Sensory analysis — Methodology — Duo-trio test Published (Edition 4, 2026)

Abstract

This document specifies a procedure for determining whether a perceptible sensory difference or similarity exists between samples of two products. The method is a forced-choice procedure. The method is applicable whether a difference exists in a single sensory attribute or in several attributes.

The method is statistically less efficient than the triangle test (described in ISO 4120) but is easier to perform by the assessors.

The method is applicable even when the nature of the difference is unknown (i.e. it determines neither the size nor the direction of difference between samples, nor is there any indication of the attribute(s) responsible for the difference). The method is applicable only if the products are fairly homogeneous.

The method is effective for:

determining that either:
- a perceptible difference results (duo-trio testing for difference); or
- a meaningful perceptible difference does not result (duo-trio testing for similarity) when, for example, a change is made in ingredients, processing, packaging, handling or storage;
selecting, training and monitoring assessors.

Two forms of the method are described:

the constant-reference technique, used when one product is familiar to the assessors (e.g. a sample from regular production);
the balanced-reference technique, used when one product is not more familiar than the other.

General information

Status : Published

Publication date : 2026-05

Stage : International Standard published

Edition : 4

Number of pages : 22

ISO

ISO 7928-2:2026

ISO 20198:2026

ISO 19717:2026

ISO 19916-4:2026

ISO 5364:2026

ISO 11092:2026

ISO 7902-3:2026

ISO 10399:2026

ISO 24063:2026

ISO 877-3:2026

ISO 20681:2026

ISO 4625-3:2026