exchemist Posted April 7, 2022 Share Posted April 7, 2022 11 hours ago, zapatos said: I learned about that when I put potatoes in the fridge and made potato salad that tasted AWFUL it was so sweet! 😄 This is really interesting and may provide the answer to something that has bothered me for a while as a cook. When I make sauté potatoes, I generally steam them first, then slice them (skin still on) and fry them in hot oil. If I use a floury variety, they generally come out golden and crisp on the outside, which is what I am aiming for. However sometimes I find this fails and instead they go dark brown in patches, don't crisp up, leaving them unpleasantly oily, and taste sweet. I had put this down to sugars forming, which caramelise on frying, but could not work out why this sometimes happens and sometimes doesn't, even when consistently using the same type of potato (Maris Piper, usually). I now wonder if it could be due to the supermarket storing them at too low a temperature as, when we go to France in summer, I never have this problem. The potatoes are fresher there and probably not kept in a cold store, whereas I suspect the English supermarkets shove all their fresh produce into a cold store so it is pot luck whether or not they are there long enough to develop sugars. Do you know the mechanism of the sweetening? I assume it must be breakdown of the starch polysaccharide to sugar monomer, but what triggers that? Some enzyme? Link to comment Share on other sites More sharing options...
mistermack Posted April 7, 2022 Share Posted April 7, 2022 I've never heard of this, but obviously it's there. I usually keep potatoes in the fridge and have never noticed any raised sweetness when I do. As they are stored cool anyway, maybe it's hard to tell. I have to cofess, I like the taste of burnt things, which I knew was bad, but what the hell, you only live once anyway. I bake my own bread, and like it dark. I like my toast almost burnt, and I like my chips dark all over. It's too late to change now. Maybe you could counteract this fridge effect by buying a less starchy variety, and to allow for the slight starch increase from refrigeration. But I think it is very slight, I've certainly never detected a difference. Link to comment Share on other sites More sharing options...
exchemist Posted April 7, 2022 Share Posted April 7, 2022 1 minute ago, mistermack said: I've never heard of this, but obviously it's there. I usually keep potatoes in the fridge and have never noticed any raised sweetness when I do. As they are stored cool anyway, maybe it's hard to tell. I have to cofess, I like the taste of burnt things, which I knew was bad, but what the hell, you only live once anyway. I bake my own bread, and like it dark. I like my toast almost burnt, and I like my chips dark all over. It's too late to change now. Maybe you could counteract this fridge effect by buying a less starchy variety, and to allow for the slight starch increase from refrigeration. But I think it is very slight, I've certainly never detected a difference. Got it! See this: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-3040.2012.02565.x To summarise: when potatoes are stored cold there is an imbalance between the rate of starch breakdown and the rate of sugar utilisation by the cells, presumably because their metabolic rate is decreased by more than the rate of starch breakdown. This leads to a build-up of free sugars. These, on frying the potato, undergo the Maillard reaction with amino acids, leading to dark brown compounds. (Apparently if the amino acid is asparagine, acrylamide can be formed, which is a suspected carcinogen. Yikes!) But in spite of this, potatoes are commercially kept in a cold store, to stop them sprouting or going off. So the solution seems to be to use the freshest potatoes you can get. Possibly better from a market stall than a supermarket, though not necessarily: all depends on time between field and sale. Possibly best to fry potatoes in the summer and autumn, when they have not been kept so long, as well. Anyway, a few things to try. 1 Link to comment Share on other sites More sharing options...
mistermack Posted April 7, 2022 Share Posted April 7, 2022 Sounds like caramel sweets and molasses are to be avoided too. And Guinness. I might as well kill myself now ! Link to comment Share on other sites More sharing options...
exchemist Posted April 7, 2022 Share Posted April 7, 2022 15 minutes ago, mistermack said: Sounds like caramel sweets and molasses are to be avoided too. And Guinness. I might as well kill myself now ! Well no, it is the presence together of asparagine and simple sugars that forms acrylamide. Caramel doesn't have asparagine in it, as it is formed by heating sugar alone. But there is some in molasses and also in dark bread crust and things like that. It appears acrylamide has been shown to cause cancer in rats at some level, but it is unclear whether the levels at which it occurs in most food items are at all risky. There is always, in these cases, the question of whether there is a safe dose, below which any mutagenic effects can be corrected by the body. The same argument is perennial in discussion of radiation doses, I understand. Since the body has mechanisms for repair to genetic damage, it seems reasonable to think that there is may be a safe dose, below which any damage can be handled, but this is contested by some, I gather. Link to comment Share on other sites More sharing options...
CharonY Posted April 23, 2022 Share Posted April 23, 2022 On 4/7/2022 at 6:13 AM, exchemist said: There is always, in these cases, the question of whether there is a safe dose, below which any mutagenic effects can be corrected by the body. The same argument is perennial in discussion of radiation doses, I understand. Since the body has mechanisms for repair to genetic damage, it seems reasonable to think that there is may be a safe dose, below which any damage can be handled, but this is contested by some, I gather. Yepp that is indeed the question. Also similar to radiation, the long-term effects can be tricky to assess as it depends on how much you ingest, but also how fast you can eliminate it. Especially chemicals that accumulate in adipose tissue and are resistant to biological modification/degradation (including PFOA, PFOA and other "forever chemicals") continually accumulate over one's lifetime. At the beginning, coinciding with the development of more sensitive instruments, the hazards of acrylamide appear to be overestimated. But at the same time, it might pose a cumulative risk with all the other exposures we have. In that regard certain chemicals, such as alcohol, are a higher risk, due to the much higher level of consumption. Link to comment Share on other sites More sharing options...
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