Abstract
Up to 40% of produce in the UK is wasted every year, due to blemishes that are often caused by oxidation. The unwanted produce is either composted or used for animal food when the blemishes could have been easily prevented. Simply soaking the produce in common household solutions can help to slow down the enzymatic browning process, allowing for more physically appealing produce. Knowing which solution to use is tricky though. Out of five solutions (lemon juice, orange juice, white vinegar, 1 tbs of salt dissolved in 1 cup of water, and sprite), which will slow down the browning process in apples, pears, and avocados the most? Saltwater inhibits the polyphenol oxidase (browning) enzymes from properly working by limiting it's access to oxygen, significantly slowing the time that it takes for produce to turn brown.
At the start of the experiment, the temperature in the room was set to exactly 19 degrees Celsius; this was maintained throughout the whole experiment. Then, the apples, pears, and avocados were cut into small cubes and then soaked in the five different liquids for two seconds. One cube of each fruit was not submerged into any liquid, as it was used as a control group. The fruits were placed on a glass tray and were labeled using small sticky notes in order to differentiate the different liquids. The cubes were compared to a brown colour chart five minutes, thirty minutes, one hour, two hours, and six hours into the experiment, in order to analyze the level of oxidation. This was repeated two more times, on different days, and labeled as trial two and trial three.
Both the salt water solution and the lemon juice solution had the most effective results in the slowing of the enzymatic browning process in apples. All of the other liquids created a gradual increase in the brown shade throughout the experiment, but the lemon juice and the salt water completely stopped the browning process until the six-hour mark. This is because the lemon juice significantly lowered the pH level of the apple cubes, which interfered with the polyphenol oxidase enzymes, and the chloride ions in the salt also interfered with the browning enzymes. The water also limited the enzymes access to oxygen, which slowed down the oxidation process. These results were mimicked in the pears and the avocados, with lemon juice and salt water being the most effective in slowing browning. Surprisingly, the avocados only slightly browned until the six-hour mark. At that point, the avocados went as high as thirteen on the colour scale, making it the darkest fruit that was tested on. This is due to the large amounts of polyphenol oxidase enzymes present in avocados.
The results of the experiment supported the hypothesis, in which it showed that salt water was superior to the other solutions, in slowing the oxidation of apples, pears, and avocados. It also showed that lemon juice is effective in slowing the oxidation process, but not as much a salt water.
At the start of the experiment, the temperature in the room was set to exactly 19 degrees Celsius; this was maintained throughout the whole experiment. Then, the apples, pears, and avocados were cut into small cubes and then soaked in the five different liquids for two seconds. One cube of each fruit was not submerged into any liquid, as it was used as a control group. The fruits were placed on a glass tray and were labeled using small sticky notes in order to differentiate the different liquids. The cubes were compared to a brown colour chart five minutes, thirty minutes, one hour, two hours, and six hours into the experiment, in order to analyze the level of oxidation. This was repeated two more times, on different days, and labeled as trial two and trial three.
Both the salt water solution and the lemon juice solution had the most effective results in the slowing of the enzymatic browning process in apples. All of the other liquids created a gradual increase in the brown shade throughout the experiment, but the lemon juice and the salt water completely stopped the browning process until the six-hour mark. This is because the lemon juice significantly lowered the pH level of the apple cubes, which interfered with the polyphenol oxidase enzymes, and the chloride ions in the salt also interfered with the browning enzymes. The water also limited the enzymes access to oxygen, which slowed down the oxidation process. These results were mimicked in the pears and the avocados, with lemon juice and salt water being the most effective in slowing browning. Surprisingly, the avocados only slightly browned until the six-hour mark. At that point, the avocados went as high as thirteen on the colour scale, making it the darkest fruit that was tested on. This is due to the large amounts of polyphenol oxidase enzymes present in avocados.
The results of the experiment supported the hypothesis, in which it showed that salt water was superior to the other solutions, in slowing the oxidation of apples, pears, and avocados. It also showed that lemon juice is effective in slowing the oxidation process, but not as much a salt water.