Newsletter 13
Citric Acid Citric acid is a weak organic acid that occurs naturally in citrus fruits. Lemons and limes have the greatest concentrations of citric acid but it is also found in oranges, grapefruits, tomatoes and pineapples. It is commonly used as a flavouring and/or natural preservative in many commercial food products, soft drinks and sweets. It also has powerful antioxidant properties meaning it can help to extend the freshness and shelf life a product. Within the European Union citric acid may be denoted by the E number E330.
The History of Citric Acid Use It is thought that citric acid was discovered by a Persian alchemist in the 8th century AD. A Swedish chemist isolated it from lemon juice in the late 18th century. Industrial scale production of citric acid began in the late 19th century. Today more than half the world’s annual production of citric acid is used in beverages. Approximately 20% is used in food products, another 20% is used in cleaning products and 10% is used in pharmaceuticals, cosmetics and the chemical industry.
Citric Acid and Kidney Stones According to the University of Michigan, citric acid inhibits the formation of kidney stones and prevents new ones from forming. The formation of urinary calculi or stones is known as urolithiasis. Stones may form in any part of the urinary system including the kidney, bladder or ureter. Kidney stones may cause blood in the urine and pain in the abdomen, groin or back. The development of stones is associated with decreased urine volume, decreased urinary citrate levels and increased excretion of stone forming components such as calcium oxalate. It is estimated that 1 in 20 people will develop kidney stones at some time in their lives with numbers on the increase in many parts of the world. The reasons for the increase include a high intake of sodium and animal protein which may both lead to increased urinary calcium excretion (1). Urinary citrate is a potent, naturally-occurring inhibitor of urinary crystallization. Citric acid has been shown to increase urinary citrate and thus may act as a nutritional preventative of calcium stone formation. This effect may be especially useful for patients with hypocitraturia (low urinary citrate). Beverages containing citric acid have been shown to increase the volume of urine thus reducing its saturation with calcium and other crystals. Citrate retards the formation and growth of calcium oxalate and calcium phosphate kidney stones by binding with urinary calcium and reducing the supersaturation of urine (2). In short, there are a number of mechanisms by which citric acid may be useful as a preventative against kidney stone formation.
Citric Acid as Food Preserver, Antimicrobial and Antioxidant An investigation into the antioxidant, antimicrobial and preservation effects of a solution of citric acid found that putting fresh cut apple slices into the citric acid solution delayed browning and reduced microbial activity even after 10 days of treatment. A considerable antioxidant potential was observed (3). Other freshly cut fruits and vegetables are likely to benefit from the same preservation properties (4)
Place the flower heads in a large non plastic bowl or pan with the sliced lemon. Bring 1.5 litres of water to the boil and pour over the elderflowers and lemon slices. Cover and leave overnight.
Citric Acid as a Cleaning Agent Citric acid has a chelating action meaning it can bind to metals. It is the primary ingredient in many commercial descaling products that are recommended for removing lime scale from bathrooms, kitchens, kettles and glass ware.
Citric Acid in Cosmetics and Personal Care Products Citric acid is widely used to balance the pH of creams and lotions. It is not always labelled on products as it is considered a processing aid rather than an active ingredient. It is an alpha-hydroxy acid (AHA) meaning it may be used as an active ingredient in chemical peels. Citric acid is often added to bath bombs and bath salts.
Remove the elderflower heads and discard. Strain the liquid through a muslin cloth or jelly bag into a sauce pan. Add the sugar and citric acid to the strained liquid. Gently bring to a simmer and cook for a few minutes until the sugar has dissolved.
Citric Acid in Medications
Using a funnel, pour the hot syrup into sterilised bottles. Seal the bottles and store until needed.
Citric acid is often found in effervescent indigestion remedies along with sodium bicarbonate.
Hot and Sour Soup
Citric Acid in Food Products
2 tbsp toasted sesame oil
Citric acid may be added to ice cream as an emulsifying agent to prevent fats from separating. It is added to caramel to prevent the sugar from crystallising. It may also replace fresh lemon juice in many recipes.
350g/12oz silken tofu, cubed
How to Use Citric Acid at Home
100g/4oz oyster mushrooms, sliced
Citric acid can be used in bread baking, cheese making, pickles, jams, chutneys, cordials, home made ice creams and as a substitute for fresh lemon juice in many recipes. To prevent cut fruit and vegetables from turning brown put them in a bowl of water with a heaped tsp of citric acid dissolved in it.
