7.0 THE CAVIAR SHOP

A special draining room with controlled atmosphere will be needed if the draining time lasts for hours. The packaging area is a dry room with a controlled, pressurized envi-ronment. Figure 7.3 shows a draining room.

FIGURE 7-3: Draining Room

The investments in constructing this line are not significant, whereas the gain in labour and quality is significant, as many manual handling operations are eliminated.

Full scale caviar processing is done on-boat or on-shore. Tens of processing barges are producing sturgeon caviar in the Volga, Ural and Amur rivers thus extracting ovaries within hours after catch. Full scale salmon and pollack caviar shops in the Soviet Union are operating on larger mother-boats at sea. In Canada, Japan and Alaska, on-shore salmon caviar operations prevail. Whitefish and lumpfish operations are exclusively on-shore.

7.2 PLANNING A SALMON CAVIAR OPERATION

The duration of the processing season is short and careful preparation is advisable. A hypothetical example is discussed below. Suppose, the concept of the operation is to purchase extracted and rinsed fresh chum ovaries and sell unpasteurized, chemically preserved chum caviar in institutional plastic pails (3 Ibs. each). The processing will take place in a facility licensed for caviar production.

The facility has a cold room to store ovaries, freezing chambers and good quality water supply. All the numbers in this exercise are set arbitrarily. The actual efficiencies in-volved could be exceeded or lowered.

The expected harvest of 60/000 Ibs. of roe will yield about 50/000 Ibs. of caviar, of which 75% will be grade No. 1 and the rest grade No. 2. Grade No. 2 ovaries can be processed as sujiko (salted ovaries) or converted into bait. Daily landings are set at 2 to 8,000 Ibs. Number of working days during the two-month processing period - 20.
Required screening capacity is planned assuming a 16-hour working day (two shifts) for the record landing day of 8,000 Ibs. Hourly screening capacity 8,000:16=500 Ibs/hour. Providing each screen accommodates two screeners and each of the screeners performs at a rate 125 Ibs/hour, we need two full size screening devices.

The suggested size of salting batch is 100 Ibs. and the duration of every salting cycle is on average 18 minutes. This would include salting in two steps, the second salting tak-ing place in unused brine and brine used not more then twice. For an egg/brine weight ratio of 1:3 we have to fill the salting tank with 3 x 100=300 Ibs. of brine. At 1.2 g/cm3 density this requires (300 x 0.45) 1.2=112 liters net volume for brine. Taking into ac-count the displacement volume of added salt, eggs, tools and headspace we can con-clude, that a salting tank of 250-300 liter capacity will suffice.

The number of batches salted per hour is 60/18=3.3 or 330 Ibs/hour. This means we need two salting tanks to provide for the maximum planned output 500 Ibs/hour. It is advisable to have one spare salting tank to eliminate the wasted waiting time for each tank being filled up, discharged or rinsed during processing. Thus the total number of salting tanks is 3.

If brine is used only twice at 1:3 ratio the daily consumption of 100% saturated brine is:

Brine-making device productivity should be:

To prepare this amount of brine 9 x 1.2 x 0.26=2.8 tons of salt will be used. To process 50/000 Ibs. of caviar/17.5 tons of salt are required.

Other materials:

The number of 3 Ibs. plastic containers:

It is important not to underestimate the draining space capacity needed. A standard fish-eries basket 40 x 26 cm with an egg layer 6 cm high will hold approximately 10 Ibs. of caviar. This means that for the projected maximum 8,000 Ibs. production 800 baskets are needed, unless packaging starts when salting is not yet finished. This translates into about 110 M2 of draining shelves.

Labour needed for each operation is given in Table 7-1 for the critical 8,000 Ibs. per day/ and average 2-3,000 Ibs. per day production. The packing operation, even for in-stitutional packages, is the most time-consuming operation. This is the reason that the conveyor type operation 'ovaries in - caviar out' has expensive labour costs. If caviar is left draining overnight, packaging can be done by the same crew members the next morning/ providing they are not busy with roe processing.

TABLE 7-1

CAVIAR PROCESSING CREW

Extending the draining-curing time overnight and doing packing next day will provide for the time needed for quality control and manual picking out debris.

In the case of maximum landings of 8/000 Ibs., a 16-hour shift is considered or the number of workers should be increased. It is advisable to have many crew members who are able to screen ovaries/ so workers on the screening operation could alternate. Screening is a labour intensive and tiring operation. It is assumed that a central brinemaking station is providing brine supply, and containers for packing are already washed.

