Statistical procedure for the composition of a sensory panel of blends of coffee with different qualities using the distribution of the extremes of the highest scores (original) (raw)
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2015
Os metodos automaticos de classificacao tem sido amplamente utilizados em inumeras situacoes, nas quais o metodo boosting tem se destacado por utilizar um algoritmo de classificacao que considera um conjunto de dados de treinamento e, a partir desse conjunto, constroi um classificador com versoes reponderadas do conjunto de treinamento. Dada essa caracteristica, esse trabalho tem por objetivo avaliar um experimento sensorial relacionado a testes de aceitacao com cafes especiais, tendo como referencia grupos de consumidores, treinados e nao treinados. Ao grupo de consumidores, foram avaliadas quatro caracteristicas sensoriais, tais como aroma, corpo, docura e nota final, atribuidos a quatro tipos de cafes especiais. Com o proposito de obter uma regra de classificacao que discrimine provadores treinados e nao treinados, utilizaram-se a analise discriminante de Fisher convencional (LDA) e a analise de discriminante via algoritmo de boosting (Adaboost). Os criterios utilizados na compar...
Tasters’ performance in a coffee quality contest in Brazil
Coffee Science, 2021
The objective of this work was to evaluate the performance of coffee tasters in five annual editions of Minas Gerais Coffee Quality Contest. The repeatability coefficients of the tasters' scores for sensory attributes were estimated, as well as the minimum numbers of tasters required for consistent sensory results, and the groups of tasters by (dis)similarity of sensory scores. For the repeatability analysis, the treatments (coffees) were tested with the repetitions, constituted by the tasters. The repeatability coefficients were estimated using the analysis of variance, principal component and structural analysis methods. The minimum number of tasters was obtained based on pre-established determination coefficients. Euclidean distance matrices between tasters were determined, which were used as a measure of dissimilarity for cluster analysis by the Tocher optimization method. The tasters' performance in five annual editions of Minas Gerais Coffee Quality Contest is reliable using COE or SCA sensory analysis protocols. Although not fully calibrated, most tasters are grouped with similar cupping results. Unless efficient calibration prior to the contest is adopted, the number of tasters to be used in the next contest editions can not be drastically and randomly reduced, since the estimated minimum number varied over the years. Calibration activities are suggested to improve two main aspects of the Minas Gerais Coffee Quality Contest: distinguishing the best coffees and trainning tasters.
Molecules, 2019
The quality assessment of the green coffee that you will go to buy cannot be disregarded from a sensory evaluation, although this practice is time consuming and requires a trained professional panel. This study aims to investigate both the potential and the limits of the direct headspace solid phase microextraction, mass spectrometry electronic nose technique (HS-SPME-MS or MS-EN) combined with chemometrics for use as an objective, diagnostic and high-throughput technique to be used as an analytical decision maker to predict the in-cup coffee sensory quality of incoming raw beans. The challenge of this study lies in the ability of the analytical approach to predict the sensory qualities of very different coffee types, as is usual in industry for the qualification and selection of incoming coffees. Coffees have been analysed using HS-SPME-MS and sensory analyses. The mass spectral fingerprints (MS-EN data) obtained were elaborated using: (i) unsupervised principal component analysis ...
Monte Carlo based test for inferring about the unidimensionality of a Brazilian coffee sensory panel
Food Quality and Preference, 2010
Sensory science uses the human senses as instruments of measurement. Sensory analysis makes it possible to study organoleptic properties of products using a panel of assessors. say that a good sensory panel should provide results that are accurate, discriminating and precise. Thus, in a successful analysis, it is key to have a set of robust tools for monitoring individual assessor's performances as well as the performance of the panel as a whole.
Recent Advances on Numerical Simulations [Working Title], 2020
The sensory analysis of coffees assumes that a sensory panel is formed by tasters trained according to the recommendations of the American Specialty Coffee Association. However, the choice that routinely determines the preference of a coffee is made through experimentation with consumers, in which, for the most part, they have no specific ability in relation to sensory characteristics. Considering that untrained consumers or those with basic knowledge regarding the quality of specialty coffees have little ability to discriminate between different sensory attributes, it is reasonable to admit the highest score given by a taster. Given this fact, probabilistic studies considering appropriate probability distributions are necessary. To access the uncertainty inherent in the notes given by the tasters, resampling methods such as Monte Carlo’s can be considered and when there is no knowledge about the distribution of a given statistic, p-Bootstrap confidence intervals become a viable alt...
