Liquid rennet in an industrial way. Soxhlet's way of making liquid rennet is not perfect, because quite a lot of undesirable protein bodies pass into rennet, mostly mucins, which make it often sticky and cloudy. In addition, a lot of rennet ferment is lost in unfiltered residues.
Therefore, I am following Leitch with a more perfect method of preparing rennet, used with various changes in industrial plants.
The main feature of this method is the use of influence, which takes time to reduce the mucus and viscosity of the mucins. This makes it easier to extract as much of the ferment as possible and obtain it in a clear extract.
The main periods of rennet production are as follows:
1. selection and preparation of raw material,
2. preparation of the extract,
3. methods of clarifying and preserving the extract.
Rennet makers use already partially prepared stomachs. The raw material is already dried and requires little handling and storage, as long as the warehouses were dry. However, the raw material is not uniform and often contains harmful microorganisms. The best results are obtained, using stomachs 3 week old calves. Immediately after slaughter, the abomasum must be cut off, squeeze out its contents and immediately peel the muscle and fat parts clean, which is much easier to do in a fresh state than after drying. The grasses prepared in this way are puffed up and dried in the way we already know. It should be dried as soon as possible with 25 up to 30 ° C and with strong ventilation, because during slow drying, weaker or stronger gastric rotting and decomposition of the rennet leaven occur.
Dried stomachs are kept in dry and cool warehouses within 6 do 12 months. Then they "mature."”. This settling, when well dried, greatly reduces the transfer of mucins to the extract and facilitates subsequent filtering.
In a fresh state, stomachs can be salted, then dried. Doing so has the advantage, that parasites attack salted stomachs less than unsalted ones, but also this disadvantage, that they soak up moisture in the air and lose a lot of the rennet enzyme as a result.
Before the extraction, the stomachs are cut into small pieces with a razor and poured over them with a quantity of water 1 1 for two stomachs.
* Fluid composition, which is used for the extract, is quite important.
Regular brine gives good results. The amount of table salt used may be 7 do 20%.
Mixed extract of table salt and calcium chloride po 5 kg in 100 1 water is also effective and used, when stomachs "matured too briefly."”. The pH concentration is then to be 6,0 do 6,4, fluid temperature 12 do 15°C. If the stomachs are unstable and prone to fermentation, is used too much 2 do 3% boric acid, glycerin or thymol. When the lift is strong enough, which usually happens after 4 do 10 days, sinks (decant) carefully. The exhaust gas during this cloudy period can be run through a centrifuge, especially if it was dense and stringy.
A bit of table salt is then added to the extract, until it is achieved 14 do 16°Be, that is, to the specific weight 1,101 do 1,112. This addition of salt causes a slow precipitation.
The liquid prepared in this way should be left alone, that the sediment settles to the bottom of the pan, which should be tightly closed and protected from light. After a few weeks, when the rennet clears by itself, it can be poured into other vessels using a siphon without disturbing the cloudy layer. However, if noticed at the beginning of etching, that the rennet does not clear up, you shouldn't wait long, but to filter it.
Most filters adsorb excessively the rennet slurry. It can be seen, that the rennet seeps through the filter most often until it is not clear, until its pores are partially clogged or a semi-permeable layer forms within it. Charcoal filters adsorb a lot of rennet and therefore cannot be used here. On the other hand, sand filters give good results (very fine sand), and so do clay filters. However, the most common rennet is used in multi-chamber filters with fabric inserts, working under pressure.
Floaters obtained from fresh rennet extracts can also be clarified by precipitation or protein-like folding. Unfortunately, except table salt, most of these agents also rennet along with mucins, which kidnap her. Lactic acid in quantity 0,05%, sweet whey, 2% Cooked milk are also useful precipitants, but very dilute alum is most often used, as the most effective.
Most rennets are stained with caramel in saline or neutral orelate. This is supposed to prevent some of the sun's harmful effects, rather, it is about making the pillow pretty, yellowish cognac color.
The quality of rennet stored in warehouses often deteriorates due to the presence of certain microorganisms. You can find staphylococci in buyable rennet, streptococci, coli, putrefying bacteria, like Bact. putrificus, Bact. subtilis i mycoides, Cl. sporogenes, and in rennet stored in open vessels - also yeasts.