Sweating is an essential process to maintain the human body at an optimal temperature. Nevertheless, even with a good body hygiene, sweating may induce two major inconveniences during the day: wet sensation and malodor. Excessive sweat can be induced by different parameters such as high environmental temperature or stress. Malodor is a consequence of the action of bacteria, particularly at the vicinity of the apocrine glands, in the armpits area by example. In fact, these bacteria contribute to the transformation of sweat long-chain components into smaller volatile unpleasant smelling molecules.
That is why, a deodorant development strategy should be oriented through at least 3 main axes: humidity sorption, bactericidal action and malodor coverage with fragrances.
Deodorant efficacy is commonly assessed in vivo by standard gravimetric and sniff tests.
But for an optimal ingredient combination, many ingredients must be tested during the formulation process.
We developed several screening tests (from the simplest to breakthrough technologies) to support the selection of efficient ingredients before running in vivo testing.

On the one hand, humidity sorption and desorption studies were conducted on several powders by quantifying the maximal amount of liquid absorbed by powder before saturation and gravimetry respectively, leading to a first classification.
Selected powders were studied using Environmental Scanning Electron Microscopy (ESEM). Electron microscopy permitted the characterization of individualized particles, while the Environmental mode allowed to control the relative humidity inside the microscope chamber. Thus, the evolution of particles during hydration and dehydration processes were followed in real time.

On the other side, sweat odor was analyzed using an electronic nose technology. This method is based on biochemical sensors and surface plasmon resonance imaging technology in order to detect the volatile organic compounds.
We collected and analyzed sweat samples of volunteers after physical effort for initial characterization and evolution after bacterial action.
Results showed common characteristics in the evolution of the olfactive profile for all the samples. Intensity of sweat signal increased in time for specific sensors.
We were able to assess the efficiency of fragrances in masking odor by activating new sensors, generating a new odor.
Furthermore, the presence of ingredients reducing the bacteria growth reduced the intensity of olfactive sweat signal.
Ingredients selected with these technologies were introduced in deodorant formulations at different percentages and proposed to volunteer for appreciation, in terms of wet sensation and odor during the day.

In this work we propose a step by step approach using screening efficacy assessments on essential actions of a deodorant product.
We classified absorption capacity of powder to select the best ones. Thanks to the ESEM real-time monitoring technology, we are clearly able to visualize and understand the behavior of powders in terms of humidity sorption and desorption capacities
The electronic nose technology opens a new way of body odor assessment. It allowed us to measure performance of fragrances in masking odor, or the impact of bactericidal active ingredients on odor development.
This strategy permits the development of a new deodorant including a technical screening approach before in vivo efficacy testing.