Germination of Potatoes - and Its Effect on Cooking

[exchemist]

As a cook, I have noticed with frustration that, when I roast or shallow-fry cooked potato (in chunks or slices), sometimes they come out golden and crisp with floury interior, and sometimes they quickly turn dark brown and come out flabby and a bit sweet. I think it may correlate with whether or not the potatoes have started to sprout in storage. I can imagine that the starch may possibly start to break down to simpler sugars when germination is triggered. I wonder if this accounts for what I have experienced, the sugars caramelising with the frying etc.

Does anyone know? And, more to the point, what can I do to ensure this does not happen to my potatoes. My experience has mostly been with supermarket Maris Piper. When we go to France in the summer, the varieties I have tried mostly seem to be fine. I wonder if the supermarkets in the UK store them too long or something.   

[Phi for All]

1 hour ago, exchemist said:

I think it may correlate with whether or not the potatoes have started to sprout in storage.

There are some glycoalkaloids in potatoes that become concentrated as they age. I always thought the green bits weren't ripe yet, but apparently that's chlorophyll being concentrated with age and light, like the toxins. I wonder if this is responsible for altered texture and taste. I used to store potatoes and onions together, until someone told me it makes the potato sprouting worse. I can't remember why, but I throw away fewer potatoes now.

[exchemist]

1 hour ago, Phi for All said:

There are some glycoalkaloids in potatoes that become concentrated as they age. I always thought the green bits weren't ripe yet, but apparently that's chlorophyll being concentrated with age and light, like the toxins. I wonder if this is responsible for altered texture and taste. I used to store potatoes and onions together, until someone told me it makes the potato sprouting worse. I can't remember why, but I throw away fewer potatoes now.

Yes, I gather potatoes are from the nightshade, solanum, family (as are tomatoes), and that the green parts are poisonous (solanine). But I think that's another story.

I have found some information that storage at excessively low temperature can make potatoes sweet. (This reminds me of  the old theory that parsnips are best eaten after the first frosts).  However I keep mine in the cellar of my London Victorian house, which rarely goes below 10C, so I rather doubt that explains it. 

I have also read that washing potatoes can start processes of some sort going. The ones I buy in polythene bags at the supermarket have definitely been washed. The ones I buy in France are unwashed, too.  I'm going to experiment this weekend with so-called "baking potatoes", which are sold loose and unwashed. It will be interesting to see if I can steam them and then cut them up, without them disintegrating......  

[Phi for All]

1 hour ago, exchemist said:

I have also read that washing potatoes can start processes of some sort going. The ones I buy in polythene bags at the supermarket have definitely been washed. The ones I buy in France are unwashed, too.  I'm going to experiment this weekend with so-called "baking potatoes", which are sold loose and unwashed. It will be interesting to see if I can steam them and then cut them up, without them disintegrating......  

It doesn't seem likely that getting the outside of a potato wet would start a process, since they surely get wet in the ground. My mother-in-law swore by a light vinegar wash for potatoes (she was Czech/German), but I never saw much difference. The washed/unwashed process is the same in the US, now that I think about it. Reds and golds are washed, but Russets and other baker types have a bit of dirt on them. 

[exchemist]

2 hours ago, Phi for All said:

It doesn't seem likely that getting the outside of a potato wet would start a process, since they surely get wet in the ground. My mother-in-law swore by a light vinegar wash for potatoes (she was Czech/German), but I never saw much difference. The washed/unwashed process is the same in the US, now that I think about it. Reds and golds are washed, but Russets and other baker types have a bit of dirt on them. 

Yes, the article I read was vague as to what process would be started by washing. Maybe washing or not is a red herring, after all. Anyway, I'll have another data point after this weekend, on these "baking potatoes" (variety unspecified).

[Sensei]

7 hours ago, exchemist said:

As a cook, I have noticed with frustration that, when I roast or shallow-fry cooked potato (in chunks or slices), sometimes they come out golden and crisp with floury interior, 

If you want them to have always golden color, crisp skin with nice interior forget about shallow-frying.. Try this: cook potatoes with salt, vinegar and sugar at least 15 min. Dry carefully using paper and put them for max 6 mins in deep hot oil. Some use mixture of two oils to have higher temperature. Shallow-frying disallows them to evenly fry from all sides therefore you need to double time of frying. If you want to learn how much they took oil measure their mass before and after frying using both methods.

[studiot]

There are lots of ways to achieve a crisp exterior to potatoes when cooking them.

Results depend upon the variety,  age and condition of the tuber, including its water content.

If you want good results with shallow frying you are best to parboil or par microwave them first.

The European method of making chips uses this method for both deep and shallow frying.

I think the most important thing is that the final operation should be intense heating of the potato whether roasting, baking or frying.

If you obtain the crisp external coating too soon in the cooking sequence you will either end up with a part cooked interior or have to turn the heat down and I find the crisp exterior goes soft  - You often find this in restaurents that have kept roast potatoes warm (hot) too long.

It should be noted that it is possible to produce the crisp exterior even if the potatoes are floating in water (gravy), this is done in the traditional Lancashire hotpot dish for instance.

