Why won’t an avocado ripen?

In this brief guide, we will answer the query, “Why won’t an avocado ripen?” and will discuss the ways to ripen the avocado.

Why won’t an avocado ripen?

The avocado is a climacteric fruit. This means that it has the ability to ripen after it is picked from the tree. Other climacteric fruits are apples, bananas, apricots and tomatoes, while, for example, citrus, grapes and strawberries are non-climacteric. The natural climacteric ripening process is associated with increased rise in cellular respiration. However, a prerequisite is that the avocado is mature when it is harvested, in order to ripe properly after it comes off the tree. The avocado fruits are picked non-ripe, hard and light green. The fruits are kept in low temperature (3°C-6°C) when shipped overseas to reach the final destination in a basket on the fruit dealer’s shelf. They may have been in transit for up to 2 months. At such a stage, the avocado frequently lacks the appealing flavor, and consistency. The taste is bitter due to high contents of acid (1). 

After harvest, avocados go through a ripening process aided by ethylene gas (a naturally occurring catalyst). However, if avocado producers hurry to harvest them too soon, they will never attain physiological maturity on the tree and hence will not mature correctly when they are picked.

When an avocado won’t ripen, what’s the reason?

Is there an explanation for this? Avocados do not ripen on the tree as we discovered in the harvesting article. This has been previously attributed to a possible role of C7 sugars (mannoheptulose and perseitol) acting as inhibitors and controlling the ripening process and the fruit can hang on the tree for more than 12 months, time far beyond needed to reach physiological maturity to be able to ripen when detached  (2).

 The ripening of avocados occurs after harvest, generally with the aid of ethylene gas (a natural catalyst). This can only happen if avocados have reached a specific level of ripeness on the tree before they may be harvested. Physiological maturity is the minimal point at which an avocado may be picked for appropriate ripening and is the maturity level at which this is possible. (Tomatoes go through a similar procedure.). Physiological maturity is also defined as the stage of development when an avocado fruit will continue ontogeny even after it has been detached from the tree. On the other hand, horticultural or commercial maturity is defined as the developmental stage where the harvested avocado fruit possesses the prerequisites for utilization by consumers and will undergo normal ripening and provide good eating quality (3).

During the physiological maturity stage, the farmer must sample avocados to check whether they meet the minimum oil content and dry weight, which are two universal harvest maturity indices (indicators of when avocados are ready to be harvested) across various cultivars of avocados. Using the dry weight %, farmers may determine the amount of avocado oil in the edible section of the fruit.

Because the avocados haven’t reached the physiological maturity stage on the tree, they won’t ripen correctly after harvest if producers speed the process.

Are Avocados More Common at Certain Times of the Year?

Yes. To receive a premium price at the beginning of the season, producers may harvest early to meet that deadline.

When selling avocados in California, which is the country’s principal avocado-growing area, there is state legislation that sets a minimum oil content requirement. This ensures that the market is fair for all California producers, maintains a particular quality for customers, and encourages repeat purchases. It may rapidly spoil the customer experience if avocados from various nations don’t meet the same minimal oil content criteria. If you’ve had a lot of poor-quality avocados recently, it’s a good idea to find out where your avocados were farmed.

Depending on the variety and growth conditions, the oil content of fresh mesocarp tissue of the avocado fruit ranges from a minimum of 8 to 30% and does not change with time after harvest. The oil fraction can be up to about 70% of the mesocarp dry matter, although variations in oil content and composition have been observed due to growing regions, cultivar, harvest time, and spatially within the fruit (3). Starting in 1925, a minimum standard of 8% oil content in the pulp of avocado fruit was used in the California Avocado Industry in the United States, but, since the eighties, they began using minimum oil content percentages for each cultivar (e.g. 10.0% for Fuerte and 11.2% for Hass) (4).

How to ripe unripe avocados?

While picking all of your avocados for the week, you discover that they are not quite ripe enough for your favorite guacamole recipe. Don’t give up hope! Here are a few tricks for speeding up the ripening process while still allowing your avocados to develop their luscious buttery flesh and nutty taste naturally.

To ripen an avocado, put the avocado and a banana in a brown paper bag. This may sound like a crazy technique, but it really works! Ethylene, a naturally occurring plant hormone found in ripe bananas, is responsible for the fruit’s ripening process. The ethylene gas generated by the fruit is trapped in the paper bag, which speeds up the ripening process. Ethylene is important for fruit maturation since they tightly control fruit ripening in climacteric fruit by initiating and coordinating the ripening process. It is hypothesized that ethylene is the signaling molecule once perceived that halts lipid biosynthesis and programs changes in the fatty acid profile of avocado. On the other hand, the high level of polyamines in avocado fruit during development provokes the repression of ethylene production and lack of ripening while the fruit remains attached to the tree (2).

Ripeness may occur quickly with avocados, so it’s critical to check on them regularly.

Make the process of maturation more efficient by using a basic staple like rice, such as brown rice. Submerge your avocado in a bowl of rice until it is thoroughly coated on all sides, then remove it. Using uncooked rice as an ethylene gas trap is a no-brainer because of how well it works. Just be sure to keep tabs on the improvements every day. Some days will be needed to achieve full maturity using this strategy.

Placing an avocado in direct sunshine can quickly and easily ripen it. Putting avocados in direct sunlight can speed up the ripening process, so place them on a window sill or in a sunny area of your house.

Make sure to check out our other video instructions for advice on how to detect whether an avocado is ripe, or how to slice and dice an avocado.

Unripe avocados may be used in a variety of ways.

You unwrap your avocado and discover that it isn’t ripe. Unripe avocados should not be eaten. Simply place the fruit in a cool, dark place to mature. You can keep a chopped avocado until it’s ripe by following these easy procedures.

Here’s how to keep an open, unripe avocado safe:

·         Use lime or lemon to rub the avocado’s flesh.

·         The avocado halves should be reassembled and squeezed together tightly.

·         Refrigerate the avocado after wrapping it in plastic wrap.

·         Even after being sliced open, an unripe avocado may be stored with ease. Wait for it to ripen.

·         Then savor it when it’s done. If you don’t examine it every day, you won’t know how ripe an avocado is until you apply light pressure on it.

Because they go well with just about everything, Avocados from Mexico are always a good investment. Find out more about how you may use them in your favorite dishes by reading this guide.

Check out other helpful guides for additional advice on preserving avocados! 

Other FAQs about Avocado that you may be interested in.

How to make avocado ripen after cutting? (+7 Health benefits)

How to pick avocado at the grocery store? (3 tips)

Can you eat avocado peel? (+5 Health benefits)

Conclusion

In this brief guide, we answered the query, “Why won’t an avocado ripen?” and discussed the ways to ripen the avocado.

References

1. Lin, Xiaobo, et al. Ripening of avocado fruits studied by spectroscopic techniques. J Biophot, 2020, 13, e202000076.
2. Pedreschi, Romina, et al. Primary metabolism in avocado fruit. Front Plant Sci, 2019, 10, 795.  
3. Magwaza, L.S., Tesfay, S.Z. A Review of Destructive and Non-destructive Methods for Determining Avocado Fruit Maturity. Food Bioproc Technol, 2015, 8, 1995–2011. 
4. Carvalho, Catarina Pedro, María Alejandra Velásquez, and Zelda Van Rooyen. Determination of the minimum dry matter index for the optimum harvest of’Hass’ avocado fruits in Colombia. Agron Colomb, 2014, 32, 399-406.