Sensory and rheological characterization of light cheese curd with whey protein concentrate

Os teores de água e de gordura são os principais fatores que influenciam a textura do requeijão, portanto, a relação entre eles deve ser estudada no desenvolvimento do produto com teor reduzido de gordura. Neste contexto, o objetivo deste trabalho foi avaliar o efeito da variação destes componentes nas características sensoriais e reológicas de requeijão light adicionado de CPS. Foram desenvolvidas e processadas nove formulações de requeijão contendo diferentes concentrações de gordura e água. O perfil sensorial foi desenvolvido por meio de uma equipe de nove julgadores treinados e os atributos avaliados foram: cor característica, aroma característico, sabor característico, consistência, viscosidade, espalhabilidade e adesividade. A caracterização reológica foi determinada por meio de análises instrumentais, medidas às temperaturas de 10ºC e 25ºC. A correlação entre as medidas sensoriais e instrumentais foi realizada por meio do coeficiente de Pearson. A aceitabilidade sensorial dos requeijões foi avaliada por 100 consumidores e os resultados, analisados por meio da técnica Mapa de Preferência Interno. Os resultados obtidos pela análise sensorial e reológica demonstram haver efeito significativo pelo teste F (p0,10) para todos os atributos avaliados. Assim este método se apresentou com potencial para descrever quantitativamente os atributos sensoriais dos alimentos.Water and fat content are the main factors influencing texture of cheese curd, so, the relationship between them must be considered in developing a product with reduced fat content. In this context, this work aimed at evaluating the effect of variation of these components on sensory and rheological properties of light cheese curd with Whey Protein Concentrate. Were developed and processed nine formulations of cheese curds containing different fat and water concentrations. The sensory profile was developed by a nine trained judges panel and the attributes evaluated were characteristic color, characteristic aroma, characteristic flavor, consistency, viscosity, spreadability and adhesiveness. Rheological characterization was determined by instrumental analysis, measured at temperatures of 10ºC and 25°C. The correlation between sensory and instrumental analysis was done by Pearson's correlation. Sensory acceptability of cheese curd was evaluated by 100 consumers and results were analyzed by internal preference mapping technique. Results obtained by sensory and rheological analysis show significant effect by F test (p 0.10) for all attributes. So this method showed the potential to quantitatively describe food sensory attributes.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Optmized descriptive profile: number of judges, designs and validation

