TASTE PERCEPTION, FOOD QUALITY AND CONSUMER ACCEPTANCE

Consumer acceptance is a more measurable parameter than the ill defined concept of quality. Thus, it is better to consider how the taste, and indeed all the sensory characteristics, of foods can be manipulated to improve consumer acceptance. If tastes are to be manipulated, it is necessary to understand something about taste mechanisms so that the researcher can avoid the all too common artifacts and biases involved in gustatory measurement. Discussed here are some aspects of sensory information processing in the brain, the problems of crosssensory confusion, sensory adaptation and taste categorization.     

THE SENSE OF SMELL IN FOOD QUALITY AND SENSORY EVALUATION

The sense of smell is the major contributing sensory system in the perception of food aromas and volatile flavors. Illustrations of the importance of olfactory sensations can be found in the literature on product quality defects and in the importance of aroma andflavor characteristics in driving consumer acceptability of foods. Assessing olfactory-mediated characteristics of flavors is challenging, however, for a number of reasons. There are wide individual differences in olfactory acuity, as suggested by the existence of specific anosmias. Panelists are often strongly influenced by the immediate context in which samples are judged. Developing a useful consensual language to describe smells in sensory analyses can also be difficult. In spite of these challenges, the human sense of smell is the ultimate discriminator of food aroma and flavor quality; instrumental analyses are a poor substitute. Even in cases in which chemical components of food flavors have been identified, these must be cross-referenced against human sensitivities in order to estimate their sensory impact.     

MICROBIOLOGICAL AND SENSORY EVALUATION OF COOKED ROAST BEEF PACKAGED IN A MODIFIED ATMOSPHERE

Sliced cooked roast beef was packaged in a modified atmosphere (MA) consisting of 75% CO2, 15% N2 and 10% 02 and stored at 4.4°C for 42 days to evaluate the MA's effectiveness at controlling the outgrowth of Pseudomonas fragi, Clostridium perfringens, Staphylococcus aureus and Salmonella typhimurium after inoculation. Additionally, a taste panel was conducted to monitor the effects of modified atmosphere packaging (MAP) on sensory parameters of uninoculated samples. P. fragi was able to grow only to a limited extent in the MA, but grew to high numbers in air. The three pathogens were unable to grow in the MA, probably due to the effects of temperature. Numbers in S. typhimurium and C. perfringens declined more rapidly in the MA than in air but S. aureus numbers did not decrease in either atmosphere. High numbers of molds were recovered from the uninoculated samples stored in air but none were recovered from MAP samples. Sensory analysis indicated that most product deterioration occurred within the first 7 days of storage.     

SENSORY EVALUATION OF FOOD FIRMNESS

How people test foods for firmness without eating them, was studied using 131 respondents and 9 different pairs of foods representing a wide range of firmness. The results were related to correctness of judgment and objective characterization by the Instron machine. Evidence was obtained that the kind of sensory firmness test employed depends on the firmness of the food. Viscosity/ consistency, deformation, puncture, and flexure were used as the degree of ‘firmness’ increased from a low (whipped toppings) to a very high (carrots) level.     

SENSORY ATTRIBUTES AND THIAMINE CONTENT OF ROASTING CHICKENS COOKED IN A MICROWAVE, CONVECTION MICROWAVE AND CONVENTIONAL ELECTRIC OVEN

Fresh whole roasting chickens were cooked to an internal temperature of 79°C (175°F) in either a microwave, convection microwave or conventional electric oven. The sensory attributes of breast meat samples from chickens cooked in the three ovens were evaluated by untrained and laboratory panels. Untrained panelists found convection microwave cooked samples to be more acceptable in terms of juiciness than microwave cooked samples. Laboratory panelists rated the chicken cooked in the conventional oven as significantly more tender and juicy but similar in flavor intensity to chicken cooked in the microwave ovens. Thiamine retention on a dry weight basis ranged from 77% in conventionally cooked chicken breasts to 98% in microwave cooked chicken legs.     

FIRMNESS EVALUATION OF SWEET CHERRIES BY A TRAINED AND CONSUMER SENSORY PANEL

The objective of this study was to examine cherry firmness and the ability of a trained and consumer panel to differentiate between cherries of different firmness values. For the trained panel ( n =  12) and consumer panel ( n =  100) evaluations, two late-maturing, commercially important cherry cultivars were evaluated, "Selah" and "Skeena." For trained panel evaluations, the analytical firmness value of each cherry was determined, although for the consumer panel, cherries were characterized into different firmness categories (low, intermediate and high), after which, a series of paired comparisons were made. "Selah" was the less-firm cultivar by approximately 20 g/mm and consumers could distinguish the more-firm cherry in all comparisons ( P <  0.05). For "Skeena," consumers could only distinguish soft versus firm. Trained panelists were able to distinguish between cherries of a minimum analytical firmness value of ∼40 g/mm. A model was developed to predict sensory firmness from analytical determinations of firmness ( r =  0.63).

PRACTICAL APPLICATIONS

Developing prediction models to estimate sensory response from analytical data will benefit the fruit industry by potentially allowing the use of analytical measurements as a proxy for sensory evaluation. In addition, understanding the importance of firmness on cherry acceptance and knowing the specific firmness values at which individuals can perceive a difference in sensory firmness is useful for cherry growers to produce a cherry with acceptable texture.     

