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GB 5009.229-2025: National food safety standard - Determination of acid value in foods Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB 5009.229: Historical versions
Similar standardsGB 5009.229-2025: National food safety standard - Determination of acid value in foods---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB5009.229-2025GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National food safety standard - Determination of acid value in food Issued on. MARCH 16, 2025 Implemented on. SEPTEMBER 16, 2025 Issued by. National Health Commission of the People’s Republic of China; State Administration for Market Regulation. Table of ContentsForeword... 3 1 Scope... 4 First method -- Cold solvent indicator titration method... 4 2 Principle... 4 3 Reagents and materials... 4 4 Instruments and equipment... 6 5 Analysis steps... 6 6 Expression of analysis results... 8 7 Precision... 9 Second method -- Cold solvent automatic potentiometric titration... 9 8 Principle... 9 9 Reagents and materials... 9 10 Instruments and equipment... 10 11 Analysis steps... 10 12 Expression of analysis results... 12 13 Precision... 12 Third method -- Hot ethanol indicator titration method... 12 14 Principle... 12 15 Reagents and materials... 12 16 Instruments and equipment... 13 17 Analysis steps... 13 18 Expression of analysis results... 14 19 Precision... 14 Forth method -- Spectrophotometry... 14 20 Principle... 14 21 Reagents and materials... 14 22 Instruments and equipment... 15 23 Analysis steps... 16 24 Expression of analysis results... 19 25 Precision... 19 26 Others... 19 Annex A Impurity removal and drying and dehydration of oil and fat samples... 21 Annex B Schematic diagram of titration end point determination by automatic potentiometric titration method... 23ForewordThis Standard replaces GB 5009.229-2016 “National food safety standard - Determination of acid value in food”. Compared with GB 5009.229-2016, the main changes of this Standard are as follows. - MODIFY the scope of application of the standard; - MODIFY the sample weight; - ADD the forth method -- Spectrophotometry; - DELETE the original Annex B, Annex C, and Annex D. National food safety standard - Determination of acid value in food1 ScopeThis Standard specifies the determination methods for acid value in food. The first, second and third methods are applicable to the determination of acid value in food [except non-dairy cream, powdered oils and fats, margarine, compound seasonings (mayonnaise, salad dressing, oil-based chili sauce, nut and seed sauce, hot pot base and other semi-solid seasonings)]. The fourth method is applicable to the determination of acid value in non-dairy cream, powdered oils and fats, margarine, compound seasonings (mayonnaise, salad dressing, oil-based chili sauce, nut and seed sauce, hot pot base and other semi-solid seasonings). First method -- Cold solvent indicator titration method2 PrincipleBased on the principle of acid-base neutralization reaction, potassium hydroxide or sodium hydroxide standard titration solution is used to neutralize the free fatty acids in the sample solution, and the titration end point is determined by the acid-base indicator. The acid value of the sample is calculated based on the consumption of the standard titration solution.3 Reagents and materialsUnless otherwise specified, the reagents used in this method are analytically pure, and the water is grade 3 water specified in GB/T 6682. 3.1 Reagents 3.1.1 Isopropyl alcohol (C3H8O). 3.1.2 Anhydrous ether (C4H10O). 3.1.3 95 % ethanol (C2H5OH). 3.1.4 Phenolphthalein (C20H14O4, CAS No.. 77-09-8). 3.1.5 Thymophthalein (C28H30O4, CAS No.. 125-20-2). 3.1.6 Alkali blue 6B (C37H29N3O3S, CAS No.. 1324-76-1). 3.1.7 Liquid nitrogen (N2). purity > 99.99 %. 3.1.8 Petroleum ether. the boiling range is 30 ℃ ~ 60 ℃. 3.1.9 Anhydrous sodium sulfate (Na2SO4). 3.1.10 Potassium hydroxide (KOH). 3.1.11 Sodium hydroxide (NaOH). 3.2 Preparation of reagents 3.2.1 Cold solvent. mix anhydrous ether and isopropyl alcohol (or 95 % ethanol) in a volume ratio of 1.1. 3.2.2 Phenolphthalein indicator (10 g/L). weigh 1 g of phenolphthalein, dissolve in 95 % ethanol and dilute to 100 mL. 3.2.3 Thymophthalein indicator (20 g/L). weigh 2 g of thymophthalein, dissolve in 95 % ethanol and dilute to 100 mL. 3.2.4 Alkali blue 6B indicator (20 g/L). weigh 2 g of alkali blue 6B, dissolve in 95 % ethanol and dilute to 100 mL. 3.3 Preparation of standard solutions 3.3.1 Potassium hydroxide standard titration solution (0.5 mol/L and 0.1 mol/L). prepared and calibrated according to the requirements of GB/T 5009.1, or purchase a standard titration solution certified by the state and awarded a standard material certificate. 3.3.2 Potassium hydroxide standard titration solution (0.05 mol/L). before use, obtained by diluting potassium hydroxide standard titration solution (0.5 mol/L or 0.1 mol/L), or purchase a standard titration solution certified by the state and awarded a standard material certificate. 3.3.3 Standard sodium hydroxide titration solution (0.5 mol/L and 0.1 mol/L). prepared and calibrated according to the requirements of GB/T 5009.1 or GB/T 601, or purchase a standard titration solution certified by the state and awarded with a standard material certificate. 