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Only the nose knows

Literature suggests that the human nose can detect at least 1 trillion different odors! Incredible! We took this amazing number for a reason to have a closer look at 'the noses' at SGS proderm and our studies with deodorants and antiperspirants. Therefore we conducted an interview with Frederike Falk, Study Site Manger Elmshorn and Marianne Brandt, COO, who both have extensive experience with these kinds of studies. They happily answered a number of questions from the editorial team.

Welcome Frederike and Marianne. How can one assess the efficacy of deodorants and antiperspirants?

FREDERIKE: Well, we either measure the efficacy in terms of odor reduction or in terms of sweat reduction. 

MARIANNE: In order to determine the amount of sweat, we perform gravimetrical measurements following sweat induction under standardized conditions, for example in our hot room, which we perform according to FDA and Clearcast guidelines. The sweat from the armpit is collected with a cotton pad which is then weighed. The amount of sweat produced is then compared to the baseline as well as to a control. We also offer ATS (AntiTranspirant Screening), which is performed on the subject's back and up to 8 formulations can be tested at one time. In this case, sweating is induced in the sauna.

Oh so we ask the participants to sit in a sauna to induce sweating! I was wondering whether we asked subjects do exercise or not, but the sauna is much more relaxed.

MARIANNE: Yes the participants sit in the sauna for 15-20 minutes, but there are also other ways to induce sweating; it depends on what the customer is looking for. There are different types of sweating resulting from different metabolic situations! For example we can induce sweating passively via the sauna or hot room, as well as actively over a period of time on a cross trainer or exercise bike. We once carried out a study in which the customer wanted to investigate the efficacy of their product against stress related sweating.

A stress test! How do you go about that?

MARIANNE: We had a psychologist come in and interview our subjects with emotive questions. This worked really well!

I always wondered why we sweat when we're stressed; perhaps there is an evolutionary link between survival and smell! Apropos malodor, what about the smelly aspect of sweat, how do you measure body odor?

MARIANNE: Our standard is the axilla deodorant test. This is performed by our odor judges, who also go by the unofficial term of 'Sniffers'; they perform 'sniff tests' (or odor intensity evaluation) by smelling the subject's armpit and rating the intensity of the odor. We have 2 approaches to the odor rating: an analogue scale which is a bit easier for the judges to use, they just judge if in comparison to the untreated area – or, alternatively, we use an ordinal scale of 0-5 to categorize the odor intensity in one step, which requires a little more training. However, if you achieve an improvement with your deodorant on the ordinal scale, you can be sure that the consumer in the real world will notice the affect.

FREDERIKE: Yes, and it is important to mention that initially, the noses of the odor judges are tested with isovaleric acid, which is one of the odor causing components of sweat, in order to identify any judge who on the day would not be able to rate the intensity of this component, perhaps due to a cold, and thus would have to be replaced. The judges then smell both armpits before deodorant application and rate this, then the subject applies the test product to one armpit and the judges then perform a second sniff test at each armpit . In this way we can compare treated with untreated before and after product application to assess deodorant efficacy.

So who are these talented individuals who make up our panel of odor judges, can anyone become one?

MARIANNE: Well it's not like anyone can say 'OK today I want to be an odor judge'. Not everyone has the required ability in detecting the intensity of odors.

FREDERIKE: And even if they do, they must undergo regular training. They have to be trained according to a recognized standard. For instance our odor judges are trained once a year and again directly before every study to ensure their noses are calibrated, so to speak.
Our odor judges are trained by Olfasense, which is a company specializing odor measurement and are based in Kiel. An Olfasense trainer will visit us with an Olfactometer and train our judges on site.

And how is this 'odor judge training' performed?

MARIANNE: there are some standard substances, which are close to the those found in actual sweat; and the judges have to smell these and then rate the intensity of the odor according to what they perceive, and then this is compared to what the instrument (Olfactometer) measures. This process is repeated until they are in-line with each other; at the end of the training the judge's rating will match the instrumental measurement. Initially, the sensitivity of the judge's nose is assessed to see if they are suitable for this particular study, i.e. that their sense of smell is sensitive enough in order for them to be able to detect these substances at different intensities.

FREDERIKE: Yes, the sensitivity of the judge's nose is first determined against n-butanol and a panel of other sweat related odors. We find the minimum concentration that can be detected by the judge and then they have to grade the concentrations. Actually this year I had the opportunity to take part in the training and it's really hard, it sounds easy but it's not! Especially the n-butanol is really challenging.

MARIANNE: Though all this training may sound like quite the investment and it certainly brings extra challenges to these studies, it is essential in order to deliver good quality results to our customers.

How easy is it to find odor judges? I can't imagine there are too many people willing to spend their days smelling these… let's say… less than fragrant odors.

FREDERIKE: It is not so easy. Not only do they have to have the desire to do it, they have to have the sensing ability as Marianne said; and they also have to be very flexible because they do not just come in for 5 or 10 minutes, they will be here for up to 4 hours at a time, maybe 3 or 4 days a week; sometimes in the afternoon, sometimes in the morning. And additionally we need very polite and friendly individuals as judges because they are obviously working very closely with the participants of the study.

MARIANNE: Furthermore, as to the natural ability of people to detect different odors so accurately, if you think of perfume developers, they are also very rare. Not that many people have sensitive enough noses for such complicated odor analysis.

So if I am correct the judges smell the armpit directly? Or do we collect the sweat and it's odor in a pad?

FREDERIKE: The judges smell the armpit directly. There is a wall between the subjects and the judges in order to prevent any bias; and there is a small hole in the wall at armpit height through which the judge can smell the armpit.

MARIANNE: There are also other study designs of course, for example if the body odor should be assessed after a certain period of everyday activity a pad can be worn by the subjects to collect the sweat odor and the pad is returned and then placed in a sealed vial so that the judges can come a bit later to evaluate the odor. The training of the judges remains the same. It is just the odor detection or sample preparation method which would be different in this case. This is something we can now offer since becoming part of SGS. Both are valid published methods, but the direct sniffing approach means that one can evaluate what is occurring on the skin. At the end of the day, the direct sniff method is closer to the consumer perception of the product. Nevertheless, both methods deliver valid results for claim substantiation.

What types of studies with sniffers are the most common? Are they only underarm deodorant studies?

MARIANNE: Well, sweat odor assessments are most common, In addition to body odor assessment for deodorant efficacy evaluation, the judges also   can evaluate the perfume component of the test product as an additional parameter, so they must indicate whether they can perceive the perfume and whether they find it pleasant. We also sometimes use odor experts to assess oral or food odor. Both of which obviously require different training than body odor studies. 

And what would be the most unique study which has come your way?

FREDERIKE: Well, a study scheduled for next year will look at incontinence pads and their ability to bind odor. Our odor judges will be involved in that study.

Ok, well I was thinking of perhaps getting my sense of smell tested to see if I have what it takes to become an odor judge, but now I'm going to reconsider. Which gets me thinking - do we always use odor judges for these odor assessment studies or are there also alternative odor detection methods available?

FREDERIKE: For the oral odor studies there is a device that can be used.

MARIANNE: Yes the OralChroma. You take a sample of breath with a syringe which is then injected into the OralChroma, this instrument then detects the different odorous substances. But in general we have not found an alternative method that can reliably replicate what the odor judges can detect. Therefore, when we offer these alternative methods we usually work with odor judges and use both methods to complement each other.

Well it is good to know that humans are not getting replaced by technology in all areas! Many thanks to you both and much respect to our talented odor judges!


Marianne Brandt

Division Manager Cosmetics

Frederike Falk

Group Leader Study Site Elmshorn

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