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Below we have provided you with an interesting excerpt from the BRAUWELT magazine, which highlights the topic “Use of hop pellets from previous harvests”:
After scarce hop harvests, pellets from older vintages are increasingly being used. There is multiple evidence that their quality remains virtually unchanged over at least five years. However, the prerequisite is that they are filled inert and stored cold. The composite film must be diffusion-proof – especially against oxygen – and the packaging must be protected from any injury. Since a-acids decrease over a long period of time even without oxygen in an inert atmosphere, the question arises whether and how this decrease should be taken into account when dispensing in the brewhouse.
On pellets from older vintages, moderate decreases in the conductometer values over the storage period are observed, provided they are kept inert and cold. According to the analyzes, pellets that are several years old should also be dosed at the time of manufacture. A reduction in the conductometer value is opposed by the formation of iso-a-acids. Although this only covers around 40% of the KW losses, the higher yields of iso-a acids in wort compensate for this. The hop oil does not undergo any noteworthy changes. Only the Hop Storage Index increases due to the formation of iso-a acids.
BRAUWELT No. 11, 2016, pp. 302, 304