To tell if a certian fruit is ripe, follow this node. Apples and Oranges are omitted because they are easy to tell when ripe.

Peaches: Peaches with a creamy to gold undercolor that best indicates ripeness. The amount of red blush on fruit depends on the variety and is not always a sign of ripeness. Two other indicators of ripeness are a well-defined crease and a good fragrance. Select fruit that has begun to soften for immediate use. Firm, ripe fruit can be held a few days at room temperature to ripen further. Never pick peaches with a green undercolor since they will not ripen well. They will shrivel, become flabby and never achieve a good flavor.

Pineapples: An old myth is that a pineapple is ripe if you can remove a leaf from the crown. This is untrue because pineapples are picked ripe and ready to eat, after approximately an 18-month growth period. The pineapple color varies with time of year, so color does not indicate ripeness. Look for plump fruit with a fresh aroma at the stem end and store at room temperature.

Avocados: A ripe avocado is relatively firm, but will yield to gentle pressure when held in the palm of the hand and squeezed. Color cannot always be trusted to determine whether or not an avocado is ripe. Indeed, the squeeze test is the most accurate.

Bananas: When a banana is yellow with brown spots, it is at its peak of ripeness and sweetest in flavor. There is a ripeness chart at this website
http://www.freshdelmonte.com/faq_banana_ripe.cfm. If you'd like to ripen a banana quicker, place them in a brown paper bag with an apple or tomato overnight. They will work together to speed each other's ripening.

Mangos: Pick up the mango and check the area around the stem. If it looks plump and round, the mango is ripe. Most mangos in the store aren't ripe. Ripen the mangos yourself at home by leaving at room temperature for a day or two.

In the Netherlands, ripe fruit is generally hard to come by. Most fruit is sold in a state in which it will never ripen no matter what you do. Most varieties developed locally have been carefully cultivated to never ripen.

An obvious reason for this is convenience for the producer and transporter: unripe fruit is hard and when cooled properly, will keep for weeks or even months; ripe fruit is vulnerable and must be sold within hours.

However, after years of (admittedly casual) investigations with fruit sellers and fellow customers, it has become clear to me that the primary reason for this state of affairs is customer demand. Most customers value the properties of unripe fruit: a stainless and clean appearance, easy to keep, less messy and smelly when processed. Few value the qualities of ripe fruit, namely, taste and sweetness. This may partly be due to unfamiliarity with the concept.

Some evidence.

  • Looking at a batch of lemons that are half yellow, half green, I ask the greengrocer whether he has any ripe lemons. "These lemons are ripe." I should have looked for a yellowgrocer.
  • Looking at a batch of tomatoes that are half red, half green, I ask the greengrocer (not the same, obviously) whether he is also selling any ripe tomatoes. He asks me to explain. Well., I say, I like my tomatoes red and soft, you know, with the taste of tomato. His reply: these are "nice hard tomatoes", it's what most people want.
  • A few years ago there was a decline in tomato sales; market research brought out that customers were complaining of lack of taste. Within months, groceries were selling "taste tomatoes", at twice the usual price, with an all-red appearance and slightly more taste. While this proves that the market is demand driven, you still get 5 times the taste at 1/5th of the price out of a can of Italian tomatoes.


So how to find ripe fruit? There are a couple of rules to follow.

