The research toolbox
Using sensory panels and instrumentation to evaluate cooked meat flavor and tenderness.
In 1978, the American Meat Science Association (AMSA) first published Guidelines for cookery and sensory evaluation of meat (AMSA, 1978). During the next 17 years, these AMSA “Guidelines” were very useful to both AMSA members and nonmembers involved in meat cookery/sensory evaluation. Interpretation of published reports was much easier when the AMSA Guidelines were used to guide the research. Research that utilized the AMSA Guidelines has greatly assisted in determining key factors responsible for differences in sensory, instrumental texture, and cooking properties of meat. In addition, the AMSA Guidelines provided greater consistency in multi-institutional projects.
In 1995, a much-needed update was published titled Research guidelines for cookery, sensory evaluation, and instrumental tenderness measurements of fresh meat by the AMSA and the National Live Stock and Meat Board (AMSA, 1995). Numerous changes had occurred in cooking equipment and meat products since the Guidelines were first published. As a result of diet/health concerns, meat products were leaner and often smaller in portion size. Precooking followed by reheating and the use of microwave cookery was more prevalent than in 1978, and there was much more variety in meat entrees. Certainly, food safety concerns were greatly elevated from producers throughout the entire processing and marketing chain, including consumers.
AMSA just released a new version that is more comprehensive, as much additional and updated information is provided in this revision. As was stated in the previous Guidelines, this manual is not a “standard” to which everyone will be expected to adhere for every research study. It is, as the title suggests, “Research Guidelines.” The researcher must decide the most appropriate methods to use to answer the question at hand. The methods and approaches described herein, however, are accepted and recommended as the most appropriate for most circumstances. They are designed to control unwanted variability, to determine the most accurate answer to the questions being addressed with the most relevant methods possible, and, when feasible, to allow for valid comparative interpretation of published research.
Information is included on recommendations for collecting and preparing appropriate samples for sensory and/or tenderness evaluation for fresh beef, pork, and lamb steaks/chops, roasts, and ground patties; but it also may be applicable to certain enhanced, cured, or comminuted products. Additional topics covered include product handling, cookery methods, sensory panel methods, and a data analyses overview.
The development of sensory evaluation as a science has undergone tremendous expansion in the last 25 years. The efforts of the American Society for Testing and Materials Committee E-18 (ASTM), the Society of Sensory Professionals, and the Institute of Food Technologists (IFT) have led to numerous recent publications and annual workshops on sensory evaluation. Thus, although more comprehensive details are included in this revision than in the previous version, more detailed approaches and procedures can be found in the references provided. The reference section has been expanded to include important sources of information (especially for sensory evaluation) that have occurred mainly in the past 25 years.
Before initiating an experiment, the cooking and handling procedures, sensory method, and testing parameters should be determined. Factors to consider in method selection include following:
- What is your hypothesis? ?
- What questions are you trying to answer (test objectives)? ?
- How will the results be used? ?
- How large of a difference are you trying to detect? ?
- How much variability is there within and between samples?
The diagram shown in Figure 1 may be useful in selecting the most appropriate test method. If, based on the preliminary work, the sensory differences among treatments are not expected to be detectable; the lack of significant differences can be verified using discrimination or descriptive analysis methods. If, however, the sensory differences are expected to be detectable, consumer testing methods would be more appropriate. It would be important to determine if the differences are detectable to consumers, and if detectable, how they affect consumer acceptability.
Quantitative sensory methods can be grouped into three primary categories: (1) discrimination, (2) descriptive analysis, and (3) consumer. Discrimination methods can use either trained panelists or untrained consumer panelists, depending on the test objectives. If the test objectives are to determine with a high degree of certainty if treatment differences are significant, trained panelists are suggested. Trained panelists are carefully selected, highly trained, and hypercritical as compared to average consumers. When using consumers for discrimination tests, consumers are not as critical and may not detect differences. The selection of a testing method should be based on the objectives of the study. Data should be interpreted based on the sample population used for the study.
Descriptive methods use trained panelists. Panelists can be defined as trained (6 to 10 training sessions) to highly trained (6 months or more of training) or expert (10 or more years of experience). As the amount of training and experience increases, panelists can detect smaller differences in attributes between samples. The amount of training should be noted and data presented based on the panelists’ level of training. Descriptive tests are used to quantify the level of an attribute within the samples. Depending on the testing method selected, scales and attributes may vary, but each test is used to determine if samples differ in sensory attributes.
Consumer evaluation can be either qualitative or quantitative. Qualitative consumer methods provide input from consumers on their opinions on a product(s) based on more loosely structured questions that provide opportunities for consumers to give their opinions and inputs. These data are very valuable, but they do not give quantitative results that can be statistically analyzed. Consumer quantitative testing provides an avenue to measure consumer opinions using questions on a ballot with a scale that is or can be converted to numerical values for statistical analyses. This provides a method of quantifying consumers’ responses and determining differences. Test-booth conditions, coded containers, and scoring methods used in central location tests (CLTs) are certainly not typical of normal conditions of food consumption. Consumer home placement or home use tests (HUTs) provide the opportunity to include in-home preparation, family opinions and environment, and use of normal containers.
When selecting the test to use, sensory professionals should always remember that consumer panels differ from trained panels. Although members of a trained panel are consumers, their opinions and preferences may not be representative of the general population. Trained panelists should therefore never be asked to respond with their opinions on preference or liking. More information on the testing methods and considerations is provided in the appropriate sections. Meat scientists are strongly encouraged to understand each testing method and the strengths and weaknesses of each method when determining the method that provides the best procedures to meet the test hypothesis and objectives.
For more information, visit the AMSA website at www.meatscience.org/sensory.