7.3 WATER QUALITY

It is mainly salt and water, apart from fish eggs, which are used in caviar processing. The quality of both is of crucial importance for this non-cooked and perishable product.
Both dry and brine salting are common procedures in food technology. However, the perishable nature and pH range (4.3-5.8) of caviar products requires specific strict brine quality.

Water used for brine preparation should be of the highest drinking water (potable) qual-ity possible. Water from the mains of a municipal supply is usually disinfected (chlorin-ated) and regularly tested. It is supposed to be free from pathogenic organisms, deleteri-ous chemical substances and radioactive matter. It is usually potable and free of objec-tionable colour, odour and taste.

Because the public will not accept water hardness in excess of 500 mg/L of calcium carbonate, different softening measures are sometimes undertaken which may affect the taste of water. Very hard water may contribute to hardening of caviar after brining. In some situations e.g. for soft eggs this may be an advantage and it would be advisable to use unsoftened water. It is conceivable that the desire to process caviar on the fishing grounds in order to obtain the freshest product possible, may result in using an inde-pendent fresh water supply, where disinfection is not practiced. In this case it is advis-able to examine the water for the presence of Coliform organisms and the general bacte-rial population using the Standard Plate Count method.

According to the Guidelines for Canadian Drinking Water Quality the maximum ac-ceptable concentration for microbiological quality is:

For brine preparation purposes residual chlorine levels could be as high as 0.4 ppm. Wa-ter used for tool washing may contain 5 ppm of residual chlorine.

Another effective solution would be to use ultraviolet water purifiers. There are many designs of sterilizers where high intensity ultraviolet light waves permeate the water flowing through disinfection chambers. They provide not only bacterial inactivation, but also destroy viruses, yeasts, molds, algae and spores. They do not constitute any health risk.

The traditional Russian and Japanese good manufacturing practices require the brine to be boiled, filtered and then cooled or that the brine be prepared from previously boiled water. This provides for an additional product safety barrier. Boiling would also help to prepare 100% saturated brine in the absence of industrial brine makers. However, boil-ing is costly.

7.4 SALT QUALITY

Salt used for caviar should be of the highest possible quality. Its purity has a strong in-fluence on the salting process and the taste. This is especially true for caviar products which are prepared by the dry salting process and also when there are no special

brinemakers equipped with filters for the brine salting process. Table 7-2 contains specifications for the chemical composition of salt used for dry salting of sturgeon caviar.

TABLE 7-2

CHEMICAL ANALYSIS OF RECOMMENDED SALT (%)

The salt can be preheated to 150-160°C for two hours as an extra precaution to fight pos-sible microbiological contamination and excessive moisture which may occur because of improper storage.

The composition of salt for dry salting should provide 100% passage through 0.8 mm mesh and 95% through 0.5 mm mesh. There is no special size limitation for salt used in brine preparation as long as its solubility does not hinder the chosen brine making tech-nological process. The so called Fisheries brining salt produced by compacting fine granulated salt into high purity flakes may dissolve too slowly in low intensity dissol-vers.

The majority of salt used in the fisheries industry for brine preparation comply with the above mentioned stringent requirements in terms of chemical composition and dryness if produced in vacuum pans from chemically purified brines, and properly stored. Preheat-ing is then not needed. Cases are known where the use of solar dried salts, or other lower grade salts, resulted in active mould growth caused by salt tolerant organisms introduced with the salt. Another typical hazard is excessive amounts of calcium and especially magnesium salts, the later generating a bitter aftertaste in the product.

Salt is hygroscopic. Pure sodium chloride absorbs moisture from the air if the relative humidity is more than 76%. Chlorides of calcium and magnesium and sulphates of so-dium and magnesium are highly hygroscopic even at lower humidities.

The solubility of salt in water depends only slightly, on water temperature, see Table 7-3.

TABLE 7-3

SALT SOLUBILITY vs TEMPERATURE IN % Wt.

7.5 BRINE PROPERTIES

Brine is the general term for a solution of sodium chloride in water of any concentra-tion. Natural brine forms while dry salting. When salting salmon caviar we use saturated brine. Saturated brine provides for a quick and well controlled technological salting process with consistent results. Saturated brine's boiling temperature is 108°C. When rinsing eggs or ovaries low concentrated brines are used. As opposed to rinsing with wa-ter, rinsing with brines is advantageous, as it dissolves or detaches from the egg surface any protein and fat containing residual substances, connective tissue, slime and other impurities. Use of low concentration brines as opposed to water shortens the rinsing time.

