Creation of oral care flavours to deliver breath-freshening benefits.

OBJECTIVE: Oral care products deliver breath freshening primarily via mechano-chemical cleaning or by antimicrobial active systems. Dental flavours provide taste benefits, and freshen breath mainly by sensorial masking. We aimed to determine whether flavours could deliver breath freshening in products by inhibiting bacterial volatile sulphide compound (VSC) production. SUBJECTS AND METHODS: Flavour materials were screened for inhibition of hydrogen sulphide formation by Klebsiella pneumoniae in vitro, grouped by efficacy, and data provided to flavourists. Flavours were formulated to maximize the content of VSC-effective ingredients and re-screened to confirm performance. Extensive, iterative testing of flavours identified reliable creative rules to deliver efficient inhibition of H2S generation. Breath-freshening flavours in whole products were then tested in-house in a 'breath freshness panel'. MAIN OUTCOME MEASURES: Malodour of panellists (not preselected for malodour score) was scored before and after product use, on the 'Rosenberg' 0-5 scale, together with residual flavour score, by extensively trained judges. Products were tested in double-blind, crossover studies, and results analysed using ANOVA. RESULTS AND CONCLUSIONS: Products flavoured using these rules delivered significantly greater breath freshening at 2 h than control products, and equivalent benefits to products containing 0.1% (w/w) triclosan or 0.2% (w/w) zinc sulphate.

Perfume interactions with sodium dodecyl sulphate solutions.

Synopsis Vapour phase concentrations of aroma chemicals above a model shampoo system containing sodium dodecyl sulphate (SDS) have been measured using headspace gc methodology. It was shown that, to a first approximation, headspace concentrations were directly related to the phase volumes ratio (water/SDS), and that this could be rationalized in terms of simple partitioning. The headspace behaviour of the same materials dissolved in water and in diethyl phthalate was also investigated with a view to understanding the effect of the medium on the perfume 'profile'. The octanol/water partition coefficient was identified as a potentially useful parameter in this connection. Since the phase structures of the surfactant systems were not known, the results for all the materials were expressed in terms of 'apparent activity coefficients', calculated from headspace concentrations and mole fractions. It was found that, to a first approximation, the headspace concentration of benzyl acetate above these surfactant systems was directly proportional to the phase volumes ratio (water/SDS), and that this could be rationalized in terms of a simple partition model. It was clear, however, that a more sophisticated model would require data on the surfactant/perfume component interaction in the absence of water-such data could be more conveniently obtained using liquid analogues of SDS.

Insight into how skin changes perfume.

Synopsis Overall consumer perception of personal products such as colognes, deodorants, talc, and soap is often strongly influenced by the presence and nature of the fragrance incorporated into these products, which is also true for the corresponding olfactory characteristics of skin during and after application. Although extensive research has been carried out to define the morphology and characteristics of living skin, relatively little is known about the physical or (bio)chemical behaviour of perfume once deposited onto skin. It is widely acknowledged that some perfumes may perform very differently on different skins, but little definitive information is available to elucidate the associated mechanism(s). Rationalization of this may necessitate understanding both the physical and the chemical interactions between perfume and skin. To assist studies in this area, techniques based on headspace analysis and solvent swabbing have been developed to monitor fragrance concentrations on and above skin in use. Using these techniques, we have carried out some initial exploration into the physical and chemical interactions between skin and perfume. (a) Physical interactions: differences in perfume behaviour when on skin and when on a relatively inert surface (vitreous tile) were quantified to build up at least a qualitative idea of the importance of physical interactions between skin and perfume. (b) Chemical interactions: the potential for skin-mediated chemical transformation of perfume was examined across a wide range of functional groups relevant to perfumes, but was found to be low under 'non-forcing'conditions (i.e. clean dry skin). However, some evidence has been found for changes in perfume ingredients in the underarm, probably arising from microbially catalysed reactions. It is envisaged that it may be possible to harness such transformations usefully - for example, to deliver unusual fragrance effects or enhance fragrance longevity. In addition, product-mediated transformation on skin is feasible, and a specific case has been investigated based on the pH sensitivity of citral acetalization.