Sensory Difference Tests Research Articles

Nomilin, Taste Threshold and Relative Bitterness

ABSTRACTAqueous taste thresholds for nomilin, a bitter citrus limonoid, were established by a combination of ascending series and sensory difference (triangle) tests. Results from the 25‐member screened panel indicated a detection or stimulus threshold of 0.8 ppm and a recognition threshold of 2.1 ppm. Panelists described nomilin as either astringent or lingeringly bitter. Triangle taste thresholds determined from statistical and graphical techniques ranged from 3.5 ppm for LOGIT calculations to 1.7 ppm for log probability plots. Paired comparisons of individual nomilin and limonin solutions in equal concentrations of 1, 2, 3 and 4 ppm could not be differentiated with statistical significance (P = 0.05).

Statistical properties of simple sensory difference tests: Confidence limits and significance tests

AbstractThe Normal approximation to the binomial distribution is used to obtain confidence limits for the proportion of correct responses in a simple sensory difference test and the proportion of assessors able to discriminate between two products. Improved approximations, which should be considered with small panels or when the proportion of correct responses is close to 0 or 1, are discussed. To permit comparison of the discriminating ability of different panels, or investigation of the effect of a change in the products assessed, tests of the significance of the difference between two proportions are presented, based on the Normal approximation and the x2 statistic. The methods are illustrated with some data from an investigation on fish flavour.

Sensory panel of the food group new directions in sensory difference tests

Sensory panel of the food group new directions in sensory difference tests

SHORT‐CUT SIGNAL DETECTION MEASURES FOR SENSORY ANALYSIS

ABSTRACTTraditional sensory difference tests demonstrate whether a difference exists or not between two flavors; to determine the degree of difference requires further scaling. The two processes can be combined for perceptually small differences using difference tests based on signal detection measures. Such measures provide a measure of degree of difference directly which being a probability value is susceptible to analysis by parametric statistics Traditional signal detection measures are complex and time consuming but the present paper outlines a short and simple means of calculating such measures.

EFFECTS OF VARYING LEVELS OF SUCROSE, CORN SYRUP SOLIDS AND VINEGAR ON THE QUALITY OF SWEET PICKLED PEACHES

ABSTRACTQuality changes in pickled peaches packed in three syrup concentrations and five ratios of sucrose‐corn syrup solids were studied. Variations in the ratios of sucrose and corn syrup solids (CSS) had no apparent effect on Brix level or pH of the syrup. Shear press values which denoted increased firmness associated with osmotic action which caused shrinkage and loss of drained weight. The more attractive color of peaches packed in high density syrups (66–69° Brix) and all sucrose syrups was related to higher Gardner “a’ values. Different ratios of sucrose to CSS in the syrups significantly affected the sensory ratings for appearance, color, aroma, texture and flavor. Sensory quality scores decreased significantly when CSS were used to replace 50% or more of the sucrose in packing syrups. Multiple‐comparison sensory difference tests closely paralleled findings from sensory quality ratings. Significant differences existed in sweetness, fruit flavor and general quality but not acidity. It was evident that sourness ratings were influenced by variations in syrup acidity. The Brix and acid levels of pickled peaches could be decreased by approximately 20% without causing significant changes in general quality and fruit flavor.

Applications of the Modified Triangle Test in Sensory Difference Trialsa

SUMMARYExperimenters involved with sensory difference tests have long used the triangle test as a basic procedure. In some circumstances, they have augmented the basic triangle test through obtaining “degree‐of‐difference” scores between the supposed odd sample and the pair of like samples. A companion paper gives a method of formally utilizing these scores in the analysis of these modified triangle tests when a computer is available. This paper summarizes the method and gives the results of applications of the modified triangle test to experimental data.