The amount of salt in brine can be characterized in many ways (see Table 7.4) such as density. Borne degrees, or % of saturation. However saturation in % is the most popular index since it is equal to the quantity of saturated brine in liters required to prepare 100 liters of brine of the desired concentration. E.g., to prepare a brine of 72% saturation one takes 72 liters of 100% saturated brine and adds 28 liters water. The density of 100% saturated brine is 1.2 g/cm3. Most often brine strength is measured with a hydrometer which is calibrated in brine density (g/cm3) or in % of saturation.
It is well known that it is difficult to maintain 100% saturation during the technological process. As the solution approaches saturation, active agitation or other intensification measures are needed. Practically it is sufficient to work within the 98% saturation range.

TABLE 7-4

BRINE SALT SOLUTIONS AT 15°C

Brine solution freezing point depends on salt concentration. Heavily salted watery sub-stances, say of 7% salinity, could be stored at -4.4°C without being frozen, whereas, lightly salted caviar, say 2.9%, will only tolerate temperatures as low as -1.8°C. Practi-cally, caviar storage temperatures could be lower by 20-30% without causing the serious quality changes typical for deeply frozen caviar.

7.6 BRINE MAKING REQUIREMENTS AND APPARATUS

Large processing facilities operate industrial brine-making stations which produce 100% brine for general use. However, since caviar requires use of the highest quality salt, whereas other salting operations could use brine made from salt of lower grades/ there might be a need for special brine making apparatus. In addition brine accumulation tanks may be needed if the brine making apparatus does not provide for the planned daily capacity caviar processing requirement.

The reuse of brine for more than two batches is not recommended. When dealing with the highest quality mature roe and the absence of broken eggs, connective tissue residu-als or blood, brine could be used three times. But it must be fortified to 100% saturation. If the screened eggs contain a lot of broken eggs/blood and impurities, the brine should be used only once.

Soiled brine contains fatty particles from the yolk which sticks to the egg membrane and hinders the salting process. Brine regeneration through mechanical or biological filtra-tion is an option but it is only economical for on-boat operations. Very soiled brines should be boiled before filtration, so the proteins and broken egg skins coagulate and are easily filtered. Another effect of boiling is inactivation of microorganisms. It was shown that the number of microorganisms in the brine after the second and third use (without cleaning of the brine) and therefore the number of microorganisms in caviar, was increased 10 to 20 fold. Reusing brine leads to cross contamination.

A two-step salting procedure has been used. Each batch is salted twice, first in brine which has been used once and then in fresh brine. The required total salting time is the sum of the salting durations in each step. Such a procedure involves an additional opera-tion of unloading roe from the salting tank. This can be done easily only if the eggs are enclosed in a container during salting.

Salting is a short process and rapid, simultaneous unloading of all the roe from the brine is recommended. For this purpose caviar lots should be salted in batches of 100 kg or less, to make it easy to handle them. Roe is salted at different egg/brine ratios in the range 1:15 to 1:5 depending on the actual circumstances. During the salting process the salt concentration in the solution is diminishing as diffusion of salt into the roe pro-ceeds. That is why the egg/brine ratio may affect substantially the timing of the salting operation. At low ratios the brine concentration diminishes drastically and the salting process slows down. At high ratios the salting process is not hindered substantially.

Coarse salt, equivalent to 10-15% of roe weight, is always added to saturated brine be-fore salting starts. The salt stays on the bottom of the tank and is agitated simultane-ously with the roe. In this way the salt concentration does not fall substantially during salting. The same result can be achieved without adding salt by using roe/brine ratios higher than 1:3. However a practice increases saturated brine consumption and becomes expensive.

The final recommendations are to use an egg/brine ratio in the range 1:2 to 1:3. The salt used for brine fortification should be of large particle, size. Tiny particles will be lifted up by agitation and will stick to the egg surface. This may result in oversalting, as these small particles will continue to dissolve after the eggs are taken out of the brine for draining and curing. The contribution to final product salinity can be substantial.

Depending on the screened egg quality brine is getting soiled. The decision of using brine for the second time should be made depending on the actual circumstances.

A widely used practice is to prepare the brine in the tanks where the roe is salted. This leads to the need to prepare many batches of brine beforehand and then store them in a tank. Such procedures are inconvenient, thus a brine making apparatus is essential for brine salting caviar operations. Two types of apparatus, one available on the market, the other self fabricated, are shown on Figure 7-4. In both designs salt is added manually to keep the desired salt layer. Being heavier than water, brine collects at the bottom of the tank and becomes 100% saturated.

FIGURE 7-4: Brinemakers

Brine makers should be fabricated from stainless steel or polyethylene. In all these de-signs brine is produced without stirring.

