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Sensory analysis of drinks

21 December 2017
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By Michael Trommer

Sensory analysis of drinks

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A key element to ensuring quality and product acceptance by consumers, sensory analysis can be applied to any type of beverage

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Sensory analysis is a scientific discipline used to “evoke, measure, analyze, and interpret reactions to those characteristics of foods and materials as they are perceived by the senses of sight, smell, taste, touch, and hearing.” (IFT, 1975). It has been defined as scientific discipline in 1975 by the Institute of Food Technology (IFT).

Acceptability and quality of food can be determined through sensory analysis, with the help of the sense organs. It is widely used from sensory teams in the industry to the analysis of the effect of the package on the product, as well as monitoring, improvement or launching of new products on the market.

This is considered an ancient practice in European beer, wine, and spirits industries. In Brazil, it was first used in 1954, by tasters for the classification of Brazilian coffee.

Application

According to Dutcosky (1996), sensory assessment provides technical support for research, manufacturing, marketing, and quality control. Among countless applications of sensory analysis in the food industry and research institutions, some of the most important are:

a) control of the development stages of a new product, such as descriptive analysis of test samples – classify samples according to established standards and/or determine that one out of many trial products is equal or better than the standard;

b) technological processing of the final product;

c) cost reduction;

d) control of the effect of the package on final products;

e) quality control;

f) stability during storage (shelf life);

g) market testing for new or reformulated products.

Sensory perception

Perception is the act or effect of perceiving, recognizing through the senses a characteristic of the object of study. This perception occurs through the five senses:

·        sight ­­(physical stimulus);

·        smell (chemical stimulus);

·        touch (physical stimulus);

·        hearing (physical stimulus);

·        taste (chemical stimulus).

Sensory characteristics

The sensory attributes are:

Appearance – color, gloss, and translucency;

Odor – thousands of volatile components;

Taste – the classic tastes are sweet, sour, salty, and bitter (nowadays the list includes umami);

Texture – physical properties like hardness, fracturability, grittiness, density etc.

Sound – effervescence and sound of carbon dioxide.

For the study of these characteristics, it is necessary knowledge in several fields, such as psychology (human behavior – perception, motivation), physiology (functions of the sensory systems), chemistry (food composition), and statistics (mathematical quantification of data).

Senses involved in sensory assessments

  •         Sight

The eyes are the physical organs that provide us with the sense of sight. The receptor is the retina, which has two kinds of cells: cones and rods. Cones detect color, and rods serves for perception of shapes in dim light. Through the sight, it is possible to obtain the first impressions of products regarding general appearance, which encompass characteristics like color, size, shape, gloss, impurities etc.

Sensory analysis can be used to support
product marketing and development

Colored lights can be used in order to mask color differences and reduce their influence in the sensory assessment.

  •         Smell

The nose is the physical organ that provides us with the sense of smell, enabling us to perceive smells when we are physiologically healthy. Smells are produced by a complex mix of odoriferous molecules. Odor is the organoleptic property perceptible by the olfactory organ when certain volatile substances are inhaled, being subject to variables such as fatigue and adaptation. The term “smell” is avoided in sensory analysis.

·        Touch and hearing

The senses of touch and hearing simultaneously allow the perception of the texture of food and drinks. The mouth and the hand can provide tactile information about the food.

Density is an important physical attribute of food, perceptible in drinks. It can be perceived through the sense of touch by the mouth of who is consuming the drink.

·        Flavor

The flavor is the mixed experience of olfactory, gustatory, and tactile sensations perceived during tasting.

Pungency is the term used for the sensation of pain caused, for example, by the carbon dioxide in carbonated beverages or when smelling acetic acid (2 to 5%). The sensation of hot or cold can also be caused by substances such as alcohol (hot).

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Methods used in sensory analysis

1 - Is the product accepted by consumers? What is the consumer’s preference? g affective tests

2 - Is there a perceptible difference between the test product and any similar conventional product? g discrimination tests

3 - What are the main points of difference? What sensory qualities are present? How intense are they? g descriptive tests

According to certain works, the tests can be broken down into:

-       Analytic: include descriptive and discrimination tests;

-       Affective: acceptance and preference

tests.

Taster selection and training

There must always be two types of tasters in order to perform sensory analysis: trained and untrained. In analytic tests, tasters are used as instruments, so there is no need to train them. However, trained tasters cannot be used in affective tests.

In the MEBAK method for beer tasting training, a large number of trained testers – between 10 and 20 people – is necessary for tasting with analytic quality.

During selection, the candidates interested in being part of the sensory team are trained and tested in their ability to identify:

·        carbonated water (with carbon dioxide);

·        beer sweetened with cane sugar, as well as with iso-alpha acid;

·        beer with added bitterness;

·        beer without any additions (blank sample).