O Perfil Descritivo Otimizado (PDO) é uma nova metodologia de descrição sensorial que foi proposta recentemente com o objetivo de reduzir o tempo do teste sensorial. No PDO a avaliação dos atributos sensoriais é realizada de forma quantitativa por meio da avaliação de um painel semi-treinado. A avaliação da intensidade dos atributos em uma escala intervalar possibilita a identificação da magnitude de diferença entre os produtos, aumentando a aplicabilidade do método e o destacando entre as técnicas sensoriais rápidas. A proposta do presente estudo foi validar a técnica PDO como metodologia descritiva, além de determinar as condições experimentais ideais para a aplicação do método, sendo abordados estudos de determinação do número de julgadores e de comparação entre delineamentos experimentais. Na determinação do número ideal de julgadores, foi realizado um estudo de simulação computacional, utilizando a técnica de re-amostragem de dados de um painel original, considerando 10.000 sub-grupos com reposição. Os critérios considerados foram: (i) obtenção de um erro experimental menor ou igual ao erro verificado na metodologia referência (Perfil Convencional), (ii) discriminação das amostras semelhantemente à discriminação obtida pela equipe completa, e (iii) mínima perda de informação no mapa sensorial. Para a avaliação do critério (i) foi realizada uma coleta na literatura de valores de erro experimental obtidos em estudos prévios com o Perfil Convencional, sendo estabelecido um ponto de corte para a determinação do número ideal de julgadores no PDO. Na análise dos resultados, foi verificado que, no mínimo, dezesseis julgadores devem compor a equipe sensorial para atendimento do PDO ao critério da magnitude do erro experimental, sendo os demais critérios atendidos plenamente quando este número de julgadores foi utilizado. No estudo de delineamentos experimentais, foi avaliada a viabilidade da utilização do Delineamento em Blocos Incompletos Balanceados (DBIB) para coleta de dados segundo o protocolo do PDO. Para tanto, um mesmo conjunto de amostras foi avaliado por três painéis independentes, sendo que cada painel avaliou as amostras segundo uma metodologia e delineamento específico. Dois painéis avaliaram as amostras segundo a técnica do PDO, sendo uma equipe conduzida sob o Delineamento em Blocos Completos Balanceados (DBCB) e outra equipe sob o DBIB. A terceira equipe avaliou as amostras por meio da técnica Perfil Convencional (PC), utilizando uma equipe treinada. Os escores médios obtidos nas diferentes técnicas/delineamentos não apresentaram diferença significativa pelo teste F (p > 0,05), considerando os diferentes atributos sensoriais. Foi verificado elevado grau de similaridade entre os mapas sensoriais originados pelas diferentes técnicas/delineamentos, apresentando coeficiente RV superior a 0,95. O DBIB se apresentou como uma alternativa para coleta de dados no PDO sem perda na qualidade dos resultados. No estudo de validação da metodologia PDO foram mensuradas a exatidão, a precisão (repetibilidade e reprodutibilidade) e a robustez. A exatidão dos dados gerados pelo PDO foi mensurada por meio da comparação com o método referência (PC), considerando diferentes matrizes alimentares. A precisão foi mensurada em nível de painel (repetibilidade) e inter- laboratorial (reprodutibilidade). Na robustez foi avaliada a sensibilidade do método quanto à redução do número de julgadores no painel. Na mensuração dos critérios de validação, a metodologia PDO apresentou atendimento aos critérios estabelecidos, apresentando grau de proximidade com a metodologia referência superior a 95%. Na avaliação da repetibilidade de medições, considerando três repetições das avaliações por um mesmo painel, o PDO apresentou igualdade estatística entre as repetições (p > 0,05) e com grau de proximidade superior a 99%. O método apresentou reprodutibilidade dos dados quando os laboratórios foram alterados, apresentando combinação perfeita entre os perfis sensoriais. O PDO se mostrou robusto mesmo reduzindo o número de julgadores, sendo que painéis menores apresentaram variação aleatória ainda menor que o painel completo. O PDO foi validado com sucesso e apresentou as medidas de validação com elevado grau de certeza, considerando diferentes matrizes alimentares.The Optimized Descriptive Profile (ODP) is a new methodology for sensory description that was recently proposed in order to reduce the time of sensory testing. In the ODP, the evaluation of sensory attributes is performed by means of quantitative evaluation by a semi-trained panel. Evaluation of attributed intensity on an interval scale permits identification of the magnitude of difference between products, increasing applicability of the method as well as its relevance among fast sensory techniques. The purpose of this study was to validate the ODP technique as a descriptive methodology, as well as determine the optimal experimental conditions for application of the method, including studies on determining the number of judges and comparison of experimental designs. In determining the ideal number of judges, a computer simulation study was conducted, using the re-sampling technique for data from an original evaluating panel, considering 10,000 sub-groups with replacement. The criteria considered were: (i) obtaining an experimental error less than or equal to the error found in the reference method (Conventional Profile), (ii) discrimination of samples as discriminated obtained by the complete panel, and (iii) minimal loss of information in the sensory map. For evaluation of criterion (i) a literature review was performed to collect experimental error values obtained in previous studies with the Conventional Profile, establishing a cut-off for determining the optimal number of judges in the ODP. In analyzing the results, it was found that at least sixteen judges should make up the sensory panel so that the ODP meets the criteria for magnitude of the experimental error, where the remaining criteria were fully met when this number of judges was used. In the study of experimental designs, was evaluated the feasibility of using a Balanced Incomplete Block Design (BIBD) to collect data according to the protocol of the ODP. Thus, an identical set of samples was evaluated by three independent teams, where each team evaluated the samples using a specific methodology and design. Two panels evaluated the samples using the ODP technique, where one panel used the Balanced Complete Block Design (BCBD) and the other the BIBD. A third panel evaluated the samples according to the Conventional Profile technique (CP) using a trained judges panel. The mean scores obtained in the different techniques/designs showed no significant difference by the F- test (p > 0.05), considering the different sensory attributes. A high degree of similarity was found between the sensory maps obtained by different techniques/designs, presenting RV coefficients greater than 0.95. The DBIB is presented as an alternative to collecting data in the ODP without loss in quality of the results. In the validation study of the ODP methodology, accuracy, precision (repeatability and reproducibility) and robustness were measured. Accuracy of the data generated by the ODP was measured by comparison with the reference method (CP), considering different food matrices. Precision was measured at the panel (repeatability) and inter-laboratory levels (reproducibility). Robustness considered evaluation of the sensitivity of the method with regards to reducing the number of judges making up the panel. In measuring of the validation criteria, the ODP methodology met the established criteria, presenting a degree of proximity with the reference methodology greater than 95%. In evaluation of measurement repeatability, considering three repetitions of the evaluations by a single panel, the ODP showed statistical equality among the repetitions (p > 0.05) with degree of proximity exceeding 99%. This method also showed reproducibility of the data when laboratory were altered, presenting a perfect combination among sensory profiles. The ODP showed to be robust in reducing the number of judges, where smaller teams presented less random variation than the complete panel. It was also successfully validated and presented validation measures with a high degree of certainty, considering different food matrices.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Balanced incomplete block design: an alternative for data collection in the optimized descriptive profile