I find that 'scallops' are thus the best shape for shallow frying.

 

Some commercial chips (fries) are made from extruded precooked and reconstituted potato.

 

On the issue of supermarket supply, I find it is always worth removing vegetables from their plastic bags (even the perforated bags) as soon as possible as the seat in the bags initiating deterioration.
Carrots seem particularly prone to this and also some supermarkets seem to treat them particularly harshly so they start going black on the outside within a day or two.
It should be noted that the washing process also involves som form of mechanical scrubbing.

 

 

 

[exchemist]

1 minute ago, studiot said:

There are lots of ways to achieve a crisp exterior to potatoes when cooking them.

Results depend upon the variety,  age and condition of the tuber, including its water content.

If you want good results with shallow frying you are best to parboil or par microwave them first.

The European method of making chips uses this method for both deep and shallow frying.

I think the most important thing is that the final operation should be intense heating of the potato whether roasting, baking or frying.

If you obtain the crisp external coating too soon in the cooking sequence you will either end up with a part cooked interior or have to turn the heat down and I find the crisp exterior goes soft  - You often find this in restaurents that have kept roast potatoes warm (hot) too long.

It should be noted that it is possible to produce the crisp exterior even if the potatoes are floating in water (gravy), this is done in the traditional Lancashire hotpot dish for instance.

I find that 'scallops' are thus the best shape for shallow frying.

 

Some commercial chips (fries) are made from extruded precooked and reconstituted potato.

 

On the issue of supermarket supply, I find it is always worth removing vegetables from their plastic bags (even the perforated bags) as soon as possible as the seat in the bags initiating deterioration.
Carrots seem particularly prone to this and also some supermarkets seem to treat them particularly harshly so they start going black on the outside within a day or two.
It should be noted that the washing process also involves som form of mechanical scrubbing.

 

 

 

All good background, but this does not address my issue, which is the lack of reproducibility of results, from batch to batch, as I described in the OP. 

[studiot]

2 hours ago, exchemist said:

All good background, but this does not address my issue, which is the lack of reproducibility of results, from batch to batch, as I described in the OP. 

I am wondering if you cooking technique has something to do with it.

Although I would not waste the higher priced maris piper on roasties, occasionally we have one or two to use up and they go in with the standard 'english whites' and seem to come out the same when roasted together.
Traditionally, of course, King Edwards are the premium roasting spud.

In any event, I wonder if you are not using perhaps too much oil ?

Oil has a lower BP/MP than traditional fat so may not let the surface of the spud reach the higher temperature that drier cooking or deep frying would.

 

12 hours ago, Sensei said:

Some use mixture of two oils to have higher temperature.

Really ?

Please explain how this works.

[Sensei]

@studiot Edible oils are not one uniform chemical compound. They are a mixture of saturated, monounsaturated and polyunsaturated fatty acids. What is the difference between e.g.    refined olive oil and virgin olive oil? The percentage of fatty acids. Along with the difference in content, there are also differences in the physical properties of the entire mixture e.g. smoking point.

A couple tables worth reading:

https://en.m.wikipedia.org/wiki/Template:Smoke_point_of_cooking_oils

and here table with percentage content they are made of, and how it influences properties (smoking point):

https://en.m.wikipedia.org/wiki/Vegetable_oil#Composition_of_fats

 

 

Edited May 14, 2021 by Sensei

[studiot]

55 minutes ago, Sensei said:

Edible oils are not one uniform chemical compound.

Exactly.

Mixtures have a lower boiling / melting point than any pure substance they are mixed from.

[exchemist]

2 hours ago, studiot said:

I am wondering if you cooking technique has something to do with it.

Although I would not waste the higher priced maris piper on roasties, occasionally we have one or two to use up and they go in with the standard 'english whites' and seem to come out the same when roasted together.
Traditionally, of course, King Edwards are the premium roasting spud.

In any event, I wonder if you are not using perhaps too much oil ?

Oil has a lower BP/MP than traditional fat so may not let the surface of the spud reach the higher temperature that drier cooking or deep frying would.

 

Really ?

Please explain how this works.

No it's something in the potatoes. You can see it in their appearance after being steamed and before they are cut into chunks for frying. If they look floury at that stage, they will come out well. If they look moist, they will go dark, sweet and flabby. 

[dimreepr]

9 minutes ago, exchemist said:

No it's something in the potatoes. You can see it in their appearance after being steamed and before they are cut into chunks for frying. If they look floury at that stage, they will come out well. If they look moist, they will go dark, sweet and flabby. 

I am wondering, if different types of potatoes might have something to do with it?

It's no coincidence, that some types end up in a can...

[Sensei]

37 minutes ago, studiot said:

Mixtures have a lower boiling / melting point than any pure substance they are mixed from.

Counter example: salted water has higher boiling point than pure water. Brine has ~ 109 C. When salt NaCl is added, the freezing point is lowered and the boiling point is raised.

Edited May 14, 2021 by Sensei

[exchemist]

44 minutes ago, studiot said:

Exactly.

