Abstract:
A consumer and a trained descriptive panel was utilized to
determine liking ratings and flavor profiles, respectively, for
commercial brands of pre-stirred yogurt. Once the consumer and
descriptive panel data was collected, the data was combined to
determine the interrelationship of these two sets of data and to
determine the conditions necessary to optimize the sensory
characteristics of commercial yogurt. This study was broken down
into two parts: (1) evaluation by a 90 to 182 member consumer
panel and an 11 member descriptive panel for 14 strawberry and 6
lemon yogurt brands, and (2) correlation of the sensory measures of
sweetness and sourness, and analytical measures of sugars and acids
for 14 strawberry, 12 raspberry, 6 lemon, and 17 plain yogurt
brands.
Large sensory differences were found between yogurts for
both flavors (strawberry and lemon) by both panels. Correlation and
principal component analysis (PCA) indicated that two distinct
groups of descriptors contributed to the liking of the yogurts: one
associated with the fruity and sweetness characteristics, and the
other related to the plain yogurt and sourness descriptors.
Consumers based their overall liking ratings on fruit flavor,
sweetness, sourness, and a balance of sweetness/sourness liking.
Males and females rated samples differently by as much as one full
scale value on a 9-pt. hedonic scale. Use of PCA to relate the two
panels revealed that high consumer acceptance corresponded with
the PC loaded with fruity and sweet characteristics while lower
consumer acceptability was noted with high loadings on PC2 which
was comprised of plain yogurt, acetaldehyde, and sourness
descriptors. The results from the first part of the study indicate that
to produce a highly acceptable yogurt, processors should strive to
provide a balance between sweetness and sourness and provide
enough fruit flavor to mask plain yogurt characteristics.
In the second part of this study, titratable acidity and pH were
measured for all the yogurts, while sugars were measured by HPLC
only for the fruit flavored yogurts. Consumer overall liking was
significantly correlated with sweetness intensity, sweetness:sourness
(sw:so) ratio, and the summed impact of sweetness and sourness
from the trained panel for strawberry and raspberry yogurt. No
correlations between analytical measures and overall liking were
found for any of the yogurts. A sw:so ratio greater than 1.0 for
strawberry, and .8 for raspberry and lemon appeared necessary for
high consumer acceptance. Generally, it was found that the sweeter
the yogurt, the higher the consumer acceptance of fruit flavored
yogurt. No relationships were found for any sensory and analytical
measures for predicting the overall liking of plain yogurt. However, the best predictors of consumer liking of fruit flavored yogurt were
the descriptive panel ratings.
