C.METHOD FOR CHECKING THE EXTRANEOUS MATTER CONTENTU.K.
1.Determination of the leaf, stalk and waste contentU.K.
Sieve five 100 gram samples (or one 250 gram sample) using a 2 to 3 mm sieve. Collect the lupulin, waste and seeds and separate the seeds by hand. Place the samples on one side. Transfer the contents of the 2 to 3 mm sieve to a 8 to 10 mm sieve and sieve again.
The hop cones, leaves, stalks and extraneous matter are collected by hand from the sieve while cone leaves, seeds, lupulin waste and some leaves and stalks pass through. All this is sorted by hand and divided into the following groups:
leaves and stalks,
hops (cone leaves, hop cones and lupulin),
waste,
seeds.
Whereas it is extremely difficult to separate the waste and the lupulin precisely it is possible, using a sieve with a mesh size of 0,8 millimetres, to determine approximately the relative proportions of the waste and the lupulin.
When estimating the proportion of lupulin, it should be taken into account that the density of the lupulin is four times greater than that of the waste.
The various groups are weighed and the percentage which each group represents in the weight of the original sample is determined.
2.Determination of the seed contentU.K.
Place a 25 g sample in a metal container with a lid and heat in a drying oven for two hours at 115 °C in order to neutralise the sticky resin.
Wrap the dried sample in coarse cotton cloth and rub vigorously or beat mechanically in order to detach the seeds from the hops. Separate the dried and finely fragmented hops from the seeds with a grinder or a 1 mm metal sieve.
Separate any items remaining with the seeds using either a sloping surface covered with emery paper or any other method which gives the same result, i.e. retains the stems and other matter and permits the seeds to roll off.
Weigh the seeds and determine the percentage of seeds relative to the weight of the original sample.