Choice models with mixtures: An application to a cocktail experiment

Data from choice experiments are analyzed using choice models. Proper modeling allows a good understanding of the consumer preferences, the identification of consumer segments and the optimization of products, and, eventually, offers opportunities for competitive advantage. However, in the analysis of choice data, products that are mixtures of ingredients have been largely overlooked. In this paper, we combine traditional choice models and traditional mixture models. We apply the resulting mixture choice models to data from a real-life experiment in which consumers made pair-wise comparisons involving seven cocktails. For the choice models, we first assume consumer homogeneity. Next, we allow for heterogeneity among individuals. Therefore, we discuss the multinomial logit model, the mixed logit model and the latent class model. For identifying segments, besides the latent class model, we explore various two-stage segmentation approaches in which forces, hierarchical Bayes estimates and Firth individual-level estimates are used as input for a cluster analysis. The results show that the mixed logit model and the latent class model describe the data better than the multinomial logit model. The optimal cocktails for the segments we identified using the various methods are not identical, but show many similarities.     

Implementation of a modified Fuzzy C-Means clustering algorithm for real-time applications

Every month new applications of fuzzy logic to image processing appear. The lightly tight nature of fuzzy algorithms simulates human vision and thus, the field of applications widens. This paper implements in hardware a very popular fuzzy algorithm, the Fuzzy C-Means algorithm. The version of the algorithm allows a high degree of parallelism, which makes the hardware implementation suited for real-time video applications.     

Supercritical carbon dioxide extraction of 2-acetyl-1-pyrroline from Pandanus amaryllifolius Roxb

A comparative evaluation of the extraction of 2-acetyl pyrroline (2-AP) from Pandanus amaryllifolius Roxb. using either solvent extraction (3:1 chloroform:methanol), Likens–Nickerson apparatus or supercritical fluid extraction (SFE) with carbon dioxide extraction was carried out. SFE at 450 bar pressure for 3 h at 60 °C, at a constant flow rate of 0.1 l min⁻¹ of CO₂, could extract 2-AP from P. amaryllifolius Roxb. in yields greater than those obtained by solvent extraction or Likens–Nickerson extraction. This extract could find novel applications in food flavouring.     

Pectin: new insights into an old polymer are starting to gel

Pectin is a high value functional food ingredient widely used as a gelling agent and stabilizer. It is also an abundant, ubiquitous and multifunctional component of the cell walls of all land plants. Food scientists and plant scientists therefore share a common goal to better understand the structure and functionalities of pectic polymers at the molecular level. The basic properties of pectin have been known for nearly 200 years, but recently there has been tremendous progress in our understanding of the very complex fine structure of pectic polymers and pectinolytic enzymes. This has been made possible by synergies between plant and food research and by the application of a range of state-of-the-art techniques including enzymatic fingerprinting, mass spectrometry, NMR, molecular modelling, and monoclonal antibodies. With this increased knowledge comes the prospect of novel applications. Producers are beginning to develop a new generation of sophisticated designer pectins with specific functionalities. Moreover, the ability to manipulate pectin in planta would have a major impact on fruit and vegetable quality and processing, as well as on pectin production.     

Maintaining postharvest quality of fresh produce with volatile compounds

The postharvest quality of strawberry (Fragaria ananassa Duch.) and tomato (Lycopersicon esculentum L.) fruit was evaluated after treatment with eucalyptus (Ec: Eucalyptus globulus L.) and cinnamon (Cn: Cinnamomum zeylanicum, Blume) volatile oil compounds and storage at 13 °C during or following vapour exposure. Fruit decay decreased in fruit treated with oil vapours and transfer to ‘ambient air’ (AA). Cn-treated tomato maintained fruit firmness during exposure, but the effects were not persistent following storage to AA. However, no effects on fruit firmness were observed for Ec-treated tomato and strawberry-treated with Ec-and Cn-vapours. Oil vapours stimulated levels of total soluble solids during exposure but effects were persistent only for ‘cherry’ tomatoes following exposure. Fruit samples treated with oil vapours did not differ in percentage weight loss, organic acid content, sweetness and total phenolic content during or following vapour exposure compared with untreated fruit. The results suggest that essential oil vapour may improve fruit quality-related attributes on top of the well-documented antimicrobial protection during fresh produce storage and transit.     

Efficiency of the proportion of azidiol on preservation in ewe’s milk samples for analysis

Accuracy of milk component analysis is very important to most dairy farmers and to the dairy industry. Many factors contribute to the variation of the parameters analysed for payment purposes; one of the these factors is the method used to preserve the sample of milk prior to analysis in milk-testing laboratories. The aim of this work was to test the efficiency of different proportions of azidiol on the preservation of ewe’s milk. Fresh ewe’s milk from several origins was incubated to obtain increasing bacterial contamination ranges. Control samples versus samples preserved with azidiol (Az) or with half dose of preservative (Am) were compared. Samples were stored at different temperatures for different periods of time. Both doses Az and Am were effective enough to preserve milk either at 6 ± 2 °C for three days or at room temperature for 15 h. A dose-dependent underestimation of Bactoscan counts was detected in preserved samples versus the original counts measured in control samples. Samples preserved with Am showed results more similar to Control samples and therefore appeared to reflect with more accuracy the bacteriological condition of raw milk at origin.     

Consumer segmentation based on food neophobia and its application to product development

When evaluating the acceptability of food products, companies often focus on specific demographics for recruiting and screening consumers. However, this information may not necessarily explain the variability in the test results. Other elements, such as consumer psychographic profiles, may help better understand test participants’ responses. The objective of this study was to investigate the effect of food neophobia (reluctance to/avoidance of novel foods) on acceptability of novel food items. Six salad dressings with novel flavor combinations were chosen for evaluation in a central location test. Consumers were screened using the food neophobia scale (Pliner & Hobden, 1992) as well as liking of salad dressings. Each subject evaluated three of six dressings for hedonic and diagnostic attributes. Neophobic subjects rated the salad dressings significantly lower (p < 0.05) than neophilics for all hedonic attributes with the exception of appearance. These results were consistent for all dressings. However, when looking at the hedonic mean scores from both groups, the products were ranked in similar order in that the best liked and least liked dressing for the neophilic group was the same as those for the neophobic group. For diagnostic attributes, while the mean scores were significantly different for neophobics and neophilics, the percentage of “just-about-right” scores did not differ. These results suggest that food neophobia may impact the degree with which a product is liked or disliked by consumers, but it may not affect how products are ranked based on hedonic mean scores. Therefore, while understanding the psychographic composition of a consumer test respondent base may help explain why some products score higher or lower in acceptability, it may not alter the sensory guidance provided to product development regarding the specific flavor and texture attributes that were tested.