FISH

FISH are lower vertebrates that inhabit water. They belong to two classes of the vertebrate subphylum (Vertebrata) of the phylum Chordata—Marsipobranchii and Pisces. The former includes the cyclostomes (Cyclosto-mata)—lampreys and hagfish, while the latter includes true fish. Cyclostomes are characterized by the absence of jaws, a single unpaired nasal cavity opening to the outside with one orifice, and smooth, slimy skin completely devoid of scales. The gill openings either open independently (in which case there are seven or more pairs) or the gill channels on each side of the body flow into one common channel, in which case there are only two external respiratory openings (hagfish). Among the features of internal structure, it should be noted that the skeleton of cyclostomes is cartilaginous, and in addition, they retain the notochord (chord) throughout their lives. The skull consists of a connective tissue capsule that undergoes cartilaginous transformation; the auditory and nasal cartilaginous capsules connect with the proper skull. The mouth opening and tongue are covered with conical horn teeth. The heart is two-chambered. They are either separate sexes (lampreys) or hermaphrodites (hagfish). They reproduce with subsequent postembryonic development. They live in seas or fresh water as predators or parasites; they are pests of commercial fish. To cyclostomes belong the sea lamprey (Petromyzon marinus), river lamprey (P. fluVIatilis), etc., hagfish (MyXIne glutinosa), etc. Lampreys are eaten and prepared smoked. Digestive tract diseases have been repeatedly noted after eating lampreys. These disorders are associated with the toxicity of the secretions of the skin glands, of which lamprey skin is very rich. To neutralize lampreys, the caught fish is immediately salted; under the influence of chemical irritation, a large amount of mucus is secreted from the skin; then the lampreys are well washed and put into processing. True fish (class Pisces) have diverse body shapes, which are typically compressed from the sides and taper forward and backward. The head connects directly to the trunk with a broad base, which transitions into the tail at the rear. The body of fish bears paired and unpaired appendages called fins, which are typical aquatic limbs. With their help, fish swim (tail fin, pectoral and pelvic fins); unpaired fins act as keels. The skin of fish usually has scales, less often it has bony shields or, conversely, is completely bare. Both scales and shields are remnants of the external skin skeleton. The skin of fish is rich in single-celled glands. In some fish, there are continuous multicellular glands located in the grooves of the bony rays of the fins or in the spines of the gill cover. These glands are poisonous, and a sting from such fish is painful to varying degrees (sea scorpion, snakefish, etc.). The skeleton of fish is cartilaginous or bony. The skull is formed by a cartilaginous capsule; in many fish, the capsule ossifies at various points; in addition, due to connective tissue of the skin, the skull has additional bones. Generally, in bony fish, the skull is formed by a large number of bones. The visceral skeleton or gill arch skeleton is adjacent to the skull; the first pair of them is phylogenetically transformed into jaws. The skin scales of the tooth-shaped-placoid type transform into teeth covering the jaws. Fish breathe with gills, which in the form of rows of delicate lobes cover the gill arches. Between them lie gill slits. The digestive tract canal receives the ducts of the liver and pancreas. There are no salivary glands. In cross-mouthed fish, the hindgut opens into the cloaca, while in other fish it opens to the outside through the anus. For many fish, a swim bladder is characteristic, which is a hydrostatic organ and a gas gland; in open-bladder fish (salmon and other fish), it opens into the esophagus or stomach. Lungs are phylogenetically associated with it. The heart is two-chambered-venous; there is a venous sinus. In the venous system, the characteristic presence of anterior and posterior cardinal veins, which merge into the Cuvierian ducts, in turn forming the venous sinus. The kidneys are primary (Wolffian body). In cross-mouthed fish, the ureters open into the cloaca, while in other fish they open independently to the outside or form a terminal urinary bladder. They are separate sexes; rarely hermaphroditic. They spawn, rarely are viviparous. The brain consists of five sections lying in one plane and varying greatly in their development in different species of fish. There are 10 pairs of cranial nerves. Only the inner ear is present. They live in fresh or sea water. Both fish meat and roe are excellent food. From cod liver, fish oil rich in vitamins is obtained. From the swim bladder of cartilaginous sturgeon fish, fish glue (Colla piscium) is obtained; from fish, gelatin is also obtained and flour is prepared for fertilization. From the swim bladder, condoms are made. Shark skin is used for technical purposes. Commercial fish are of particular importance, which provide mass runs and are the subject of mass procurement (drying, smoking, salting, canned food, etc.). Some fish are artificially bred in fishponds. Successful attempts are being made to acclimatize fish. Of particular interest are attempts to acclimatize tropical viviparous fish—gambusia, which in masses destroy mosquito larvae and pupae. They are therefore used to combat malaria and other mosquitoes. Harm to humans from fish is determined by 1) the possibility of attack by large sharks, which maim and devour people, 2) stunning by blows from electric fish, 3) toxicity, 4) transmission of parasites. Fish are poisonous either when consumed as food (see below—fish as a food product) or when pricked with spines equipped with poisonous glands. Classification of fish. Subclass Selachia, or cross-mouthed (Selachia)—lower fish with a cartilaginous skeleton and a wide transverse mouth: sharks (Scillium canicula, Acanthia vul-garis), rays (Raja batis), electric ray (Torpedo marmorata), sawfish-P. (Pristis). Shark meat is of low quality, but is still eaten. From their fins, gelatin is obtained, the liver gives a low grade of fish oil. Subclass Teleostomi. Order cartilaginous or sturgeon fish (Chondrostei). They are very important commercially, as they provide very valuable products and delicious meat. The notochord is sold under the name of vizhiga. The roe and meat (balyk) are very nutritious and tasty: sterlet (Acipenser ruthenus), stellate sturgeon (A. stellatus), beluga (Huso huso), etc. Sturgeon fish, affected by bacteria but not