SENSORY AND INSTRUMENTAL EVALUATION OF TEXTURE OF COOKED AND RAW MILLED RICES WITH SIMILAR STARCH PROPERTIES

Three pairs of milled rices with similar starch properties (low gelatinization temperature waxy, and low gelatinization temperature low amylose, and intermediate gelatinization temperature intermediate amylose) were assessed for cooked rice properties by two industry taste panels and for raw and cooked rice properties by 30-member Filipino consumer panels. Only slight differences in texture within pairs were noted by the two industry taste panels who had not been trained to assess boiled raw rice or waxy rice. The Filipino consumer panel gave significantly higher ranked scores for one low-amylose variety in both raw and cooked forms. Malagkit Sungsong suman sa antala was ranked higher than modern waxy rices. Instrumental methods for translucency and whiteness of raw rice and Instron hardness and stickiness of cooked rice were not able to detect differences perceived by the Filipino consumer panels.     

NOTES ON CONSUMER ORIENTED SENSORY EVALUATION

There are two approaches of sensory evaluation to consumer-product assessment. One can either start with (1) the taxonomy or list of different test methods, and show where these are applied, or else, (2) begin with a series of business decisions which require consumer feedback, and illustrate different sensory tests that are used to insure the adequacy of these decisions. This paper shows the second approach. It illustrates how consumer responses can be adequately gauged in situations where the result is measured by marketing decisions with dollars and cents returns.     

SENSORY AND MICROBIOLOGICAL QUALITY EVALUATION OF VACUUM-PACKED SLICED COOKED CHICKEN BREAST. SHELF-LIFE ESTIMATION

Abstract The shelf-life of vacuum packed, sliced, cooked chicken-breast based on sensory and microbial changes as a function of temperature (2.3, 6.5, 10, 13.5 and 17.7C) was determined. Sensory evaluation and a microbiological study charted the development of lactic acid and psychotropic bacteria and of Brochothrix thermosphacta. Six different sensory methods were used to estimate product shelf-life; of these, the method based on average smell and taste was deemed the most suitable, since these parameters had a greater impact on shelf-life. From a microbiological point of view, mean shelf-life times were estimated at each temperature and compared with the estimates of the tasting panel. In the samples stored at the three lowest study temperatures (2.3, 6.5 and 10C), lactic acid and psychotropic bacteria counts of 10⁷–10⁸ cfu/g were not achieved; this agrees with the absence of sensory rejection at the end of the experiment. At 13.5 and 17.7C, mean shelf-life estimated microbiologically was shorter than that estimated using sensory methods. This difference, which here amounted to at least 8 days, is due to the so-called "delayed change", reported in previous experiments with cooked meat products.     

A COMPREHENSIVE FORMULA FOR THE ACCEPTANCE OF FOOD TEXTURE, AND ITS GENERALIZATION TO OVERALL FOOD ACCEPTANCE

A survey is made of factors contributing to food texture (atoms, molecules, structure, mechanics) together with factors leading to food texture acceptance (stimulus-response, preferences), and a formula is developed for the relations among all these factors. An extension to general acceptance, involving all sensory quality factors, is also made.     

INSTRUMENTAL AND SENSORY CHARACTERIZATION OF COOKED POTATO TEXTURE

Uniaxial compression, Texture Profile Analysis (TPA) and chemical measurements were related to sensory texture evaluation of potato quality during storage. Principal component analysis grouped the varieties into three types of variation: mealiness versus firmness and springiness (PC1), moistness versus adhesiveness (PC2) and hardness versus adhesiveness and moistness (PC3). In uniaxial compression the variable 'stress', 'work up to fracture' and 'total work during compression' described the same type of information in the data. These uniaxial data and most of the TPA data were highly correlated. Uniaxial compression data (stress, strain, modulus of deformability), starch structural data (area, roundness, aspect ratio), specific gravity and pectin methyl esterase activity discriminated between the varieties and harvest times. Partial Least Squares Regression showed stress, strain, modulus of deformability and specific gravity to be the most important variables in distinguishing between two groups of sensory texture attributes explaining 65% of the total variance in the sensory data. Coefficients of correlation between predicted and measured sensory attributes were in the range 0.36–0.79. The TPA data were not found to be relevant substitutions for the sensory attributes.     

CONSUMER ACCEPTANCE OF GROUND CHICKEN

In a study of marketing opportunities for fresh dark chicken meat, focus group participants (n=34) identified the most important attributes of chicken products and their packaging. Acceptance of chicken ground through various size plates (2.4, 4.7 and 9.4 mm) and containing various concentrations (0, 1 and 2%) of sodium tripolyphosphate (STPP) was evaluated by consumers (n=73). STPP concentration was not a significant variable for any of the sensory attributes. Texture ratings increased significantly with grind size. Yield increased with increasing concentration at the 2.4 mm grind size of STPP. A simulated supermarket setting test was conducted to verify findings from a mailed survey (n=115) and actual purchase behavior by consumers (n=121). A calculated desirability index indicated a ranked preference to be: breasts > kabobs > stir-fry > boneless, skinless thighs > scallopini > bone-in, skin-on thighs > ground chicken. The lack of acceptance of ground chicken by consumers suggests that future emphasis should be focused on other dark chicken meat products.