Hop Storage Index¹

1 Contribution of the Oregon Agricultural Experiment Station in cooperation with the Science Education Administration, U.S. Department of Agriculture, both at Corvallis, OR 97331. Technical paper 5172 of the former.

Presented at the 45th Annual Meeting, Portland, OR, April 1979.

Abstract

The hop storage index (HSI) is used to estimate losses of α-acids and β-acids during storage and handling. HSI is determined from the ultraviolet absorbance measured in the spectrophotometric analysis of hops. Collaborative tests of the HSI measurement gave 1.3% within-laboratory and 2.8% between-laboratory coefficients of variation. The relationship between % (α +β) lost and HSI shows some year to year variation. The slope of the equation % (a +β) lost = slope X log(HSI/constant) was 101.8, 111.3, 114.5, and 114.6 for the 1969, 1975, 1976, and 1977 crop years, respectively. The HSI has been used in evaluating varietal differences in storage, measuring permeability and antioxidant levels in lupulin glands, determining hopping rates in breweries, and evaluating grower and dealer handling practices.

• α-Acids
• β-Acids
• Hop storage
• Spectrophotometric analysis