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Louw L.,Stellenbosch University | Louw L.,Distell Ltd | Oelofse S.,Distell Ltd | Naes T.,Oslovegen 1 As | And 6 more authors.
Food Quality and Preference | Year: 2015

Partial napping has been validated as a suitable sensory profiling method for brandy evaluation. However, it was found that, compared to conventional profiling, very little useful information could be extracted on brandy mouthfeel when it was evaluated as part of overall in-mouth perceptions. This study aimed to optimise the partial napping method to improve information output on the mouthfeel of brandies. Panellists' proficiency in visual, aroma and in-mouth evaluation of brandies were scrutinised after which three partial napping protocols were tested to identify the most effective solution for the successful capturing of mouthfeel differences between brandies. The results showed that panellists were equally efficient in aroma and in-mouth evaluations, but that in-mouth perception (defined as retronasal flavour, basic taste and mouthfeel) was not a useful construct as it did not contribute to the product configuration that could be obtained with visual and colour assessments alone. Instructing panellists to ignore retronasal flavour delivered more useful results. Using dark glasses and nose-clips to eliminate visual, aroma and retronasal flavour perceptions were not necessary to obtain a reliable and interpretable representation of the mouthfeel differences between brandies. Clear glasses and written instructions were sufficient to generate useful mouthfeel information under conditions more representative of the consumer product experience. © 2015 Elsevier Ltd.

Louw L.,Stellenbosch University | Louw L.,Distell Ltd | Oelofse S.,Distell Ltd | Naes T.,Oslovegen 1 As | And 6 more authors.
Food Quality and Preference | Year: 2015

Projective mapping is a rapid sensory profiling method used to obtain overviews of the sensory differentiation in product sets. Elongated projective mapping tasting sheets, i.e. rectangles, have been hypothesised to bring forth more prominent sample differences, while shapes with equal perpendicular bisectors, such as circles or squares, could reportedly be used to visualise more subtle sample differences. This hypothesis was tested in the present study using a set of eight different brandy products, in order to gain a better understanding of the practical implications of using different tasting sheet shapes for different project goals. The results showed that very similar product configurations were obtained with square, rectangular or round tasting sheets. Panellists performed better with round tasting sheets, leading to more accurate results. Square tasting sheets delivered the most different results when compared to round and square tasting sheets. The practical significance of using different tasting sheet shapes to elicit either more prominent or more subtle sample differences could not be established in the set of brandy samples used in this study. © 2014 Elsevier Ltd.

Naes T.,Oslovegen 1 As | Naes T.,Copenhagen University | Mage I.,Oslovegen 1 As | Segtnan V.H.,Oslovegen 1 As
Journal of Chemometrics | Year: 2011

This paper is about how to incorporate interaction effects in multi-block methodologies. The method proposed is inspired by polynomial regression modelling in the case with only a few independent variables but extends/generalises the idea to situations where the blocks are potentially very large with respect to the number of variables. The method follows a so-called type I sums of squares strategy where the linear effects (main effects) are incorporated sequentially and before the interactions. The sequential and orthogonalised partial least squares (SO-PLS) technique is used as a basis for the proposal. The SO-PLS method is based on sequential estimation of each new block by the PLS regression method after orthogonalisation with respect to blocks already fitted. The new method preserves the invariance already established for SO-PLS and can be used for blocks with different dimensionality. The method is tested on one real data set with two independent blocks with different complexity and on a simulated data set with a large number of variables in each block. © 2011 John Wiley & Sons, Ltd.

Fadda C.,University of Sassari | Sanguinetti A.M.,University of Sassari | Naes T.,Copenhagen University | Naes T.,Oslovegen 1 As | Del Caro A.,University of Sassari
International Journal of Food Science and Technology | Year: 2014

A methodology of sensory and instrumental texture analysis was developed on a Protected Designation of Origin artichoke. Descriptive sensory analysis was applied on artichokes collected in two different geographical areas during the harvest time. Eight trained assessors evaluated the thistle odour, sweet, bitter, astringent, crunchy, fleshy and tender attributes. Instrumental texture, on artichoke heads and leaves, was evaluated with a texture analyser applying the cutting test and the texture profile analysis. The geographical area seems to affect the profile less than the harvest time. Instrumental texture analysis highlighted significant differences between the two geographical areas and during the harvest time. It can be assumed that, at the end of the biological cycle, artichokes are more suited to processing rather than for fresh consumption. © 2013 Institute of Food Science and Technology.

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