Analysis of sensory assessors in texture profiling of potatoes by multivariate modelling

The aim of the present study was to analyse the reliability and performance of the sensory assessors in texture profiling by a univariate (ANOVA) and a multivariate procedure using discriminant partial least squares regression (DPLSR). Assessor×product modelling is relevant in the data analysis of sensory data, since potato tubers are slightly heterogeneous, even when grown under controlled conditions and sorted with respect to size and density. Thus, different assessors may in fact get “different” products. Also the assessor level differences were removed by the modelling. Signal to noise plots for all attributes showed reflection, mealiness and firmness to be the most reliable attributes, and springiness and chewiness to be the least reliable attributes. Signal to noise plots for each attribute illustrated some assessors to be good in evaluation of some attributes and less good in others. The assessors were questioned about psychological states after each session in order to study if individual differences influenced the assessors’ performance. Some assessors reporting that they felt concentrated, were in fact found to be less reliable than others who felt stressed.     

Sensory characterisation of ewe's milk cheeses using direct and indirect similarity measures: a comparison

The purpose of the present study is to compare several direct and indirect (profile and hedonic scores) similarity measures. Moreover, the main relationships among assessors, sensory attributes and ewe's milk cheeses have been explored using different statistical techniques. For this purpose, visual inspection and correlation coefficients among cheese sample sensory dimensions have been considered. All the solutions lead to very similar spatial configurations, except for preference data. In this case the considered techniques are very useful tools in the study of sensory attributes. Individual differences among assessors have been demonstrated to be quite high. Thus it is clear that methods that consider this variability in the data should be used, to which end, assessors should undergo specific training depending on the tests to be performed. © 2002 Society of Chemical Industry     

Relationships of Sensory Bitterness in Lager Beers to Iso‐α‐Acid Contents

Iso‐α‐acids and their chemically modified variants play a large role in evoking the bitter sensory attributes of lager character, but individual consumers may vary in their perception of bitterness. Sixteen lagers were scored in rank‐rating for bitterness by 14 trained assessors and the concentrations of the six bitter components in these beers were determined by high performance liquid chromatography. Relationships between bitterness intensity and the bitter components were modelled well using partial least square regression with a correlation value of 0.92. When 8 assessors carried out time‐intensity scoring of bitterness, profiles for single products were very different. However, single assessor profiles for multiple products showed qualitative similarities but quantitative differences. That individual assessors perceived bitter characters differently in relation to time has implications for new product development.     

基于品评小组可靠性筛选葡萄酒的香气描述符

利用定量描述性分析（0～5标度法）评价9 款国产‘赤霞珠’干红葡萄酒的香气特性,结合方差分析和多元统计分析方法,评估品评小组可靠性和规范葡萄酒香气特性感官描述符的筛选方法。结果表明,利用平均重现性指数Ri、检验统计量F值、均方误差（mean-square error,MSE）值和Manhattan图等能够有效评估品评员的重现性、辨别能力、可重复性以及品评小组的一致性。以可靠品评小组的感官数据为原始变量,通过几何平均值（M值）计算和排序,结合主成分分析（principal component analysis,PCA）和聚类分析（cluster analysis,CA）,规范了葡萄酒特征香气描述符的科学筛选方法,明确了实验‘赤霞珠’干红葡萄酒的香气特征：以黑醋栗、红醋栗等果香为主,有突出的焦糖、烟熏等焙烤类香气,兼有胡椒等佐料香气。     

Diversity of the sensory characteristics of traditional dry sausages from the centre of France: Relation with regional manufacturing practice

Quality labelling of traditional products may be based on identifying specific sensory properties and linking these to particular compositional characteristics or manufacturing practices. Methodology to do this in the presence of large sensory variation is required. In order to study the sensory diversity of traditional dry sausages, a typology was performed on the small scale food processing facilities in the centre of France and this identified six types of small-scale facilities with specific manufacturing practice. From these six groups, 15 small-scale facilities were chosen in order to perform a QDA^® test on dry sausages with a panel of 11 trained assessors who used 24 attributes related to appearance, texture, aroma and flavour. The list of attributes used by the panel was composed of terms such as marinade aroma, roast aroma, wine flavour and roast flavour which may be specific to traditional dry sausages. The major variation among the products was related to the type of the raw material used and to the texture of the dry sausages linked to the drying time. Hierarchical cluster analysis on the sensory data led to six groups of traditional dry sausages. These sensory groups did not exactly correspond to the groups given by the typology. However, a high correlation was found by canonical correlation analysis between the typology data and the sensory data on the first factors. Moreover, the discriminant analysis showed that it was possible to classify 100% of the traditional dry sausages into specific manufacturing practice groups based on the sensory data. The methodology used in this study is well adapted for the attribution of quality labels to products manufactured by a group of producers on a defined territory.     

