Nu­tri­tion

How to make a drink from juice of the vi­ta­min C-rich cit­rus fruit with­out de­stroy­ing the good­ness.

New Zealand Listener - - CONTENTS - by Jen­nifer Bow­den

How to make a drink from vi­ta­min C-rich le­mons with­out de­stroy­ing the good­ness.

Ques­tion:

Does pour­ing boil­ing wa­ter over juice to make a lemon drink cause the same loss of nu­tri­ents as cook­ing some veg­eta­bles?

An­swer:

Su­per­foods, fresh foods, real foods – there’s much ado about which foods are the best nu­tri­ent sources. But you raise an equally, if not more, im­por­tant point: how food is pre­pared has a big ef­fect on the nu­tri­ents avail­able to us. The fac­tors that most af­fect ­veg­etable nu­tri­ent loss are how finely the veg­eta­bles are chopped and the vol­ume of wa­ter they’re cooked in. Many of us will re­mem­ber par­ents or ­grand­par­ents boil­ing veg­eta­bles such as cab­bage or brus­sels sprouts in a saucepan full of wa­ter un­til they were un­recog­nis­able by sight, smell or taste.

Whether you choose to mi­crowave, steam or boil veg­eta­bles, leave them as in­tact as pos­si­ble, and cook them in only a small amount of liq­uid to ­con­serve wa­ter-sol­u­ble vi­ta­mins. The smaller you chop veg­eta­bles, the greater the sur­face area ­avail­able for nu­tri­ent loss by leach­ing into the cook­ing wa­ter. Wa­ter-sol­u­ble mi­cro­nu­tri­ents such as thi­amine and other B vi­ta­mins, folic acid and vi­ta­min C are par­tic­u­larly sus­cep­ti­ble to leach­ing. They’re also dam­aged by heat. In con­trast, fat-sol­u­ble nu­tri­ents such as ­carotenoids and vi­ta­mins A, D, E and K aren’t af­fected by cook­ing. Min­er­als are mildly af­fected by leach­ing but not by heat.

Cook­ing ac­tu­ally makes nu­tri­ents such as the ly­copene in toma­toes more bioavail­able. Canned ­toma­toes that have been heated dur­ing ­pro­cess­ing have more avail­able ­ly­copene than the raw fruit.

Ly­copene is a carotenoid found in only a hand­ful of fruits and

­veg­eta­bles, in­clud­ing guavas, wa­ter­mel­ons and pink grape­fruit, giv­ing them their red colour. It is an an­tiox­i­dant and may be re­spon­si­ble for some of the health ben­e­fits of eat­ing toma­toes and other veg­eta­bles, such as re­duc­ing LDL choles­terol lev­els and in­flam­ma­tion.

Ly­copene-con­tain­ing foods may also re­duce can­cer risk. A 2016 study, for in­stance, found that men who ate more ly­copene had an 11% lower risk of prostate can­cer than those who con­sumed the least.

So, what hap­pens to lemon juice, a rich source of wa­ter-sol­u­ble and heat-sen­si­tive vi­ta­min C, when it is heated? Pak­istani re­searchers in­ves­ti­gated.

They found that at 25°C, lemon juice con­tained 10mg of vi­ta­min

C per 100ml; at 50°C, the level was 9.33mg; and at the max­i­mum tested tem­per­a­ture of 52°C, the level had fallen to 6.66mg.

In this study, the lemon juice was heated rather than boil­ing wa­ter be­ing added, which would have meant it was hot for longer. The longer it is at a high tem­per­a­ture, the greater the dam­age to the vi­ta­min C. Con­versely, evap­o­ra­tion of wa­ter from the juice would have con­cen­trated the vi­ta­min C.

Since about twothirds of the vi­ta­min C in the lemon juice was re­tained after the re­searchers’ ­heat­ing, it’s prob­a­bly safe to as­sume a sig­nif­i­cant ­pro­por­tion of the vi­ta­min C in your lemon wa­ter would be re­tained even after boil­ing wa­ter was added.

But if you want to re­duce losses, you could use very hot rather than boil­ing wa­ter, and drink it sooner rather than later to pre­vent more

­dis­ap­pear­ing.

You can re­duce the vi­ta­min C loss by us­ing very hot rather than boil­ing wa­ter.

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