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Author Topic: One small step for Sainsburys.  (Read 4950 times)
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« Reply #15 on: June 27, 2018, 12:50:35 PM »

Ethylene actually.

I am not aware of any reason why tomatoes sold in the supermarket "on the vine" are any better than not
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« Reply #16 on: June 27, 2018, 01:00:31 PM »

Thanks, interesting link.  I had a vague memory that fruits like bananas emit ethylene whilst ripening which is why if you place a bunch of bananas near other fruits it makes them go off more quickly.  
I didn't realise that ethylene was used in commercial ripening though.

That article had the following paragraph about "vine ripened" tomatoes - ?


Some new varieties of tomatoes are marketed as ‘vine ripened’.  These ‘truss tomatoes‘ develop their colour and flavour while still attached to the plant.  They have been developed through cross-breeding with non-ripening tomato varieties and are usually grown hydroponically in greenhouses. They develop colour without softening like conventional tomatoes and remain firm for harvest, packing and distribution. These tomato varieties do not exhibit a climacteric like conventional tomato varieties but remain susceptible to external ethylene.

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« Reply #17 on: June 27, 2018, 04:21:27 PM »

Please read the link supplied above,  < > to find out a bit more about the ripening process of tomatoes.

Specifically the extract from the link about Ethylene:

'Ethylene is present as a gas produced by the plant. As levels of ethylene increase with plant development while other hormones are balancing in accordance, the effects of ethylene become more pronounced. Ethylene promotes fruit ripening, or "maturing". This signals the plant that it's life cycle is changing or ending. Tomatoes turn red and small flowers begin to wither. It will signal the plant to transfer it's nutrients back into the stem tissue from the leaves and other storage tissue.
Abcission (the process where leaves drop) is attributed to decreasing levels of auxin produced by the leaves, allowing further expression of abscic acid and ethylene. This response is brought on by shortening days and cooler nights.

Tomatoes can be grown with an ethylene inhibitor, shipped green for shelf life and resistance to handling damage, and then exposed to a sealed environment with controlled levels of ethylene to ripen the fruit at their point of destination. Burning fossil fuels, such as CO2 generators produce small amounts of ethylene. Inefficient and un-inspected burners may produce ethylene levels high enough to seriously harm plants. Ethylene is found in abundance in the skin of ripening fruit such as apples or green bananas. By placing unripened plant material in a paper bag with a green banana you can hasten ripening, bringing out flavour and aroma. If done at warmer temperatures fresher material will convert stored starches to sugars.'

Interesting reading to help prevent panic amongst the tomato-eating amongst us.  Smiley



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« Reply #18 on: June 27, 2018, 06:45:25 PM »

Is ethylene used on tomatoes anywhere other than in the US? The Dutch growers don't mention using it and I can't see the EU allowing it as it is a greenhouse gas. CO2 is used to stimulate growth in many places where it is available as a byproduct of heat and power.
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« Reply #19 on: June 27, 2018, 09:29:13 PM »

I don't think of ethylene as a hormone - for one thing it is applied externally and hormones are usually considered to be internal chemical messengers, also it is a remarkably simple molecule compared with most hormones.  And who is to say that a biologically-active molecule won't have an undesirable effect if it's released inside another organism where it isn't designed to be?

Also a tray of picked tomatoes being brought to ripeness when needed by using the gas probably isn't a big deal either, although I can see the greenhouse gas problem.  There are some remarkable blind-spots in legislation and practice when it comes to greenhouse gases though.

The point made to me about "vine tomatoes" by the ex-Min of Ag lab botanist I worked with was that hormones (that she wouldn't accept in her diet) were used to either to stop the early ones ripening so that the whole bunch could be triggered to be ready together, or maybe to accelerate ripening so the whole bunch were ready, some prematurely.   I don't think Ethylene (at the end of the process) came into it.
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