3.3.4 Standard sodium hydroxide titration solution (0.05 mol/L). before use, obtained by diluting sodium hydroxide standard titration solution (0.5 mol/L or 0.1 mol/L), or purchase a standard titration solution certified by the state and awarded with a standard material certificate.4 Instruments and equipment4.1 Burette. capacity of 10 mL, minimum graduation value of 0.05 mL. 4.4 Food grinder or pounder. 4.5 Laboratory oil press. screw press, non-heating type. 4.6 Porcelain mortar. 4.7 Constant temperature water bath. 4.8 Constant temperature blast drying oven. 4.9 Centrifuge. speed ≥ 8000 r/min. 4.10 Rotary evaporator or equivalent equipment. 4.11 Soxhlet extraction device.5 Analysis steps5.1 Preparation of samples 5.1.1 Animal and vegetable oils and fats, edible hydrogenated oils, shortening, cocoa butter substitutes At room temperature, liquid samples are fully mixed and then directly sampled for testing. For solid (or semi-solid) samples, take a representative sample and place it in a warm water bath or a constant temperature blast drying oven to heat and melt, mix well and then take the oil and fat for testing. If the oil and fat sample is obviously turbid, emulsified, stratified or precipitated, it shall be treated with impurity removal and dehydration according to Annex A. 5.1.2 Vegetable oils, nuts and seeds Direct pressing method is used for samples susceptible to lipase, such as raw and dried sesame. Take a representative sample, use laboratory oil press to press at room temperature, collect the squeezed material and filter it with filter paper immediately, and then take the oil and fat for determination. If the residue is obviously turbid, emulsified, stratified or precipitated, it shall be treated with impurity removal and dehydration according to Annex A. 5.2 Weighing of samples According to the estimated acid value of the sample, weigh the oil and fat sample according to the sample weight specified in Table 1 and place it in a 250 mL conical flask. 5.3 Determination of samples Add 50 mL ~ 100 mL of cold solvent to the weighed oil and fat sample, shake the sample gently until it is completely dissolved, add 3 ~ 4 drops of phenolphthalein indicator, and immediately titrate with potassium hydroxide or sodium hydroxide standard titration solution of the concentration specified in Table 1 until the solution turns slightly red and does not fade for 15 s, which is the end point. Perform a blank test at the same time (if the cold solvent is adjusted to neutral with a standard titration solution before the sample is determined, V0 = 0 mL).6 Expression of analysis resultsThe acid value (in terms of KOH) in the sample is calculated according to formula (1).7 PrecisionWhen the acid value is ≤ 1 mg/g, the absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 15 % of the arithmetic mean; when the acid value is > 1 mg/g,8 PrincipleBased on the principle of acid-base neutralization reaction, potassium hydroxide or sodium hydroxide standard titration solution is used to neutralize the free fatty acids in the sample solution, and the titration end point is determined by the “pH jump” caused by the neutralization reaction. The acid value of the sample is calculated based on the consumption of the standard titration solution.9 Reagents and materialsUnless otherwise specified, the reagents used in this method are analytically pure, and the water is grade 3 water specified in GB/T 6682. 9.1 Reagents 9.2 Preparation of reagents Cold solvent. mix anhydrous ether and isopropyl alcohol (or 95 % ethanol) in a volume ratio of 1.1. 9.3 Preparation of standard solutions Same as 3.3.10 Instruments and equipment10.1 Automatic potentiometric titrator. with automatic pH electrode calibration function and dynamic titration mode function; controlled by a microcomputer, capable of automatically drawing and recording the real-time pH-titration volume change curve and the corresponding first-order differential curve during titration; the titration accuracy is 0.01 mL/drop, the electrical signal measurement accuracy is 0.1 mV; the titration port is equipped with an anti-diffusion head. 10.2 Composite pH electrode for non-aqueous phase acid-base titration. using Ag/AgCl internal reference electrode, with movable sleeve diaphragm and electromagnetic shielding function. 10.3 Magnetic stirrer or device with stirring function.11 Analysis steps11.1 Preparation of samples Same as 5.1. 11.2 Weighing of samples According to the estimated acid value of the sample, weigh the oil and fat sample according to the sample weight specified in Table 1 and place it in a 200 mL beaker. 11.3 Determination of samples Add 50 mL ~ 100 mL of cold solvent to the weighed oil and fat sample, then add a polytetrafluoroethylene magnetic stirrer, and place the sample on a magnetic stirrer to stir and dissolve. Then, insert the electrode and burette connected to the automatic potentiometric titrator into the sample solution. Note that the glass bulb of the electrode and the anti-diffusion head of the burette shall be completely immersed below the liquid surface of the sample solution and it shall avoid touching the inner wall of the beaker. Start the automatic potentiometric titrator and titrate with potassium hydroxide or sodium hydroxide standard titration solution. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. |
