October 2019 Spray 33
pumps, increasing the pressure means decreasing the piston
diameter of the pump or it can mean decreasing the size of the
hole by placing an insert, which is a part attached to the actuator.
Sometimes a laser is used to make such a small and accurate
hole.
Either way, one has to apply more pressure without breaking
the piston (or one’s finger) to make the particle come out as
small as possible through the narrow hole of the actuator. Commercially
viable technology can generate, on average, particles
of 80 to 150 microns in size. This is ideal for the application of
perfumes and cleansers where two to three intermittent applications
will satisfy consumer demand very well.
Aerosols also have this same partitioning mechanism present
in Bag-on-Valve (BOV) dispensers without having gas mixed with
the formulations. The pressure of the propellant outside the bag
causes the bulk to reach the actuator orifice in a non-intermittent
and continuous spray.
Thermodynamic partitioning
During the vaporization of liquefied propellant molecules
solubilized in the bulk—when a temperature drop due to the
adiabatic process changes the propellant from the liquid phase
to the vapor phase—the propellant drags fragments of this same
micronized bulk, producing even smaller particles than those
already produced in the actuator by mechanical partitioning. For
lack of a better term, I teach this in Brazil as “thermodynamic
partitioning.” Thank you in advance to readers who can suggest
a better name for this phenomenon.
State-of-the-art dispensing
What exists today to dispense salt?
1. Reach into a container and take out a small amount to
apply on a food’s surface. Rub by hand to reduce the bulk
layer thickness in order to spread the best one can.
Technology: 8,000 BC or older
2. Make an O/W emulsion, coating the active lipophilic
with a large amount of water. Until now, water has been
the cheapest and most environmentally acceptable solvent.
The active is spread/sprayed intermittently on a surface.
The water needs to dry so that the salt can come in
contact with the surface.
3. Spray using an aerosol container, producing smaller
particles that are easier to spread. The propellant vaporizes
almost immediately and allows a more optimal application
of the active. Once micropulverization is obtained, it is
much easier to dispense nanoparticles from well-formed
microparticles.
Obviously, there are many other variables to consider, but more
generally it turns out that a good micronization serves as the
vehicle for smaller gauge particles.
This convergence of ideas (salt + aerosol dispenser) resulted in
a very fruitful historical encounter—my association and subsequent
friendship with Dr. Eduardo Caritá,
who already worked with nanoparticles in
the food sector. Together in his laboratory
at FunctionalMikron in Valinhos and in my
lab at AeroService in Campo Limpo Paulista,
we started aerosol salt testing in 2013. This
resulted in horrible valve cloggings, achieving
stability only in 2016. For the purposes of
intellectual property security, we created the
patent for NanoSal aerosol nanosalt, along
with visionary marketer Jose Luiz de Paula.
There was a pre-launch of NanoSal planned
Dr. Eduardo Carita
for 2016, but it was interrupted because there was no applicable
regulation issued by the Brazilian Ministry of Health and the
product was considered “disruptive technology” in the aerosol
food sector. The product was far too innovative for our government.
Incongruently, Brazil allows the importation of thematic food
oils with hydrocarbons, but does not have legislation authorizing
local manufacture. The regulatory work to change this is already
underway through the Brazilian Aerosol Association (ABAS),
where I currently occupy the post of VP.
Curiously, without our prior knowledge, a sample of a commercial
batch of NanoSal was submitted to the Paris Aerosol &
Dispensing Forum (ADF) by our aluminum can supplier Tubex—
and to our surprise—it won the ADF Food Innovation Award
in January 2017. We are very grateful to the initiative of Dr.
Leopold Werdich of Tubex (also the President of International
Organization of Aluminum Aerosol Container Manufacturers
AEROBAL) and the support of Dr. Hugo Chaluleu, President
of both ABAS and the Latin American Aerosol Federation
(FLADA).
We still use an 8,000-year-old technology to process table salt to a particle
size suitable for human consumption.