The optimized descriptive profile (ODP) is a new descriptive methodology which proposes an optimized sample evaluation by no trained assessors. To permit that assessors with a low degree of training quantitatively evaluate samples consistently, this method proposes the presentation of reference materials ("weak" and "strong") together with all set of samples at the time of evaluation. The attribute-by-attribute protocol is recommended on the ODP technique to allow for comparison among the samples and avoid fatigue, since only one attribute is evaluated at a time. Simultaneous presentation of the samples, together with the reference materials, is the "key point" of the ODP, and therefore the number of samples may be a limiting factor in this technique. The purpose of the present study is to determine if the balanced incomplete block design (BIBD), used in descriptive techniques traditionally, may be an alternative for data collection on this specific methodology, the optimized descriptive profile (ODP). The BIB design does not allow for comparison among all samples together, but only among a fraction of them. Therefore an assessment of the data quality obtained through this design is necessary to increase the applicability of the ODP. In this experiment a specific set of grape juice formulations was used, which presented variations in pulp and sugar contents. Sensory evaluation was conducted with two independent panels, where each panel evaluated the samples using the ODP protocol in a specific design. Thus, one panel evaluated the samples using the balanced complete blocks design (BCBD) and the other panel the balanced incomplete blocks design (BIBD). The data obtained by the two designs were compared in relation to analysis of variation, F-test power and regression models. Data obtained by the ODP conducted in the BIBD was very similar to that of the ODP in the BCBD. In the ANOVA, the formulations differed (p < 0.05) in relation to all attributes, showing a test power (1 - β) greater than 0.95. The regression models obtained in the different designs indicated overlapping of the confidence intervals (CI 95%). Therefore, the BIBD presents itself as an alternative for data collection in the ODP without loss in quality of the results

Artificial neural networks (ANN): prediction of sensory measurements from instrumental data

