Sensory acceptability limits based on hedonic scores
require a cut-off score to be decided, which is sometimes
selected in an arbitrary manner. For example, the end of
shelf life may be determined as the storage time at which
the mean acceptance reaches 5.0 (neither like nor dislike)
on a 9-point hedonic scale (e.g., Montes Villanueva and
Trindade 2010), a score of 6.5 (between like slightly and
like moderately) on a 9-point hedonic scale (e.g., Muñoz
et al. 1992) or any other value set by researchers. Shelf
life limits determined this way do not always accurately
reflect consumer behavior in deciding whether to accept or
reject a product for consumption, and may give little
information on what consumers would normally do when
faced with the product. For example, Gimenez et al.
(2007) found that when evaluating breads, Spanish consumers
gave lower scores before rejecting the samples than
Uruguayan consumers, and that a failure criterion of 6.0
on a 9-point hedonic scale gave shelf lives that would be
too conservative for a product such as bread. In contrast,
hedonic ratings for alfajor (a chocolate-coated individually
wrapped cake) had to fall below 4.9 on a 9-point hedonic
scale before the product would be rejected by 25%
of consumers (Gambaro et al. 2004b). Thus, the hedonic
score selected as the cut-off point is likely to be product
dependent as some product types will never score highly,
even when fresh. In addition, acceptability scores may not
be directly linked to rejection frequencies. For example,
although acceptability of yoghurt samples decreased
during early storage, rejection rates remained low.
Over the subsequent 3-week to 2-month storage period,
acceptability scores remained relatively constant but
rejection rates increased from 6 to 50%