The brine pickle which is formed during the eight days is not allowed to run to waste, but is used for filling up the barrels after they have been repacked. This brine pickle contains amino bases, together with small quantities of coagulable proteids, and is of distinct nutritive value. The Poles and Russians, who are great consumers of these salted herrings, actually use the pickle as a kind of sauce or gravy, dipping their bread in it. This, together with the general demand for salted herrings in these two countries, may very largely be due to the comparative scarcity and high price of salt there.
A cran of herrings (about 1,000 fish, weighing approximately 3 cwts.) uses up 1 cwt. of salt and, when completely salted, just fills a barrel. The curer estimates that 5 to 6 tons of salt will be sufficient for 100 crans of herrings. Herrings salted in this proportion should be exported and consumed before the warm weather comes, as they are liable to decay if the temperature rises above 70° F. The herrings that were packed for the British Government (1920-1921) were salted more heavily than usual (7 to 8 tons of salt per 100 crans), as, owing to the uncertain condition of the Russian and German markets, it was necessary to keep some of the fish in stock for a considerable time. Such a heavily-salted fish would be unpalatable to the home consumer.
In Yarmouth and Lowestoft, and also in Scotland, 100 crans of herrings should fill, when cured, from 125 to 130 barrels.
Herrings are sometimes salted at sea, 1 ton of salt being used to each last (10 crans) of herrings. Such herrings are mostly used to make “red herrings.”
Red Herrings. A considerable trade in red herrings is done with the Mediterranean and the Levant. For this trade, the fish must be thoroughly smoke-cured, otherwise they will not keep in the comparatively warm climate. The fish are first of all dry-salted in concrete tanks about 10 ft. square and 6 ft. deep, arranged under the floor of the curing house. Fresh fish and salt are simply thrown in and mixed up, and left to develop their own pickle.
Generally speaking, 1 ton of salt is used to 10 crans of herrings, and each tank will hold from 20 to 30 crans of the fish. The fish should be left in these salting tanks for five days at least; sometimes, of course, they are left for months, according to the trade, in which case the tanks practically serve as storage tanks for the salted fish. The fish are removed from the tank as required, washed, and put on “speets” and smoked. A “speet” is a wooden rod about 3 ft. 6 ins. long and pointed at one end. The fish are threaded on the speet through the gill openings and mouth, each speet holding from 20 to 30 fish. The speets are then stacked horizontally on racks in the smoke house “loves” (lofts), about 6 ins. apart and about 12 ins. above each other, until the smoke house is filled from the roof to within a few feet of the floor. When the smoke-house is filled, fires are lighted on the floor. Generally, the fuel used is oak turnings, shavings, and sawdust. This material burns quickly, and gives a very resinous smoke which not only dries the fish, but also permeates it thoroughly.
The rate of curing and the character of the finished product depend upon the temperature of the smoke, and the proportion of antiseptic resinous materials in it. When the oak or other suitable hard wood fuel is in the form of turnings or dust it burns quickly, and thus produces a fairly hot smoke, containing antiseptic substances—for example, guaiacol and creosol. Such a smoke will cure the fish quickly.
If oak billets or logs are used they burn comparatively slowly. The smoke, therefore, is not so hot and, since slow combustion in this case probably means more complete combustion, the proportion of resinous constituents in the smoke is liable to be considerably diminished. When oak billets are used, therefore, curing takes place much more slowly.
The temperature in the smoke house will also depend very much upon the prevailing weather temperature outside. In cold weather it is difficult to keep the temperature up sufficiently. The curing takes longer, and results in a hard cured product. In very warm weather, on the other hand, it is difficult to keep the temperature down, and a “fired” fish is sometimes produced, i.e. one which is half-cooked and soft. Such a fish is clearly unsuitable for packing for export.
Generally speaking, the temperature of the smoke should be such that the curing takes about 10 days.