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.

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 - ß) 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.

Acceptance of microfiltered milk by consumers aged from 7 to 70 years

Microfiltration of milk reduces its microbial load providing a longer shelf life and preserving its nutritional and sensory characteristics. The present study compared the effect of the microfiltration treatment and of the milk pasteurization regarding the sensory acceptability by consumers aged from 7 to 70 years using a 7-point hedonic scale. The obtained results were evaluated by variance analysis and Duncan’stest. Microbiological, acidity, instrumental color and heat treatment extent analyses were also performed. Microfiltered milk showed a higher microbial counting reduction and lower acidity; and lesser change incolor coordinates was found when compared to pasteurized milk, indicating the lack of reactions causedby heating. In the sensory acceptability, two groups were formed (p > 0.05) for microfiltered milk, being a group consisted of children, adolescents and elderly, who rated the highest sensory scores, and these cond one formed by adults. Comparing the two kinds of milk, pasteurized and microfiltered samples, no difference in the acceptation was found only in the group constituted by children. These findings highlights the importance in assessing the sensory quality of milk, seeing that the sensory perception is linked with the consumer purchase choice.

Otimização da aceitabilidade sensorial de requeijão cremoso light / Optimization of the sensory acceptability of light cream cheesecurd

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 por cento, 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 percent, originated from different combinations of fat and moisture, were those with better acceptance by consumers, demonstrating the importance of DDE in sensory acceptance.