Developing sensory evaluation methods for consumers with low-literacy levels applicable in developing countries

Abstract

Conventional consumer sensory methods take literacy and language capabilities for granted. Consumers with low-literacy levels are considered as people lacking reading proficiency to fill out basic forms or read simple instructions. The conventional format of the paired preference test requires participants to read instructions and indicate which one of two samples is preferred. The first objective of the project was to develop formulations for two ginger biscuits that differed perceptibly but subtly in salt content only to use as test materials for paired preference test trials using consumers with low-literacy levels. The signal biscuit contained 0.65% salt on a flour basis and the high salt biscuit contained 4.54%. Physicochemical analysis showed that the two biscuits were significantly different in total carbohydrate, moisture, ash, protein, fat and Na+ contents as well as texture by instrumental analysis. However, biscuits weren t different in terms of their colour values. Sensory analysis revealed that the high salt biscuit was perceptibly more salty compared to the signal biscuit, but not different in hardness in contrast to the instrumental analysis. An untrained panel of literate student participants preferred the signal biscuit over the high salt biscuit. The second objective was to develop variations of the conventional paired preference method and to determine the effects of variations of the basic elements of the method on task performance by low-literate consumers. Seven individual paired preference tests were carried out at seven different test stations using 50 participants per method. The conventional method was less efficient and time-consuming with a mean time of 5.6 min taken per participant. The efficiency of the paired preference method was improved to an extent that almost no assistance was needed and the mean time to complete the test was 4.2 min with the modify methods. Participants performing the test claimed that, combination of audio and picture instructions positively influence their performance and improved understanding of test instructions. For the conventional paired preference test, 34% of participants struggled to follow the test instructions and only 52% of participants appeared confident with the procedure. For the method with limited reading and writing requirements, only 16% of participants struggled to follow the instructions and 84% appeared confident with the procedure. Basic elements developed associated to instruction to pull the coding sticker from the sample chosen to stick it on a positive smiling face was identified as the best paired preference method for independent completion by low-literate consumers.