Whipped cream and foamed milk add value and customer satisfaction to coffee bought on the high street, but they come with a burden on the environment.
Currently, whipping cream and foaming milk require nitrous oxide (N2O) as a propellant and foaming agent, which is delivered in single-use aerosol cans and siphons that are refillable with N2O charger bulbs.
N20, however, has a global warming potential nearly 300 times that of carbon dioxide (CO2).
In its 2018 Baseline Environmental Report, Starbucks said the N2O used in its whipped cream accounted for half its global Scope 1 emissions that year. The report declared an N2O emissions value for the company equivalent to nearly 160 million kilotons of CO2, representing the use of 67 million steel N2O charger bulbs in a year.
Now, Cambridge start-up Triple Line Technology has created TLT-Foamer, the world’s first eco-friendly compressed gas siphon for whipping cream and foaming milk using compressed air or nitrogen.
Either can be passed through a series of alternating shear fields with a foamable liquid to generate microfoams with bubbles under 100 microns in diameter, which is suitable for the whipped cream and foamed milk used in coffee drinks.
Company co-founder Mark Nicmanis explained that when a cream whipper is charged with N2O, the gas dissolves into the cream or other food product. When the product is dispensed, it experiences a rapid pressure drop from inside the whipper to atmospheric pressure, which causes the dissolved N2O to rapidly boil out of the solution within the product.
“This creates a massive volume expansion of the gas that 'aerates' and whips the cream or other product,” he said.
However, compressed air or nitrogen have low solubility in foods under pressure. Nicmanis added that in a conventional cream whipper, compressed air or nitrogen would sit in the headspace and act as an air-spring, forcing liquid or poorly aerated product out when dispensed.
“To use compressed gases such as air or nitrogen in a whipper, a new mechanism of including the gas into the product, whilst achieving the desired levels of gas and volume increase in the product [overrun], is required,” he said. “The technology developed by TLT is a flow path geometry, which is fed with a specific ratio of liquid product and compressed gas that forms a biphasic flow.”
Nicmanis continued: “As this biphasic flow passes through an alternating set of bends within the flow path, small bubbles are torn off from larger gas packets. This process is iterative, resulting in a homogeneous end product.”
Customer feedback indicates that the TLT-Foamer produces textural attributes that are very similar to those of traditional whipped cream products.
“However, our method of whipping cream has two distinct differences to nitrous based methods,” said Nicmanis. “It is possible to vary the geometry of our system so that different levels of gas will be incorporated in the whipped cream. This allows our system to dispense creams with a wide range of textures from slightly thickened creams, with air content around 20 per cent, to very rigid stiff creams, with air content 60 per cent and above.
“The gas bubbles in whipped cream dispensed by our system are much more monodispersed than those in a N2O based whipped cream. Hence our system tends to form much more stable whipped creams due to the reduced levels of Ostwald ripening that occur within our whipped cream.”
TLT said its compressed gas siphon can be charged using small charger bulbs containing compressed air or nitrogen. It can also be charged via a compressor or compressor base unit, a gas cylinder or a nitrogen generator, which removes the need to manufacture, fill, ship and dispose of the charger bulbs.
The company added that its patented solution could also offer an alternative to single-use foam aerosols in other retail and industrial sectors.
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