changing in taste, color, or odor, can cause severe poisoning, often leading to death from 'fish poison'. Order bony fish, with a bony skeleton (Teleostei). Most currently living fish belong to this order. Salmon fish (Salmonidae): salmon (Salmosalar), trout (S. fario), chum salmon (Oncorhynchus keta), whitefish (Coregonus lavaretus), herring (Clupea harengus), sprat (Clupea sprat-tus), and many others. Carp fish: carp (Cyprinus car-pio), crucian carp (Carassius vulgaris), roach (Leu-ciscus rutilus), catfish (Silurus glanis), tench (Tinea vulgaris), bream (Abramis brama), marinka (Schi-zothorax intermedius) (Central Asia)—with poisonous roe. Eels: eel (Anguilla vulgaris), moray eel (Muraena helena)—a marine fish that causes painful bites. Perch-pike fish: mullet (Mugii cephalus). Spiny-rayed fish—with spiny fin rays: perch (Регса fluVIatilis), ruffe (Acerina cernua), red mullet (Mul-lus barbatus), goby (Cottidae), sea scorpion (Scorpaena porous) (Black Sea)—with poisonous spiny fins, sea bass (Sebas-tes norwegicus) (North Atlantic)—same, Synan-ceia (tropical seas)—same, weever fish (Trachinus draco)-(Black Sea)—with poisonous spines of the gill cover and dorsal fin, plaice (Pleu-ronectes platessa). Cod fish: cod (Gadus morrhua) (fish oil from liver, salted cod, labrador), burbot (Lota vulgaris, navaga (Gadus navaga). Suture-jawed (Plectogna-thi)—tropical seas, in the Pacific Ocean to Japan—pufferfish, Spheroides, etc.; among them are many poisonous ones due to the toxic properties of their roe, e.g., Tetrodon fahaea, Spheroides-chrysops, Ostracion, etc.; these fish are called pufferfish; their meat is tasty and harmless. Fish as disease transmitters. The harmfulness of fish in this respect is determined by their importance as intermediate hosts of human helminths and their role in poisonings. Regarding parasitic protozoa, fish have no significance for humans. Oocysts of coccidia parasitizing in the liver, gonads, and other organs of fish, when insufficiently cleaned fish are eaten, can pass transit through the intestine; when the feces are examined microscopically in such cases, they can be mistaken for parasites of the person themselves, whereas in fact there is a phenomenon of pseudoparasitism. However, many fish are intermediate hosts of a number of flukes and tapeworms, which humans become infected with when eating fish that is insufficiently heat-treated. It is remarkable that only bony fish are intermediate hosts of parasitic worms of humans. Among these fish, the following species deserve mention: family Salmonidae—trout (Trutta fario)—with plerocercoids of the broad tapeworm (Diphyllobothrium latum); Oncorrhynchus perryi (Japan, same);

Plecoglossus altivelis (Japan and Formosa) - encysted metacercariae of Metagonimus yokogawai; grayling (Thymallus vulgaris) - plerocercoids of the broad tapeworm; whitefish (Coregonus lavaretus) - same; vendace (Coregonus albula) - same; Family Cyprinidae: Carp (Cyprinus carpio) - metacercariae of Opisthorchis felineus; Goldfish (Carassius auratus) (China, Japan) - metacercariae of Clonorchis sinensis (Chinese fluke) and Metagonimus yokogawai; Barbel (Barbus fluviatilis) - second intermediate host of Opisthorchis felineus; Hemibarbus labeo - metacercariae of Metagonimus yokogawai; Pseudogobio sinensis (China, Japan) - metacercariae of Clonorchis sinensis; Pseudogobio rivularis (China), Biwia zezera (Japan), Leucogobio coreanus (Korea), Leucogobio strigatus (Korea), Leucogobio Güntheri (Japan), L. mayedae (Japan), Sarcocheilichthys variegatus (Schlegel) (Japan), S. nigripinnis (China), S. sinensis (China), S. morii (Korea), Abbottina psegma (China, Japan, Korea), Pseudorasbora parva (Japan, China), Ps. fowleri (China), Xenocypris davidi (China), Ctenopharyngodon idellus (China, Formosa) - all serve as second intermediate hosts of the Chinese fluke (Clonorchis sinensis); Leuciscus waleckii - metacercariae of Metagonimus yokogawai. Dace (Leuciscus rutilus) - metacercariae of Opisthorchis felineus; Idus jesus and Tinca vulgaris, same for Echinochasmus perfoliatus; Rudd (Scardinius erythrophthalmus) and Rhodeus sinensis (China) - metacercariae of Clonorchis sinensis; Acheilognathus limbatus (Japan), A. lanceolatus (Japan), A. cyanostigma (Japan), Paracheilognathus rhombeus (Japan), Pseudoperilampus typus (Japan), Acanthorhodeus atranalis (China), A. gracilis (Korea), Hypophthalmichthys nobilis (China) - metacercariae of the Chinese fluke; Bream (Abramis brama) - metacercariae of Opisthorchis felineus and larvae of Echinochasmus perfoliatus, Blicca bjoerkna - same; Asp (Aspius rapax) - second intermediate host of Echinochasmus perfoliatus; Culter brevicauda (China) and Hemiculter kneri (China) - metacercariae of the Chinese fluke. Family Esocidae - Pike (Esox lucius) - plerocercoids of the broad tapeworm and metacercariae of Echinochasmus perfoliatus. Family Gadidae: Burbot (Lota vulgaris) - plerocercoids of the broad tapeworm. Family Percidae: Perch (Perca fluviatilis) - same; Ruffe (Acerina cernua) - same. Family Osphronemidae: Macropodus opercularis (China) - metacercariae of the Chinese fluke. Family Gobiidae: Gudgeon (Gobio gobio) - metacercariae of Metagonimus yokogawai; Eleotris potamophila (China) - metacercariae of the Chinese fluke. Family Mugilidae: Flathead mullet (Mugil cephalus) (Egypt) - metacercariae of Heterophyes heterophyes. The distribution of larvae of parasitic worms in the body of fish varies. Plerocercoids of the broad tapeworm in pike and burbot are localized mainly in internal organs, whereas in perch the majority of plerocercoids are located in the body muscles. Among the internal organs, the liver, stomach wall, spleen, and ovary can be infected; in the latter case, plerocercoids can be found in the roe. Metacercariae of Metagonimus yokogawai are found exclusively in the scales, gills, and fins; metacercariae of Clonorchis sinensis are located in the muscles and under the scales of fish. Knowledge of the localization of invading forms of worms in fish is important, as it allows one to judge the degree of infectivity of fish for humans and makes it possible to take measures to decontaminate fish. In relation to plerocercoids of the broad tapeworm, it has been established that they lose viability after a two-week storage of fish on ice. In refrigerators, this period is significantly shortened. Fish with metacercariae are decontaminated by reliable heat treatment during preparation for food. Protection of fish themselves from infection with worms parasitic in humans can be achieved by public health measures aimed at protecting water bodies from the feces of parazitonositeley.

