E. Costell

A comparison of sensory methods in quality control

Many different types of sensorial methods have been proposed and used to evaluate and control the sensory quality of foods. However, not all of them are suitable for incorporation in to quality control programmes. To simplify comparison a distinction is proposed between methods that can be used to define sensory specifications or to select a product quality standard and those that can be used to check if a product complies with stated requirements. With this approach, the appropriateness and limitations of different methods and their practical applicability, according to their use with or without a previously selected or developed standard (product, mental or written), are discussed.

Rheological and optical properties of commercial chocolate milk beverages

Abstract Flow behaviour and colour of nine commercial samples from three different lots of chocolate flavoured milk beverages were analysed. Experimental shear stress–shear rate relationships, obtained at 25°C, fitted mostly to the Newton model, as for plain milk, though some samples fitted better to Ostwald-de Waale and Bingham models. Newtonian viscosity values ranged from 2.67 to 18.68 mPa s for samples of one lot. At 5°C, as expected, Newtonian viscosity of samples was higher and pseudoplasticity increased (n values were lower). Six of the nine samples showed consistent viscosity values through the lots. Main differences in colour of samples were detected for parameter L ∗ (brightness), ranging from very light (L ∗ =53.5) to dark (L ∗ =18.3) samples. Except for two samples brightness values were consistent through the lots. Hue (h ∗ ) values were consistent for all samples. However, chromaticity (C ∗ ) values differed from one lot to the other, except for two other samples, showing the difficulty in controlling this attribute in industry.

Inulin-enriched dairy desserts: physicochemical and sensory aspects.

The aim of this work was to study how adding inulin of different average chain lengths (long-chain, native, and short-chain inulin) at a concentration of 7.5% (wt/wt) would affect the physicochemical and sensory characteristics of starch-based dairy desserts formulated with either skim or whole milk. The results have shown that the effect of adding 7.5% inulin of different average chain length can give rise to products with different rheological behavior and different sensory characteristics. The skim milk sample with long-chain inulin and the whole milk sample without inulin showed similar flow behavior. Both samples were perceived to have the same creaminess and consistency intensity, but addition of long-chain inulin increased roughness intensity and, consequently, the sensory quality could be negatively affected. The information obtained may be of great interest in designing new products with nutritional and sensory characteristics that meet consumer demands.

Inulin blend as prebiotic and fat replacer in dairy desserts: Optimization by response surface methodology

The purpose of this work was to optimize the formulation of a prebiotic dairy dessert with low fat content (<0.1g/100g) using a mixture of short- and long-chain inulin. Response surface methodology was applied to obtain the experimental design and data analysis. Nineteen formulations of dairy dessert were prepared, varying inulin concentration (3 to 9 g/100g), sucrose concentration (4 to 16 g/100g), and lemon flavor concentration (25 to 225 mg/kg). Sample acceptability evaluated by 100 consumers varied mainly in terms of inulin and sucrose concentrations and, to a lesser extent, of lemon flavor content. An interaction effect among inulin and sucrose concentration was also found. According to the model obtained, the formulation with 5.5 g/100g inulin, 10 g/100g sucrose and 60 mg/kg of lemon flavor was selected. Finally, this sample was compared sensorially with the regular fat content (2.8 g/100g) sample previously optimized in terms of lemon flavor (146 mg/kg) and sucrose (11.4 g/100g). No significant difference in acceptability was found between them but the low-fat sample with inulin possessed stronger lemon flavor and greater thickness and creaminess.

Review: Use of Methods of Research into Consumers’ Opinions and Attitudes in Food Research

Among the different factors that influence the acceptance or rejection of food, attitudes, beliefs and opinions of their potential consumers are relevant and can in some cases be decisive. The influence of these factors on food choice and purchase is especially important in the acceptance of some types of foods (organic or ecological, genetically modified or functional) that are presented to the consumer as a possible alternative to conventional food. This review paper describes the main qualitative and quantitative methods applicable to the investigation on the consumers’ opinions and attitudes towards food. Comments are made on some of the features of the information gathered.

Influence of Color on Perception of Sweetness and Fruit Flavor of Fruit Drinks

The objective of this work was to study the effects of color on the perception of both sweetness and fruit flavor of different fruit (peach, orange, kiwifruit and berries) beverages. Four samples of each fruit beverage were prepared by adding different colorants but maintaining the same composition. Color was measured using a Hunter Lab colorimeter. Samples of each of the different fruits were ranked for color, sweetness and typical fruit flavor by a group of assessors. Color was found to influence sweetness only in orange drinks but it affected intensity of typical flavor in all fruit drinks.

