The power of citrus fruits

Citric acid's power to tenderize and make flavours sparkle means that citrus fruits are versatile ingredients.

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Two dozen guests in a crowded room begin nibbling tentatively at freshly cut lemon wedges. Within a few moments, every one of us is laughing and exchanging looks of incredulity and amazement. We've just downed miracle berries: innocuous, cranberry-like, commercially grown fruits of West African origin. These berries make the lemon slices taste as sweet as candy; anything sour we consume over the next hour or so will be transformed into confectionery the moment it hits our tongues. Over the next hour, we chug vinegar (fruit punch!) and chow on chevre (cheesecake!) with the giddiness and elation of sugar-hyped five-year-olds. Later, while passing a bottle of antacids back and forth, we're reminded that no matter how delicious a lemon tastes going down, it's still a lemon. (So just make lemonade already.)

The winter following the miracle berry party, a farmer friend brought over a basket of various citrus fruits, the likes of which I'd never seen before. I've always adored the Meyer lemon, a fragrant, thin-skinned variety of lemon that takes particularly well to juicing and baking. Citrus limetta is a species of citrus that includes varieties such as Mediterranean sweet lemon and Palestine sweet lime, and unlike the mouth-puckering Meyer lemon, these specimens promise to be as sweet as lemon drops. But these were reminiscent of ordinary Eureka lemons without the requisite acid snap. At first, I wondered if the miracle berry had corrupted my palate.

As kids, we held annual lemonade stands, charging pocket change for plastic cups of cold lemonade, in its regular and pink iterations. Pink lemonade, originally made by Native Americans who used crushed red sumac berries for colour and maple sugar for sweetening, has since evolved into nothing more than orthodox yellow lemonade tinted rose with natural or artificial pink food colouring.

As I get older, I find that my sweet tooth has waned considerably. Nevertheless, I can usually find room after dinner for a bite of lemon curd Napoleon or a slice of Key lime pie. Hot, honey-sweetened cloudy lemonade, infused with mint, is a common folk remedy for a sore throat in the Arab world, but I love it as an alternative to herbal tea any day of the week. In the UK, "lemonade" refers to lemon and/or lime-flavoured carbonated drinks. In the US and elsewhere, "lemonade" refers to a blend of lemon juice and water, sweetened with sugar and sipped during the warmer months (with extra points for porches and rocking chairs as props).

Ceviche, made from fresh raw fish marinated in lemon or lime juice and enlivened with chilli peppers, is a popular dish in Central and South America. Guacamole or foul medames without a squeeze of fresh citrus juice? Unthinkable. Citric acid, which can constitute as much as 8 per cent of the dry weight of lemons and limes, brings life to pie fillings and sorbets; preserves freshness and colour; brings dimension and snap.

The word "citrus" is derived from the ancient Greek word for cedar (kedros); some believe this is due to similarities between the scent of cedar and those of citrus leaves and fruit. As a child in Ras Al Khaimah, I picked a pomelo the size of a basketball from a tree in my grandmother's yard and brought it home to my parents. I was amazed by the volume of cottony pith and the delicate, floral flavour of the fruit. At that point in my life, I had never encountered anything as exotic as even a ruby-red grapefruit (although an obsession with them loomed in the near future).

My favoured citrus fruit is the Cara Cara navel orange, a red-fleshed fruit that tastes of cherries, raspberries and flower petals. But what would Emirati cuisine be without the Omani lime, a small, salted dried lime with a very strong sour flavour and citrusy aroma? It is an indispensable seasoning also known as loomi or black lime. I routinely make Moroccan-style preserved lemons at home: meltingly soft lemons aged with coarse salt, coriander seeds, a bay leaf, a dried chilli and a cinnamon stick. In the past, I've attempted (without success) to grow oroblanco and Rangpur lime. I've made marmalade from "bitter" or Seville orange, and I've candied kumquat, citron and calamansi. I've juiced Valencia orange, tangelos, Minneola and tangors and blood oranges for juices. I've experimented with dishes containing yuzu, Persian limes, Ugli fruit, kaffir lime and Buddha's Hand. Over a lifetime, I've eaten my weight in Mandarin oranges such as satsuma, tangerines (a classification based on colour rather than botany), and clementines. Finally, I desperately covet the red-finger lime, a rare delicacy from Australia.

In college my best friend, an Iranian raised in Kuwait, had such a long-standing cultural aversion to salad dressing, and such a penchant for sour flavours, that she routinely doused her daily salad lunch with nothing but the juice of two or three lemons. After a sobering visit to her family dentist, however, I received a tearful phone call. "I was told that I should give up lemon juice," she sobbed, "If I want to keep my teeth, that is."

Lemon juice, in excess, is corrosive. I know this first-hand, having been one of many impressionable teenagers who painted lemon juice on to my skin and hair, in an attempt to lighten both. I ended up with painful telltale red welts on my upper lip and browline. In moderation, citric acid's powers to tenderise and can make flavours sparkle. In marinades, acid helps break down the collagen in meat, but it can also cure it if left for too long, leaving you with steak that has all the appeal of an old running shoe.

During the 1930s, when some were struggling to be fed, others were struggling to lose weight using the Hollywood Diet, a regime that revolved around black coffee, Melba toast and grapefruit. During the Great Depression, welfare offices issued food stamps redeemable for a free grapefruit, which introduced the fruit to many who had never heard of it. Subsequently, complaints were lodged that no amount of cooking made it edible. Of course, a spoonful of sugar can make a few things go down with ease.