How does lemon juice(or anything similar) slow down the reaction of the enzymes in the apple with oxygen?
445427
Enzymes are very sensitive to their environment. The acidic environment denatures the enzyme (causes the enzyme to change its shape by destroying some vital chemical bonds that constrain it into the proper shape) Most enzymes are like the toys toddlers play with to learn their shapes. The square only fits the square opening--the same principle applies here. Once an enzyme loses its shape it loses its function.
4619
oxidation, i think.\n\nin this case, simple sugar reacting with oxygen in the air.\n\nIt's been a long time since my Chemistry 101 days.  Hope I got it right.
1175970
well..\nlike they mentioned earlier ,plasmolysis is an important process for plants..but it also has a lot of commercial purposes.\nnot only is it used in jams and pickles to prevent bacteriafrom surviving in them it is also used for some blood tests.
827670
Decrease because there is less oxygen. I think.
317579
Hi xighlun,\n\nFRUCTOSE (one of the major sugars found in orange juice) is of key importance in the rate of decomposition of Vit C in orange juice: high levels of fructose drive high rates of decomposition of ascorbic acid (Vit C).  On the other hand, high levels of citric acid and malic acid tend to stabilise Vit C (act to slow the rate of decomposition).\n\nBecause fructose is already a major component in the juice, you cannot prevent decomposition - it occurs naturally, due to reactions between the sugar and the ascorbic acid, mitigated by the citric and malic acids.  These reactions proceed even whilst the orange is still attached to the tree.  The best we can do in practical terms is to slow the rate of attack by the fructose on the ascorbic acid.  We usually do this by keeping the juice at a very cool temperature.  The ultimate way of achieving the lowest rate of decomposition of Vit C is to concentrate and freeze the juice ASAP after juicing - this is known as FCOJ (frozen concentrated orange juice); the resulting concentrate has the highest retention of Vit C - higher than freshy-squeezed or NFC (not-from-concentrate) juice.\n\nI think the degradation of Vit C generally speaking, would probably occur through oxidation.  This means that looking for the mechanism of degradation in OJ means looking for things in the juice that could act as an oxidant?\n\nU will find plenty of websites on all aspects of chemistry - maybe try googling some obvious keywords, eg: mechanism degradation vitamin c orange juice.
224573
It literally slows the bacteria that make it spoil down. It also inhibits some chemical processes like oxidation.
799952
Mostly citric acid (like all citrus fruits), some ascorbic acid (vitamin C - also like all citrus fruits)
429346
Oxygen is a oxidizer, it oxidizes the apple the same way as oxygen makes steel rust. Almost everything reacts to Oxygen. The browning is caused by enzymes in the fruit reacting to the oxygen in the air. I have included a link below to an experiment with the apple. In reading the experiment, you will find out what effect say sugar has on the browning effect of the apple. The chemical equation posted above, 4 Fe + 3 O2 -----> 2 Fe2O3 is that of rusting iron, not of an oxidized apple.Good Luck with your experiment, you might wish to google the terms "Oxidation + Foods" and do a little more research.
69995
Potassium Cyanide affects the ultimate step of the respiration, that is transfer of electron to Oxygen to form water. It stops this step and therefore no electron transfer takes place and therefore no Oxygen utilization. \n\nI've heard that Potassium Cyanide effect can be reversed if the person is given Methylene Blue immediately. Though I am not sure about it.
471742
Ummm...You will have to figure out which is faster... but I can give an idea as to proceedure...First, try to answer this question: What are all the colored species in grape juice? You need to know that first. Hopefully there is only one. That would simplfy things. Then you need an extinction coefficient for that compound, if you can find one. Using that, you can take several absorbance measures and use Beer's law to establish the concentration of that species in your stock solution. Beer's law states that Absorbance = extinction coefficient x concentration x path length. Your path length is the width of your cuvette, which is usually 1 cm. Beer's Law will not be valid if you use a solution that is so concentrated that it gives you an absorbance value greater than 2. At Absorbance = 2, well over 99% of light is being absorbed. A reading over 2 is thus considered analytically unusable. Your juice can be diluted, if necessary, with DEIONIZED (aka distilled) water. Once you do that, I would roughly time each reaction by just looking at it with my eye, adding just a drop or so of bleach/peroxide initially, and increasing the amount only if necessary. Make sure to add exactly the same amount of bleach/peroxide to exactly the same volume of grape juice. Once you have the reaction basically set up to your satisfaction, then place your juice sample in the colorimeter and get ready to add your reagent. Remember to take a measurement before you add any bleach/peroxide for EACH of the two tests. And take your measurements on the same time frame (ex: every 30 sec.)Good Luck!!! :-)
619144
Lemon juice. People use it on their elbows.
267985
well it is quite simple you see acidic substances tends to cut grease and kills bacteria, the real lemons will possess the natural acidsin the juice required to do this but artificial lemon only produces the lemon scent and flavour not the actual natural acids required to kill bacteria or cut grease.
103696
It is more of a regulator enzyme than a catalyst. When there is a high concentration of ATP, the production of pyruvate is low, hence the slowing down of glycolysis (no more energy is needed).
701048
The bleaching effect from lemon juice is limited and may only serve to dry out your skin.  You may want to consult a Dermatologist about this.  There may be more here than meets the eye.
775735
Coffee contains more antioxidants than fruit or vegetables. So if anything I would think it slows it down.
612140
This question has been asked numerous times.  Theses are User estee06's words.  I put a link below.\n \n\nApples and other produce (e.g., pears, bananas, peaches, potatoes) contain an enzyme (called polyphenol oxidase or tyrosinase) that reacts with oxygen and iron-containing phenols that are also found in the apple. The oxidation reaction basically forms a sort of rust on the surface of the fruit. \n\nYou see the browning when the fruit is cut or bruised because these actions damage the cells in the fruit, allowing oxygen in the air to react with the enzyme and other chemicals
831565
Alpha-hydroxy acids (AHAs) are found in milk, lemon juice, vinegar, blackberries, grapes, oranges, tomatoes, and apple juice exfoliate the skin by dissolving the glue that holds dead skin cells together. \n\nThey cleanse the top layer of skin, allowing the body's natural emollient oils to reach the surface cells and help moisturize and relieve dryness. They help cleanse oily skin and remove blackheads. \n\nAHA chemical peels of between 20 and 70 percent acidity are available from some doctors, but they are so strong they can leave scars, and the FDA believes that these strong peels could expose the skin to an increased risk of sunburn. \n\nThe ingredients such as organic apple cider vinegar, is an all-natural AHA that you can use at home (avoid the eyes), has seven percent acidity, and is a safe and sure way to get the benefit of fruit acids without danger to the skin (although even at this low level, you should be aware of the increased risk of sunburn). \n\nThe benefits of homemade fruit acids become evident as soon as you start using them; your skin starts feeling soft and smooth. \n\nTo my skin's great benefit I squeeze a lemon once a week and keep its juice in the refrigerator. In the morning, I dab some of the juice on my fingers and pat it onto my face, leave it on for ten minutes or so and then rinse.