A novel Device for the Study of Antimicrobial Activity by Vapor-Contact of Volatile Substances on Food Products

A novel device for the study of antimicrobial activity by vapor contact of volatile substances have been
designed. This "big size" system, made up in inert acrylic material, is furnished with a fan and an hot plate
with the aim to have a quick evaporation of volatile substances. It is able to contain fruits or other food
products under controlled atmosphere and it can simulate real condition of storage or as well real
condition of food pretreatment by antimicrobial volatile substances. Such system is suitable to perform
both in vitro (disk diffusion test) and in vivo (exposure and testing of food products) experiments. To shed
light on the behavior of this chamber the concentration in the head space of several substances have been
monitored by GC-MS analysis during the time. Both single (monoterpene compounds) and mixture of
terpenoids have been studied.
Different behaviors have been founds depending on the starting molecules studied. limonene, myrcene
and eucalyptol, in single standard experiment, show a similar shape of head space concentration curve
versus the time: the concentration increases at the beginning, then reaches a maximum and decreases
until it reaches a plateau. In contrast linalool shows an head space concentration curve constant during
the time, whereas mixtures of terpenes like myrcene and linalool show a concentration curve of vapor
phase in agreement with Raloult’s Law. The experiments carried out with Essential Oils (EOs) shows that
in our system only more volatile fraction of EOs compose the vapor phase.