Part of the role of a QA/R&D/Production specialist is to conduct sensory testing of food or beverages to confirm product quality and shelf life and craft new products based on defined taste profiles. Knowing which sensory tests to implement is important because results must be both scientifically valid and actionable. In a previous blog, we talked about the sensory complexity of certain foods and the application of sensory evaluation techniques in the quality and new product development field. In this post, we will describe scenarios that showcase particular sensory methodologies and discuss the design of sensory tests.
Scenario 1 – Difference Tests (Triangular Test)
You are the Quality Manager at a medium-sized industrial winery. The production supervisor brings today’s production of the company’s best-selling white blend to the lab for quality evaluation. The manufacturing of this wine is made according to a bill of materials. You suspect an error was made during blending. This product is a consumer favorite and must display a consistent and recognizable aromatic and taste profile year-round. As part of your finished wine inspection/release procedures, you conduct a discrimination test that compares the library sample (the approved sensory reference for the wine) to the sample that was just bottled. To release the wine, there needs to be no significant difference between the test sample and the control in a blind triangular test. The sensory evaluation is performed by the winery sensory panel and uses olfaction and taste. Statistical tables are used to conclude whether the blend deviates or not from the approved specifications. A 95% confidence interval is chosen for the test. How is this test implemented?
Triangular testing is used to detect an overall difference between two food or beverage products that differ slightly in appearance, taste, texture, or aroma. Three samples are served of which two are the same and one is different. Panelists must identify the odd sample. Black glassware may be used to mask differences in colour and appearance. The panel coordinator must follow strict protocols to ensure consistency of serving temperature and sample size to avoid skewing the results. Three glasses are presented to the panel members who taste all samples blind. Based on the correct number of responses, the panel coordinator concludes that the samples are different or the same. A minimum of 7-10 responses must be collected for results to be robust. Borderline results may require a larger sample size in which case the sensory panel leader will need to recruit more panelists. Based on the results, the winery may choose to re-blend the wine or market it as a special release with different sensory specifications.
Scenario 2 – Sensory Profiling (Pivot test or QDA®)
The pastry chef at a sustainable chocolate startup is conducting a sensory test of chocolate to optimize formulation (sugar addition, blends of cocoa beans, % cocoa, and cocoa powder) and conching time. She decides to compare various recipes that have been manufactured following different ingredient ratios and process parameters. A group of chocolate connoisseurs from the trade is invited to a tasting event where the different samples will be evaluated. The pastry chef will distribute aroma wheels to the panel to describe the aromas of chocolate. What sensory test would she choose to conduct and how many experts must she invite?
This scenario involves an exercise in sensory profiling or describing the sensory characteristics of chocolate. Experts who are familiar with chocolate descriptors must taste each sample blind and comment on or rate the sensory profiles of the products. This is an objective task that does not involve expressing likes or dislikes about a product. The startup business may elect to perform a Quantitative Descriptive Analysis (QDA®) assessment or Pivot Test depending on the backgrounds of the panelists and whether they have received prior training in attribute scoring using QDA®. A minimum of 6 to 8 assessors are required for descriptive sensory testing. When conducting research, recruiting and screening 15 to 20 judges or even more is advised.
With QDA®, expert panelists are trained to score each sample using defined attributes. For instance, 20 sensory descriptors ranging from creaminess, bitterness, sweetness, coarse texture, vegetal, floral, or nutty character may be used to describe chocolate. The rating of these attributes involves using, for instance, intensity scales ranging from 0 (low attribute intensity) to 10 (high intensity). Score averages are then calculated and compared statistically to identify differences between the samples. Sensory profile maps for each product are generated, and outliers and product groupings are identified.
When using the Pivot methodology, the judging can take the form of free comments where experts use their own words to describe each chocolate sample. The panel’s comments are analyzed using lexical analysis then graphed and statistically processed. AI is a newly emerging tool that lends itself well to lexical analysis.
Scenario 3 – Consumer Tests
You work as a brewmaster at a microbrewery. The person in charge of marketing at the brewery has asked you to help conduct a beer tasting to compare the brewery’s flagship beer against the competition. Marketing would like to know which beers are preferred in the same price category and how much your beer is liked or disliked and why. You organize a blind tasting with the brewery staff and patrons. What type of sensory test do you conduct? How many assessors do you require for this test to be valid? Do they need to be certified brewmasters?
This scenario involves conducting a consumer test with non-experts. The panel is expected to share their taste preferences so the evaluation is hedonic in nature. A small in-house consumer test usually requires at least 25 participants. For consumer research, you would be requiring 50 to 75, and sometimes over 100 consumers to perform market segmentation. Two or more beers will be served blind so that consumers are not influenced by the brand or label unless you seek feedback on the brand or packaging. The consumer questionnaire will generally include demographic survey questions and a sensory section where consumers rate a product and say whether they like or dislike it. Different types of scorecards can be utilized and the data graphed and statistically analyzed to establish differences between the brews. Based on the results, the brewery may want to match its style of beer to the sensory profile of the products that the consumers preferred the most. It might also want to appeal to a specific demographic. With this type of test, the sample size is important to capture a representative group of consumers.
Scenario 4 – Sensory Profiling (Mapping)
The winemaker of a small winery organizes a tasting to select finishing tannins and oak staves that will be used in their red winemaking. Winery staff assemble in the tasting room to evaluate many wine samples crafted with various tannins and oak products. Different tannin finishes and oak profiles are presented and use the same unoaked wine as their base. With a large number of samples to evaluate, what sensory test is best suited for the winery?
This exercise is similar to scenario 2, above. Wine experts are tasked with assessing the sensory profiles of a large number of wine samples. Quantitative Descriptive Analysis (QDA®) assessment or Pivot methodology could be used but the objective is not to obtain a detailed organoleptic profile of the samples. Instead, the goal of the exercise is to quickly screen the wines rejecting the profiles that are unsuitable and selecting only those that may deliver the wine style the winery wants. To accomplish this, the winemaking team groups wine samples in a two-dimensional space according to how similar or different they perceive the wines to be from one another, placing samples that display similar sensory profiles close together and samples that are different further apart. The assessment can be conducted on a flat surface (table or workbench) or virtually on a computer screen. Profiles of each sample are generated based on the input of the sensory panel. The assessors must know the product sensory space well to conduct these evaluations.
Sirocco Food + Wine Consulting uses Tastelweb® software for the design of consumer and sensory questionnaires, data entry, processing of results, and reporting. Five tests are currently offered: Consumer Tests, QDA®, Mapping, Triangle, and Pivot tests. Individual tests can be purchased through the store (no contract needed). Sirocco Consulting and Tastelweb® will be at the Pangborn Sensory Symposium this summer.