The objective of this study was to predict by means of Artificial Neural Network (ANN), multilayer perceptrons, the texture attributes of light cheesecurds perceived by trained judges based on instrumental texture measurements. Inputs to the network were the instrumental texture measurements of light cheesecurd (imitative and fundamental parameters). Output variables were the sensory attributes consistency and spreadability. Nine light cheesecurd formulations composed of different combinations of fat and water were evaluated. The measurements obtained by the instrumental and sensory analyses of these formulations constituted the data set used for training and validation of the network. Network training was performed using a back-propagation algorithm. The network architecture selected was composed of 8-3-9-2 neurons in its layers, which quickly and accurately predicted the sensory texture attributes studied, showing a high correlation between the predicted and experimental values for the validation data set and excellent generalization ability, with a validation RMSE of 0.0506

ACEITAÇÃO SENSORIAL DE IOGURTE SABOR PÊSSEGO ACRESCIDO DE DIFERENTES CONCENTRAÇÕES DE AROMA E POLPA POR MEIO DA TÉCNICA DE MAPA DE PREFERÊNCIA

The objective of the present study was to evaluate the effect of different pulp and artificial flavor concentrations on the physicochemical and sensory quality of peach-flavored yogurt, applying the statistical technique of the Principal Component Analysis (PCA) for developing an Internal Preference Map. Therefore, an acceptance test was performed with 150 consumers using the nine-point hedonic scale. Physicochemical determinations of titratable acidity, lipids, lactose and sucrose were also conducted. There was a significant difference (p < 0.05) between the yogurt formulations in relation to sensory acceptability, while in the case of the physicochemical measurements the formulations showed no difference at the level of 0.05 probability by the F-test. It was found that the addition of artificial flavor during yoghurt processing may be suspended at the Lindo Vale Dairy without altering sensory acceptability of the product, thus reducing production costs while maintaining the sensory quality of the product. However, the pulp concentration in peach-flavor yogurt cannot be reduced without altering sensory acceptability, so that the pulp concentration in the dairy product is maintained.Objetivou-se com o presente trabalho avaliar o efeito de diferentes concentrações de polpa e aroma artificial na qualidade físico-química e sensorial de iogurte sabor pêssego, aplicando-se a técnica estatística de Análise de Componentes Principais (ACP) na elaboração de um Mapa de Preferência Interno. Para tanto, foi realizado um teste de aceitação com 150 consumidores por meio da escala hedônica de nove pontos. Também foram realizadas determinações físico-químicas de acidez titulável, lipídeos, lactose e sacarose. Verificou-se que houve diferença significativa (p < 0,05) entre as formulações de iogurte em relação à aceitabilidade sensorial; já para as medidas físico-químicas, as formulações não apresentaram diferença ao nível de 0,05 de probabilidade, pelo teste F. Foi identificado que a adição de aroma artificial no processamento de iogurte pode ser suspensa pelo Laticínio Lindo Vale sem alterar a aceitabilidade sensorial do produto, diminuindo assim o custo de produção e mantendo a qualidade sensorial do produto. Porém, a concentração de polpa no iogurte sabor pêssego não pode ser reduzida sem que haja diferença na aceitabilidade sensorial, sendo interessante para o laticínio manter a concentração de polpa do produto

Methodology for determination of two new sensory thresholds: Compromised acceptance threshold and rejection threshold

The existing methodologies for determining thresholds generate unreliable estimates of the point at which the intensity of a stimulus begins to compromise acceptance or result in sensory rejection of a product. Thus, a new methodology was proposed for determination of two new sensory thresholds: the compromised acceptance threshold (CAT) and the rejection threshold (RT). In this new methodology, increasing or decreasing series of stimulus intensity are measured together with a standard stimulus (control sample) by means of acceptance tests. In the present study, the CAT and RT were determined for sucrose concentrations in grape nectar, demonstrating that when reducing the sucrose concentration of grape nectar form 9.00% (w/v) to 6.87% there begins to occur impairment of product acceptance (CAT), and when reducing the sucrose concentration from 9.00% to 3.83% there begins to occur sensory rejection (RT) of the product. When compared to existing threshold determination methodologies, the proposed methodology permitted for calculating, with greater reliability, the points at which compromise of acceptance (CAT) and sensory rejection (RT) of the product begin to occur. In addition to the case study presented, the proposed methodology has a wide range of applications in science and in the food, cosmetic and pharmaceutical industries

