The new national standard for soybean isoflavone testing: GB/T 23788-2026 is officially released. How should laboratories respond?

Key points of this article

① "Determination of soy isoflavones in health foods" (GB/T 23788-2026) has been publishedIt will be released in February 2026 and will be implemented on August 1, 2026, fully replacing GB/T 23788-2009 that has been in use for more than ten years.

② The revision focuses on three key technical aspects: scope of application, sample processing, and chromatographic conditions, to specifically solve the problems of narrow scope of application and low specificity of the old version of the method.

③ The detection object coversCovering the three glycosidic components of daidzein, daidzein, and genistein and their corresponding three free aglycones (didzein/didzein, daidzein, and genistein), a total of six components.

④ The implementation of new standards means that relevant detection methods need to be re-verified. The six-component high-purity reference standard is the basic guarantee for method verification and daily quantification.

1. Standard revision background: from GB/T 23788-2009 to 2026 edition

Soy isoflavones are a type of phytoestrogens naturally found in soybeans and other leguminous plants. They have long been a popular raw material in the health food industry. According to data from the State Administration for Market Regulation, there are currently more than 80 types of soy isoflavone health foods registered in China, and the product forms are mainly tablets and capsules. GB/T 23788-2009 "Method for Determination of Soybean Isoflavones in Health Foods - High Performance Liquid Chromatography", which the industry has long relied on, has been widely reflected after more than ten years of application.Narrow scope of application and weak specificityproblems, it is difficult to fully cover the current testing needs for a wide variety of categories and complex matrices.

Based on this, the National Technical Committee for Standardization of Special Foods (TC466) organized the completion of a new round of revisions. The new national standard was officially released by the State Administration for Market Regulation in February 2026. The standard number is GB/T 23788-2026. It will be implemented from August 1, 2026, completely replacing GB/T 23788-2009. This revision focuses onScope of application(Expand method coverage and adapt to increasingly diverse product forms),Sample processing(Optimize the pre-treatment process and improve the adaptability to complex matrices),Chromatographic conditions(Adjust separation and detection parameters to improve specificity) Optimize three technical links. For testing institutions and manufacturing companies, this means that the current testing SOP needs to be re-examined or even re-validated after the standard is implemented, and any method verification cannot avoid high-purity, well-defined component reference standards.

2. Detection objects: six components, two forms of existence

Soy isoflavones are not a single substance, but a group of secondary metabolites of the phenylpropanoid metabolic pathway. Naturally, they occur in soybeans in two forms:free aglyconeandconjugated glycoside——Glycosides will be hydrolyzed in the body or during processing to release the corresponding aglycones. This is one of the reasons why the sample pre-processing step is particularly critical in this type of testing. The currently recognized six main components and their corresponding relationships are as follows:

Note: The above CAS numbers and molecular formulas are general physical and chemical data of the compounds themselves, for verification and comparison by testing personnel; the specific quantitative limits, chromatographic parameters and other technical details in the standard are subject to the official text of GB/T 23788-2026.

3. Technical thresholds that cannot be avoided in method verification

The simultaneous quantitative detection method of six components faces at least two types of challenges in actual operation:

One is the morphological stability of aglycones and glycosides.Glycosides will be converted into aglycones to varying degrees under acidic conditions, heating or enzymatic treatment. Small differences in pre-treatment conditions may affect the final measured proportions of the six components. This is also the technical background for this new standard to focus on optimizing the "sample processing" link.

The second is the chromatographic separation of six structurally similar components.The three pairs of aglycones/glycosides are highly similar in polarity and retention behavior. The chromatographic conditions (mobile phase composition, column temperature, gradient) need to be finely adjusted to ensure baseline separation. This corresponds to another focus of optimizing "chromatographic conditions" in the new standard.

No matter how the method is adjusted, the verification of these two links relies on the same premise: the testing institution must have a six-component standard with a clear structure, reliable purity, and batch-to-batch stability, which can be used to prepare standard curves, conduct system suitability tests, and methodological verification. The quality of the standard directly determines whether the test results can truly reflect the actual content of the product.

4. CATO soybean isoflavone series standard products

As a standard supplier that has passed both CNAS (RM0030) and ANAB (AR-2832) dual-system ISO 17034 certification, CATO uses triple characterization of HPLC, NMR, and MS to confirm the structure and purity of the six-component soy isoflavone reference standard. The uncertainty is marked in the COA (±2.0% within the 95% confidence interval) and is accompanied by a complete original map, providing traceable data support for companies to verify methods in response to the new standard.

The above is a representative SKU display. Please check the complete catalog of soy isoflavones and related natural extract reference materials.CATO official websiteOr contact customer service to obtain it.

FAQ

Q1: After the implementation of GB/T 23788-2026, do the test reports previously issued based on the 2009 version need to be re-tested?
The implementation date of the new standard is August 1, 2026. Reports previously issued in accordance with GB/T 23788-2009 are generally still valid during its validity period; however, it is recommended that companies evaluate the scope of application of their own detection methods, pre-treatment processes and chromatographic conditions in advance against the new standard, and complete method revalidation simultaneously to avoid method non-compliance in the future.

Q2: Do glycosidic components such as daidzein, daidzein, and genistin need to be quantified separately during detection, or can they be directly converted into the total amount of aglycone?
Whether glycosides and aglycones need to be quantified separately depends on the specific standards and product claim requirements; since the molecular weights of glycosides and aglycones are different, the selection of coefficients in the conversion process will directly affect the accuracy of the results. Enterprises should strictly follow the calculation methods specified in the standards to avoid simplifying the conversion logic on their own.

Q3: What qualifications should companies focus on when selecting soy isoflavone reference substance suppliers?
It is recommended to give priority to whether the supplier has an authoritative measurement/standard material certification system (such as ISO 17034), whether it provides structure and purity data jointly confirmed by multiple technical means (such as HPLC+NMR+MS), and whether the COA discloses uncertainty information. These are the basic conditions to ensure that the test data is traceable and reproducible.