When choosing an avocado, hold it in the palm of your hand and apply gentle pressure. If it yields a little, it’s ripe enough to eat. As you’re sorting through all the avocados, don’t squeeze too hard and don’t press the ends. You’ll damage the fruit, leaving nothing but a mess for the next shopper. If it’s a Hass you’re shopping for, look for dark fruit, as the skin turns nearly black when ripe. Steer clear of avocados with bruises or dents in the skin, as that means the flesh is overripe.
How to ripen it
Just one of the avocado’s many quirks is that it doesn’t ripen until after it has been picked. This is a good thing for growers and distributors, as the fruit can be picked, shipped and sold without spoiling en route. As some avocados have a long way to go before reaching your neighbourhood grocery store, they’re often picked when the fruit is still very hard, and then stored in the cold to prevent them from ripening. The harder the fruit, the less damage it gets in transit, and the longer it can wait before a hungry shopper takes it home.
You may have a bit of trouble finding a ripe avocado at a moment’s notice. Solution: Plan ahead, at least where this fruit is concerned! Two to five days at room temperature is all it takes for an avocado to go from too firm to perfectly ripe. You can also put it in a paper bag with ethylene-producing fruits, like bananas or pears, to hurry things along.
Light doesn’t help: You can’t speed up the process, for example, by putting those avocados on a sunny windowsill. Once ripe, this fruit is best stored in the fridge, and will stay at its peak for a few days.
Despite everyone trying to get the most delicious avocado onto their table, sometimes you’ll find that an unripe fruit looks great on the outside, but once you bring it home and open it up after it’s ripened, it has major brown spots and lines on the inside. This isn’t from bruising in shipping, but instead from something called a “chilling injury.” It means that the avocado was stored at too low a temperature before ripening – a common problem with tropical fruit. Solution: Avoid putting an unripe avocado into the fridge when you get home from the grocery store. Leave it on the countertop until it’s just right, then store it in the cold.
How to keep it from browning
Shortly after being cut open, the avocado’s flesh begins to brown significantly. It may look unsightly, but the taste isn’t affected. But given that most people tend to eat with their eyes first, it’s best to minimize the damage! Browning is the result of a series of chemical reactions that occur when three things come together: an enzyme (polyphenol oxidase) and colourless molecules (phenols) present in the fruit’s flesh, as well as oxygen from the air. The enzyme and phenolic compounds are kept separate in different compartments of the cell.
When the fruit is cut or crushed, not only is the pulp exposed to air, but the cell walls also break, allowing the enzyme to react with the phenolic compounds. When all three come together, a chain reaction occurs, which results in the formation of new, brownish molecules. This change in colour is referred to as enzymatic browning.
To prevent browning, you need to keep one or more of the three elements from engaging. The most effective way is to squeeze lemon or lime juice on the avocado, or include these juices in the recipe. Lemon and lime are effective for two reasons: First, they’re very acidic (and the polyphenol oxidase enzyme doesn’t like acidity) and second, they contain ascorbic acid (vitamin C), a powerful antioxidant that blocks oxygen from taking part in the browning process.
Want to find out more? We tried two experiments for ripening an avocado. Check out these two articles for the results.