comprises the following steps: weighing 10g of acetic fermentation vinegar mash, adding 90mL of neutral water, soaking for 2h, filtering a soaking solution, putting 1mL of filtrate into a 250mL triangular flask, adding 50mL of neutral water, dripping two drops of phenolphthalein indicator, titrating to pink with 0.1M NaOH, taking no color change within 30s as an end point, recording the amount of NaOH, and calculating the acidity of the vinegar mash. In the process, due to the fact that the positions of the obtained filtrates are different, the deviation of the quality of the vinegar grains and the deviation of the amount of the neutral water are weighed, the judgment of the titration end point is greatly influenced, the error is large, whether the fermentation is finished or not is judged inaccurately, the peroxidation of the fermentation is caused, and the fermentation quality is influenced.
Disclosure of Invention
The invention overcomes the defects of the prior art, provides the vinegar culture acidity testing method which can judge whether fermentation is finished or not more intuitively, and the test data is more accurate and intuitive.
In order to solve the technical problems, the invention adopts the technical scheme that: a vinegar culture acidity testing method specifically comprises the following steps:
(1) taking vinegar grains fermented by acetic acid, and extruding juice;
(2) and taking 1mL of the extrusion solution into a beaker by using a pipette, adding 50mL of neutral water, titrating by using 0.1M NaOH under magnetic stirring until the display value of a pH meter is 8.2, recording the using amount of the NaOH, and calculating the acidity of the vinegar grains.
In the step (1), 100g of acetic acid fermented grains are taken, and the vinegar grains are placed into a buckwheat baking machine for squeezing juice, wherein the volume of the squeezed juice is 30 mL.
In the step (2), a beaker with the volume of 100mL is selected.
In the step (2), the acidity calculation method comprises the following steps:
b＝{[(V1-V2)*c*0.06]/[V3*(10/100)]}*100
in the formula:
b-total acid content in sample (in terms of acetic acid), g/100 mL;
V1titration of the test sample diluent depleted in volume, mL, of sodium hydroxide standard titrant;
V2-titration of the reagent blank sample to consume the volume of sodium hydroxide standard titration solution, mL;
V3-aspirating the volume of the test sample, mL;
c, concentration of sodium hydroxide standard titration solution, mol/L;
0.06-mass of acetic acid equivalent to 1.00mL of sodium hydroxide standard solution [ c (sodium hydroxide) ═ 1.000mol/L ], g.
The reagent blank sample is experimental water.
Compared with the prior art, the invention has the following beneficial effects.
The acidity of the vinegar substrate can be accurately measured by adopting the vinegar substrate extrusion juice based on a large amount of experimental data and taking the titration to the pH value of 8.2 as the titration end point, because the acetic acid fermentation is based on the alcohol fermentation, the acetic acid fermentation process is the process of converting alcohol into acetic acid, the acetic acid acidity when the acetic acid fermentation is finished is theoretically proportional to the alcohol, and the acidity of the juice after the juice extrusion is detected to be the alcoholic strength when the alcohol fermentation is finished, so that whether the acetic acid fermentation is finished or not can be displayed more intuitively, and a more accurate and more intuitive guiding effect on production can be realized.
Compared with the traditional vinegar grain acidity testing method, the method has the advantages that the artificial operation error in the operation process is smaller, and the titration end point is more accurately judged.
The consumption of 1MNaOH consumed by the method is about 10-15 mL, while the consumption of 1MNaOH consumed by titration by the traditional method is about 1-1.5 mL, the method has the advantages of large consumption volume, small error influence and more accurate calculation result.
Fourthly, the testing of the acidity of the vinegar grains takes about 0.5 hour, the traditional method takes at least 2.5 hours, and the time is long, so that the method can save time and has more timely and accurate guiding significance for production.
Detailed Description
The present invention is further illustrated by the following specific examples.
A vinegar culture acidity testing method specifically comprises the following steps:
(1) squeezing 100g of acetic acid fermented grains by using a buckwheat baking machine to obtain about 30mL of juice;
(2) the 1mL of the extrusion was pipetted into a 100mL beaker, i.e., V3After adding 50mL of neutral water to 1mL of the solution, titrating the solution with 0.1M NaOH under magnetic stirring to a pH value of 8.2, and recording the amount of NaOH V1；
(3) Taking a reagent blank sample, namely 50mL of experimental neutral water, titrating the reagent blank sample by using 0.1M NaOH until the pH value displayed by a pH meter is 8.2, and recording the using amount V of the NaOH2And calculating the acidity b of the vinegar grains.
For the same batch of fermented products, 100g of vinegar grains are taken every day for juicing assay, and the acidity record data is as follows:
TABLE 1 acidity of vinegar
During the fermentation process, the vinegar culture is tested, when the numerical value of the test method, namely the juicing result, does not increase for three consecutive days, the completion of the fermentation can be judged, and the acidity of the vinegar culture is basically consistent with the alcoholic strength.
