Why does ripening occur

When a banana turns black, is peeled and gives off a strong alcoholic sent, I have been told that it hasn't fermented because it takes longer to naturally ferment, but is likely the alkaloids I am smelling.

However, I peeled plantains that had turned mostly black for which the whole stem of bunches was cut a week in a half ago to two weeks ago and they had a very potent alcoholic smell. Last night there was only a bit of syrup. Are these signs of natural fermentation and the smell is basic alcohol without other additives like yeast or is it just an intense phase of ripening and a very potent alkaloid smell?

Are plantains and bananas safe to eat at this stage? They are still yellow, albeit a deep, deep yellow. They are very mushy but can still be sliced. There is very little browning, but only tiny sections on the surface of the mushy fruit. Is the syrup edible? The smell is also present in the syrup.

I have read that there are probiotic benefits to fermented bananas as well. Would these have that? Already a subscriber? Log in. Get the print magazine, 25 years of back issues online, over 7, recipes, and more.

Start your FREE trial. Fine Cooking. Sign Up Login. Save to Recipe Box. Add Private Note. Saved Add to List Add to List. The cold will ruin their flavour. Keep the berries cold and dry — if you wash them before storing, they are likely to turn mouldy quite quickly!

Arrange the berries without washing or removing the stems on a paper towel-lined tray and cover with plastic wrap; then refrigerate. Before eating or using them, wash the berries under cool water and then remove stems. Enzymes, which occur naturally in live fruits and vegetables are part of the natural aging process.

Fruit and vegetables decompose from the moment they are harvested due to attacks from enzymes, oxidation and microorganisms. Micro-organisms speed produce deterioration through structural decay. The fruit that rots quickest are the softer fruits such as berries, bananas, peaches, plums, kiwis, satsumas and clementines as well as tomatoes, kale, spinach, lettuce — to name but a few!

Get advice and recommendations by emailing our friendly team. Fruit ripening and storage Get the best out of your fresh fruit delivery. The vapors were causing surrounding plants to grow abnormally. Three decades later, researchers found that plants not only responded to ethylene, but they could produce their own, and production of the gas increased when the scientists cut injured the fruit with a knife.

Researchers later discovered that plants produce ethylene in many tissues in response to cues beyond the stress from heat and injury. It is made during certain developmental conditions to signal seeds to germinate, prompt leaves to change colors, and trigger flower petals to die. Because the gas diffuses easily it can travel within the plant from cell to cell as well as to neighboring plants, serving as a warning signal that danger is near and that it is time to activate the appropriate defense responses.

Special receptors in plant cells bind to the ethylene. The first known plant genes involved in this process, ETR1 and CTR1 , were identified in ; they keep the fruit ripening genes from activating until ethylene is made. Once that happens, ETR1 and CTR1 turn off, which allows a cascade that ultimately turns on other genes that make various enzymes: pectinases to break down cell walls and soften the fruit; amylases to convert carbohydrates into simple sugars; and hydrolases to degrade the chlorophyll content of the fruit resulting in color change.

Such changes invite animals to consume the fruit and disperse the mature undigested seeds via their defecation. However, these fruits can still ripen if they are exposed to an external ethylene source, such as a ripening climacteric fruit. These include strawberry, grape, and citrus fruits [ 3 ].

We will focus on ripening of climacteric fruits that are influenced by ethylene. For climacteric fruit, exposure to an initial, small concentration of ethylene causes the fruit to produce greater quantities of ethylene until a peak concentration is achieved [ 4 ]. The methods we described above for slowing down ripening work in this way, because, in general, low temperatures reduce metabolism in fruit. Controlled atmospheres limit the amount of oxygen around the fruit, and oxygen is needed to make ethylene.

Ethylene action is inhibited by carbon dioxide and by 1-MCP. Another method for slowing down ripening is to remove ethylene from the storage environment by using materials that absorb ethylene, such as potassium permanganate. Once the fruit reaches its destination, it can be ripened by exposure to ethylene gas. The effect of ethylene on ripening is dependent on many factors. The fruits need to be mature enough to be able to respond effectively to ethylene.

In highly sensitive species, like cantaloupes or bananas, ripening is immediately stimulated by ethylene, but the more immature the fruit, the greater the concentration of ethylene required to cause ripening. In the less sensitive species, like tomatoes or apples, ethylene treatment reduces the time before ripening occurs. Some fruits, such as avocados, do not ripen while attached to the tree and gradually increase their sensitivity to ethylene with time after harvest [ 6 ].

All plants produce some ethylene during their life cycle. Ethylene production can increase up to fold or more during particular stages—for instance in response to a wound [ 1 ]. Ancient Egyptians used to cut figs to enhance their ripening, since ethylene produced by the injured fruit tissue triggered the ripening response. Similarly, the ancient Chinese used to burn incense in closed rooms with stored pears, because ethylene was released as a by-product of the burning incense. Ethylene gas is commercially used to ripen fruits after they have been picked.

Fruits, such as tomato, banana, and pear are harvested just before ripening has started typically in a hard, green, but mature stage. This allows time for the fruit to be stored and transported to distant places. Once the fruit reaches its destination, ripening is conducted under controlled conditions. This is usually carried out in specially constructed ripening rooms, with optimum ripening temperature, humidity, and ethylene concentration.