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Aerated chocolate

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An Aero bar, split to show the aerated chocolate within

Aerated chocolate is a type of chocolate that intentionally contains gas, forming bubbles. Aerated chocolates have a lower density than regular chocolates and melt more smoothly in the mouth. Aerated chocolate was first brought to market in 1935 by British chocolate maker Rowntree's under the brand Aero. Other companies ignored the process's patent, and today multiple producers make aerated chocolate.

There are four types of aerated chocolate. The main type, seen in Aero, has large bubbles and is produced under a vacuum or by beating gas into liquid chocolate under pressure. Aerated chocolate with tiny bubbles uses the same beating gas method but uses nitrogen. Aerated chocolates containing long tubes of air are extruded rather than moulded. The final type, an aerated chocolate held together by a skeleton of solid particles rather than fats are produced by forming an emulsion between ingredients and sugar dissolved in water, and then reducing the water content by freeze drying or regular evaporation and drying.

History

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In September 1935, British chocolate manufacturer Rowntree's brought the first aerated chocolate, Aero, to market.[1] At the time, Rowntree's had been struggling for several years to compete with Cadbury Dairy Milk and was looking for a new product to this end.[2] The new chocolate was the outcome of significant research[3] focused on developing a "count line" chocolate,[a] inspired by the recent introduction of the Mars bar to the UK market.[5] Rowntree's covered their aerated chocolate under a broad patent, capturing products including variants such as chocolate with inclusions.[6] As it was released to market, the new chocolate garnered strong sales and positive reviews, although some concerns were voiced within Rowntree's that the product would be a novelty.[7]

Rowntree's initially promoted aerated chocolate as more digestible than solid chocolate and as avoiding regular chocolate's "cloying after-taste",[8] though this was objected to by rival chocolate manufacturer Cadbury, who petitioned Rowntree's to stop putting down rival chocolate makers in their marketing.[9] Cadbury positioned their crumbly Flake, and chocolate maker Fry's their aerated-honeycomb-filled Crunchie bars as competition, but neither were seen by customers as "aerated" in the same sense as Aero.[3] Further to their objections about aerated chocolate's digestibility, Cadbury contested the validity of the patent itself.[9] In September 1936, Fry's released an aerated Crunchie bar made entirely of chocolate. They justified this move, saying it did not breach the patent as it was not a block but a bar.[10] As Aero sales began to dip, Rowntree's brought out new product lines, selling the first aerated chocolates with fruit and nut inclusions.[10]

After Fry's launched a second aerated chocolate in August 1937 called Ripple, Rowntree's agreed to allow chocolate manufacturers to manufacture aerated chocolates after June 1938 if they committed to paying Rowntree's a sum upon releasing new aerated chocolate lines and a 0.5% royalty on sales.[11] After this agreement was put in place, Cadbury only released aerated chocolate products in overseas dominions where Aero was not established.[12] Nestlé-produced aerated chocolates included a chocolate called Bubblo, made in the UK for export to New Zealand under a New Zealand patent.[13] By 1936, Aero was being successfully exported to Australia.[14] The American chocolate maker Hershey's purchased the Aero patent the following May, later altering the flavor and texture for the American palate.[15] During 1937, Rowntree's produced machinery for production in Ireland, Canada and South Africa, as well as for the companies Lindt and Van Houten.[16]

After production was temporarily paused in the UK during World War II, Aero returned to market, introducing aerated chocolate to a new generation, and by 1950 a product containing aerated chocolate coating wafers was released.[17] Wartime impacts on production were also observed in Canada and South Africa.[18] Beginning in the late 1950s in an effort try to improve falling Aero sales, Rowntree's began releasing new varieties. These included coffee and orange varieties that were sold only briefly, but also included peppermint, which became a permanent fixture. Marketing for these products abandoned the emphasis on aerated chocolate as a "unique" type of chocolate, instead focusing on the "bubbly" structure.[19]

A Wispa bar, split. Cadbury produced this chocolate using a secret, unpatented technique.[20]

In the 1970s, biscuit manufacturers began using micro-aeration to process chocolate for moulded products. This was a cost-saving measure: with less chocolate, the same volume of coated biscuit could be maintained. In 1981 or 1983,[20][21] Cadbury released Wispa, an aerated chocolate with a more chunky shape than Aero bars, made using a secret, non-patented process. The launch of Wispa was successful, but it soon encountered manufacturing difficulties and was temporarily withdrawn from the market. While Wispa was off the market, Rowntree's developed and launched a chunky Aero which they successfully launched and was still being sold as of 2008.[20] Wispa was discontinued in the early 2000s[21] so Cadbury could bring in a new aerated chocolate product aligned with the Cadbury Dairy Milk brand: Dairy Milk Bubbly.[b][22] Following an internet campaign in 2007, Cadbury reintroduced Wispa.[23] Today, Aero is manufactured by Nestlé.[1]

