Why is root beer the only carbonated soft drink that seems to retain its head indefinitely? Does root beer generate so much foam for the same reason that alcoholic beer does?
Traditionally, as its name implies, root beer was flavored by extracts from the roots and bark of plants, most commonly sassafras. The foam associated with root beer is linked inextricably to proteins in the product. According to Brendan Gaffney, senior research specialist at Pepsi-Cola, makers of Mug root beer; “Protein stretches in contact with surfaces such as water, air and other contact surfaces to form films under turbulent conditions (shaking, pouring, pressure, etc.) that produce foam bubbles.”
The same sassafras that traditionally provided the flavoring for root beer also tended to produce and preserve the foam (so did the birch in birch beer).
But about thirty years ago…
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