A brine maker as shown on Figure 7-3 or, at 90 cm diameter and 120 cm of height will continuously pump saturated brine at a rate 36 liters per minute, dissolving salt at a rate of 650 kg per hour. Water enters the brine maker through a level controlled valve (4). The water enters the salt dissolving zone through a distributor (7). As brine is drawn off by a pump the water passes down through the salt bed and the 15 to 25 cm thick gravel filter (11) and into the collector (8).

One should note regarding the volume of the saturated brine, e.g. by diluting 52 kg of salt in 148 kg of water 200 kg of saturated brine is obtained but, the brine volume will be 186 liters.

7.7 SALTING TANKS

Dry salting of roe is usually done manually in small batches of 10-15 kg. Mixing by hand takes place in stainless steel or plastic bowls, or cylindrical vats, see Figure 7-5. Mechanical low revolution mixers, or mixing drums could be used to salt resilient eggs, e.g. pollack or herring caviar.

FIGURE 7-5: Dry Salting

Brine salting Figure 7-6 requires active agitation of the eggs in tanks. They are addition-ally mixed manually by a flat narrow paddle, and/or a wider meshed paddle. The meshed paddle catches membrane fragments, blood clots, lumps with attached eggs, Figure 7-7.

FIGURE 7-6: Top Drive Agitator

FIGURE 7-7: Meshed Paddles Catch Broken Eggs and Lumps

These paddles are made of nylon or metallic netting with the mesh size being twice the size of the first screen mesh size. It is advisable to use 8-10 clean mesh paddles for each batch, because they soil very quickly. These paddles are used to catch debris for both manual and mechanical salting tanks.

The salting tank commonly used in B.C. and Alaska is shown in Figure 7-5. It is a top drive agitator with two sets of blades. The lower one is meant to turn the excess salt which is put on the bottom of the tank to fortify the brine. The central shaft of the tank makes it inconvenient to scoop out the salted eggs after salting is over. The scooping is done using plastic roe baskets, different stainless steel mesh scoops, or bamboo baskets. Figure 7-8. Some losses always occur, as it is impossible to scoop out 100% of the eggs.

FIGURE 7-8: Scooping

To avoid this inconvenience, bottom drive (Figure 7-9b and c) salting tanks or pivotal shaft tanks (Figure 7-9e) are recommended.

FIGURE 7-9: Brine Salting Tanks

In salting tank design (Figure 7-9d) the eggs are agitated through the action of a brine jet. The brine is pumped through a filter and returned to the tank cleaned of debris. The brine may be reused several times if fortified to saturation by a buffer tank. A meshed screen (9) attached to the tank is used to catch debris and to enhance agitation.

If the salting tanks are free from a central shaft a 'half-circle' shaped scoop can be used to scoop out 100% of the eggs in one operation. The 'half-circle' scoop diameter should match the tank diameter, see Figure 7-10.

FIGURE 7-10: Half-Circle Scoop

Further development of salting tanks involves elimination of the scooping operation. In this case the eggs are salted in a perforated metal basket, placed in a rotating tank, see Figure 7-11. The bottom of the perforated basket consists of louvres, which can be opened (vertical position) or closed.

It is advisable to keep the egg/brine ratio in this unit to 4:1. The basket with 30-40 kg eggs is lowered by means of a hoist into the tank. The louvres are opened and the tank rotates at 60 r.p.m. To achieve better agitation and pick up debris, a manual or mechani-cal meshed paddle is used. After salting is finished, the tank is stopped and the majority of the broken egg membranes and debris falls to the bottom within 60-90 seconds. The louvres are then shut and the brine pump empties the tank. The eggs settle on the bottom of the basket. The basket is then lowered onto the support and the tank is rotated at 100 to 200 r.p.m. to dewater the eggs. Dewatering lasts 5-15 minutes. When the tank stops the eggs fall back from the walls to the louvred bottom and the basket is lifted out and emptied. The advantage of using a louvred basket bottom is two-fold: it facilitates the brine circulation in the tank and allows the broken membranes to be sucked out with the brine before the eggs settle onto the basket bottom. Solid bottom baskets with longitudi-nal narrow slits are also used. They too provide for the broken membranes and debris to be pumped out with the brine through the slits, whereas the eggs remain inside the bas-ket.

7.8 MISCELLANEOUS TOOLS, INSTRUMENTS AND MECHANISMS

The caviar processing shop environment subjects all tools, mechanisms and instruments to corrosion due to the concentrated brine. Egg yolk from broken eggs penetrates any small clearances and after it dries it sets up like glue which is very difficult to clean.

These specific conditions make it necessary to use non-corrosive materials like alumi-num alloys, plastic and stainless steel. Some cleaning solutions may be corrosive to aluminum. Stainless steel is the best ma