E. Pavlovsky. Fish as a food product. The nutritional value of fish is determined by the high content of basic nutritional elements (fats and proteins); in some cases, fish acquire greater value due to the high vitamin content of their individual parts or organs (fat, liver, fish meat) or due to the content of mineral substances (phosphorus, iodine, manganese, iron). Fish have the highest nutritional value and therefore high food value during the period of virginity, which is expressed in the abundant fat content with underdeveloped sexual organs (ovaries and milt). The nutritional value of fish is determined by the degree of fat accumulation; fish have the highest fat content in the period immediately preceding the spawning run; in the early period after spawning, fish have a low fat content and poor taste properties; their meat is tough and tasteless. Marine and freshwater fish differ from each other in composition and nutritional value and in the degree of fat accumulation. The nutritional value of marine fish (herring, salmon, mackerel, cod species) is enhanced by their high vitamin content, especially that of liver fat. Fish of rivers, lakes, and ponds are distinguished by the tenderness of their meat, but lower fat content. Fish species with high nutritional value are those that, while containing large amounts of proteins and fats, have an even accumulation of the latter in the muscles, and the fats belong to liquid fats, for example, among salmon - noble salmon, whitefish, nelma, as well as whitefish, catfish, etc. Some commercial fish, on the contrary, contain incomplete proteins, an insufficient amount of fats, and in the composition of extractive substances - substances that significantly reduce the taste properties of fish. Some commercial fish species, depending on food and environment, acquire a tinge in smell and taste that reduces the taste properties of fish meat (for example, carp in still water acquire a muddy taste, iwashi and Pacific herring acquire a specific taste of algae, etc.). With appropriate processing, this taste disappears or weakens. The commercial food value of fish is related to the percentage of edible and inedible parts; this percentage varies considerably; the amount of waste reaches 62% in perch and bream and does not exceed 14.4% in sturgeon. The amount of waste depends not only on the fish species but often also on its age. In some fish species, the percentage of edible parts, as an exception, reaches 100 (in lampreys). It is more correct to determine the nutritional value of fish by the composition of fish meat, in particular by the sum of the percentages of proteins and fats. The amount of protein in fish varies among different species from 11% to 26%, fats - from 0.2% to 34.1%. The water content in fish varies among different species within wide limits - from 53% to 84% (lamprey, flounder), but more often reaches 70-80%. The fat of fish meat belongs to semi-liquid fats and consists of glycerides of oleic, linseed, palmitic, and stearic fatty acids. The proteins of fish meat (proteins) in terms of nitrogenous compounds are very close to the proteins of higher vertebrate animals. Fish proteins are rich in tyrosine, arginine, cystine or histidine and lysine with a constant presence of tryptophan, i.e., they are rich in amino acids that are particularly important for the nutrition of our body. The mineral composition is of considerable importance, in certain cases increasing the nutritional value of fish. The mineral composition in percentage terms ranges from 1.0-3.0%; marine fish have a higher salt content - 3-11%. Of the elements combined with phosphoric, hydrochloric, and sulfuric acids, potassium, sodium, calcium, and magnesium are present; iron is present in small amounts; in marine fish, iodine, copper, and manganese are also found. The richness of fish meat in phosphorus-containing proteins has important physiological significance, as 'organic phosphorus' is introduced into the body with them. Small fish are rich in phosphorus proteins. Extractive substances are present in fish meat in small amounts and can be almost completely extracted during boiling or by simply infusing fish meat. They determine the taste of fish, which is why they are also called taste substances. According to their chemical composition, extractive substances are divided into nitrogenous and non-nitrogenous, and among them there can be

both indifferent substances and strongly acting ones (for example, urea in sharks, rays, and saline ammonia). There is insufficient data on the vitamin content of fish meat of various breeds. It is considered proven that vitamins A (growth) and D (anti-rachitic) are contained in the liver and fish fat of various internal organs and tissues and in the roe of F. The degree of digestibility of fish meat, besides general physiological conditions and the body's habit, also depends on the properties of the fish meat itself and its processing. It is known that fatty fish is digested more difficultly than lean fish; denser fatty F. is digested more difficultly than fatty F. but with tender tissues; salted F. of strong brine (proteins have undergone coagulation) is digested more difficultly, but when subjected to a special ripening process (herring, chum salmon and some others) it is digested well; processing (drying, smoking) improves the digestibility of F.; especially difficult to digest is fish that is salted and highly dehydrated. The digestibility of salted F. is increased with appropriate culinary processing in combination with carbohydrates (potatoes). Fresh F. with mixed food is digested better than beef. Practically, it can be considered that the proteins of fish meat are digested just as well as the proteins of beef or other meat, and better in raw form than in boiled form; smoked fish (due to good peptonization) is digested better than smoked beef. The digestibility of cod has been well studied: the meat of cod can be compared with such nutrients as beef, eggs and milk. Of the individual parts of F., the following should be noted. The milt occupies a secondary place in F. in terms of food value and is used only as an appetizer product with various seasonings. Viziga, or the outer shell of the dorsal string of sturgeon F., specially processed and dried (incomplete protein), also has little food value. The liver of F., differing in many breeds of F. (in particular cod, hake) in its high fat content, is usually not used as food, with the exception of the liver of the burbot, which, after appropriate culinary processing (boiling, canning, etc.), has high taste and nutritional properties. The greatest commercial and hygienic significance is the roe of F., which is eaten either in raw form, slightly seasoned with salt after being removed from F., or in canned form after processing with salt by rather complex methods. Roe is an extremely unstable product that sharply changes its initial freshness within 24 hours, after which it becomes unfit for food and processing. The roe of salmonid breeds and especially of sturgeon breeds differs in significant taste and nutritional properties. The nutritional value of roe F., especially of sturgeon and salmonid (and unlike freshwater F. also of cod), increases due to the content of vitamins A and B and lecithin. Organization of fish catching. The success of the development of the fishing industry is usually determined by the size of the catch. The larger or smaller percentage of salted F. released (not herring breeds) to a certain extent