Fish meal is a commercial product mostly made from fish that are not used for human consumption; fishmeal is generally used to feed farm animals in an agricultural setting. Because it is calorically dense and cheap to produce, fishmeal has played a critical role in the growth of factory farms and the number of farm animals it is possible to breed and feed.
Fish Meal manufacturing process
Fishmeal is made by cooking, pressing, drying, and grinding of fish or fish waste into a solid from. Most of the water and some or all of the oil is removed. Four or five tons of fish are needed to manufacture one tone of dry fishmeal.
Of the several ways of making fishmeal from raw fish, the simplest is to let the fish dry out in the sun before grinding and pressing. This method is still used in some parts of the world where processing plants are not available, but the end product is poor quality in comparison with ones made by modern methods.
Cooking: The fish are moved through a commercial cooker — a long, steam-jacketed cylinder — by a screw conveyor. This is a critical stage in preparing the fishmeal, as incomplete cooking means the liquid from the fish cannot be pressed out satisfactorily and overcooking makes the material too soft for pressing. No drying occurs in the cooking stage.
Pressing: The cooked fish is compressed inside a perforated tube, expelling some of its liquids, leaving "press cake". Water content is reduced from 70% to about 50% and oil down to 4%.
Drying: The press cake is dried by tumbling inside a heated drum. Under-drying may result in the growth of molds or bacteria; over-drying can cause scorching and reduction in the meal's nutritional value.
Two alternative methods of drying are used:
• Direct: Very hot air at a temperature of 500 °C ( 932 °F) is passed over the material as it is tumbled rapidly in a cylindrical drum. While quicker, heat damage is much more likely if the process is not carefully controlled.
• Indirect: The meal is tumbled inside a cylinder containing steam-heated discs.
Grinding: The dried meal is ground to remove any lumps or bone particles.
Any complete diet must contain some protein, but the nutritional value of the protein relates directly to its amino acid composition and digestibility. High-quality fishmeal normally contains between 60% and 72% crude protein by weight. Typical diets for fish may contain from 32% to 45% total protein by weight.
Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors of certain eicosanoids that are known to reduce inflammation in the body and improve hypertriglyceridemia. There has been a great deal of controversy in recent years about the role of fish oil in cardiovascular disease, with recent meta-analyses reaching diﬀerent conclusions about its potential impact. The most promising evidence supports supplementation for prevention of cardiac death.
Fish oil and omega-3 fatty acids have also been studied in a wide variety of other conditions such as clinical depression, anxiety, cancer and macular degeneration, yet their benefit in these conditions has also not been verified.
The fish used as sources do not actually produce omega-3 fatty acids, but instead accumulate them by consuming either microalgae or prey fish that have accumulated omega-3 fatty acids. Fatty predatory fish like sharks, swordfish, tilefish, and albacore tuna may be high in omega-3 fatty acids but, due to their position at the top of the food chain, these species may also accumulate toxic substances through bio magnification. For this reason, the United States Environmental Protection Agency recommends limiting consumption (especially for women of childbearing age) of certain (predatory) fish species (e.g. albacore tuna, shark, king mackerel, tilefish and swordfish) due to high levels of the toxic contaminant mercury. Dioxins, PCBs and chlordane, as well as other chlorinated cyclodine insecticides are also present. Fish oil is used in aquaculture feed, in particular for feeding farmed salmon.
Often marketed and sold for consumption as part of the diet or in dietary supplements in contemporary societies, fish oils also have found roles in external use, as emollients or as general ointments as well as in body art or for alleged insulation against cold temperatures.
The most widely available dietary source of EPA and DHA is cold-water oily fish, such as salmon, herring, mackerel, anchovies, and sardines. Oils from these fish have a profile of around seven times as much omega-3 oils as omega-6 oils. Other oily fish, such as tuna, also contain omega-3 in somewhat lesser amounts. Although fish is a dietary source of omega-3 oils, fish do not synthesize them; they obtain them from the algae(microalgae in particular) or plankton in their diets.
Caviar (also known as caviare; from Persian is a food consisting of salt-cured roe of the family Acipenseridae. Caviar is considered a delicacy and is eaten as a garnish or a spread. Traditionally, the term caviar refers only to roe from wild sturgeon in the Caspian Sea and Black Sea (Beluga, Ossetra, and Sevruga caviars). Depending on the country, caviar may also be used to describe the roe of other species of sturgeon or other fish such as salmon, steelhead, trout, lumpfish, whitefish, or carp
The roe can be "fresh" (non-pasteurized) or pasteurized, with pasteurization reducing its culinary and economic value.
The main types of caviar are Beluga, Sterlet, Kaluga hybrid, American osetra, Ossetra, Siberian sturgeon and Sevruga. The rarest and costliest is from beluga sturgeon that swim in the Caspian Sea, which is bordered by Iran, Kazakhstan, Russia, Turkmenistan, and Azerbaijan. Wild caviar production was suspended in Russia between 2008 and 2011 to allow wild stocks to replenish. Azerbaijan and Iran also allow the fishing of sturgeon oﬀ their coasts. Beluga caviar is prized for its soft, extremely large (pea-size) eggs. It can range in color from pale silver-gray to black. It is followed by the small golden sterlet caviar which is rare and was once reserved for Russian, Iranian and Austrian royalty. Next in quality is the medium-sized, light brown to rich brown Ossetra, also known as Russian caviar. Others in the quality ranking are the gray sevruga caviar, the Chinese Kaluga caviar, and the American osetra. The Siberian variety with black beads is similar to sevruga and is popular because of its reduced (5 years) harvest period, but it has a higher brine content than other kinds. The Chinese Kaluga hybrid varies in color from dark gray to light golden green and is a close cousin of beluga caviar.
Commercial caviar production historically involved stunning the fish and extracting the ovaries. Another method of extracting caviar is by performing a caesarean section, which allows the female to continue producing roe. Other farmers use a process called "stripping", which extracts the caviar from the fish via a small incision made along the urogenital muscle when the fish is deemed to be ready to be processed. An ultrasound is used to determine the correct timing. Removing the caviar by massage may yield higher quality and a more sustainable source.
Preparation follows a sequence that has not significantly changed over the last century. First, the ovaries are removed from a sedated female sturgeon and passed through a sieve to remove the membrane. Freed roes are rinsed to wash away impurities. Roes are now ready to become caviar by adding a precise amount of salt for taste and preservation. The fresh product is tasted and graded according to quality. Finally, the golden eggs are packed into lacquer-lined tins that will be further processed or sold directly to customers.
Storage and Nutritional Information
Caviar is extremely perishable and must be kept refrigerated until consumption.
Pasteurized caviar has a slightly diﬀerent texture. It is less perishable and may not require refrigeration before opening.
Pressed caviar is composed of damaged or fragile eggs and can be a combination of several diﬀerent roes. It is specially treated, salted, and pressed.
A spoonful of caviar supplies the adult daily requirement of vitamin B12, it is also high in cholesterol and salt. 1 tablespoon ( 16 g) of caviar contains: