This standard specifies the determination method of total acid in dried fruits (longan, litchi, raisin, dried persimmon). This standard is applicable to the determination of total acid in dried fruits (longan, litchi, raisin, dried persimmon). GB/T 5009.187-2003 Determination of total acid in dried fruits (longan, litchi, raisin, dried persimmon) GB/T5009.187-2003 Standard download decompression password: www.bzxz.net

ICS_67.040
National Standard of the People's Republic of China
GB/T5009.187—2003
Partially replaces GB16325—1996
Determination of total acidity in dried fruits (longan, lychee, raisin, dried persimmon)
Fruit (longan, litchi, raisin, dried persimmon) Issued on August 11, 2003
Ministry of Health of the People's Republic of China
Standardization Administration of the People's Republic of China
Implementation on January 1, 2004bZxz.net
GB/T5009.187-2003
This standard replaces Appendix B "Determination of total acid in dried fruit (longan, litchi, dried grapefruit, dried persimmon)" in GB16325-1996 "Sanitary Standard for Dried Fruit Food".
This standard is proposed and managed by the Ministry of Health of the People's Republic of China. The standard was drafted by Zhejiang Provincial Food Hygiene Supervision and Inspection Institute, Xinjiang Uygur Autonomous Region Health and Epidemic Prevention Station, Guangdong Provincial Food Hygiene Supervision and Inspection Institute, Sichuan Provincial Food Hygiene Supervision and Inspection Institute, Hubei Provincial Health and Epidemic Prevention Station, and Gansu Provincial Health and Epidemic Prevention Station. The main drafters of this standard are Chen Anmei, Liu Cuiying, Deng Hong, Lan Zhen, and Wang Xilin. 492
1 Scope
Determination of total acid in dried fruits (longan, litchi, raisins, and dried persimmons)
This standard specifies the determination method for total acid in dried fruits (longan, litchi, raisins, and dried persimmons). This standard is applicable to the determination of total acid in dried fruits (longan, litchi, raisins, and dried persimmons). 2 Principle
GB/ T5009.187—2003
Organic acids in dried fruits are measured by neutralization titration with phenolic acid as an indicator or by acidometer method using sodium hydroxide standard solution, and the result is measured as citric acid.
3 Reagents
3.10.0500mol/L sodium hydroxide (NaOH) standard solution. 3.21% phenolic acid indicator.
4 Instruments
4.1 High-speed tissue crusher.
4.2 Constant temperature water bath.
4.3 Acidometer.
5 Operation method
5.1 Sample treatment
Take the edible part of the dried fruit, cut it into pieces, and mix it evenly. , and store in a wide-mouth bottle. 5.2 Determination
5.2.1 Indicator method: Weigh 10.0g of the above sample, add water to soak (immerse) for 1h~2h, put it in a commercial tissue crusher, add a small amount of water, crush for 0.5min~1min, transfer all to a 250mL, stoppered measuring cylinder, keep warm in a 70℃ water bath for 45min, take out and cool, dilute to 200mL, and filter. Pipette 20.0mL of the filtrate into a 250mL conical flask, add 30mL of water, use phenol as an indicator, and titrate with 0.0500mol/L sodium hydroxide standard solution until it turns slightly red. Keep it for 1min without fading as the end point, and make a blank at the same time. 5.2.2 Acidometer method: Pipette 20.0mL of the above filtrate into a 50mL beaker, add 30mL of water, start the magnetic stirrer, and titrate with 0.0500mol/L sodium hydroxide standard solution until the pH on the acidometer indicates 8.2. Make a blank at the same time. 5.3 Result calculation
Where:
X = V-V2)×cX0. 064 ×100
X—total acid content in the sample (calculated as citric acid), in grams per hundred grams (g/100g); V.—volume of sodium hydroxide standard solution consumed by the sample, in milliliters (mL); V2———volume of sodium hydroxide standard solution consumed by the blank, in milliliters (mL); concentration of sodium hydroxide standard solution, in moles per liter (mol/L); 0.064—mass of citric acid equivalent to 1ml.1mol/L sodium hydroxide standard solution, in grams (g). 493
GB/T5009.187—2003
6 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 2% of the arithmetic mean. 494
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