indicates the technical imperfection in processing F. by other methods (for example, freezing, canning). The technical backwardness of the fishing industry, forced to subject a huge amount of fish to coarse salting, still exists today, and the population of the USSR is still mainly a consumer of salted F. Among the main defects in the organization of catching and preserving F. from spoilage at collection points is the insufficient development of refrigeration. The shortcomings and technical backwardness of the fishing fleet also have hygienic significance, since this creates unfavorable conditions for the timely delivery of F. to processing points. The biggest drawback is the unsatisfactory organization of fishing enterprises in a sanitary respect. A very serious sanitary moment is the enormous contamination of many of our fishing grounds in the Volga-Caspian region and partly in others with larvae of the cheese fly-jumper; decisive measures are required to combat this pest. Finally, the most important sanitary factor is the backwardness of technology, expressed in the use of crude methods of handling F., which reduce its quality condition (throwing, injuring). The hygienic assessment of various methods of catching F. is determined precisely by the conditions aimed at improving the technology of fish catching itself in a hygienic respect and preserving its freshness. Any gear can be considered hygienic if, when used, it does not cause significant damage to F. in terms of injuries, bruises and death and the depletion of its food reserves. The speed in delivering the caught F. should be considered the most essential hygienic moment. Therefore, active fishing, especially mechanized, should be considered first in terms of hygiene. This should include trawling, Norwegian purse seine, Danish seine with a cod end. Passive fishing with hook gear should be considered unsatisfactory from a hygienic point of view, since the injured, exhausted or sleeping F. remains in the water for an indefinite long time. Negative attitude should be taken towards methods of catching in the form of poisoning F. with various baits, stunning F. and so on. The transportation of F. also has great hygienic significance. The conveyor movement of fish on receiving rafts and mechanical devices for transporting F. to processing points create favorable conditions for protecting F. from bruises, injuries, and consequently from rapid spoilage. Processing of F. The purpose of processing F. is to prepare F. for storage either without significant changes in its composition and properties or by means of significant changes in properties and composition, to preserve it from spoilage or finally, together with preservation, to give it culinary processing and special taste properties. Every caught F. must necessarily undergo so-called preliminary processing, which consists of several operations. The first operation includes the inspection of F. and sorting (primarily by quality); during sorting, F. is distributed according to freshness and the condition of its body. The commercial evaluation divides it into grades (according to generally accepted standards, conditions, etc.). The rejection of F. damaged, exhausted by spawning or diseases, or having been on the gear for a long time (drifter), is at the same time a very important moment. F. prepared in large quantities for transportation in so-called fresh form is subjected to immediate cooling upon delivery to processing points, packed in containers (boxes, barrels, etc.) and layered with ice (fine crushed). Such F. is not subjected to any other operations. All other F. is usually subjected to thorough washing with water to remove mucus, dirt and other contaminants; the very important operation of cleaning and washing the gills, as a rule, cannot be carried out for technical reasons. The use of cooling is an essential condition for preserving F. in fresh condition and begins from the moment of unloading F. from the gear onto fishing vessels, which must have supplies of fine crushed ice, covered with appropriate protection (canvas, clean burlap, burlap). It is advisable to gut F. (large breeds), and this operation is more advantageous to transfer to fishing vessels, and after gutting, pieces of ice should be placed in the abdominal cavity. Live F. should be killed by piercing at the junction of the spinal and brain stem, and not by coarse mallets, which often cause bruises and contusions. Its storage until consumption as food should not, even under the most favorable conditions, exceed 15 days. The transportation of chilled fresh F. is carried out in refrigerated cars (icehouses); as an exception - in ordinary ones, and transportation of fish without ice in the same packaging is not allowed (in the spring and summer periods). Freezing of F. is of the greatest importance. From the point of view of nutritional hygiene, this method of processing F. is the best and safest. It has been established that fish frozen on hard frost or in a refrigerator in the shortest possible time almost does not lose its nutritional composition and does not differ in taste from fresh F. Therefore, the method of rapid freezing should be used. Artificial methods of freezing should include: 1) methods of freezing with cooling mixtures; 2) freezing with cold air in freezing chambers and 3) freezing in cold brines. After freezing, F. is transferred to storage chambers at a temperature not higher than -8° (storage practice requires a temperature of -10°). The average storage period for frozen F. should be considered from 5 to 7 months with variations towards lower or higher depending on the freezing method and storage conditions; even with the most careful packaging, oxidation of fish fat (rusting) occurs, which is why these periods are not recommended to be extended. The second method, which from the point of view of food hygiene performs two tasks - culinary processing and preservation - should be considered the preparation of canned food in tin cans.

Fish canning is progressing very rapidly at present; as raw material, fish of various breeds (sturgeon, salmon, perch, carp, predominantly) are used. A large quantity of so-called appetizer preserves is prepared from various fish raw materials with various spices, previously subjected to frying or blanching; the filling is vegetable oil (e.g. for sardines) or tomato, marinade with greater or lesser oil content depending on the fat content of the raw material; recently, the production of so-called food preserves, prepared from fish meat without the addition of any other products and spices except salt, has begun to develop. These preserves from F. in pieces, prepared without the addition of foreign food substances except salt and poured with broth from heads and bones, also belong to highly valuable products in terms of their nutritional properties (high content of proteins and extractive substances and fat depending on the breed and fatness of F.). In addition to sterilized preserves from F., so-called semi-preserved (unsterilized) are prepared. The latter include marinades from various breeds of F., made from fresh or salted F. with numerous seasonings. Semi-preserved are not stable, however at a temperature close to 0°, they can be preserved for up to 1 year. Sterilized tin preserves at a temperature from 2° to 4° in refrigerators can be preserved for 2 years or more, simplified storage should be carried out in cool and dry storage premises while observing other conditions. I Salting as a method of preservation is used as a special method of processing F. to make it digestible and possible to consume without additional culinary processing. Not all breeds of F. have these properties,-only herring of different 44ft species, salmon and some other breeds of F. yield a valuable product. In addition to nitrogen, during salting F. loses extractive substances, including salts of potassium, calcium and phosphoric acid. Fat extraction occurs here to a relatively insignificant extent. Methods of salting F., despite the diversity of techniques and salting periods, salt dosage, etc., come down to 2 main types: dry and wet salting; some types of coarse salting are accompanied by particularly severe consequences, which, in essence, lead to spoilage of F. The main practical instructions for salting can be formulated as follows: 1) only fresh, well and cleanly cut, thoroughly washed fish should be admitted for salting. 