Avocado's Number

Trying to find Avocado’s number

Mini-experiment 2:  Polyphenol oxidase activity in avocado

Background:  Guacamole has always been a top party favorite for picnics, family gatherings, or summer time get togethers.  Although it usually goes pretty quick, if guacamole is left out it begins to change.  An enzyme referred to as polyphenol oxidase begins a process called melanoidin.  This is triggered by contact with the atmosphere; it begins to turn brown.  Interestingly, it is only outside layer in contact with the air that begins melanoidin.  This is similar to the process with apples when they begin to brown.  There is an age old tradition that leaving the pit of the avocado in the guacamole will slow this process.  According to the Huffington Post, avocados are actually a berry and are one of the few high-protein fruits.  With its rich content of monounsaturated fat, it can actually substitute for butter in baking as well.  Although they are rich fruits, they are known to deteriorate quickly.  This was the inspiration for my mini-experiment, as our big project aims to investigate the properties of avocado to determine what will help naturally preserve the fruit a little longer.  Hopefully it will help our guacamole recipe!

Hypothesis: The seed will slow the melanoidin process in avocado compared to avocado without seed

Null hypothesis: There will not be a difference in melanoidin between avocados with the pit compared to without the pit

Independent variable: Avocado with seed in it/avocado without seed

Dependent variable: Melanoidin level

I will standardize:

-          Browning time

-          Amount of avocado (1 – two halves compared)

-          State of avocado

o   In halves (3 hours)

o   Mashed

Results

Avocado after three hours

Avocado before picture

Avocado this morning -- 18 hours from initial, 15 hours since mashed

Avocado 8 hours from initial, 5 hours after being mashed (seed on left)

The possible limitations included ripeness of the fruit, the physical state of the fruit, and the halves might not have been exactly cut into equal weighing pieces.  The limitation of the physical state of the fruit was that after three hours avocados were mashed to hopefully speed up the process.  Also it seemed to make more sense if the avocado was tested in the state that it would be in guacamole.

Discussion

The null hypothesis was accepted in this experiment as neither half of the avocado browned faster than the other.  The avocados did not deteriorate very much at all actually; as you can see by the photos, even after 8 hours the avocados still had not changed significantly as was anticipated.  The avocado was bought right before the beginning of testing and colleagues questioned the ripeness of them.  After three hours, the avocado had not deteriorated very much so it was mashed up as if to be preparing guacamole to test whether the physical state of the fruit would catalyze polyphenol oxidase.  After 5 more hours, the avocado still had not browned very significantly.  This morning, it was clear that the melanoidin level had advanced 18 hours after the initial split and 15 hours after being mashed.    

This mini-experiment relates to the final project because we aim to investigate the properties of avocados in order to try and determine a quality natural preservative to include in guacamole recipes.  My partners Tim, Tom, and Alejandro all examined different mediums of possible preservatives including concealing the fruit, adding lemon juice, and sprinkling salt and pepper over the avocado.  Although we did not receive great results from the experiment, we hope to utilize what we learned and continue to research moving forward.  

References

http://desigrub.com/tag/avoid-browning-avocado/

http://www.huffingtonpost.com/2013/08/22/avocado-health-facts-didnt-dont-know_n_3786419.html