Wikipedia:Reference desk/Archives/Science/2016 March 21

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March 21

Is that true that vegetables as well as eggs lose their vitamins while cooking or frying?

I was told that vegetables as well as eggs lose their vitamins while cooking or frying. The one who told me it explained me that the cooking or frying causes to the denaturation which cancel the vitamins. Is that true or just speculation? 93.126.95.68 (talk) 03:10, 21 March 2016 (UTC)

I believe it depends on the specific food, and the cooking temperature and duration involved, and which nutrient we are talking about. Some are indeed reduced by cooking, while others may be enhanced or made more readily available. And of course, some foods are dangerous to eat uncooked. Raw eggs, for example, may contain salmonella. StuRat (talk) 03:22, 21 March 2016 (UTC)

Thank you. I'm not talking about something specific, but generally about foods. Regarding to the eggs, sometimes there is no option to cook it before eating (for example if we make frosting which made of uncooked eggs white) 93.126.95.68 (talk) 03:30, 21 March 2016 (UTC)

Well, the statement as given is pretty much false, in that denaturation relates specifically to proteins, not vitamins. Any degradation of vitamins by heat is due to some process other than denaturation. - Nunh-huh 05:12, 21 March 2016 (UTC)

I believe denature also has a broader meaning, meaning simply "to change the nature of", as in denatured alcohol. Perhaps they are using that meaning. StuRat (talk) 06:11, 21 March 2016 (UTC)

Anyway, here's some references:-

• Effects of different cooking methods on health-promoting compounds of broccoli ("The results show that all cooking treatments, except steaming, caused significant losses of chlorophyll and vitamin C and significant decreases of total soluble proteins and soluble sugars.").
• The effects of cooking on nutrition ("Heating affects mostly the vitamin and fat content of foods... On the other hand, cooking processes that involve heating also make certain nutrients more available for the body to use. For example, the amount of total carotenoids content in carrots and other vegetable-based dishes is higher in boiled versions.").
• Effects of different cooking methods on the vitamin C content of selected vegetables ("This study shows that any raw vegetable contains the highest content of vitamin C compared to that of cooked one. Eating raw vegetables is the best way to obtain vitamin C. Cooking methods (i.e. steaming, microwaving, and boiling) have huge impacts on the vitamin C content of vegetables. Steaming is the best cooking method for retaining the vitamin C content in vegetables.").
• European Food Information Council - The Why, How and Consequences of cooking our food ("Part 2.4: ...The differences in vitamin solubility mean that the method by which foods are cooked has a substantial influence on the final vitamin content. Due to their tendency to disperse in water, water-soluble vitamins in particular are heavily affected by cooking processes that involve immersing food in water for long periods of time e.g., boiling. In contrast, fat-soluble vitamins tend to be lost during cooking processes where foods are cooked in fat e.g., frying, or when fat is lost from the product e.g., grilling.").

So the answer seems to be yes, although this varies according to the cooking technique and the type of vitamin content. Alansplodge (talk) 11:14, 21 March 2016 (UTC)

However, in the case of boiling, since the vitamins leach into the water, the cure is to drink the water, as in soup. StuRat (talk) 16:58, 21 March 2016 (UTC)

You wouldn't have said this if you'd read the sources: "As well as the cooking medium, the length of heating can also affect the vitamin content of foods. Both fat-soluble and water-soluble vitamins are susceptible to heat, with the latter being particularly sensitive.""--TMCk (talk) 18:03, 21 March 2016 (UTC)

I already mentioned that in the first reply. My point is that for foods that really do need to be cooked, for food safety reasons, or to make them palatable, boiling is a much better choice, so long as you then drink the water. Steaming is also good, but frying is bad all the way around. As far as the reduction in nutrition from the heat, eating more can compensate for that. Since veggies have few calories, you can eat quite a few. StuRat (talk) 18:32, 21 March 2016 (UTC)

And e coli. Cook your vegetables as you would cook your beef because the same animals fertilize both. Cooking and 8 billion people are not coincidence. --DHeyward (talk) 09:03, 23 March 2016 (UTC)

With eggs you actually lose vitamins by not cooking - see egg white injury. With other vegetables I'd need to see a specific analysis - breaking down the tissue might release some components to be absorbed, and might allow others to become soluble in cooking water that is disposed of, and might even damage some chemically (though I'm not sure what) ... it really needs an empirical test for a specific substance. Wnt (talk) 11:20, 23 March 2016 (UTC)

What is the substance in eggs which cause them to be foamed while mixing (and at all)?

