yoghurt {icensBKL}

Sensory Shelf Life of Yoghurt

Description

For the current study, the objective was to determine the sensory shelf life (SSL) of whole-fat, stirred yoghurt with strawberry pulp. A reversed storage design was used in which yoghurt pots of 150 g were kept at 4°C, and some of them were stored in a 42°C oven for 0, 4, 8, 12, 24, 36 and 48 hours. These times were chosen because previous experiments showed that deterioration in flavor occurred quickly up to approximately 12 hours and then slowed down. After being stored at 42°C, the samples were refrigerated at 4°C until they were tasted. More details about the experiment can be found in Hough (2010).

Fifty adults between 18 and 30 years and 50 children between 10 and 12 years who consumed stirred yoghurt at least once a week were recruited from a town in Argentina. For each of the 7 samples presented in random order, the subject tasted the sample and answered the question: “Would you normally consume this product? Yes or No?”. If a subject would consume the samples up to 8 hours' storage but not the samples with 12 hours' storage or longer, it is known that SSL is somewhere between 8 and 12 hours storage. The data are thus interval-censored. Right-censored data occur when the subject accepts all samples and left-censored data if the sample with the first storage time is rejected. For subjects with inconsistent answers, several options to construct the interval are possible. Here, the widest uncertainty interval as to the storage time at which the subject rejects the yoghurt was applied. That is, from the first “yes” before a “no” until the last “no” which occurs after a “yes”.

Several subjects were excluded from the analysis (4 adults and 3 children) because they preferred the stored product to the fresh product. The data are reproduced from Hough (2010).

Usage

data(yoghurt)

Format

a data frame with 93 rows and the following variables

left

lower (left) limit of interval that contains an event of interest, set to NA for left-censored observations.

right

upper (right) limit of interval that contains an event of interest, set to NA for right-censored observations.

adult

a binary variable indicating whether respondent is child (0) or adult (1).

fadult

factor derived from variable adult.

Source

Hough, G. (2010). Sensory Shelf Life Estimation of Food Products. CRC press. ISBN 9781420092912.

References

Hough, G. (2010). Sensory Shelf Life Estimation of Food Products. CRC press. ISBN 9781420092912.

Examples

data("yoghurt", package="icensBKL")
summary(yoghurt)