lettuce

lettuce /oss/taxonomy/term/762/all en Let Us Talk About Lettuce Water /oss/article/critical-thinking-general-science/let-us-talk-about-lettuce-water Macbeth knew about sleep deprivation, as we can infer from his thoughts in the second scene of Act 2. Sleep that knits up the raveled sleeve of care, The death of each day's life, sore labor's bath, Balm of hurt minds, great nature's second course, Chief nourisher in life's feast. Wed, 06 Dec 2023 18:02:30 +0000 Joe Schwarcz PhD 9750 at /oss Why does lettuce turn brown? /oss/article/general-science/why-does-lettuce-turn-brown That’s an interesting question. How lettuce turns brown is well known, but why this happens is a different story. Let's deal with the how first. Mon, 21 Mar 2022 19:45:04 +0000 Joe Schwarcz PhD 9057 at /oss Why does lettuce turn brown? /oss/article/nutrition-you-asked/why-does-lettuce-turn-brown That’s an interesting question. How lettuce turns brown is well known. But why this happens is a different story. Let's deal with the how first. The chemistry that takes place when lettuce leaves become brown is the same chemistry we see when an apple is cut and turns brown, when green guacamole turns brown or when a green olive ripens and turns black. All these reactions occur when chemicals in the fruit or vegetable called polyphenols react with enzymes called polyphenoloxidases. Enzymes are specialized protein molecules made within cells and serve as catalysts. Fri, 04 Jun 2021 20:24:53 +0000 Joe Schwarcz PhD 8755 at /oss Why does lettuce turn brown? /oss/article/you-asked/why-does-lettuce-turn-brown That’s an interesting question. How lettuce turns brown is well known. But why this happens is a different story. Lets deal with the how first. The chemistry that takes place when lettuce leaves become brown is the same chemistry we see when an apple is cut and turns brown, when green guacamole turns brown or when a green olive ripens and turns black. All these reactions occur when chemicals in the fruit or vegetable called polyphenols react with enzymes called polyphenoloxidases. Enzymes are specialized protein molecules made within cells and serve as catalysts. In other words, they speed up chemical reactions. Normally within a cell the enzymes and the polyphenols are separated, but when cells are damaged as in cutting an apple or tearing lettuce, their contents leak out an the polyphenols and the polyphenoloxidase mix. The result is a reaction that oxidizes the polyphenols and allows them to link up with each other to produce a brown pigment. When lettuce leaves torn, some cells are damaged and the browning reaction begins. But even if there is no tearing, even if we have a whole head of lettuce, there will eventually be browning. That’s because aging of the cells also leads to damage and mixing of the polyphenols with the enzyme. The age old question about lettuce is what causes more damage, tearing or cutting? Actually it seems not to make much difference. Some cooks argue that cutting is more destructive and leads to quicker browning but experiments do not bear this out. Some cooks say that they can taste metal in a salad if a knife has been used. I think this is culinary snobbery. In any case, if the lettuce is eaten soon after it is prepared, as far as potential browning goes, it doesn’t matter if it was cut or ripped. One more item about preparing lettuce. The dressing should always go on at the last moment because oil soaks into the leaves readily and makes them soggy. And noting that lettuce is soggy is not culinary snobbery. So that’s the how. What about the why? Actually we don’t know. The main theory that crops up is that the brown pigment has anti-fungal and insecticidal properties. In other words, the damaged fruit or vegetable is trying to protect itself. he argument is that historically damage was caused by insects and fungi and that at the first sign of such damage the enzymes would swing into action to ward off further destruction. The fly in this ointment is that nobody has clearly demonstrated that the brown pigments really do have anti-fungal or insecticidal properties. But there certainly is some interesting chemistry there. Thu, 11 Oct 2018 17:00:00 +0000 Joe Schwarcz PhD 7388 at /oss Do Egg Shells Prevent Slugs and Snails From Eating My Plants? /oss/article/you-asked/do-egg-shells-prevent-slugs-and-snails-eating-my-plants Snails and slugs, which are basically snails without shells, share dietary habits. They like to feast on garden plants such as tomatoes. Maybe the snails are just exercising revenge for their brethren that have ended up as escargot. When it comes to the garden, obviously these slithering creatures are not welcome guests, so the question is what to do about them? According to some widely circulating advice, they can be disinvited to the party by placing crushed eggshells around plants. The rationale is that crawling over the sharp edges will deter an invasion. Thu, 31 May 2018 18:00:00 +0000 Joe Schwarcz PhD 7119 at /oss Why does lettuce sometimes turn brown? /oss/article/food-you-asked/why-does-lettuce-sometimes-turn-brown <a href="http://blogs.mcgill.ca/oss/?attachment_id=3363" rel="attachment wp-att-3363"><img alt="lettuce" height="150" src="http://blogs.mcgill.ca/oss/files/2012/11/brown-lettuce-150x150.jpg" width="150" /></a>The chemistry that takes place when lettuce leaves become brown is the same chemistry we see when an apple is cut and turns brown, when green guacamole turns brown or when a green olive ripens and turns black. All these reactions occur when chemicals in the fruit or vegetable called polyphenols react with enzymes known as polyphenoloxidases. Enzymes are specialized protein molecules made within cells that serve as catalysts. In other words they speed up chemical reactions. Normally within a cell the enzymes and the polyphenols are separated, but when cells are damaged, as in cutting an apple or tearing lettuce, their contents leak out and the polyphenols and the enzymes mix. The result is a reaction that oxidizes the polyphenols and allows them to link up with each other to produce a brown pigment. <a href="http://blogs.mcgill.ca/oss/2012/11/18/why-does-lettuce-sometimes-turn-brown/">Read more</a> Mon, 19 Nov 2012 00:25:06 +0000 Joe Schwarcz PhD 1808 at /oss