Otimização da aceitabilidade sensorial de requeijão cremoso light

O requeijão cremoso é um tipo de queijo fundido originalmente brasileiro, fabricado em todo território nacional com algumas variações de tecnologia. Este é um dos principais tipos de queijos produzido e consumido no Brasil e apresenta como característica o elevado teor de gordura. Por outro lado, a gordura apresenta papel fundamental na aparência, sabor e textura de requeijão, portanto desenvolver um produto light com qualidade sensorial semelhante à versão tradicional é um grande desafio à indústria de alimentos. Nesse contexto, o objetivo deste trabalho foi avaliar a composição química e a aceitabilidade sensorial de requeijão cremoso light, com diferentes níveis de redução de gordura, em relação à textura e impressão global. O experimento seguiu um delineamento de superfície de resposta, o Delineamento Composto Central Rotacional (DCCR) com dois fatores (gordura e umidade). A aceitabilidade sensorial foi avaliada por 100 consumidores, utilizando a escala hedônica de nove pontos. Os resultados obtidos demonstraram que os requeijões com diferentes níveis de redução de gordura apresentaram aceitabilidade sensorial semelhante quando combinados a um aumento proporcional do teor de umidade. Os produtos que apresentaram extrato seco desengordurado (ESD) de aproximadamente 19,3%, originados de diferentes combinações entre gordura e umidade, foram os que apresentaram melhor aceitação por parte dos consumidores, demonstrando a importância do ESD na aceitabilidade sensorial.Cream cheesecurd is a type of processed cheese, originally Brazilian, produced throughout the entire Brazilian territory with some technological variations. This is one of the main types of cheese produced and consumed in Brazil and it is known for presenting an elevated fat content. On the other hand, the fat plays a fundamental role in appearance, flavor and texture of cheese, then developing a light product with sensory quality similar to the traditional version is a major challenge to food industry. In this context, the objective of this study was to evaluate the chemical composition and sensory acceptability of light cream cheesecurd with different levels of fat reduction for texture and overall impression. The experiment followed a design of response surface, the Central Composite Rotatable Design (CCRD) with two factors (fat and moisture). The sensory acceptability was evaluated by 100 consumers, by the hedonic scale of nine points. The results showed that the cheesecurds with different levels of fat reduction had similar sensory acceptability when combined with a proportional increase in moisture content. The products that presented dry defatted extract (DDE) of approximately 19.3%, originated from different combinations of fat and moisture, were those with better acceptance by consumers, demonstrating the importance of DDE in sensory acceptance

Optimized Descriptive Profile: A rapid methodology for sensory description

The objective of this study was to propose a rapid method for obtaining sensory descriptions of foods utilizing semi-trained judges and the quantitative evaluation of sensory attributes, called the Optimized Descriptive Profile (ODP). It was proposed that reference materials be present during final evaluation of the products. Therefore the judges could compare samples with the reference materials, facilitating the allocation of attribute intensity on the unstructured scale. The description obtained by the ODP was compared with the Conventional Profile (CP). Comparative analyses were made between the graphical representations obtained by the Principal Components Analysis (PCA), t-test and correlation analysis. Correlation between sensory measurements obtained by both methods and the instrumental texture measurements was also evaluated. The proposed methodology provided a sensory profile that was very similar to that of the evaluation trained panel (CP) in relation to the graphical configuration of the samples and the correlation of attributes with the principal components. Results of the sensory description presented significant correlation without significant differences according to the t-test at the probability level of 0.10. Sensory data obtained by the CP and ODP presented significant correlation (p < 0.10) with the instrumental properties of texture. The proposed descriptive analysis thus has the potential to quantitatively report sensory attributes, reducing the time and cost of sensory tests and facilitating the correlation of sensory and instrumental measurements