Combining extrinsic and intrinsic information in consumer acceptance studies

This paper proposes a methodology for combining extrinsic and intrinsic attributes in consumer testing of food products. The paper attempts to focalize on the main sensory drivers of liking or choice probability and their interaction with additional information, and to investigate effects related to the population as well as how consumers differ in their assessments. Two different data analysis approaches are considered and compared on choice probability data from a consumer study of orange juice. One of the methods is based on mixed model ANOVA of individual differences, the other approach is based on fuzzy clustering related to regression residuals. The main results show that extrinsic consumer attributes are easily and efficiently related to the sensory properties of products, allowing for interactions. The methodology estimates population or segment means and gives an overview of individual differences in choice intent or liking.     

Anthocyanin composition and extractability in berry skin and wine of Vitis vinifera L. cv. Aglianico

BACKGROUND: The present article reports the anthocyanin content in the berry skin and wine of the Italian red grape cultivar Aglianico (clone VCR11 grafted onto 1103 Paulsen), one of the most ancient vines and famous for its deep‐red colour. Anthocyanins were extracted from frozen berry skin in an acidified methanol solution. The extraction mixtures, monitored for 120 h, were analysed by high‐performance liquid chromatography. RESULTS: The extraction from berry skin of delphinidin, petunidin and malvidin appeared to be a time‐independent process, whereas the concentration of peonidin increased linearly with time. Peonidin‐O‐acetyl‐glucoside was transferred from skin more slowly than petunidin‐O‐acetyl‐glucoside and malvidin‐O‐acetyl‐glucoside. The anthocyanin composition of the resulting wine showed that the total anthocyanin content was about one‐tenth of the corresponding berry skin content. The ratio acetyl/coumaroyl anthocyanins in the wine was sharply higher than the value in berry skin (0.85 and 0.10, respectively), indicating an enrichment of acetyl derivatives in the wine. CONCLUSION: Levels of single anthocyanins in wine were not always correlated with those detected in grapes, as they were affected by winemaking. The high values of some anthocyanins in Aglianico wine could ameliorate its quality, increasing the chromatic properties, aging stability and product acceptance. Copyright © 2011 Society of Chemical Industry     

Effect of winemaking practices on color indexes and selected bioactive phenolics of Aglianico wine

ABSTRACT:  Phenolic compounds are responsible for the sensory properties of wine as well as the properties beneficial to human health. The objective of this study was to establish the effect of the use of SO₂ and pectolitic enzymes in the prefermentative phase, maceration time, and oak aging on color, anthocyanins, tannins, (+)-catechin, (–)-epicatechin, rutin, trans -resveratrol, and quercetin content of Aglianico wine. Color indexes and phenolics were analyzed by HPLC and spectrophotometric methods. The addition of SO₂ and pectolitic enzymes before fermentation caused an increase in color intensity, color stability, total phenolics, anthocyanins, (+)-catechin, (–)-epicatechin rutin, trans -resveratrol, and quercetin content in Aglianico wine. Longer maceration times gave wines richer in total phenolics and with better chromatic characteristics. Storage in oak caused a decrease in anthocyanins, (+)-catechin, (–)-epicatechin, trans -resveratrol, and quercetin content but an increase in total phenolic content, and a stabilizing effect on color also occurred.     

Sensory profiling of aroma in Greek dry red wines using rank-rating and monadic scoring related to headspace composition

Rank-rating and monadic scoring were compared in profiling sensory aroma character of 27 Greek dry red wines with 16 attributes. In parallel wine headspace volatiles were quantified using solid-phase micro-extraction gas chromatography but not identified. In rank-rating, 14 aroma attributes showed discriminations with P<0.05 and 11 P<0.001. In scoring, 6 of 16 attributes showed P<0.05. Principal component analysis (PCA) explained 88% variance in rank-rating data, with six significant components (PCs), in scoring 40% in two PCs. PCA analysis of 83 common flavour volatiles explained 48% variance in six PCs. Partial least-squares regression (PLS1) modelling achieved more and better models for attributes using rank-rating, 8 of 14, than for scoring, 3 of 16; PLS2 explained greater variance in rank-rating. For wine sensory/instrumental correlation studies, rank-rating has distinct advantages over monadic scoring in deciding volatiles contributing to sensory character prior to identification strategies such as HRGC–mass spectrometry.     