Mixtures have a lower boiling / melting point than any pure substance they are mixed from.

Agree about melting points but, on boiling points, that's not how I recall Raoult's Law.  

Edited May 14, 2021 by exchemist

[dimreepr]

Just now, Sensei said:

Counter example: salted water has higher boiling point than pure water. Brine has ~ 109 C.

Counter, counter example; isn't it true that a burnt chicken had an excess of heat, rather than an excess of time...

 

[studiot]

1 hour ago, Sensei said:

Counter example: salted water has higher boiling point than pure water. Brine has ~ 109 C. When salt NaCl is added, the freezing point is lowered and the boiling point is raised.

 

1 hour ago, exchemist said:

Agree about melting points but, on boiling points, that's not how I recall Raoult's Law.  

Yes you are right,  I thought about it after I shut down and went out, but it was too late then and I was rushing.

[geordief]

 

On 5/14/2021 at 2:40 PM, exchemist said:

No it's something in the potatoes. You can see it in their appearance after being steamed and before they are cut into chunks for frying. If they look floury at that stage, they will come out well. If they look moist, they will go dark, sweet and flabby. 

https://www.bbc.com/future/article/20210519-the-hidden-reason-processed-pet-foods-are-so-addictive

 

 

"Finally, no list of palatants would be complete without pyrophosphate, described in Popular Science as "cat crack". This common additive performs a number of roles in human food, such as preventing potato products from going dark after they're cooked – none of which involve improving its taste. Nevertheless, cats go nuts for it, possibly because it intensifies the flavour of  amino acids.

 

Any connection to what you were wondering about?

Edited May 20, 2021 by geordief

[exchemist]

33 minutes ago, geordief said:

 

https://www.bbc.com/future/article/20210519-the-hidden-reason-processed-pet-foods-are-so-addictive

 

 

"Finally, no list of palatants would be complete without pyrophosphate, described in Popular Science as "cat crack". This common additive performs a number of roles in human food, such as preventing potato products from going dark after they're cooked – none of which involve improving its taste. Nevertheless, cats go nuts for it, possibly because it intensifies the flavour of  amino acids.

 

Any connection to what you were wondering about?

I don't believe Sainsbury's coats its raw Maris Piper spuds in pyrophosphate. And if they did, this would not lead to a batch to batch variation, which is the issue here. 

[geordief]

1 hour ago, exchemist said:

I don't believe Sainsbury's coats its raw Maris Piper spuds in pyrophosphate. And if they did, this would not lead to a batch to batch variation, which is the issue here. 

If your potatoes had started to sprout in storage I would expect them to be fit for throwing out.

If I am looking for potatoes I try to buy them firm and plump.

 

Could someone where they are stored have been detailed to remove any chits from the spuds  so as to make them seem better and not throw them out..?

If they were stored  at close to freezing  maybe that might have damaged them too.

 

[exchemist]

5 minutes ago, geordief said:

If your potatoes had started to sprout in storage I would expect them to be fit for throwing out.

If I am looking for potatoes I try to buy them firm and plump.

 

Could someone where they are stored have been detailed to remove any chits from the spuds  so as to make them seem better and not throw them out..?

If they were stored  at close to freezing  maybe that might have damaged them too.

 

At this time of year they start to sprout after only a week. Do you think if I kept them somewhere warmer and drier, i.e. in the kitchen, that would stop them sprouting? Or should I keep them somewhere even cooler, e.g. the bike shed?  

[geordief]

25 minutes ago, exchemist said:

At this time of year they start to sprout after only a week. Do you think if I kept them somewhere warmer and drier, i.e. in the kitchen, that would stop them sprouting? Or should I keep them somewhere even cooler, e.g. the bike shed?  

Well,I keep mine in the fridge  and have no problems(had some small ones  there that had been unused but looked OK for maybe 8 weeks until we threw them out out of boredom)

If you are actually trying to get them to germinate because you are planting  I think the advice is to give them  light  and so I always put away any potatoes that I am going to eat away from the light.

 

I would imagine that  a cooler temperature  is better for storage.

There is a thing called a clamp where you store potatoes in situ in the garden or field.

 

https://www.allotments4all.co.uk/smf/index.php?topic=61705.0

Edited May 20, 2021 by geordief

[exchemist]

1 hour ago, geordief said:

Well,I keep mine in the fridge  and have no problems(had some small ones  there that had been unused but looked OK for maybe 8 weeks until we threw them out out of boredom)

If you are actually trying to get them to germinate because you are planting  I think the advice is to give them  light  and so I always put away any potatoes that I am going to eat away from the light.

 

I would imagine that  a cooler temperature  is better for storage.

There is a thing called a clamp where you store potatoes in situ in the garden or field.

 

https://www.allotments4all.co.uk/smf/index.php?topic=61705.0

That suggests maybe I should try the bike shed - at least while the cool weather persists. Or maybe try a different supplier: possibly Sainsbury's keeps them too long in the supply chain, so they are already about to germinate by the time I buy them.