Recipes Elderflower Cordial 20-25 elderflower heads 1 lemon, sliced 1.5 litres of water 1kg/2lb sugar 2 tbsp citric acid
2 tsp root ginger, finely sliced 4 spring onions, finely chopped 1 cup of savoy cabbage, finely shredded ½ tsp cayenne pepper 1 tbsp tamari 1½ pints of vegetable stock or water 1 tbsp miso paste 1 tsp citric acid 2 tbsp fresh coriander, chopped Heat the toasted sesame oil in a large pan and add the tofu, ginger, spring onions, mushrooms, cabbage and cayenne pepper. Stir well to coat the vegetables in the oil. Add the tamari and cook for a few minutes. Pour the stock into the pan, bring to the boil and turn down to a simmer. Cook for a few minutes.
Remove some of the liquid from the soup and mix it with the miso paste. Return this to the pan along with the citric acid. Serve into bowls and sprinkle with fresh coriander.
De-Scaling Solution
Leave to dry in a warm, dry place for a couple of hours. Keep them out of direct sunlight. Putting them in nests of tissue paper or shredded paper helps them to dry and prevents round bath bombs from flattening on the bottom. Once dry store your bath bombs in an air tight container or wrap them in plastic bags. They will keep for a few weeks. They may lose their fizzing power if stored for too long.
This is particularly useful in hard water areas where lime scale gets deposited around the bathroom and kitchen. Add 25g/1oz of citric acid to 1 pint of water and mix well. Use to de-scale the kettle, coffee maker, taps, tiles, glass ware, sinks, bathroom and shower head. Hot water creates a more powerful de-scaler.
Please Note: It is best to make the bath bombs in dry conditions as high humidity can lead to the activation of the ingredients. Some people may react to the ingredients in the bath bombs so those with sensitive skin should use them with caution.
Lavender Bath Bombs The combination of bicarbonate of soda which is alkali and citric acid which is acidic produces carbon dioxide which will make your bath fizz! 225g/8oz bicarbonate of soda 100g/4oz citric acid 100g/4oz corn flour A handful of dried lavender (optional) 2 tsp of lavender essential oil 2-3 tbsp almond oil or sesame oil Put the bicarbonate of soda, citric acid, corn flour and dried lavender in a completely dry glass or ceramic bowl and mix really well – they need to be thoroughly combined. Combine the lavender oil and almond or sesame oil in a glass bowl or jar and whisk or shake well until well combined. Gradually add the wet ingredients to the dry about a tsp at a time, mixing the ingredients together as you go. If the mixture starts to fizz you are adding the wet ingredients too fast. Mix well to stop the fizzing and reduce the amount you add each time. Once all the ingredients have been combined you should have a mixture the consistency of damp sand that holds together when pressed, although it will still be fairly crumbly. Your bath bombs can be any shape you like. For round bath bombs shape the mixture into balls and place them in paper cake cases. Alternatively put some paper muffin cases into a muffin tin and press the mixture firmly into the paper cases. Ice cube trays, shot glasses, chocolate moulds, cookie cutters or jelly moulds are other options for shaping your bath bombs.
References Aruga S, Honma Y. Renal calcium excretion and urolithiasis. Clin Calcium 2011 Oct;21(10):1465-72 Penniston K, Nakada S, Holmes R, Assimos D. Quantitative Assessment of Citric Acid in Lemon Juice, Lime Juice, and Commercially-Available Fruit Juice Products. J Endourol. 2008 March;22(3):567-570 Hakkim FL, Mathiraj, Essa MM, Arivazhagan G, Guizani N, Hyuk S. Evaluation of food protective property of five natural products using fresh-cut apple slice model. Pak J Biol Sci. 2012 Jan 1;15(1):10-8 Chiumarelli M, Pereira LM, Ferrari CC, Sarantopoulos CI, Hubinger MD. Cassava starch coating and citric acid to preserve quality parameters of fresh-cut “Tommy Atkins” mango. J Food Sci. 2010 Jun;75(5):E297-304.
Writtten by Josie Cowgill Newsletter Design, Illustration and citric acid photo by New Gaia Designs Elderflower steeping in lemon slices photo by Madzik
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