How To Keep Avocado Fresh After Cutting
Avocados turn brown on oxidization, catalyzed by the enzyme polyphenol oxidase (PPO). Keep cut avocado fresh for 5 days by refrigerating it at 5ºC or with chopped onions, which emit sulfur dioxide that curbs PPO activity. To keep it for 2 days, dab lemon juice on it, then refrigerate. Or if it's just a day, plastic-wrap it or put it in an airtight container in the fridge to cut off air contact.
Avocados are becoming a staple ingredient in the meals of health-conscious individuals. That’s hardly a wonder given this green-skinned fruit with creamy texture and mild flavor is loaded with nutrients, like vitamins and fiber. Whether as guacamole or in milkshakes, whether as part of an elaborate salad or raw with a sprinkling of salt or paprika, most of us love to eat avocados. But what do we do when we require just a slice of the fruit or, at most, one half and want to store the rest?
As avocado lovers, we know that putting it in the refrigerator is not the solution, for it turns brown and slimy the next morning. Why not explore some tips and tricks to keep cut avocado fresh so that we can enjoy a second helping anytime we want?
Why Does Avocado Turn Brown?
The reason avocado flesh browns really quickly when exposed to air is the presence of an enzyme called polyphenol oxidase (PPO) in it.1 Much of the nutritional value of avocado comes from the phenols it contains. But when these phenols come in contact with oxygen, PPO aids their rapid oxidization into quinones, and smaller molecules of quinone join to form a long chain of polymers called polyphenols.
This polymerization manifests itself in the browning of the avocado flesh. And not just avocado, any fruit containing phenols, such as apples, would show such browning. The trick to keeping the fruit fresh is to delay this reaction.
Is It Safe To Eat Browned Avocados?
While it is safe to eat a slightly browned avocado if you don’t mind the bitter flavor or the rancid odor, it is best to just scoop off the brown part and eat the rest of the flesh. However, if the cut fruit has been lying in the open for a long time, you’d better discard it, not so much because of the oxidization but because of the potential growth of bacteria and mold on it.
How To Store A Cut Avocado?
Here are a few ways that will keep avocados fresh for longer.
Store It With Chopped Onions
While this might sound strange to you, refrigerating the cut avocado with chopped onions is by far the most effective technique of maintaining the freshness of a cut avocado. When cut, the onion gives off sulphur dioxide, which is an effective inhibitor of polyphenol oxidase and is widely used to control enzyme-caused browning.2
This method will preserve the fruit for up to five days.
Deep Freeze It At 5ºC
Yet another method is to store the fresh-cut avocado at 5ºC. A study showed that when stored at this temperature, the softening and the darkening of the pulp was lower. This is because low temperature slows down enzyme activity, and 5ºC is low enough to slow down polyphenoloxidase.3
This will give the avocado a shelf life of five days.
Dab It With Lime Juice
Sprinkling or dabbing lime or lemon juice on the exposed area of the fruit ensures freshness for a relatively longer period. A study showed that 90–100 percent PPO inhibition was obtained when apple cubes were dipped in a mixture of ascorbic acid (vitamin C) and citric acid.4 Limes and lemons, being rich in both these acids, could help protect the avocado surface from browning by inhibiting the activity of polyphenol oxidase.
If you apply these juices and refrigerate it, the avocado will stay fresh for at least two days.
Plastic-Wrap It Or Store In An Airtight Box
The chemicals in the avocado pulp react with oxygen, which gives it the brown color. If you minimize its contact with air, you could reduce the oxidization of the fruit. To do this, tightly cover the unused portion with a plastic wrap, making sure to keep out any air bubbles, and refrigerate. Or you could keep the fruit in an airtight container for a similar effect.
Storing the avocado in an airtight container will keep it fresh for a day.
So now that you know the methods of preserving your fruit, bid adieu to wastage or forced overeating, because even good things, in excess, can be harmful.
References [ + ]
|1.||↑||Golan, A., Varda Kahn, and A. Y. Sadovski. “Relationship between polyphenols and browning in avocado mesocarp. Comparison between the Fuerte and Lerman cultivars.” Journal of Agricultural and Food Chemistry 25, no. 6 (1977): 1253-1260.|
|2.||↑||Underhill, S. J. R., J. Bagshaw, A. Prasad, G. Zauberman, R. Ronen, and Y. Fuchs. “The control of lychee (Litchi chinensis Sonn.) postharvest skin browning using sulphur dioxide and low pH.” Frontier in Tropical Fruit Research 321 (1991): 732-741.|
|3.||↑||Pinheiro, Ana Carla Marques, Vilas Boas, Eduardo Valério de Barros, Alessandra de Paiva Alves, Marcelo La Selva, and Adimilson Bosco Chitarra. “Quality of fresh-cut avocado (Persea americana Mill.) stored under different temperatures.” Ciência e Agrotecnologia 33, no. 4 (2009): 1095-1102.|
|4.||↑||Pizzocaro, Francesco, Danila Torreggiani, and Gianluca Gilardi. “Inhibition of apple polyphenoloxidase (PPO) by ascorbic acid, citric acid and sodium chloride.” Journal of Food Processing and Preservation 17, no. 1 (1993): 21-30.|