2) Clean salt should be used for salting. 3) It is more expedient to carry out salting with simultaneous or preliminary cooling of F. in vats and tubs by dry or wet method at reduced air temperature. 4) Fish to be salted during the warm season, in the absence of low temperatures, is more expedient to salt by dry salting without any addition of brine. With this method, removal of gills, blood, all internal organs and flattening is required. Smoking and drying belong to the oldest methods of processing fish for direct consumption in food. Two methods of smoking are used: a) hot (otherwise steam) and b) cold. For steam smoking, fresh fish is most often used, for cold smoking-only salted. For smoking (especially for hot), sufficiently satisfactory raw material should be used; fresh and salted fish of low quality gives a poor product, and during the smoking process it does not stay on the hooks and falls to the floor or into the fire. Before packaging, F. should be subjected to cooling and drying. Transportation of F., smoked by the hot method, is recommended only for short distances or under the express tariff. It can be stored only for a few days at reduced temperature in a hanging position or laid out on shelves; mold, souring and rotting of F. are very common phenomena with careless storage and non-compliance with established rules: cooling period, packaging in perforated or slatted boxes, hanging or laying out individually during storage, etc. Balyks are made from the most valuable fatty breeds of fish (sturgeon, salmon and some other breeds, e.g. asp, catfish, etc.). Drying of F. is also carried out in special ovens (e.g. smelt, smelt) without preliminary salting; during drying, the fish under the ovens is covered with salt, and the F. itself is also covered on top with a layer of salt. A common dried-salted fish product is cod in the form of so-called stockfish and clipfish. To unsatisfactory methods, which are used by northern and uncultured peoples, should be included the processing of F. by natural "fermentation". In this case, the meat of F. not only becomes soft but often completely disintegrates and becomes a product with an offensive smell and taste and is not safe in terms of poisoning. To industrial methods of processing F., which should be recognized as unsatisfactory from a hygienic point of view, also belongs the method of skinning F., caused by industrial considerations of the leather industry. In addition to the loss of food value due to the loss of part of the fat and partial spoilage of F. itself (fat oxidation) with this method of processing, the fish may become contaminated with bacteria causing food diseases and poisonings. From the point of view of prevention, various methods of processing or correcting defective F. are of great interest; despite their diversity, they mainly come down to the effect of table salt or salt solutions on defective fish, and salting of defective fish produces extraction to a greater or lesser degree of products of putrefactive bacteria together with water and helps to correct the properties of such F.; as a "therapeutic" agent, acetic essence in various dilutions is used. The technique of "treating" or correcting defects in F. does not give completely reliable results; a sufficiently scientific basis has not yet been found. The indicators of corrected F. are subjective, and very great experience is needed to understand the individual details and borderline (between suitability or unsuitability) indicators of fish quality and to decide on the suitability for consumption of corrected defective fish, all the more so that laboratory analysis in its simplified form does not allow for quite definite conclusions. Large or small deviations from the norm in the complex of organoleptic indicators (in terms of consistency, color, taste and smell) sometimes serve as the only support for one or another assessment. Sometimes a "provocative" test for salting, cooking, smoking resolves the question of the admissibility of defective F. for processing or already processed F. Despite the significant amount of defective F. being processed, there is as yet no precise and definite sanitary regulation of the methods of reprocessing. Boiling and frying as methods of final (culinary) processing of F. have limited use in the fish industry. For the most part, these methods are the most common for preparing various delicacies (marinades, etc.) or ready-made dishes in public catering establishments. Microflora of live and processed F. The microflora of F. has been insufficiently studied. The tissues of F., and roe of live or just killed fish are found to be sterile. The gates of entry and paths of contamination of the meat of F. with bacteria are the gills, pharynx, intestine, and anus. From the point of view of practical classification of microorganisms in the food industry, it is customary to distinguish 3 groups of them: a) bacteria-causes of food "diseases and poisonings" (see Food infections, poisonings); b) microflora in the form of bacteria, fungi and yeast, which are the cause of various spoilage of food products, including F., and c) a group of useful microbes used in various branches of the food industry. The second group occupies the main place among pests and represents enormous diversity in the number of species and properties. Particular importance is acquired by bacteria of contaminated soil, water, as well as production equipment and contaminated hands and bodies of workers. It has been experimentally established that thorough washing with clean water with removal of skin and gill mucus, care in the hygienic respect of further processing of F. (gutting) without damaging the intestine, careful handling of F. during fishing, hygienic maintenance before processing, and speed and continuity of processing are the moments guaranteeing the freshness of F. In bacteriological examination of spoiled F. (fresh or salted), in the surface layers of meat, abundant bacterial population (aerobic bacteria, spore-bearing rods, sarcina, molds) is usually found; in the foci of putrefactive process-Bac. proteus, sometimes almost in pure culture. The microflora of fats of F. is of great practical importance; among its representatives, rods, cocci and sarcina are encountered; the rods are mostly spore-bearing, partly thermophilic; some of them coagulate milk casein, some peptonize milk, liquefy gelatin, release ammonia and hydrogen sulfide, some cultures lipase. Spoilage of fats is caused by: a) bacteria that decompose protein, present in the fatty tissue as impurities, and b) bacteria that split fats. In salted F.

