An Israeli company has become famous and made millions of dollars around the
world with its liquid-carbonating device. But new research from the Monell
Chemical Senses Center in Philadelphia has shown that bubbles are not necessary
for the unique “bite” of carbonated beverages. Bubbles do, however, enhance
carbonation’s bite through the light feel of the bubbles picked up by our sense
The refreshing bite of carbonation is an integral part of
beverages consumed around the globe. Carbonated beverages are produced when
carbon dioxide is dissolved in a liquid, typically under high
This can happen naturally in certain spring waters or in
fermented beverages like beer. Carbon dioxide also can be added to beverages
through production processes.
In either case, when pressure is reduced by
opening a bottle or can of a carbonated beverage, some of the carbon dioxide is
released from the solution in the form of bubbles. After a sip, enzymes in the
mouth convert the remaining free carbon dioxide into carbonic acid. The acid
then activates sensory nerve endings, which signal the mild irritation that we
refer to as “bite.”
In the study, published in the journal PLoS One the
Monell researchers examined the role that bubbles play in carbonation bite. In
the first experiment, they took advantage of the fact that bubbles cannot form
when atmospheric pressure is raised above a certain level. Twelve healthy adults
were comfortably seated in a hyperbaric chamber and asked to rate the bite
intensity of several concentrations of carbonated water. The ratings were
collected once while under normal atmospheric pressure (with bubbles) and a
second time at higher pressure (no bubbles), equivalent to diving to a depth of
10 meters in sea water.
There was no difference in the bite reported in
the two conditions, even though bubbles are physically unable to form at the
“Because the subjects experienced the same bite when
bubbles weren’t present, the findings clearly told us that carbonation bite is
an acidic chemical sensation rather than a purely physical, tactile one,” said
study author Dr. Bruce Byant, a sensory biologist at Monell.
bubbles aren’t necessary for bite, they still could be contributing to the
overall sensation of carbonation.
Thus, a second experiment was designed
to address this possibility. In this experiment, 11 adults rated the intensity
of bite in a laboratory setting.
The ratings were made for carbonated
water under normal conditions and again when additional air bubbles were added
to the liquid. The researchers were surprised to find that air bubbles enhanced
the bite of the carbonated bubbles, presumably by stimulating the sense of
touch. “We thought the touch of the bubbles would suppress the painful aspects
of carbonation, much as itching a mosquito bite or rubbing a sore muscle does,”
Together, the studies reveal that carbon dioxide bubbles are
not directly responsible for the bite of carbonation. However, by stimulating
the sense of touch inside the mouth, bubbles do enhance the bite sensation
beyond the chemical irritation caused by carbonic acid. “Pain from some cancers
also depends on acid formation in tissue,” noted study lead author Dr. Paul M.
Wise, a sensory psychologist at Monell.
“Because the bite from
carbonation can be considered to be a mild type of pain, the fact that pain
intensity can be enhanced via the sense of touch may have implications for
understanding these types of cancer pain.”
Plant lovers who take long vacations usually worry over how their
green friends will be able to survive in their absence – unless they can have a
friend come over periodically to water them. Now students at the Shenkar College
of Engineering and Design in Ramat Gan have developed a device that uses solar
energy to irrigate plants. Amit Rothheiser and Erez Kaganovsky, advised by Dr.
Ofer Schwartzgals, said the device gives houseplants just enough water, not too
much or too little.
The flower pot, when standing on a balcony or next to
a sunny window, is “energetically independent,” meaning that it obtains all the
energy it needs to operate it from the environment, and is also mobile so it can
be placed anywhere in the home or outdoors without having to be connected to a
Every pot has two sides, one containing the plant and the
other containing a large amount of water. The reservoir is able to release the
necessary amount according to whether the sensors detect if the soil is moist or
As the device can save time when residents are at home as well, it
turns on a red light at the base when there is no more water so it can be
refilled. Besides an opaque-pot version, the designers also made one with glass
walls and LED lights.