1) What is the substance in eggs which cause them to be foamed while mixing (and at all)?

2) Are detergents considered foamed substances or they are not? Because I always see that soap has foam. If it is something that is added to the soap, what is the reason for that? Does it help in cleaning? 93.126.95.68 (talk) 03:23, 21 March 2016 (UTC)

1) Albumin causes foam. StuRat (talk) 03:25, 21 March 2016 (UTC)

2) Not directly answering your Q, but note that soap and detergent are two different things. StuRat (talk) 03:48, 21 March 2016 (UTC)

Sodium laureth sulfate is a very common foaming agent and detergent found in bath soaps and the like. EvergreenFir (talk) Please {{re}} 04:12, 21 March 2016 (UTC)

Thank you for your comment. I always thought that the active ingredient in soap is the detergent. 93.126.95.68 (talk) 04:09, 21 March 2016 (UTC)

The wiktionary entry (detergent) claims a detergent is a "non-soap cleaning agent, especially a synthetic surfactant". Personally I'm skeptical. I think it's correct to say that soap is properly a detergent, but that in common usage, if you mean soap, you just say soap, so if you say detergent, you usually mean one of the other ones. --Trovatore (talk) 05:26, 21 March 2016 (UTC)

Ah, the IUPAC Gold Book asserts explicitly that "soaps are ... detergents". I'm not a huge fan of IUPAC and their attempts to uniformize naming, but at least this should provide an example of "detergent" used inclusively. --Trovatore (talk) 05:31, 21 March 2016 (UTC)

The substances in eggs that cause them to make foam when beaten are proteins that trap bubbles of air - see [1]. Richerman (talk) 07:08, 21 March 2016 (UTC)

I know this wasn't your question but FYI the water from a can of chickpeas is usable as an egg-white substitute because it foams in the same way. Apparently it's not known why though. 78.148.107.251 (talk) 23:19, 22 March 2016 (UTC)

Which substance does increase the output while drinking tea or coffee?

I've read in professional article by laboratory professor (here) that tea or coffee cause to increasing in urine output. My question is which substances that are found in these drinks, cause the increasing of the urine output? or by which mechanism if it's known 93.126.95.68 (talk) 04:04, 21 March 2016 (UTC)

The main substance in coffee or tea that causes increased urination is water. In addition caffeine has a modest diuretic effect, but this appears to diminish with regular consumption. Shock Brigade Harvester Boris (talk) 04:09, 21 March 2016 (UTC)

Thank you. But when people drink water they don't have increased urination as they have while the drink tea, water or beer (which all of them actually contains less H2O than water) 93.126.95.68 (talk) 04:31, 21 March 2016 (UTC)

In the case of tea (without sugar or milk), it's got to be over 99% water. StuRat (talk) 05:41, 21 March 2016 (UTC)

Also, drinking any water-based liquid in sufficient quantity would cause the body to urinate to maintain homeostasis. I think what the article you linked is saying is that tea and coffee will increase urination above and beyond what a comparable amount of water would cause. Shock Brigade Harvester Boris is right that the diuretic effect of tea and coffee is almost certainly due to its caffeine content. EvergreenFir (talk) Please {{re}} 05:57, 21 March 2016 (UTC)

That's true for coffee, but tea -- black or green tea (Camellia sinensis), not herbal tea -- has a rather strong diuretic effect, largely due to its theobromine content. Looie496 (talk) 14:11, 21 March 2016 (UTC)

Alcohol (i.e. the ethanol in beer) is, by itself, a diuretic. This is mentioned at Vasopressin#Regulation, see also some popular science coverage [2] [3] and this research article [4]. SemanticMantis (talk) 16:20, 21 March 2016 (UTC)

Perhaps a bit late to the discussion, but as I recall, metabolites of caffeine (e.g. theobromine) cause vasodilation, increased blood flow to the kidney (afferent arteriole) and renal corpuscle, and an increase in filtration into bowman's capsule. This would elevate urine production. I don't remember if there is an inhibitory affect on Antidiuretic hormone as there is with ethanol. If I had to guess, I'd say no.  Wisdom89 ^♦talk 17:44, 22 March 2016 (UTC)

Airplane susceptibility to winds

Why is that when a plane is airborne, it's more susceptible to strong winds and wind shear compared to standing on the ground with engines shut off (ignoring parking brake)? And why the engines of an airborne plane often can't offset a strong wind, while with engines shut off during parking the airplane is capable to stand still? Thanks. --93.174.25.12 (talk) 08:38, 21 March 2016 (UTC)