(as well as fresh) in adipose tissue, point-like or small focal lesions from putrefactive processes caused by anaerobic putrefactive bacteria are found; oxidation and decomposition of fat are sometimes accompanied by a change in color (orange, yellow, grayish), occurring due to the activity of pigment-forming bacteria. Up to 50 species of different bacteria and several species of molds have been found in roe. The following species develop massively in roe: 1) bacillus coli, 2) red bacillus (B. ruber) and 3) green bacillus (B. fluorescens Liquefaciens). These bacteria, along with others, cause spoilage of roe. Molds, when they get into roe, manifest their activity only in the presence of oxygen (which is observed with poor, loose sealing of jars, barrels). In spoiled roe, chemical analysis reveals significant acidity and increased ammonia content. Acidity and ammonia content in fresh roe and in salted roe (granular roe in jars, 4% brine). Quality of roe Content in 100 g of roe of milk acid ammonia Fresh, not yet salted Granular roe of good quality Granular roe, unfit for consumption due to 0.124 to 0.320 over 0.50 to 20 mg over 20 mg A certain interest is presented by a special type of spirochete, the colonies of which are pale pink or deep red in color and live and multiply in moist salt and strong brine; these bacteria cause reddening of salted F. during storage. Molds most frequently found on F. and fish products differ in superficial spread (green and white molds); under favorable conditions (moist environment and access to oxygen) the process can be detected in deep parts, but often it is combined with phenomena of bacterial spoilage. Relatively rarely does one encounter a pronounced autolytic process in fresh F. without the participation of bacteria. Fish meat that has undergone autolysis is tasteless. The process intensifies and complicates with access to O₂ by oxidation and decomposition of fats. The action of bacterial enzymes, added to the process of autolysis, accelerates and intensifies it; depending on the type of bacteria, the process of autolysis is accompanied by the process of acid fermentation or putrefactive decomposition. Uncomplicated by the activity of microflora, the specific process of fish fat oxidation is observed in its pure form much more often than the process of autolysis. This process is accompanied by the formation on the surface of F. of a yellow coating of various shades, so-called rust, most often in the abdominal area of F.; there is an assumption that in frozen fish, droplets of fat are released, which then oxidize. Fatty F. are most susceptible to this type of oxidation: in salted F. (e.g., herring) at a relatively high temperature causing melting and release of fat, the process can proceed violently; sometimes complete "fattening" of F. occurs: a yellow or brown sticky coating forms, penetrating deep into the tissues.-Fish products and F. are often attacked by fungi (molds). High humidity of the air and insufficient dehydration of fish products, as well as moisture accumulation during unsatisfactory storage, are favorable conditions for the development of molds. Molds are capable of relatively quickly penetrating through the dense tissue of F. skin, gradually decomposing the F. body; this process occurs significantly faster in skinned F. and in its processed products (dried and smoked loins, etc.). Fish products (salted, smoked and dried) are attacked by a mass pest of fish goods, the so-called skipper (cheese fly larva), and to a lesser extent (mainly dried fish goods) the dermestid beetle larva. During the warm season, the cheese fly can, under favorable conditions, produce up to 5 generations (Sakharov). The larva in its development goes through 3 stages. Larvae can live on F. of the strongest brines and in brines, if they contain fish remains and the environment is aerobic; larvae in the 3rd stage (so-called skippers, which in this stage acquire the ability to jump up to 1 m) can tolerate very low temperatures and for a long time remain alive with cocoons through the autumn-winter period. The superficial location of larvae on the skin covers of F. and in the gills does no harm to the product; upon penetration into the tissues and prolonged stay there, the product loses its taste properties; the tissues undergo putrefactive decomposition due to contamination with putrefactive microbes. With the onset of cold, the larvae gather in deep layers of F. in colonies and then cocoon. The main reasons for the development of the cheese fly: 1) dirty and non-disinfected containers from under salted products; 2) storage of salted F. in unreliable containers and without brines; 3) poor ice supply to "exits" of salted fish goods. Defects of F. affected by the dermestid beetle larva are approximately the same as in F. infected with the skipper; the first does not have such widespread distribution, mainly affects dried F. or smoked; getting under the skin and into the internal organs, this parasite is capable, during prolonged storage, to eat not only the internal organs but also the tissues along with cartilage and even bones. Control measures-fumigation with sulfur of suspicious fish goods. The skipper differs from the dermestid beetle larva in appearance (yellowish color, transverse striation of the body covered with hairs). Finally, other defects of F. must be noted. F., fallen asleep on the gear, lying for a long time in water, without having well-known signs of spoilage when products are made from it, except for abnormal consistency (flabby or spreading), has a bad taste due to leaching of extractive substances by water, and most importantly, due to the autolytic process, sometimes complicated by the activity of bacteria. The most common types of spoilage of F.-various stages of the acid-putrefactive process, affecting limited areas or the entire body of F. Sound: F. (paired and fresh-frozen). Fresh, just caught F. (not longer than 4-6 hours) and thawed frozen F. (after quick freezing within 4-6 hours after death) can be classified as absolutely sound F.; icing, storage in a refrigerator at 0-1° can delay postmortem changes in F., expressed in phenomena of rigor mortis and reddening of the outer covers due to impregnation with a blood coloring substance, in a change in reaction (neutral, slightly acidic). Organoleptic signs of fallen asleep or killed absolutely sound F.: shiny scales (skin), tightly and evenly sitting on the body, covered with a small amount of transparent mucus, gradually thickening and increasing in the process of rigor mortis; gradually developing (red-crimson) uneven reddening (not in all breeds and not to the same degree); clean gills with a small amount of transparent mucus of the color characteristic of the given breed (bright red, saturated red, dark red, brown, etc.); fins spread out; opening of the intestinal canal (outgrowth) not swollen, reddened; no changes on the F. skin, head, gills; eyes transparent, mostly slightly protruding. Non-scaled F. (e.g., sturgeon) has a clean appearance. The F. body has a dense consistency, does not bend on the palm, the tail part does not sag; after the end of postmortem rigor mortis, the tail part begins to sag; F. taken on the palm bends (head and tail parts). The smell of gill mucus and "mask" (mucus on the scales) is clean; upon puncture or incision of the internal organs, the smell is clean, specific, slightly spicy, without an unpleasant shade; the smell of F. tissues is also specifically fishy without foreign shades; cut fish meat is grayish-white, semi-transparent with slight moisture and stickiness. Signs of F., just thawed (if it was quickly frozen soon after death or alive), are approximately the same-high moisture due to water excretion, less expressed specific fishy smell, the same spicy smell when testing internal organs with a "knife", more water when tissues are cut. The reaction of the fish body is neutral or slightly acidic; tissues are sterile. F. with subsequent changes can no longer be classified as absolutely sound. Signs of changes may appear each separately or in combination with others; until changes in the state of the body, the fish should be considered sound (relatively); practically, for the timely prevention of spoilage, such F. can be assessed by external signs as a product in the initial stages of spoilage, despite the absence of changes in the tissues, except for a clearly expressed acid reaction, sometimes slightly alkaline. Signs of changes: flattening and clouding of the eyes, change in color from bright crimson to variegated (red-brown, red-yellow, spreading colors), slight reddening of mucus in the gills and external "mask", not disappearing after washing; no other external changes.

