Climacteric/Non-Climacteric Fruit

About consuming fruits; fresh, dried or juiced.
Stancel
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Re: Climacteric/Non-Climacteric Fruit

Post by Stancel »

Oranges ripen after picking. The idea they don't seems to be a ploy by the orange growers/importers to get people to accept unripe yellow sour oranges as edible. So they put it in the fridge because they'd rather it not go bad, but by doing that, they keep it from ripening.
dime
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(non) climateric fruits

Post by dime »

Ripening is caused by specific plant "hormones", decay is due to bacterial/fungal decomposition. But I couldn't find what changes happen during this decomposition.. maybe you can provide a reference for your claim?
Decay of citrus fruit is most often caused by fungal pathogens that grow and develop in the hot and wet conditions typical of the Florida climate. The most common postharvest fungal diseases of Florida citrus are Diplodia stem-end rot (Lasiodiplodia theobromae), Phomopsis stem-end rot (Phomopsis citri [teleomorph Diaporthe citri]), and green mold (Penicillium digitatum). Sour rot (Galactomyces citri-aurantii), anthracnose (Colletotrichum gloeosporioides), and, less frequently, Alternaria stem-end rot (black rot) (Alternaria alternata) and brown rot (primarily Phytophthora palmivora and P. nicotianae) can also cause commercially important losses of citrus fruit.
Anyway, oranges don't get better with time for me, either they get too dry or become mouldy.
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Oscar
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Re:

Post by Oscar »

I suggest you try it out yourself. Buy some oranges of the same batch, drink the juice of half of them immediately, and the other half after a few weeks. Let me know if there is any difference.
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RRM
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Post by RRM »

Though its convenient to classify fruits as either climateric or non-climateric,
this either / or approach is too black and white / simplified, and therefore incorrect in my view.
There is also no clear distinction between ripening and decay.
Bananas for example, will indeed get sweeter as they ripe, but also as they decay (due to conversion of starch into simple sugars).
In my experience, all fruits ripen after picking, but to very different degrees,
and as we like to classify things,
people made a distinction between climateric and non-climateric fruits,
while there is no clear distinction, just different levels.
The whole climateric / non-climateric seems based on whether fruits ripen in response to ethylene,
which is just one factor of ripening.
Yes, if you store a batch of sour / acid oranges for a couple of weeks,
the remaining good ones will definitely taste sweeter.
If they taste better and if they are still perfectly good,
thats ripening in my book.
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Re: Climacteric/Non-Climacteric Fruit

Post by Kasper »

Ripening is caused by specific plant "hormones", decay is due to bacterial/fungal decomposition.
So it is good to distinguish both processes.
The question is, does decay by bacterial/fungal decomposition eliminates much of the anti-nutrients in fruits.
And, does decay increase harmful substances in fruit ?
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RRM
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Re: Climacteric/Non-Climacteric Fruit

Post by RRM »

Kasper wrote: Ripening is caused by specific plant "hormones", decay is due to bacterial/fungal decomposition.
So it is good to distinguish both processes.
In theory, sure.
In practise, they cannot be separated.
Even when the fruit is still not even close to ripe, decay may already set in.
And once the fruit is picked, those plant hormones, factors and enzymes will not suddenly disappear;
that will take time, and in the meantime, the ripening lingers on, with or without simultaneous decay.
If there are still enzymes active that break down anti-nutrients, such as pectin, ripening obviously goes on.
Even when obviously decaying, ripening is also still going on.
Even without decay, compounds inside the fruit will get oxidized.
Even during the ripening process, natural beta-carbolines will form.
Nutrient contents in fruits keep on changing throughout the ripening process, and after picking,
also before decay sets in.
Those oranges that fall victim to decay, you can easily set them aside from the ones that do not.
You can tell the difference, by smell taste and looks. The ones that are still perfectly healthy, are sweeter and softer than before.
The question is, does decay by bacterial/fungal decomposition eliminates much of the anti-nutrients in fruits.
Yes (eventually the entire orange will be decomposed), but that is not important to me,
because the ones that decay, i throw away.
And, does decay increase harmful substances in fruit ?
Yes, decay products can be harmful (and/or beneficial).
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RRM
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Re: Climacteric/Non-Climacteric Fruit

