C. Chaya

Use of the STATIS method to analyze time-intensity profiling data

Abstract The sensory properties (sourness, pepper, oily, fatty/creamy and garlic) of nine Ranch salad dressing samples varying in fat and garlic flavor according to a 3 2 factorial design were evaluated by time-intensity profiling (TIP). The dynamic and complex processes involved in the perception of these attributes were analyzed with the STATIS method (Structuration des Tableaux A Trois Indices de la Statistique). STATIS allows for the simultaneous analysis of several data matrices, where each matrix consists of the data recorded by TIP at a given instant. STATIS analysis revealed the existence of a common sensory structure during the early and central portions of the time-intensity evaluations (from 6 to 50 s), i.e., the respective positions of the salad dressing samples changed very little during that time period. The compromise matrix obtained for all the instants in the evaluation provided a summary of the sensory properties of the dressing during that 6–50 s period. A different distribution of the samples was observed, however, at the beginning (3 s) and towards the end (75 and 120 s) of the evaluations, with lesser contributions of these instants to the compromise plot. The first two principal components of the compromise space, which accounted for 65 and 11% of the variance, respectively, contrasted the attribute fatty/creamy with the other four attributes. This is the first time the STATIS method has been used to analyze time-intensity curves. The main improvement of the method over other approaches is its ability to determine which portions (start, central portion, tail end) of a TI curve are most critical to the understanding of intensity and time course differences among products.

Measuring the emotional response to beer and the relative impact of sensory and packaging cues

Recent studies have highlighted that, in todays extremely competitive markets, using hedonic measurement alone is inadequate for evaluating consumer product experience. Measuring emotional response is suggested to provide a richer insight into consumer responses. The objectives of this study were to 1) measure consumer emotional responses to beer, 2) determine whether a relationship exists between sensory and emotional attributes of products, and finally 3) investigate the relative impact of sensory and packaging attributes on the emotional response to beer. Using the EsSense Profile technique, the levels of liking and emotional response to a broad range of 10 commercial lager beers were evaluated by 90 lager consumers under three different conditions: blind (liquid only), pack (packaging only), and informed (liquid plus packaging). Emotional response was shown to discriminate across the beer samples in terms of both pleasantness and engagement level. Packaging cues were more influential on emotional response, but sensory attributes did play a role. Increasing carbonation and familiarity and decreasing sweetness and alcohol content were shown to influence a more pleasant and engaged emotional response in this set of beers. This study highlights the need to evaluate both liquid and packaging characteristics to gain better insights into developing and understanding the emotional signature of beer.

EFFECT OF HEATING CONTROL STRATEGIES ON GREENHOUSE ENERGY EFFICIENCY: EXPERIMENTAL RESULTS AND MODELING

This study evaluated the energy efficiency of greenhouse heating systems in a Mediterranean climate by comparing the overall heat transfer coefficients obtained with heating strategies involving either heated floors or air heaters. The overall heat transfer coefficient is composed of the various heat transfers through the greenhouse, including losses by conduction, convection, infiltration, and radiation; it was calculated per unit of floor area. Four factors were found to influence this coefficient: wind speed, heat input, outside temperature, and heat capacity of the greenhouse. Greater heat input resulted in an increase in the heat transfer coefficient: 1 W m-2 °C-1 for every 50 W m-2 of heat input. This was explained by the heat released by the greenhouse structures and soil, which reinforced the effect of heating with low values of heat input. The thermal behavior of the greenhouse was studied by modeling. Dynamic models decreased the absolute error in the calculation of inside temperatures by more than 1°C with respect to a static model. The best dynamic model was used in simulations of control strategies. Step control of two or three groups of air heaters improved the thermal efficiency of the greenhouse (4% to 10% energy saving), and led to fewer temperature variations, compared to the use of all the heating power as one only group. With heated floor systems, a recommended strategy in mild climates is to turn off the heating at dawn.

Stratification and sample size of data sources for agricultural mathematical programming models

A comparison is made between the variance of the estimator of the total of a variable obtained from both a simple and a stratified random sampling, in which the sample sizes of some strata are equal to the stratum population size. It is shown that in this case, the advantage of the stratified sample could depend on the sample size. The paper presents inequalities that determine, as a function of the sample size, when the variance of the estimator obtained with simple sampling is lower than the variance obtained with the stratified sampling. The results give insight in order to prevent overstratification.

Internal preference mapping of milk-fruit beverages: Influence of color and appearance on its acceptability

Abstract The individual preferences of 100 consumers between 20 and 30 years old for the color of 16 milk–fruit juice beverages (MFJB) were investigated by preference mapping technique. Consumers were asked to evaluate, just by looking at the samples, how much they liked them (from “Extremely dislike” to “Extremely like”). The color of the samples was analyzed by two different instrumental techniques. Results obtained from the instrumental color measurement showed the wide diversity in hues of the beverages available in the market, and correlations between techniques proved that both of them were appropriate to analyze color. Results showed that participants preferred samples with orangish appearance instead of those with a whiter look. Anyway, punctuations given by the consumers suggest that generally, color of these products is not highly evaluated by consumers, as the best mean punctuation was 6.6.