The tissues have sufficient density; in F. with delicate structure (e.g., roach), soft consistency; smell fresh or slightly intensified fishy (smell of dampness); sometimes reddening of tissues located near the spine or skin is visible; the reaction of the meat is alkaline; Eber's reaction and for hydrogen sulfide can be both positive and negative. In fish that was slowly frozen, there are significant disorders in the consistency of tissues (wateriness and changes in smell), which must be taken into account when assessing the quality condition. When determining the wholesomeness of salted, semi-dried, and smoked F., the quality of the raw material is of great importance; in the vast majority of cases, various phenomena of spoilage and localized defects found in F. of various processing methods must be attributed to defects of the raw material or the cause of spoilage must be established depending on the processing method (e.g., salting). Salted F. from wholesome raw material and properly processed has the following characteristics: scales not knocked off, sit tightly on the skin, have a shiny appearance; some difference from fresh and fresh-frozen fish is in the color, which under the influence of salting becomes uniformly grayish-whitish; gills have a grayish color or depending on the breed dark red and brown; during salting of the gills and internal organs—smell of fresh salted F., after storage in the gills and the F. itself, shades of oxidation (rust) may appear. Smell clean, characteristic of salted F., without signs of foreign shades. Herrings of various salting methods and various breeds due to special processing conditions have specific differences and shades. Some herrings due to special salting and ripening acquire soft consistency and a special pleasant aroma. Some types of herrings (e.g., Norwegian, Scottish, Kamchatka, Pacific) of coarse salting over time during storage due to the onset of brine fermentation gradually begin to acquire a softer consistency; the herring begins to 'ripen'; the appearance of oxidation inside the tissues is a borderline defect signaling the onset of spoilage; the appearance of a rust smell and a sharp unpleasant sour smell in some breeds of herrings (e.g., in iwashi) is a sign indicating the beginning of spoilage. Often these phenomena occur faster than expected due to the absence or insufficiency of brine. Some large breeds of herrings (Astrakhan broken and semi-broken and especially Caspian lightly salted herrings) during salting undergo due to insufficiently rapid impregnation with salt autolytic processes and acid fermentation, as a result, more or less reddening of tissues (closer to the spine), sometimes darkening and a specific smell of charring (so-called tanning). Sturgeon F., prepared for various processing methods and subjected to them, can give the following picture of quality condition: the outer surface clean, from the abdominal cavity side grayish-yellow color (not dirty); the color of the beluga tissue is pure grayish-white with a pinkish tint; of the sturgeon—white, of the sterlet—yellowish from incisions of fat, marbled; reddening of tissues under the skin—result of bruising; change in the smell of fat from pure fishy to impure with a shade of rust occurs quickly after processing, during storage; redness (pinkish or more saturated color) in various areas of tissues without change in smell occurs in 'delay' of raw material (phenomena of acid fermentation in the initial stage) in fresh F. (oxidation or delay or smell of dampness). The indicated signs in salted F. are indicators of complete and relative wholesomeness. The roe of sturgeon, as well as salmon (chum, whitefish) and cyprinid breeds has the following signs of spoilage: insignificant changes in the configuration of the grain (complete or relative graininess), decrease in grain density, slight smell of dampness and a shade of bitterness or slight sour taste. Standardization of fish products from the point of view of nutrition hygiene is a necessary state act of legislative regulation. Standardization in its regulation covers the product itself, the conditions of its manufacture, regulates the quality indicators of fish products, packaging, cleaning of the fish product and labeling, and indicates the conditions that products must satisfy in complete and relative wholesomeness (highest and first grades). - Defective fish. A. Paired and fresh-frozen fish. The above changes in fresh paired and frozen fish do not transfer a given batch of F. to the position of defective or doubtful in terms of use for nutrition, but require measures for the earliest use of such F. for nutrition; the signs themselves play a signaling role here. Signs of spoilage of paired and fresh-frozen F.: sharp sour or putrid smell in the gills, changes in the consistency of the body (weak body), bloating or weakness of the belly (rupture of the belly due to tissue maceration), smell of oxidation, extending to the head (in a cross-section across the head, oxidation can be felt in the internal organs or weak oxidation in the tissues); if acid phenomena are not detected here, they may be detected in a 'pork' test (with a knife) in the abdominal cavity (smell of oxidation); sometimes (in cyprinids) a smell of oxidation is detected in the tissues near the 'growth'. In cases of advanced spoilage of F. upon opening (cutting) the belly, after removal of the internal organs and washing, macerated peritoneum can be seen and a non-disappearing smell of oxidation can be felt (these phenomena in salting can be stopped and leave a trace in the form of tanning and oxidation); b. ch. upon penetration of the acid process (autolytic-bacterial) from the gills or from the side of the internal organs, with localization at the head or along the entire line of the spine, in a cross-section limited or spread along the line of the spine redness is noted; the smell of fish meat—changed, sharp, unpleasant or sour and even sour-putrid. The listed signs may be all present or not all; some may be more pronounced than others. Borderline indicators should be considered: oxidation extending to the head, oxidation in the belly and weakness of the belly tissues (in sturgeon and salmon breeds weakness of the body and appearance of oxidation at the head or at the growth, reddening of tissues under the skin and in other places). These are the most typical signs of spoilage of F., removing the fish from the category of wholesome and permissible for direct distribution. For fresh-frozen fish the signs of spoilage remain the same, they are detected by the same methods, but their determination is facilitated after thawing F. in hot water (intensification of smell). The smell of oxidation in the gills and in the belly is easily recognized; in sturgeon and salmon (with torn bellies) smells are recognized in the tissues at the growth and in other parts of the fish also with the help of a knife. F. with the listed signs, expressed to a greater or lesser degree, is usually sent for inspection to the sanitary supervision and requires special operations for correction. If a batch of fish has significant unevenness in quality condition throughout the mass or by package, it is considered doubtful and requires special intervention for inspection and measures for sorting and reprocessing. In some cases, individual specimens of the so-called 'dried-up' F., F. that became entangled during movement or fell asleep from exhaustion on the gear, are encountered in the batch; such F. is easily recognized by the spreading or soft consistency of the tissues, even if there are no other changes or they are indistinctly expressed. Among a batch of frozen F., sometimes specimens are encountered which when sniffed with a knife give characteristic signs of putrefactive phenomena; when thawing F. the putrid smell disappears and no other changes are found. This should not confuse the researcher, since the putrefactive process in the abdominal cavity, stopped by freezing, anyway serves as a reason for special intervention, and usually during a trial boil, the rapid boiling of fish meat and a foreign smell easily resolve the question. In large breeds (sturgeon, salmon), signs of unwholesomeness—delay, oxidation—are found in various parts of the body, so inspection should be carried out here with special care. The phenomena of delay can occupy an extensive area. In thawed red F., signs of spoilage of a focal or widespread nature sometimes manifest in a clear form, whereas in frozen F. they manifest in a barely perceptible way (negligible change in smell). Often frozen F., especially fatty breeds (sturgeon, salmon), is covered with a significant layer of rust, during storage penetrating into the tissues of F.; the fat oxidation process spreads deep into the tissues; the edges of the bellies can be completely rusted (deep damage); such F. should be classified as defective. B. Salted fish products.