Types

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There are four types of aerated chocolates that have been sold:

  • Chocolate containing large, visible bubbles. Bubble diameters are between 0.05–3.0 mm (0.002–0.118 in), and the product is around half the density of regular chocolate. It is the most common type; Aero is a prominent example.[1]
  • Micro-aerated chocolate. The bubbles of this chocolate are so small as to be almost imperceptible to the naked eye. Micro-aerated chocolates are primarily used to coat chocolate biscuits in an effort to reduce the percentage of chocolate by weight.[1]
  • Chocolate containing long, continuous tubes of air.[1] These chocolates are made by extruding semi-set or solid chocolate. Cadbury used to sell this type of chocolate under the brand Spira.[1]
  • Chocolate held together by a skeleton of solid particles, particularly sugar, rather than fat which typically binds chocolate together.[24] This chocolate is used as an addition on items such as ice-creams and cakes after it is cut or roughly milled. For a time, this was sold on the Japanese chocolate market under the brand Poff.[25]

Characteristics

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Aerated chocolate has a lower density than conventional chocolate, giving it a greater volume for the same weight, a softer texture and an experience of melting more smoothly in the mouth.[1] Biting into some aerated chocolates produces an audible crunch, a phenomenon understood to be a product of its structure and texture. Upon entering the mouth, some aerated chocolates generate a "fragile mouth feel" and quickly melt when chewed. These phenomenon stem from the greater surface area, and intensify the flavor.[26] The crispiness has been attributed to the presence of larger bubbles.[27] Micro-aerated chocolates have a creamier taste and melt faster than regular chocolate,[1] while aerated chocolates held together by solid particles rather than fats can have an extremely low density (0.1–0.3 g/cm3 (0.0036–0.0108 lb/cu in)), allowing them to dissolve quickly in the mouth.[28] Chocolate foamed with nitrogen—and especially with nitrous oxide—have the most intense taste due to the larger bubbles these gases produce.[29]

Production

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Aerated chocolate containing large bubbles is produced via two methods. In the first, melted chocolate is put under a vacuum, where it foams up. As the chocolate cools, and the fats within the chocolate set, the foam structure remains. Sometimes gases such as carbon dioxide are introduced into the mixture before it is placed under the vacuum. While the method easily permits additions such as nougat or nuts, difficulty keeping production hygienic means the second method is more frequently used.[24] This second method involves working gases into liquid, tempered chocolate under high pressure.[30] Carbon dioxide is mainly used, although others include nitrous oxide.[30][26] Any gases that do not dissolve are dispersed as bubbles through the chocolate using a beater. As the chocolate is released from the high pressure conditions, the bubbles expand, foaming the product; through this, the amount of pressure directly impacts bubble size.[30] The setting chocolate is deposited in a molded shell, after which the set interior is capped with liquid tempered chocolate.[1] Factors that affect bubble size include qualities of chocolate, such as viscosity, rate of setting and ingredients (e.g. emulsifiers and milk fats). The type of gas, pressure differences and rate and change.[31][32]

Micro-aerated chocolate is created using the method of beating gases in under high pressure. Unlike aerated chocolates produced with large bubbles, micro-aerated chocolate has nitrogen beaten into the mixture. The resulting chocolate, different not only in bubble size but also flavor and texture, possibly arises from the different solubility of gas.[33] Aerated chocolates containing long tubes of air are also created using this technique, but their distinction comes from how the aerated chocolate is extruded rather than set in a molded shell.[28] The final type, those held together by a skeleton of solid particles, are produced using water evaporation methods. In the first of these, sugar is dissolved in water. This solution is emulsified with cocoa liquor and milk solids, which is evaporated and then dried using industrial machinery, until the product contains less than 2% water.[28] In the second, chocolate is emulsified with liquid chocolate and set and then freeze dried, removing the water.[33]

Research

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A major source of bubble instability is when a wide variety of sizes of bubbles are created, gases in smaller bubbles diffuses or disperses into larger bubbles. This is due to their respective Laplace pressures. As of 2023, technologies to control bubble size, distribution and movement were difficult to employ during production. "Advanced" research was underway, including by companies such as Nestlé.[27] In 2013, Chinese scientists announced results from a study using phospholipids derived from soybeans to aerate cocoa butter.[34]

Notes

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  1. ^ Count-line chocolates are those sold as individual units rather than as measured units of block chocolate.[4]
  2. ^ Cadbury replaced Wispa with Dairy Milk Bubbly as they wanted to streamline the number of brands they held, while not wanting to lose customers for aerated chocolate. It was part of a broader strategy of removing brands and reintroducing them under the Dairy Milk brand.[22]

