GB/T 39558-2020 in English

Principle of the method

This method requires the evaluator to repeatedly evaluate the known "A" sample and the "non-A" sample to be tested, and make a distinction based on the difference in sensory characteristics. The core of this method is to analyze the identification difference between the two types of samples through the χ² test or the standard normal distribution test.

Comparison of old and new standards

Key points of implementation

1. Sample preparation: The temperature, appearance and other physical properties of "A" and "non-A" samples must be consistent
2. Evaluator training: Screening according to ISO8586 standards requires unified training by the sensory analysis laboratory
3. Test design: Each evaluator evaluates 20-100 times, and the ratio of "A" and "non-A" samples can be different

Application case

In the detection of sweetener differences:

• 40g/L sucrose solution is set as "A" sample
• Sugar substitute solution with equivalent sweetness is "non-A" sample
• The chi-square test shows p=0.0004<0.05, confirming the significant difference

Technology Evolution Analysis

This standard is equivalent to ISO8588:2017, and the main improvements are:

• The statistical processing is more rigorous, and the right-side unilateral test method is added
• The laboratory conditions requirements are refined and the ISO8589 standard is quoted
• The test sample size calculation formula is clarified to improve the reliability of the results