The most common signs of spoilage in salted fish products that render them unfit for consumption are an acidic odor in the tissues, widespread 'browning' of tissues along the spine, limpness, flabbiness, doughiness of the tissues, as well as darkening or reddening of them; these phenomena may be widespread or localized. In herring, these phenomena often occur during the salting process and are masked by the ripening process; the ripening process itself sometimes occurs simultaneously with a bacterial (putrefactive) process, with the latter being suppressed at a certain stage of salting, but the changes remain. In salted F. of various breeds, under unsatisfactory storage conditions or after prolonged storage, the following types of spoilage can be encountered: sliminess of the 'skin', oxidation of the inner surface of fish layers, bacterial, bright red coating, mold, superficial or penetrating deep into the fish with or without softening of the tissues; a musty odor, the presence of 'prygunk' (a type of spoilage) in various places. In herring, signs of spoilage can occur during storage in the absence of brine - greater or lesser penetration of rust into the tissues (excluding surface coating) and at high temperatures, a special type of oxidative process (burning). During the fermentation of brine (so-called 'aging'), herring undergo the same process; when undergoing ripening, during prolonged storage they become overripe (acidic, anchovy-like odor and taste, soft, sometimes spreading consistency), and a putrefactive odor is not uncommon. Special attention must be paid to salted fish products of small, delicate breeds of F. (sprat, smelt, some small herring) - spoilage can be uniform or various stages of change and spoilage can be found in the mass of fish. In the initial stages, with an acidic or rotten odor - if the process has not yet spread to the fish, the fish have a normal appearance, slight reddening, their delicate tissue, and a pleasant odor and taste with a specific sharp aftertaste (after washing). Such signs should be considered borderline, placing the product in the 'doubtful' category. When spoilage phenomena spread to the F., it is often difficult to correct defects by processing in clean brine. B. Salted-dried and smoked fish products. Fish products released from fisheries in the form of dried, dried, and smoked may have defects due to either the lack of freshness of the raw material or the processing conditions. The former are roughly the same as for salted fish products. The latter depend on improper processing. Thus, an under-dried fish product has a tendency to quickly become slimy, be covered with mold, undergo acidic processes and decomposition. Signs of sliminess with softening of tissues, and sometimes superficial or deep decomposition (for example in sturgeon), place the product in the 'doubtful' category. The same phenomena (mold infection, sliminess, musty odor with softening of tissues) can occur in these products under unsatisfactory storage. Sometimes, besides a musty odor, fish products have no other signs. Sturgeon and salmon are particularly sensitive to improper storage and transport conditions; sliminess is a fairly common sign. Signs of spoilage in smoked fish products are roughly the same as in dried products, and the causes are the same. G. Roe of sturgeon, salmon, and cyprinid fish. I. In sturgeon roe, significant spoilage that makes the product unfit for consumption usually does not occur. More common signs of defectiveness: a greater or lesser degree of mustiness in taste, an acidic odor, a smell of rotten eggs to a greater or lesser extent; an unpleasant 'browning' aftertaste (spoilage process of fresh roe). If these phenomena are expressed to a slight degree, the product can still be considered suitable for consumption without processing; the latter reduces the nutritional and even taste properties of the roe; a trial processing in brine resolves the question of the degree of change in the roe and in some cases reduces the product to being unfit for consumption. The formation of surface or penetrating deep into the mass mold, the appearance of mustiness in odor and taste or rancidity - common signs of spoilage in pâté roe; reprocessing is difficult. - II. Granulated salmon roe has a tendency to quickly become rancid during storage, which gives the roe a greater or lesser bitterness. The most common phenomena besides surface mold or growing in spots - general acidic fermentation (yeast), putrefactive process of slime in the roe mass (smell of rotten eggs); upon inspection is found: wateriness or sliminess of the roe mass or partial change of the grains, presence of 'lopants' (a type of defect), darkening of the roe mass; acidic or rotten egg odor, disappearing or weakening when the roe is turned (refreshed); taste is sour with bitterness with various shades; unpleasant taste and odor force the roe to be considered unfit for food. Borderline signs of spoilage - a sharp, scratchy bitter taste (high acidity) or unpleasant odor and taste (grain decomposition). Laboratory research reveals a significant increase in acidity (decrease of which can be achieved by processing with salt or brine); an increase in salt ammonia content (over 40 mg per 1 kg) also signals deeper and longer-acting causes of roe spoilage. -III. Roe of cyprinid F. (asps, bream, pike perch, etc.). A very common defect is a significant admixture of sand (a sharp crunch on the teeth), sometimes to such an extent that the product cannot be allowed for food; also often as a result of spoilage of the raw material, the roe acquires an unpleasant odor and taste that cannot be removed by salting. During storage, the most common signs of spoilage: the appearance and greater or lesser spread of mold, musty odor and taste, rancid odor and taste; a borderline indicator of high acidity is organoleptically determined as a bitter, scratchy taste; significant anchovy or putrefactive shades in odor and taste easily resolve the question. Laboratory indicators (Eber's reaction and for hydrogen sulfide) provide little support for a final diagnosis, the acidity and salt ammonia indicators are more valuable. The question of the correctability or persistence of defects in fish products is usually resolved very simply on the basis of a complex of indicators through trial processing, as well as with the help of laboratory analysis. Indications of the uncorrectability of defects are phenomena of putrefactive decomposition with deep changes in tissues, with deep penetration of rust and mold into the fish tissues. In practice, the picture of spoilage is mostly varied. Fish products with correctable homogeneous or heterogeneous defects, requiring special intervention both for their evaluation and for establishing methods of reprocessing, sorting, and other operations, are classified as conditionally edible food products. Fish products that have lost their taste or nutritional properties, for example those processed for the purpose of neutralization or elimination of defects in taste or odor, or finally fish products that have acquired irreparable defects during the processing of raw material (for example, sand admixture in roe, fish meat scorched with salt, etc.), are considered inferior food products. A special category is formed by fish products unfit for nutrition. As for the methodology for evaluating defective fish, it should not be limited to only organoleptic evaluation and laboratory methods. In certain cases, the simplest method of testing or a test with hot water or a test of thawed frozen product gives much more for proper conduct of examination and evaluation than elementary chemical analysis (Eber's reaction or for the presence of hydrogen sulfide).