References

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  1. ^ a b c d e f g h i Peters (2017), p. 418.
  2. ^ Fitzgerald (1995), p. 314.
  3. ^ a b Fitzgerald (1995), p. 320.
  4. ^ Fitzgerald (1995), p. 316.
  5. ^ Fitzgerald (1995), p. 317.
  6. ^ Beckett (2008), p. 24.
  7. ^ Fitzgerald (1995), pp. 320, 323–324.
  8. ^ Fitzgerald (1995), p. 324.
  9. ^ a b Fitzgerald (1995), p. 327.
  10. ^ a b Fitzgerald (1995), p. 328.
  11. ^ Fitzgerald (1995), p. 333.
  12. ^ Fitzgerald (1995), p. 337.
  13. ^ Beckett (2008), pp. 24–25.
  14. ^ Fitzgerald (1995), p. 585.
  15. ^ Fitzgerald (1995), p. 534.
  16. ^ Beckett (2008), p. 25.
  17. ^ Fitzgerald (1995), pp. 382, 400–401.
  18. ^ Fitzgerald (1995), pp. 535, 564.
  19. ^ Fitzgerald (1995), pp. 455, 458.
  20. ^ a b c Beckett (2008), p. 26.
  21. ^ a b Campbell (2008), p. 4.
  22. ^ a b Bradley (2008), p. 317.
  23. ^ Pfanner (2007).
  24. ^ a b Peters (2017), pp. 418–419.
  25. ^ Peters (2017), pp. 420–421.
  26. ^ a b Pugh, Hamlett & Fairhurst (2023), p. 1.
  27. ^ a b Pugh, Hamlett & Fairhurst (2023), p. 2.
  28. ^ a b c Peters (2017), p. 420.
  29. ^ Haedelt, Beckett & Niranjan (2007), p. E142.
  30. ^ a b c Peters (2017), pp. 419–420.
  31. ^ Beckett (2019), pp. 126–127.
  32. ^ Hartel, von Elbe & Hofberger (2017), p. 455.
  33. ^ a b Peters (2017), p. 421.
  34. ^ Nieburg (2013).

Sources

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  • Beckett, Stephen T (2008). "The History of Aerated Chocolate". In Campbell, Grant M; Scanlon, Martin G; Pyle, D Leo (eds.). Bubbles in Food 2: Novelty, Health and Luxury. American Associate of Cereal Chemists International. St. Paul, Minnesota: Elsevier Science. ISBN 978-1-891127-59-5.
  • Beckett, Stephen T (2019). The Science of Chocolate (3rd ed.). Croydon, United Kingdom: Royal Society of Chemistry. ISBN 978-1-78801-235-5.
  • Bradley, John (2008). Cadbury's Purple Reign. Chichester, UK: Wiley. doi:10.1002/9781119206361. ISBN 978-0-470-72524-5.
  • Campbell, Grant M (2008). "A History of Aerated Foods". In Campbell, Grant M; Scanlon, Martin G; Pyle, D Leo (eds.). Bubbles in Food 2: Novelty, Health and Luxury. American Associate of Cereal Chemists International. St. Paul, Minnesota: Elsevier Science. ISBN 978-1-891127-59-5.
  • Fitzgerald, Robert (1995). Rowntree and the marketing revolution, 1862-1969. Cambridge: Cambridge University Press. ISBN 0-521-43512-9.
  • Haedelt, J; Beckett, S T; Niranjan, K (April 2007). "Bubble-included chocolate: relating structure with sensory response". Journal of Food Science. 72 (3): E138–142. doi:10.1111/j.1750-3841.2007.00313.x. PMID 17995803.
  • Hartel, Richard W; von Elbe, Joachim H; Hofberger, Randy (2017). Confectionery Science and Technology. Cham, Switzerland: Springer Publishing. doi:10.1007/978-3-319-61742-8. ISBN 9783319617428.
  • Nieburg, Oliver (13 March 2013). "Aerated chocolate: new method for bubbles in cocoa butter". ConfectioneryNews. Retrieved 8 November 2024.
  • Peters, Dave J (2017). "Non-conventional machines and processes". In Beckett, Stephen T; Fowler, Mark S; Ziegler, Gregory R (eds.). Beckett's Industrial Chocolate Manufacture and Use (5th ed.). West Sussex, UK: Wiley. ISBN 978-1-118-78014-5.
  • Pugh, RJ; Hamlett, CAE; Fairhurst, DJ (2023). "A short overview of bubbles in foods and chocolate". Advances in Colloid and Interface Science. 314 (102835). doi:10.1016/j.cis.2023.102835.
  • Pfanner, Eric (27 August 2007). "Taste of Victory: Online Outcry Revives a Chocolate Bar". The New York Times. Archived from the original on 29 April 2018. Retrieved 15 April 2025.
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