Optimising acceptability of low-sugar strawberry gels segmenting consumers by internal preference mapping

Optimisation of the acceptability of a low-sugar strawberry gel using different levels of strawberry pulp (200–900 g kg−1) and of mixed kappa-carrageenan-locust bean gums (1 : 1)(5.0–11.0 g kg−1) have been performed based on response surface methodology. A group of 91 consumers evaluated the acceptability of each one of the 16 formulations. Information obtained when considering the mean acceptance scores for all consumers as a dependent variable in regression analysis was compared with that obtained when using the mean acceptance scores for each of the consumer subgroups, segmented according to their similarity of preference by internal preference mapping. Only the linear effect of fruit was significant on the mean acceptance scores for all consumers. The three first segmented subgroups accounted for about 70% of the total consumers. The rest of consumers were randomly distributed and could not be grouped. While for subgroups 1 and 3 the composition factors considered did not show a clear influence on acceptability, for subgroup 2 variance in acceptability was very well explained in terms of fruit and hydrocolloid contents (R2=0.94). © 1999 Society of Chemical Industry

Effects of the Degree of Maturity on the Chemical Composition, Physical Characteristics and Sensory Attributes of Peach (Prunus persica) cv. Caterin

Sensory quality of peach during ripening to assess the best state for consumption was analysed. Physical and chemical parameters commonly used for establishing the commercial quality of this fruit were also determined: Soluble solids, acidity, sugars, organic acids, chlorophyll, carotenoids, resistance to compression and to penetration and colour. Relationships among these parameters and sensory characteristics were also analysed. A panel of eight trained assessors evaluated intensities of 12 sensory attributes (1 for odour, 2 for colour, 4 for flavour and 5 for texture). The sensory attributes selected allowed the description of perceivable differences between peaches of different degrees of maturity, although the variation in intensity of the attributes followed different trends. Colour intensity increased and acidity, firmness and crispness decreased significantly with ripening. Intensity of flavour, sweetness and fruitiness increased significantly from the under-ripe to semi-ripe states, and then decreased on reaching ripeness. It can be concluded that the most suitable time for harvesting and consumption of this peach variety was the state described herein as semi-ripe, and that a high correlation existed between colour intensity and hardness and the instrumental measurements of colour and texture.

Dark chocolate acceptability: influence of cocoa origin and processing conditions.

BACKGROUND Chocolate properties can vary depending on cocoa origin, composition and manufacturing procedure, which affect consumer acceptability. The aim of this work was to study the effect of two cocoa origins (Ghana and Ecuador) and two processing conditions (roasting time and conching time) on dark chocolate acceptability. RESULTS Overall acceptability and acceptability for different attributes (colour, flavour, odour and texture) were evaluated by 95 consumers. Differences in acceptability among dark chocolates were mainly related to differences in flavour acceptability. The use of a long roasting time lowered chocolate acceptability in Ghanaian samples while it had no effect on acceptability of Ecuadorian chocolates. This response was observed for most consumers (two subgroups with different frequency consumption of dark chocolate). However, for a third group of consumers identified as distinguishers, the most acceptable dark chocolate samples were those produced with specific combinations of roasting time and conching time for each of the cocoa geographical origin considered. CONCLUSION To produce dark chocolates from a single origin it is important to know the target market preferences and to select the appropriate roasting and conching conditions.

Revision: Percepción del gusto. Aspectos fisicoquímicos y psicofísicos / Review: Perception of taste. Physiochemical and psychophysical aspects

Flavor is perceived through two human senses simultaneously: the sense of taste, operating in the mouth, mainly in the tongue, and the sense of smell in the nostrils, where aromas are detected. The stimuli responsible for aroma perception are volatile compounds; their nature and properties as well as the mechanisms of perception have been widely studied. This is not the case for the taste stimuli, consisting of non-volatile compounds responsible for the accepted four basic taste sensations: sweet, sour, salty and bitter. The available information on taste perception is almost exclusively dedicated to sweet taste for obvious economic and nutritional reasons. In this paper, the present knowledge on the nature of the taste stimuli, on the mechanisms of their perception and on the interactions among them is reviewed. The effects of interactions with other sensory attributes (aroma, color, texture) are also reviewed. Interactions may be due to different causes: physical and chemical interactions among food components, competition at the receptor site, changes in the neurophysiological signal, and changes in the psychological response. Food aromas, as part of the flavor sensation, exert their influ ence on taste perception, as taste compounds affect aroma perception. Color may also modify the perception of a particular taste, but very few studies have been dedicated to this effect. On the other hand, the influence of texture (viscosity, consistency, hardness) mainly on the sweet taste has been extensively studied. Some contradictory results on how texture affects sweet or other tastes are still not satisfactorily explained. The study of these effects has been intensified in the last years, mainly because they are an important aspect of the flavor release phenomenon, so decisive for optimization of formulated foods.