Food Quality and Preference, 2002
Grading systems since their conception have aimed at facilitating commercialisation of food stuff world-wide. However, while many food products can have their quality assessed by analytical means, there are many foods that are sold according to their sensory quality and for which quality is not easily measured by conventional analytical techniques. Measuring sensory quality in some products has moved forward and utilises fully trained panels to set-up quality control systems and routine evaluations while others still rely on traditional commercial classifications and grading systems. The grading discussed here must be differentiated from grading using ''trained experts'' to evaluate food products according to legislated standards. There are specific cases in which the need to comply with national or international standards requires the development of specially trained tasting experts. Bisogni, [In D. E. Kramer, & J. Liston (Eds.), Seafood quality determination (p. 547). Amsterdam: Elsevier Science] illustrates quite well this specific scenario. The case of coffee, the most traded agricultural crop world-wide is examined here. In coffee a high diversity of classification systems is applied and the use of the ''expert cupper'' is the norm. There is not a unique and universal system applied world-wide for the quality control of green coffee. Tailor made procedures are selectively implemented by International, National, local bodies, trading institutions and private companies. Procedures are mostly geared to facilitate the trading of the commodity and sensory quality is in most cases described by ''cuppers'' or ''liquorers'' using personal opinion and tasting experience accumulated over the years. #
Sensory quality prediction of coffee assessed by physicochemical parameters and Multivariate model
Coffee Science, 2020
Beverages from roasted coffee can be classified according to their sensory quality into Gourmet, Superior, Traditional, and not recommended for supply coffees. However, the sensory evaluation of coffee has been questioned as it can induce a subjective bias, since the assessors may be influenced by psychological, physiological, and/or emotional factors. Therefore, the aim of this study was to develop multivariate models for predicting the overall quality of Gourmet, Superior, and Traditional coffees, based on the physical and physicochemical parameters. One hundred and eight ground roasted coffee samples were evaluated for particle size, degree of roasting, histological identification, moisture, ash, aqueous extract, soluble solids (Brix), pH, and sensory profiling. All categories presented fine grinding. No significant differences were observed in the moisture content and soluble solids (Brix) of Gourmet, Superior, Traditional, not recommended for supply coffee samples. The Traditional and not recommended for supply presented higher levels of aqueous extract, ash, and pH. Light degree of roast and higher acidity values were observed with the increase in coffee quality grades. The results of the physical and physicochemical parameters and the principal component analysis allowed the separation of coffees into only two classes: high-quality (Gourmet and Superior) and low-quality (Traditional and not recommended). Furthermore, the one-class classification (OCC) method showed good sensitivity and was able to satisfactorily distinguish the Gourmet coffee samples from the other samples, in this way, this model can be used to corroborate but not replace the sensory analysis.
PRINCIPAL COMPONENTS AND CLUSTER ANALYSIS FOR DESCRIPTIVE SENSORY ASSESSMENT OF INSTANT COFFEE
Journal of Sensory Studies, 1996
The relationships among 13 aroma, flavor, mouthfeel and appearance variables for 18 soluble coffees were analyzed using flavor profiling. Three-way ANOVA showed significant main effects for coffees and judges in all attributes. The data were submitted to principal component analyses (PCA) and cluster analysis (CA). Two sequential PCA were performed. The first PCA showed that flavor, bitterness and duration were the most important descriptors positively correlated with the first PC, while the variation in appearance properties dominated the second PC, negatively correlated with these attributes. Five attributes were eliminated and a subset of 8 variables was submitted to a second PCA. The meaning of the first two PC remained unchanged and, as expected, the total variation explained by the first four PC increased. Frequency of positive and negative judgments in both PC allowed to separate coffees into four categories.Confirming the choice of the variables, the CA revealed similar distribution of coffees into four clusters. Aroma, flavor and mouthfeel attributes seemed to play a more important role in the determination of clusters than the appearance variables.
Sensory quality of out-of-home coffees in Sao Paulo, Brazil
Brazilian Journal of Food Technology, 2017
Summary A field study was carried out in the largest Brazilian city in order to evaluate the quality of coffee prepared and sold for out-of-home consumption, using a logit model. It was shown that the decision on coffee quality was taken by the coffee house owner or manager based on his perception of the socio-economical class of the consumers, the prevalent gender, the participation of coffee in the invoicing and the coffee brewing method.