Aerated chocolate

An Aero bar, split to show the aerated chocolate within

Aerated chocolate, also known as air chocolate, is a type of chocolate that intentionally contains gas, forming bubbles.

Biting into some aerated chocolates produces an audible crunch, a phenomenon understood to be a product of its structure and texture. On entering the mouth, they generate a "fragile mouth feel" and quickly melt when chewed. These phenomenon stem from the greater surface area, and intensify the flavor.[1] The crispiness has been attributed to the presence of larger bubbles.[2]

History

In 1935, British chocolate manufacturer Rowntree's brought the first aerated chocolate, Aero, to market.[3] The process for making the new chocolate was covered by a broad patent, capturing a variety of tablets including ones embedded with additions such as nuts.[4] Rowntree's initially promoted aerated chocolate as more digestible than solid chocolate, though this was objected to by rival chocolate manufacturer Cadbury. Further to these objections, Cadbury contested the validity of the patent itself.[5] In September 1936, chocolate makers 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.[6] After Fry's launched a second aerated chocolate in August 1937 called Ripple, Rowntree agreed to allow chocolate manufacturers to manufacture aerated chocolates after June 1938 if they agreed to pay Rowntree a sum upon releasing new aerated chocolate lines and a 0.5% royalty on sales.[7] After this period, Cadbury only released an aerated chocolate in markets in overseas dominions where Aero was not established.[8] Nestlé-produced aerated chocolates included a chocolate called Bubblo, made in the UK for export to New Zealand under a New Zealand patent.[9]

By 1936, Aero was being successfully exported to Australia,[10] and The Hershey Company purchased the Aero patent in May 1937, later altering the flavor and texture for the American palate.[11] During 1937, Rowntree's produced machinery for production in Éire, Canada and South Africa, as well as for the companies Lindt and Van Houten.[12] In the 1970s, biscuit manufacturers began using micro-aeration to process chocolate for moulded products. In 1981 or 1983,[13][14] Cadbury released Wispa, an aerated chocolate made using a secret, non-patented process. While its launch was a success, while it was temporarily withdrawn to resolve manufacturing difficulties, Rowntree developed and launched a chunky Aero which was still on the market by 2008.[13] Wispa was discontinued in the early 2000s, and Cadbury did not sell aerated chocolate until releasing Dairy Milk Bubbly in October 2007 following an internet campaign.[14] Today, Aero is manufactured by Nestlé.[3]

Production

Aerated chocolate is less dense than conventional chocolate, giving it properties of a greater volume, a soft texture and melting experience. The most commonly produced aerated chocolates have visible bubbles with diameters between 0.05–3.0 mm (0.002–0.118 in). To make most of these products, aerated chocolate is poured into a shell. After it has set, liquid chocolate is poured over to form a smooth back.[3] Factors affecting bubble size include chocolate viscosity, how fast it sets, the type of gas, pressure differences, and the rate of change of pressure.[15] Although chocolate is typically foamed with carbon dioxide, aerating chocolate using other gases such as argon have been researched.[1] Chocolate foamed with nitrogen—and especially with nitrous oxide—has the most intense taste. This is due to the larger bubbles these gases produce.[16]

It is produced under a vacuum or by beating gas into the chocolate under high pressure.[3] In the former, liquid chocolate, sometimes mixed with a gas is placed in a vacuum, forming a foam which maintains its shape when the fat sets. This process easily permits additions (such as nuts or nougat), but is difficult to keep hygienic and as a result the latter method is more frequently used. In high pressure aeration systems, gas is worked into liquid tempered chocolate under a high pressure. Gas that does not dissolve is dispersed as bubbles using a beater.[17] Using different gases generates different bubble sizes, flavors and textures, possibly due to different solubility properties of gases.[18]

Another type is micro-aerated chocolate, which contains bubbles invisible to the naked eye, producing a faster melting and creamier product. It is used on chocolate biscuits to reduce the percentage of chocolate by weight. Semi-set or solid chocolate extruded creates a final type of aerated chocolate, containing continuous tubes of air running through. Cadbury previously sold this type of aerated chocolate under the name Spira.[3] Unlike normal chocolate where the material is held together by fat, some aerated chocolate is held together with a skeleton of solid particles (particularly sugar).[3][17] This aerated chocolate can have an extremely low density (0.1–0.3 g/cm3 (0.0036–0.0108 lb/cu in)), allowing it to dissolve quickly in the mouth.[18] It is produced by emulsifying water (optionally containing sugar sugar) with liquid chocolate or chocolate liquor and milk solids. Removing the water then leaves the aerated chocolate behind.[18][19]

Research

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.[2] In 2013, Chinese scientists announced results from a study using phospholipids derived from soybeans to aerate cocoa butter.[20]

References

  1. ^ a b Pugh, Hamlett & Fairhurst (2023), p. 1.
  2. ^ a b Pugh, Hamlett & Fairhurst (2023), p. 2.
  3. ^ a b c d e f Peters (2017), p. 418.
  4. ^ Beckett (2008), p. 24.
  5. ^ Fitzgerald (1995), p. 327.
  6. ^ Fitzgerald (1995), p. 328.
  7. ^ Fitzgerald (1995), p. 333.
  8. ^ Fitzgerald (1995), p. 337.
  9. ^ Beckett (2008), pp. 24–25.
  10. ^ Fitzgerald (1995), p. 585.
  11. ^ Fitzgerald (1995), p. 534.
  12. ^ Beckett (2008), p. 25.
  13. ^ a b Beckett (2008), p. 26.
  14. ^ a b Campbell (2008), p. 4.
  15. ^ Beckett (2019), pp. 126–127.
  16. ^ Haedelt, Beckett & Niranjan (2007), p. E142.
  17. ^ a b Peters (2017), p. 419.
  18. ^ a b c Peters (2017), p. 420.
  19. ^ Peters (2017), p. 421.
  20. ^ Nieburg (2013).

Sources

  • 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.
  • 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.
  • Nieburg, Oliver (5 July 2012). "Nestlé in space: Aerated chocolate under zero-gravity". ConfectioneryNews. Retrieved 8 November 2024.
  • 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.