Post by RRM »

The definition of non-climacteric fruit (e.g. oranges) is that they will not ripen in response to ethylene treatment.
But what if ethylene is produced inside the orange anyway?
It would mean that though you cannot accelerate ripening by exogenous ethylene exposure,
ripening will continue after picking anyway, even though at a slow pace.
Here they are comparing levels of polygalacturonase, pectin methylesterase (PME), pectate lyases and cellulase in two different navel oranges. Lei Y et al
"The mixture of enzymes constituting Pectolyase increased ethylene production 15- to 25-fold when introduced into tomato and orange fruits. The enzymes purified from Pectolyase all increased ethylene production in the fruits but the lyases were generally more effective than the hydrolases." Baldwin EA et al
So, even though oranges do not respond to exogenous ethylene,
enzymes in oranges do induce a cycle of enzyme-ethylene-enzyme-evoked ripening.
(ethylene also induces cellulase activity Rasmussen GK)

And yes, enzymes that break down anti-nutrients (pectin) in simple sugars (increasing sweetness) remain active in orange juice.
"The main localization of PMEs was in the outer cell layers of the juice vesicles, in the outer cell layers of the lamellae between the segments and in the inner cell layers of the albedo in the peel".Christensen TM et al
OJ may clarify in 3 weeks. Clarification of citrus juice is related to pectin methylesterase activity.
Particle size changes with pH and storage time Ellerbee L et al
and clarification/cloud may greatly vary due to varying levels of activities by different pectin methylesterases. Savary BJ
Pasteurization in a microwave oven Cinquanta L et al and high pressure carbon dioxide inactivates PME. After 7 days of storage there was no further decrease in its activity. Zhou L et al
With microbial activity maintained insignificant, juice processed at 42°C, rapid clarification occurred within the first 8 days, consistent with undetectable pectin methylesterase deactivation. The juices processed at temperatures >62°C were characterized by minor residual PME activities. PME was suggested as an indicator enzyme for the freshness of freshly squeezed orange juices, allowing their unambiguous distinction from minimally heat-processed juices. Hirsch AR et al

When peaches are stored at 0°C, polygalacturonase is stable for only one day. Zhou HW
So, fruit should not be stored in the fridge.
PME is also present in other fruits, such as apples, bananas and tomatoes.Ly Nguyen B
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Re: Climacteric/Non-Climacteric Fruit

Post by dime »

Does this mean that making OJ and drinking it let's say one week later is good (or at least not bad)?
What I'm interested in is whether I can make enough juice once for a whole week. Right now I'm making for three days and the juice is perfectly fine (kept in the fridge until I drink it).
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Re: Climacteric/Non-Climacteric Fruit

Post by RRM »

As long as you dont notice any effects such as fizzyness, fermentation, alcohol,
its perfectly fine and may even be beneficial.
In my experiments, 3 days is about the max.
Right now, im making juice for the whole week by also storing a number of bottles in the freezer.

The enzymes that break down pectine (not when frozen, of course) do not only decrease the level of this anti-nutrient,
they also make the juice sweeter, as this long chain of sugars is broken down in simple sugars,
and a whole bunch of simple sugars taste sweeter than when all chained up. (similar to starch vs glucose)

Decay and ripening may share exactly the same processes;
A fungus on decomposing orange peels produces polygalacturonase Siddiqui MA et al,
probably to break down this polysaccharide to use the resulting sugars for fuel.
Two other fungi related to orange rot produce cellulases Adisa VA to break down cellulose in oranges.
And a 'green mold' fungus related to post-harvest decay, produces beta-glucanases Platania C et al to break down beta-glucans in oranges (to obtain energy).
Giant snails also have beta-glucanases at their disposal Teng Y et al, so that they can eat through the skin of fallen oranges.
The chemical responsible for the ripening process is a hormone called ethylene.
The peel of an orange may also produce ethylene in response to wounding and aging.Hyodo H et al
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Re: Climacteric/Non-Climacteric Fruit

Post by dime »

Sounds perfect. Do you freeze it in the freezer? As far as I know frozen it will last a loong time without noticable degradation.
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Re: Climacteric/Non-Climacteric Fruit

Post by RRM »

Yes, exactly. You could keep it for months, i guess.
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