time you cut a pineapple, chances are you tossed the peel in the trash. After
all, what else would you do with it?
in Malaysia have discovered you can turn it into bio-fuel.
The team of
scientists used Minitab Statistical Software to study ethanol fermentation with
pineapple trimmings. Their findings suggest that pineapple waste could provide
an alternative to traditional bio-fuel production methods.
produced during the fermentation process when yeast converts sugar into energy.
It can be used as fuel, and is commonly found in beer, wine, and bread.
research team worked with Pineapple Estate—a plantation in Johor, Malaysia with
over 1.1 million acres of land planted with pineapples—to study ethanol production
using the plantation’s discarded pineapple peels.
accomplish this, the researchers needed to devise an experiment to assess the
influence of several variables on ethanol production, while using the lowest
possible number of experimental trials.
where Minitab Statistical Software comes in.
Minitab, the team applied a statistical technique called response surface
methodology (RSM) to assess the interactions between multiple variables—pineapple
peel concentration, pH level, sugar concentration, temperature, and fermentation
time—and their impact on the response variable, ethanol concentration.
researchers set low and high values to create a range for each of the five
input variables. Within each range, the variables were assigned five different
levels to use for their central composite design—a commonly used experimental
design in RSM.
experiment allowed the team to measure the effect of each factor on the ethanol
concentration level and to examine the interactions between the factors with
the fewest experimental runs—saving time, glassware, chemicals, and labor.
calculations involved in RSM can be complicated, but Minitab creates contour
plots that make it easy to visualize input settings for multiple factors
simultaneously and consider how they affect the response.
example, in the contour plot below, the third darkest green region shows where
sugar concentration and temperature can be set to optimize ethanol production
during fermentation, given pineapple peel concentration and pH level are fixed
at the highest levels of their defined ranges—14% and 6, respectively—and
fermentation time is fixed at 30 minutes, its lowest level.
team’s analysis using Minitab’s response optimizer showed the optimal ethanol
concentration of 8.637% is produced when the sugar concentration is 22°Brix,
the temperature is 26°C, Peel% is 14%, pH is 6, and the fermentation is 30
hours. These settings, combined with the naturally high content of fermentable
sugars in pineapple peels, produced ethanol with an alcohol content of 0.21%,
compared to ethanol produced under similar conditions from banana waste, which
had an alcohol content of 0.035%.
Statistical Software made it easy for the researchers to design their
experiment, analyze their data, and understand and visualize their results.
of this research suggest there is a benefit to salvaging the more than 550,000
tons of fruit peels produced at Pineapple Estate, and could have implications
for producing fuel from other fruit wastes.
This story was adapted from an article
published by the World Academy of Science, Engineering and Technology
in December 2012.