The screening and training period is three consecutive days, during which each trainee is given basic knowledge and then has their competence in recognizing flavor attributes assessed.

Those who achieve 75% or above in those tests (duo-trio) and at least 50% in the triangle test are best suited for sensory analysis. After receiving certification, the tasters receive further training in beer off‑flavors, which are in total 47 different types. These off-flavors are commonly available for purchase in capsules.

Laboratory

√ It must have uniform natural lighting;

√ It must have white or light-colored walls;

√ It must be located in a noise- and odor-free location;

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√ The sample preparation area must follow the general guidelines for the food production area.

Booths

Booths are key elements: they prevent the tasters from communicating with each other and, therefore, potentially influencing the results.

• They must have a signal light for

communication between taster and supervisor;

• They must have green- or red-colored light (colored lights can mask visual differences between products);

• They must be individual, isolating the tasters from one another;

• The walls must be a light, neutral color.

Tasting preparation

• Wash the glasses using neutral detergent;

• On the night before the test, store the beer bottles to be analyzed at the temperature of the sensory analysis. Ideally, that storing temperature should be a little colder, in order to prevent the samples from reaching a temperature out of the desired range during preparation.

     

sensory Tests used for BEER assessment

Difference or discrimination tests

Triangle, duo-trio, paired-comparison, ranking

Triangle test

2 samples are similar and 1 is different

Detects small differences

Does not evaluate degree/intensity

Globally assesses the product

Duo-trio test

1 reference sample and 2 test samples

Note: One of the samples is similar to the reference and the other one is different

Check if there is global difference

Reference is presented so as to avoid confusion

Very little intense characteristics, difficult perception

Does not evaluate degree/intensity

Paired-comparison test

One- and two-tailed

One-tailed

2 samples served together

2 samples differ in one specific attribute

Attribute identification after presenting reference samples

Measures intensity

Two-tailed

2 samples served together

2 samples differ in one specific attribute

It is unknown which sample presents higher intensity of evaluated attribute

Ranking test

3 or more samples

This test allows comparison of 3 or more samples regarding attributes like bitterness, color, sweetness, acidity etc.

Measures intensity

Preference test

Paired preference, preference ranking

Paired preference test

2 samples

Follows the same principle as paired-comparison test

Rank sum for the sample is indicated

If preference is greater or equal to the minimum table value, there is significant preference in the sample

Preference ranking test

Test with 3 or more samples

Follows the same principle as the ranking test

The assessor receives 3 or more samples, and must evaluate and rank them in increasing or decreasing order

• The tasters must be provided with a pen and a form so they can record their results.

Testing procedure

√ The tasting panel should preferably take place between 10 o’clock and noon, in an odor-free testing room with natural lighting, at a temperature of 20°C;

√ The tasters should not be allowed to communicate or even look at each other’s facial expressions, in order to avoid influencing each other’s responses.

Some types of off-flavors found in beers

Chlorophenols – They are produced when the water used in the process has chlorine, normally because the chlorine removal process is not active (activated carbon filter). Chlorophenols give the beer a medicinal flavor.

Lightstruck – It occurs when the beer is exposed to ultraviolet rays during bottling. A lightstruck beer has an aroma and flavor reminiscent of sweat.

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Dimethyl sulfides (DMS) – Normally they are produced when the wort is not boiled, or due to bacteria or yeast autolysis. Dimethyl sulfides give the beer an aroma reminiscent of egg or cooked vegetables.

Butyric acid – Bacteria produce it during wort production or storage of sugar syrup. The beer ends up with taste and aroma reminiscent of baby vomit.

Mercaptans – They are produced mostly at the onset of fermentation by the yeast, as well as when the yeast autolyzes during maturation. Mercaptans give the beer a drain-like aroma and taste.

Acetic acid – Formed during fermentation, it can be produced in the brewery through contamination of the beer by acetic acid bacteria (Acetobacter). The beer takes on a taste and aroma reminiscent of vinegar.

Michael Trommer

www.portalsaberdacerveja.com.br

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Michael Trommer

Michael Trommer, descendente de pais alemães que vieram para colonização do norte do Paraná e posteriormente migraram para São Paulo.

Com 28 anos de experiência profissional na área de bebidas (cervejas e sucos). Contudo, sua maior atuação foi na indústria cervejeira, onde atuou na área de produção, laboratório, desenvolvimento de produtos maltados e não maltados, padronização de processos (sistema da qualidade) e implantação de manutenção preventiva e preditiva. Presta serviços para empresas de pequeno, médio e grande porte do segmento de bebidas.

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