Alcohol,Tannins, and Mannoprotein and their Interactions Influence the Sensory Properties of Selected Commercial Merlot Wines: A Preliminary Study

The objective of this study was to assess the influence of the interaction among alcohol, tannins, and mannoproteins on the aroma, flavor, taste, and mouthfeel characteristics of selected commercial Merlot wines. Merlot wines (n = 61) were characterized for wine chemistry parameters, including pH, titratable acidity, alcohol, glucose, fructose, tannin profile, total proteins, and mannoprotein content. Agglomerative clustering of these physicochemical characteristics revealed 6 groups of wines. Two wines were selected from each group (n = 12) and profiled by a trained sensory evaluation panel. One wine from each group was evaluated using the electronic tongue (e‐tongue). Sensory evaluation results showed complex effects among tannins, alcohol, and mannoproteins on the perception of most aromas, flavors, tastes, and mouthfeel attributes (P < 0.05). The e‐tongue showed distinct differences among the taste attributes of the 6 groups of wines as indicated by a high discrimination index (DI = 95). Strong correlations (r² > 0.930) were reported between the e‐tongue and sensory perception of sweet, sour, bitter, burning, astringent, and metallic. This study showed that interactions among wine matrix components influence the resulting sensory perceptions. The strong correlation between the e‐tongue and trained panel evaluations indicated the e‐tongue can complement sensory evaluations to improve wine quality assessment.     

Taking individual scaling differences into account by analyzing profile data with the Mixed Assessor Model

Scale range differences between individual assessors will often constitute a non-trivial part of the assessor-by-product interaction in sensory profile data (Brockhoff, 2003, 1998; Brockhoff and Skovgaard, 1994). We suggest a new mixed model ANOVA analysis approach, the Mixed Assessor Model (MAM) that properly takes this into account by a simple inclusion of the product averages as a covariate in the modeling and allowing the covariate regression coefficients to depend on the assessor. This gives a more powerful analysis by removing the scaling difference from the error term and proper confidence limits are deduced that include scaling difference in the error term to the proper extent. A meta study of 8619 sensory attributes from 369 sensory profile data sets from SensoBase (www.sensobase.fr) is conducted. In 45.3% of all attributes scaling heterogeneity is present (P-value <0.05). For the 33.9% of the attributes having a product difference P-value in an intermediate range by the traditional approach, the new approach resulted in a clearly more significant result for 42.3% of these cases. Overall, the new approach claimed significant product difference (P-value <0.05) for 66.1% of the attributes compared to the 60.3% of traditional approach. Still, the new, and non-symmetrical, confidence limits are more often wider than narrower compared to the classical ones: in 72.6% of all cases.     

Time Intensity Parameters of Sweetness Perceptions in Lager Beers

Lagers are generally brewed to minimise the final sugar content. Residual saccharides, derived from starch, contribute little to sweetness. Despite this, certain lagers exhibit sweet characters. These have not been explored in lagers, but are thought to originate from: maltol; 4‐hydroxy‐2,5‐dimethyl‐3(2H)‐furanone (HDMF); 4‐hydroxy‐2(or 5)‐ethyl‐5(or 2)‐methyl‐3(2H)‐furanone (HEMF); hydroxymethylfurfural (HMF); diacetyl; and certain esters (ethyl acetate, ethyl caproate, ethyl caprylate, and iso amyl acetate). This study used time‐intensity (TI) profiling, employing 13 assessors, to study sweetness in 10 lagers, scored similarly for sweetness in rank rating. Single intensity maxima were obtained with all products and all assessors. Data were analysed using ANOVA of curve parameters and non‐centred and centred principal component analyses (PCA). In ANOVA only the area under curve (A_tot) values differed significantly. However, shape of TI profile, or signature, differed between assessors who could on this basis be divided into two groups. In the multivariate data analyses, non‐centred PCA showed significant differences between lagers, parametric modelling and conventional PCA did not. However TI profile data suggested sweetness intensity perceived over the 120 seconds following ingestion could differ, although differences in scoring in rank rating were not significant.