Some Relationships among Sensory Difference Tests

SUMMARY Much experimental work and some mathematical analyses have been conducted in comparing triangle and duo-trio tests in sensory difference testing. In this paper we assume the existence or conception of subjective responses on a response scale and relate these to corresponding probabilities of correct choices in triangle and duo-trio tests and to expected difference from control in the difference-from-control test. The two probabilities mentioned are expressed in terms of the power function of analysis of variance but required special evaluations in this problem. A table showing comparisons of the several tests is presented and includes some comparisons suggested by other authors. With the associations among tests developed, it is now possible to make realistic efficiency comparisons among them. Examples of power efficiency comparisons are given and it is found that the asymptotic relative efficiency of the triangle test to the duo-trio test is 112%.

Research in Food Science and Food Technology: A Status Report

This chapter presents a status report on research in food science and food technology. In the past two decades, considerable progress has been made in the knowledge of the chemistry of biologically important tissue constituents and of the metabolic processes which they undergo. The success of team work in this field is well illustrated in the recent elucidation of the composition and structure of limonin. The chapter also discusses developments in methodology. As the introduction of advances in food research, considerable progress has been made in the development of scientific knowledge of the field and in the application of scientific discoveries to the food industries. Improved methods for separating rapidly, selectively, and quantitatively even minute amounts of materials by filter paper chromatography and the development of other methods of separation, such as paper and column electrophoresis, electroosmosis, ion exchange resin chromatography, vapor phase chromatography, etc., have played an important role. Spectrophotometers for measurement absorption in the visible, ultraviolet, and infrared regions of the spectrum, emission and flame photometry, molecular fluorescence, and mass spectroscopy have been improved, and nuclear magnetic resonance spectroscopy has been introduced. The physiological, psychological, and genetic factors influencing sensory perception of differences in taste, feel, color, etc. have been investigated. The results of these investigations are basic to better planning of sensory difference tests and to the serious investigation of the consumer acceptance of foods. The investigation of interrelationship between soil, plant, animal, and humans has been emphasized. Some of the important industrial developments made have been emphasized because of trends that they indicate, such as improvement in the quality of fresh and processed meats and fruits, and development of improved puff-dried juice products.

Comparative Sensitivity of Pair and Triad Flavor Intensity Difference Tests

Alternative simple experimental designs for sensory difference tests of flavor intensity lead to the procedures termed pair, duo-trio and triangular tests (3). In the first, a unit trial consists in submitting coded aliquots of the two batches in question to a subject in the sequence (X), (Y) or (Y), (X) and requiring him to rank them in the order of appraised flavor strength. In the second, it consists in submitting identified X or Y with the coded sequence (X), (Y) or (Y), (X) and requiring the subject to attempt to match the identified with the like coded aliquot. In the third, it consists in submitting one of the completely coded sequences (X), (X), (Y); (X), (Y), (X); (Y), (X), (X); (Y), (Y), (X); (Y), (X), (Y) or (X), (Y), (Y) and again requiring an attempted matching of like aliquots. Inferences respecting the occurrence or non-occurrence of real discrimination are then made by relating the actual frequency of ranking or matching in repeated trials to percentage points of the binomial distribution expected in the absence of discrimination. It has been suggested (4) that the triangular test is obviously the most efficient but experimental evidence to the contrary has been reported (1). This note indicates some statistical considerations relevant to efficiency comparisons, and applies them to additional data.

Incomplete Block Rank Analysis: Some Taste Test Results

Bradley, Terry and co-workers (2, 3, 9) have put forward a solution of the problem of incomplete block rank analysis, and have applied it to the design and analysis of sensory difference tests of flavor and palatability. In its simplest form of paired comparisons in balanced incomplete blocks of 2, their method rests upon two basic assumptions. The first of these is that all rankings are statistically independent. The second is that if aliquots of m test samples are appraised by each of n subjects, there exist n sets of non-negative real numbers 7r1i, 7ir2i * ' ' wrni (j = 1, 2, *.. n) termed ratings and each satisfying the defining condition Ei7rii = 1, such that for all pairs of samples h and i, the probability of the jth subject ranking i above h in a single paired comparison is specified by rij/(7h + in). Appropriateness of this conceptual model in any specific instance is a question of fact. Technological interpretation of subjective test results also involves another factual consideration, namely the extent of inherent differences in the -xii characteristic of individual subjects j. Three series of experimental results bearing upon these points are reported below.