And (3) carrying out acidity measurement on fermented grains after different batches of fermentation are finished, and analyzing data:
and (3) reference alcoholic strength: after fermentation is finished, 100g of mash is taken, 250mL of water is added for distillation, when the volume of distillate reaches 100mL, the distillation is stopped, and the alcoholic strength of the mash is measured by an alcohol meter, namely the alcoholic strength x of the mash;
the acidity of the fermented grains is measured by the method, namely the juicing result b;
control group: weighing 10g of finished fermented grains after acetic fermentation is finished, adding 90mL of neutral water, soaking for 2h, filtering a soaking solution, putting 1mL of filtrate into a 250mL triangular flask, adding 50mL of neutral water, dripping two drops of phenolphthalein indicator, titrating to pink with 0.1M NaOH, taking no color change within 30s as an end point, recording the amount of NaOH, and calculating the acidity of the vinegar grains, namely a soaking result a.
TABLE 2 alcohol content and acidity data of fermented grains
Batches of
Alcohol content x
Alcohol acid
Soaking results a
Juicing result b
Difference (x-a)
Difference (x-b)
1
7.5
1.01
5.33
7.21
2.17
0.29
2
8.7
1.13
6.67
8.62
2.03
0.08
3
8.1
1.02
6.09
8.02
2.01
0.08
4
8.4
1.17
6.38
8.39
2.02
0.01
5
8.2
1.28
6.2
8.21
2
-0.01
6
8.7
1.21
6.67
8.93
2.03
-0.23
7
8.6
1.3
6.97
9.15
1.63
-0.55
8
8.1
1.47
6.67
8.13
1.43
-0.03
9
8.5
1.42
6.67
8.79
1.83
-0.29
10
7.5
1.36
5.51
6.97
1.99
0.53
11
8.1
1.42
6.06
7.94
2.04
0.16
12
8.3
1.54
6.18
8.31
2.12
-0.01
13
8.3
1.5
6.06
7.79
2.24
0.51
14
8.5
1.43
6.06
8.04
2.44
0.46
15
7.7
1.82
6.06
7.79
1.64
-0.09
16
8.5
1.36
6.36
8.34
2.14
0.16
17
8.5
1.55
5.64
7.32
2.86
1.18
18
8.4
1.58
6.54
8.39
1.86
0.01
19
7.5
1.76
5.27
6.91
2.23
0.59
20
7.5
1.76
6.07
7.64
1.43
-0.14
21
7.6
1.7
6.11
7.67
1.49
-0.07
22
7.6
1.82
6.05
8.15
1.55
-0.55
23
8.4
1.76
6.84
8.42
1.56
-0.02
Average
1.95
0.09
As can be seen from Table 2, the acidity of the fermented vinegar substrate measured by the method of the present invention is substantially consistent with the alcoholic strength, the average difference value is 0.09, and the maximum difference value is that the alcoholic strength is 1.18 higher than the acidity, which is caused by incomplete acetic fermentation.
TABLE 3 analysis of acidity measurement of fermented grains
The average value of X is calculated,
the average value of Y is calculated,
0.2317 standard deviation of X
Standard deviation of Y0.02
X confidence (90%) < 1.86 ± 0.079
Y confidence (90%) ═ 0.23 ± 0.007
As can be seen from Table 3, the total acid measured by the conventional method and the method of the present invention was 1.86 higher than that measured by the conventional method, and the difference was proportional to the measurement result of the novel method, i.e., the ratio was 0.23. The method of the invention can be used for calculating the total acid content measured by the traditional method according to the proportion when the method is used so as to slowly adapt to the method of the invention.
Assuming that the acidity result of the vinegar substrate assayed by the method is b1Then, the test result a of the conventional method is calculated1According toTo conclude a1＝0.77*b1。
The acidity of the fermented grains after the acetic fermentation is detected by the method of the invention is 0.77, which is the acidity detected by the traditional method, so that production staff can adapt to the detection data of the method by adopting the calculation method, and meanwhile, the method is well documented when being compared with the traditional detection data.
The acidity of the smoked grains subjected to smoking in the next process after fermentation is respectively measured by adopting the method and the traditional method, and the acidity numerical values are compared as follows:
TABLE 4 analysis of measurement results of smoked grains
X average value 1.94
Average value of Y is 0.22
0.1758 standard deviation of X
Standard deviation of Y0.0173
X confidence (90%) -0.97 ± 0.066
Y confidence (90%) -0.22 ± 0.007
As can be seen from Table 4, the total acid content of the fumigated grains measured by the conventional method is 1.97 higher than that measured by the conventional method, and the difference is proportional to the measurement result of the method, wherein the ratio is 0.22.
The acidity of the smoked culture detected by the method is 0.78, namely the acidity of the smoked culture detected by the traditional method.
The above embodiments are merely illustrative of the principles of the present invention and its effects, and do not limit the present invention. It will be apparent to those skilled in the art that modifications and improvements can be made to the above-described embodiments without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications or changes be made by those skilled in the art without departing from the spirit and technical spirit of the present invention, and be covered by the claims of the present invention.
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