Today in 1902, US Patent 3469992 A was issued, an invention of Frede B. Strandskov and Henry L. Ziliotto, assigned to the F&M Schaefer Brewing Co., for their “Chill Stability and Foam Adherence of Beer.” There’s no Abstract, although in the description it includes these claims:

The present invention relates to improvements in the chemical preservation of beer and more particularly it relates to the improvement of the chill stability and the foam adherence properties of beer which has been preserved against microbial growth by the addition thereto of a chemical preservative.

It is a desideratum in the beer making art to eliminate the necessity for pasteurization or refrigeration of finished beer. This is desirable (1) to avoid possible deleterious effects on the taste of the commercial product; (2) to avoid having to keep the beer refrigerated in storage before consumption; and/or (3) to obtain saving in cost per unit produced. It is known that beer may be preserved against microbial growth and the above objects thus accomplished, by treating the finished beer with heptyl parahydroxybenzoate, i.e., the heptyl ester of para-hydroxybenzoic acid as well as alkali metal or alkaline earth metal salts thereof. The discovery of the use of this compound to preserve finished beer represents a great advance in the art of beer making and provides the means by which the disadvantages of the necessity of pasteurization and/or refrigeration may be avoided. It has been discovered that the preservation in the abovemanner, however, tends to introduce complications which it is desirable to overcome if the most acceptable beer product is to be obtained.

In order to be commercially acceptable, a beer must possess certain properties; for example, it must be sparkling clear. Two additional properties which are most significant to beer connoisseurs are referred to as chill stability and foam adherence. The first of these relates to the property noted above as sparkling clear. As the name implies, on occasion a haze forms in some beer when it is chilled. As the temperature of the beer is returned to room temperature, the haze disappears, only to reappear upon subsequent rechilling. This haze is referred to as chill haze. The second of these significant properties, foam adherence, is of special importance to the connoisseurs. This property relates to the adherence of the beer foam to the sides of the drinking glass as the foam collapses or as the glass is being emptied. Beer, which in all other respects has excellent potential, may be excluded from the market solely because of the lack of an acceptable level of foam adherence. One of the marks of a beer connoisseur is his appreciation of the significance of beer foam adherence to the sides of the drinking glass.

3,469,992 Patented Sept. 30, 1969 In the instant invention it is important to note that foam adherence is notably distinct from the property of foam retention. Foam retention, or foam life, is a quality denoting the ability of the head, or layer of foam on a beer, to resist collapse with passage of time. Foam adherence as noted above refers to the ability of foam, as it collapses or as the beer is drained away, to leave a film of foam curtains or lace clinging to the walls of the container. It is from this curtain that the measurement of foam adherence is obtained. A significant foam curtain may be formed from beer, the head of which has completely collapsed and disappeared.

When finished beer is preserved against microbial growth by the addition thereto of heptyl para-hydroxybenzoate or a salt thereof, it has been found that adverse effects are sometimes produced on the acceptable values for chill stability and foam adherence. It is the object of the instant invention to overcome these adverse effects in order that the most commercially acceptable product possible may be obtained.