Frost & Sullivan Market Insight   Published: 15 Mar 2002
Can We Trust Organoleptic Testing?
Date Published: 15 Mar 2002
by Ivan Fernandez

Without being aware of it, consumers have always practiced organoleptic testing by sniffing out rotten fish, spotting mold on stale bread, or by rejecting overripe fruit that has gone soft to the touch. In an age of computerized data analysis and sophisticated diagnostic tools, the human senses still remain the first tools that consumers use to test the acceptability, or otherwise, of food. But there is growing unease over the fact that the same kind of sensory evaluation is practiced extensively even by professionals such as food researchers, manufacturers, and regulators. Is this suspicion of an age-old testing approach valid? The series of recent food-safety scares across the globe increases the relevance and immediacy of this question.
The drive toward the standardization of sensory evaluation of food came primarily from the need to grade agri-food commodities such as coffee and tea, and other foods such as oils, meats, fish, and so on. This led to the development of professional tasters, inspectors, and consultants. Organoleptic testing - as practiced in the food industry today - involves trained inspectors who assess food on the basis of taste, odor, color, texture, and appearance.
Among the major types of organoleptic testing used are:
  • Difference testing, which identifies differences from one sample to another
  • Sensitivity testing, which assesses stimulus-response dynamics
  • Preference testing, which involves ‘like’ or ‘dislike’ feedback in relation to the sample
  • Descriptive testing, which dwells on rated characteristics
Fortunately for consumers, the organoleptic approach is not as imprecise as they assume it to be. Take for instance, the inspection of meat in a slaughter house. Trained veterinarians look for an amazing number of signs of disease or contamination. These include abscesses, inflammation or suppuration, bruising, swelling, emaciation, discoloration, lesions, abnormal odor, urine and fecal contamination, blisters, faulty dressing procedures, improper bleeding procedures, dermatitis, contamination through oils, gases, toxins, adhesions, and specific symptoms related to specific diseases. The thorough examination also involves incisions and examination of internal organs for signs of disease. Their conclusions could lead to trimming of affected portions to salvage as much meat as possible without health risks, or outright rejection of the carcass.
For the organoleptic testing of food ingredients, other parameters such as color, flavor, and mouthfeel are used.
Training in Sensory Evaluation
Whatever the parameters, it is crucial that only trained and experienced investigators perform this form of testing. For instance, training an investigator for the freshness parameter would involve complete familiarization with the food in its most desired state - fresh, uncontaminated, and with the most desirable qualities - followed by familiarization with a range of samples at diminishing stages of freshness. The point where the food sample shows the first signs of decomposition is when a judgement call must be made to reject it. This simulated decomposition under controlled circumstances trains investigators to associate sensory data with specific stages of freshness, and to reach a greater level of certainty as to when food is unacceptable for consumption. This helps refine their evaluation and scoring. New statistical tools and sophisticated computer software make analysis of the scoring data much easier and more consistent today.
The legendary skill of expert wine tasters is perhaps the most romanticized of all organoleptic testing experiences, but behind the hype there is substantial grounding in technique and experience. It is possible for master wine tasters to not only ascertain the variety, quality, and maturity of the wine, but by sensing the sweetness, clarity, intensity of aroma, flavor, color, and ripeness, they can accurately unmask the development of the wine, its connection with similar wines, the growing season it came from, and the style or approach of the winemaker.
The Drawbacks
Despite the exhaustive training inputs, the confidence that comes from experience, and the support of computer software, serious reservations persist over organoleptic testing. Some of these are:
  • Inconsistencies in evaluation: Human beings differ widely in their assessment of what is considered acceptable. This is aggravated by varying degrees of sensitivity of inspectors to tastes, appearances, textures, and odors depending on their moods, health, level of hunger or fatigue, concentration, and so on. In fact, differences in cultural backgrounds or nationalities of inspectors have also been known to introduce a bias that cannot be accounted for otherwise.
  • Chemical differences not always apparent: Chemically dissimilar products may give off the same odor, or may even look similar.
  • Microbial contamination not always apparent: For instance, e-coli and salmonella contamination may elude sensory detection
  • Lack of specificity when assimilating sensory data: Stimuli such as heat, cooling, astringency, spice, and so on, may sometimes cloud the perception of smell or taste.
  • A high dependence on the context and ambience: Background odors, surface odors, or even the packaging used, which are totally unrelated to the food’s inherent characteristics, may confuse inspectors.
  • Influences of one sensory perception over the other: Color differences affect the perception of taste of foods. Unless foolproof masking of colors is done by mandatory infrastructure for manipulation of illumination, the perception of taste may suffer a bias.
  • Deadening of the senses: The human body accustoms itself rapidly to any new sensory data. Therefore, prolonged exposure to stimuli may not register as intensely with the inspector, as the body has already made perceptual adjustments.
  • Tasting limitations: Raw, unprocessed food such as meat and fish, cannot be tasted by inspectors because of the health risk it poses to them.
The Verdict
These reservations are driving some researchers toward the development of devices such as aroma scans and e-tongues, which use sensor arrays to perform the same olfactory and taste analysis, but with the specificity and uniformity which only machines can guarantee. Most of these projects are still far too limited for widespread acceptance in the food industry. The ideal solution would be to use organoleptic testing as one component of a more comprehensive arsenal of tests including chromatography, infrared spectroscopy, microanalysis, microbiological testing, pH testing, moisture and viscosity testing, mold and yeast testing, particle-size testing and so on. Thus, data from organoleptic tests would serve to validate or clarify the findings of other tests.
In all probability, organoleptic testing may never be fully abandoned. After all, despite the several drawbacks, it has its advantages. It is an inexpensive testing method requiring none of the large investments that chemical or microbial testing entail. Conclusions are arrived at rapidly. And most importantly, the assessment instruments - human beings - are readily available. However, the danger of using this method in isolation must be recognized. Only then can the food industry consistently deliver on its crucial promises of food quality and safety.