To a large extent the answer is the parking brake you're "ignoring". An aircraft in flight cannot respond to sudden gusts or changes in wind direction because it cannot accellerate quickly enough. At high altitude during cruise it doesn't usually matter very much but during landing or take-off even a small change in direction, altitude, airspeed, and/or attitude can be catastrophic. While parked an aircraft is not as sensitive to wind because it is not moving relative to the ground and the brakes and tyres provide a lot of resistance to movement. In severe weather parked aircraft can also be tied down to the ground for extra security. Roger (Dodger67) (talk) 12:57, 21 March 2016 (UTC)

(ec) An airborne airplane must maintain controlled Flight by continually balancing the forces of lift, thrust, drag and directional Aerodynamics where every external air movement can cause immediate deviation in any of the flight dynamic angles i.e. pitch, roll and yaw. The control task is so difficult that automatic Fly-by-wire computers are sometimes introduced to replace a pilot's conventional manual flight controls. In contrast, a plane parked on the ground is in a stable equilibrium; it should be safely imobilised against winds by both parking brake and Wheel chocks and its flaps not be left in take-off configuration so that not even a strong wind can lift the plane's weight. There is no need to explain why a plane can park undisturbed in a headwind that its engines would lack enough thrust to fly against. AllBestFaith (talk) 13:03, 21 March 2016 (UTC)

Wind speed increases with altitude. A plane in flight will (generally) be subjected to stronger winds than one on the ground. Iapetus (talk) 13:48, 21 March 2016 (UTC)

The original premise is incorrect. Airspeed is airspeed; it doesn't matter whether the relative motion of air with respect to the airfoil it is caused by natural wind or as a consequence of applying engine power to produce thrust. There are a handful of minor details, like propeller wash, p-factor, or slipstream effect - and these only apply to some types of aircraft (check the official pilot's operating handbook for each aircraft!) - but these confounding factors don't change the basic fact: the wing does not know why air is rushing past it. It will produce lift if there is sufficient airflow.

Some of the most difficult and potentially hazardous elements of operating an aircraft are the difficulties taxiing (driving on the ground) during strong winds.

Have a look at the Airplane Flying Handbook, section on taxiing; and next, take a look at the chapter on Transition to Tailwheel Airplane, for some of the maneuvers pilots must learn to stay on the ground, moving in the correct direction.

As far as shear: low level wind shear is hazardous because it can cause an aerodynamic stall at very low altitude as the aircraft escapes the surface zone and the ground effect. The hazard is because at low altitude, there is very little room for error in applying a correction. Abrupt changes in the wind direction or wind vertical component will require careful, coordinated adjustment of the flight control, angle of attack, and/or engine power. Otherwise, wind shear is no different at altitude or on the ground.

For very small and light airplanes, like Citabrias, the airplane stays parked on the ground during a stiff breeze because it is tied down with ropes. If the winds are strong enough... well, here's a famous video from c. 2014. The wind was very strong - exactly strong enough to cause the airplane to fly (with or without the engine running). Some fast-reacting aviators spun up the engines so that they could maintain control of the aircraft and take them out of the area.

Nimur (talk) 16:26, 21 March 2016 (UTC)

Several redlinks show up in my post: apparently we don't have articles on everything!

Some specific references, for interested readers:

• Low Level Wind Shear: Invisible Enemy To Pilots (from NOAA), on the science and the history, including a fatal 1985 airline disaster
• Our article on wind shear and Low level windshear alert system
• The PHAK, Chapter 11-11, is on Low Level Wind Shear
• On prop wash and slipstream: the Airplane Flying Handbook, Chapter 4, Slow Flight, and certainly elsewhere in the book, there is extensive discussion of these aerodynamic phenomena...
  • The section on high performance maneuvers and slow flight both discuss the risks of wind and gusts during operations that are close to the critical angle of attack.
  • Read and memorize the unintuitive bits. Unintentionally stalling at low altitude still requires the exact same recovery procedure as intentionally stalling at high altitude - pitch forward. Pilots who encounter abrupt wind shear that causes a stall on takeoff must therefore unintuitively steer "toward the ground" to recover from the stall. (The uninitiated pilot may pull back to fly "away" from the ground, but that's not how airplanes work). Reluctance or hesistation to correctly recover from a low altitude stall will bring about a rapid reacquaintance with the ground. Here is a great historical film, Stalling for Fun and Profit Safety (1974).
• There probably ought to be separate articles on deep stalls and tail stalls...

Some time later this week, I'll try to create some articles for those redlinks.

Nimur (talk) 16:40, 21 March 2016 (UTC)