green is unripe, yellow is ripe
in Dutch, "green" and "unripe" are actually synonyms, when used figuratively; this is no accident. Most fruits (all citrus fruits, apples, pears, mangos, pineapples, bananas, even Reine Claude prunes) are green when unripe and colour yellow or orange, as they ripen - some are edible (Granny Smith) or even ripe (Reine Claude) when green, but green is rarely the final stage of ripening - exceptions are the avocado and the Cantaloupe melons
shiny is ripe
fruit often takes on a waxy shine when it is ripe - this goes for cherries, to some extent apples, and citrus fruits especially; but take note that many producers actually wax their fruit to make it look better and for protection
soft is ripe
ripening mellows fruits, so don't buy anything that resists squeezing. You can't leave a dent and then not buy it, of course, so this really is not a very practical criterion. However, the motto i see so frequently in groceries: "Don't squeeze us - we don't squeeze you!" is stupid: you would squeeze me if you had to eat me!
buy on the market
out on the market there is more choice, and more importantly, much less effort and money is spent on presentation and on keeping a sterile environment - as a consequence, you get a better idea of what the fruit is really like
buy seasonal produce
fruits should really be picked ripe, or as close to ripe as possible - the ripening process can't be extended indefinitely. Local cherries are only offered during three weeks of July/August, so those are the weeks to eat cherries - at any other time, you'll be buying cherries flown in by airplane from God knows where and more tampering will need to be done to make them look fresh by the time you see them - at the expense of their taste
buy on warm days
the ripening process is greatly influenced by temperature; in the Netherlands, the average temperature is too low for most fruits to grow or ripen properly. So when you buy imported fruits in search for something ripe and tasty, it greatly helps to do it during a heat wave, when the fruit will ripen after you buy it, and is much cheaper on the market to boot (the vendors won't be able to sell the same batch topmorrow). (Even some of the locally grown fruit may ripen, or be ripe, when bought in the right season.)
smell
ripe fruit will usually spread a delicious scent that it can be recognised by - but only at room temperaturep; here in the Netherlands, most fruit is considerably colder at the time you buy it, even when it is at arm's reach, so scent really is not a very useful indicator in practice

Specific advice:

apples
don't - unless you like the lack of taste of unripe fruit, most apples sold today do not have much to offer. They do not really ripen. Sweet apples are out of fashion - only sour and bland varieties are common today. Among the best, as far as taste is concerned, is Cox's Orange, not coincidentally, the most orange coloured of any apple I know
pears
pears, almost always sold green, often months after they were picked, are exceptionally good at ripening after you buy them, but the process may take weeks. Popular varieties in the Netherlands are Doyenné du Comice and the similar Conférence and Beurré Hardy. I prefer the first, which will melt on the tongue when ripe. Whether or not they will ripen depends on how they have been stored, something that as far as I know cannot be judged from the pears when you buy them. Find a reliable vendor.
oranges, mandarins, lemons, grapefruit
when ripe they emit an inflammable liquid from the skin, which grows soft and shiny as a result. A ripe lemon is still sour, but edible. If the fruit has become squishy it's become dehydrated; this takes away from the taste and appears to stop the ripening process. Moulding (always green penicillium) somehow accelerates ripening; oranges slightly affected by it are among the best I've had.
limes
usually sold green, but yellow when ripe, however, due to their small size, they usually dry out before they are ripe, even more so than the other citrus fruits
bananas
start to ripen when brown spots appear on the peel - the point where most natives will throw them away. The ripening process can be emulated by frying them, preferably wrapped in flour or dough, a delicious treat
mangos (mangas)
the yellow, smaller kind are generally tastier than the big, red-and-green kind, but both need to ripen - the main risk is of black spots developing, a sign of black areas developing within the flesh. This is decay and although it does not seem to affect the rest of the fruit, is a waste of valuable mango
avocado
like mango, they tend to develop black spots, or areas within, rather easily - I believe this is fungus, because it develops brown threads throughout the fruit, and in any case, leaves it without any taste. Note however that avocados come in two varieties, shiny green and 'bumpy' purplish; the second variety is reputedly better, but of course, black is harder to spot on it
tomato
buy them canned (see above)
strawberry
the smaller, more irregular kind are usually the ones that have grown outside, and generally have more flavour; they shine when ripe, but the strawberry smell is a better indicator
pineapple
a ripe pineapple, at least in my experience, is always yellow - green spots on the outside means unripe, and brown means they have passed the point of freshness, usually without ever being ripe. Properly ripened pineapples are a novelty in the Netherlands, especially in the last year they have become very common; you can always pick them by their smell. The first time I had a ripe pineapple I couldn't believe my taste buds - they are sweeter than canned pineapple.
peach
peach is hard - some will ripen nicely, some won't - but as a general rule of thumb, it's better to buy "white" (light) peaches, they don't look as nice but usually have more flavour
I could go on but the above should give you something to start with.

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