2.5 sensitively smell test
The sensitivity test was performed by means of 10 triangular tests with smell strips, prepared as reported in Meier- Dinkel, Sharifi et al. 2013. In brief, a solution of 20ml of D-carvone, androstenone or skatole was dripped on the end of a paper strip, placed in a tube and allowed to dry overnight in a fume hood before it was closed. The odd sample in the triangle test was only the solvent (propylene glycol). One triangular test with D-carvone (mint-like-odor:15% v/v) was initially presented to the consumers to train them in the methodology of the triangle test evaluation. This was followed by three triangular test with androstenone at the high concentration(5.0mg/g) and three triangular tests with skatole(1.0mg/g). the three test tubes of each triangle were placed in a glass (before the beginning of each triangular test), thus randomizing the position of the odd sample. The number of correct triangles within each compound and concentration was used to classify consumers according to their sensitivity. Consumers were classified as very sensitive to androstenone (detection threshold _1.0mg/g: codified as “no”) if they failed in at least one of them.
At the end of the set of triangles, consumers also smelled one extra strip each with androstenone (5.0mg/g) and skatole (1.0mg/g) to indicate the pleasantness of the odor using a 9-point scale from 1: “extremely dislike” to 9: “extremely like”. The consumers were instructed to choose score 5 (neither like nor dislike) if they could not smell the compound. This means that the neutral answer include both consumers that did not smell androstenone or skatole as well as consumers that neither liked nor disliked its smell.