Fundamentals of food technology study manual

Figure 13 
2. The most common body shapes of commercial fish: - torpedo-shaped: and - 
salmon; b - cod; - swept (shuka); — flat (flounder); IV - serpentine (eel). thickened 
from the beginning, strongly narrowed towards the caudal peduncle and slightly 
compressed from the sides (cod, herring, salmon, whiting, shark, tuna, bluefish, 
mug, etc.); 9-segmented - the body is elongated, at the same height, the back and 
anal fins are pushed far back to the caudal fin (saury, pike, garfish); flat - the body 
is strongly compressed laterally, high, narrow (bream, flounder, halibut) or very 
low, wide from the back (slope); serpentine - the body is very long, rounded or 
slightly compressed laterally (eels, lampreys). 
Figure 14 
Dimensions. The size of the fish is estimated by its body length or weight. 
According to GOST, the length of the fish (or fish body) is measured in a straight 
line from the end of the beak to the beginning of the middle rays of the caudal fin 
(excluding its length). In some cases, the total (absolute) length of the fish is also 
measured - from the end of the beak to the middle of the straight line connecting 
the ends of the extreme rays of the tail fin. When designing machines for cutting 
fish, along with the length and weight of the fish, separate parts of the fish body - 
head, carcass, tail fin, as well as the height and thickness ratio of the fish body are 
taken into account. 
In addition to the linear dimensions, the specific surface area of the fish, that 
is, the ratio of the surface area of the fish to the volume or mass (expressed in cm 2 
/ cm 3 or cm 2 / g, respectively) is of great practical importance. The larger the 
specific surface of the fish, the faster it cools, freezes, saltes and heats up. All types 
of processing fish according to GOST 1368-55. "Length and weight" fish are 
divided according to length and weight. In this case, the smallest fish allowed to be 
caught is determined by the fishing regulations. Some fish are divided into large, 
medium and small according to weight or length, others are not divided according 
to length and weight, and some small fish belong to the small things of the first, 
second or third group. The fish is in the front of the body, closer to the head, so 
when free falling and moving along an inclined plane, it is always the first in the 
direction of movement. Density b is the ratio of fish mass (kg) to its volume (m3). 
The density of a live fish or a sleeping fish with an intact swim bladder is about 
1000 kg/m3, which is close to the density of water. The density of fresh water at a 
temperature of 4 °C is 1000 kg/m3, sea water at a temperature of 15 °C is 1020-
1030 kg/m3. This allows the raw fish to be transported by hydrochutes in the 
factories in the water flow. The density of the gutted fish and individual parts of its 

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body is greater than the density of water, and therefore it sinks. The density of fish 
and fish meat in the intestines is from 1050 to 1080 kg/m3, 
The density of fresh water at a temperature of 4 °C is 1000 kg/m3, sea water 
at a temperature of 15 °C is 1020-1030 kg/m3. This allows the raw fish to be 
transported by hydrochutes in the factories in the water flow. The density of the 
gutted fish and individual parts of its body is greater than the density of water, and 
therefore it sinks. The density of gutted fish and fish meat is between 1050 and 
1080 kg/m3, 10 L The density of a live fish or a sleeping fish with an intact swim 
bladder is about 1000 kg/m3, which is close to the density of water. The density of 
fresh water at a temperature of 4°C is 1000 kg/m3, sea water at a temperature of 
15°C is 1020-1030 kg/m3. This allows the raw fish to be transported by 
hydrochutes in the factories in the water flow. The density of the gutted fish and 
individual parts of its body is greater than the density of water, and therefore it 
sinks. The density of fish and fish meat in the intestine is from 1050 to 1080 
kg/m3, 10 L, and therefore it sinks. The density of fish and fish meat in the 
intestine is from 1050 to 1080 kg/m3, 10 L, and therefore it sinks. The density of 
fish and fish meat in the intestine is from 1050 to 1080 kg/m3, 10 L 3. Fish 
measurement scheme: - full length of fish; 2 - body length; 3 - head length; 4 - 
carcass length; 5 - the greatest height of the body; 6 - the greatest thickness of the 
body. skin - from 1070 to 1120 kg/m3 and scales - from 1300 to 1550 kg/m3. Oily 
fish are less dense than lean fish. For example, fat content is 5-10% The density of 
lean herring is 1060 kg/m3, fat herring (15-23% fat) is 1030-1050 kg/m3. During 
freezing, due to the increase in the size of the fish due to the formation of ice, its 
density decreases significantly. Thus, the density of uncut carp at 15 °C is 987 
kg/m3, at -8 °C - 922 kg/m3. Volumetric, silt and bulk, mass a - fish mass (kg or t) 
per unit volume (m3). It is necessary to know this indicator when calculating 
containers for salting and storing fish, determining the areas of raw material 
reception and assembly shops in factories, calculating containers for vehicles and 
packaging. The weight depends on the type of fish, its body shape, size, 
physiological and post-mortem condition, etc. Kill the live fish container It fills 
more densely and has a larger mass than lyk fish. The mass of fish in the stage of 
hard death or frozen is less than that of fish after the loss of hard dead or before the 
appearance of hard dead. The mass density of Atlantic herring is 0.85-0.91 t/m3, 
sardine - 0.85, mackerel - 0.96, mackerel - 0.81, live silver hake - 0.928, partially 
hardened - 0.853; live roach - 0.810, dead - 0.790, frozen - 0.440 t/m3. Natural 
slope angle. A fish placed on a horizontal surface forms a cone, the surface of 
which has a certain angle to the surface; is called the angle of silence. The angle of 
rest depends on the type and condition of the fish. Thus, the angle of repose of a 
dead zander is 34 °C, Baltic herring - 21 °C, bream - P °C, pink salmon - 16 °C, 
Caspian anchovy branch - 30 °C, anchovy - 40 °C. A live carp has a resting angle 
of 24°C, a dead carp has a resting angle of 34°C, and a frozen carp has a resting 
angle of 51°C. In order to correctly organize the transport of fish along the plains, 
the angle of slip and the coefficient of friction must be known. The sliding angle is 
the angle of inclination of the plane at which the fish under the influence of gravity 
overcomes the frictional force on the plane and begins to slide down. The tangent 

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of the sliding angle is called the coefficient of friction. The value of these 
indicators depends on the type of fish, its size and condition. In order to establish 
ri, the sliding angle and the coefficient of friction must be known. The sliding 
angle is the angle of inclination of the plane at which the fish under the influence 
of gravity overcomes the frictional force on the plane and begins to slide down. 
The tangent of the sliding angle is called the coefficient of friction. The value of 
these indicators depends on the type of fish, its size and condition. In order to 
establish ri, the sliding angle and the coefficient of friction must be known. The 
sliding angle is the angle of inclination of the plane at which the fish under the 
influence of gravity overcomes the frictional force on the plane and begins to slide 
down. The tangent of the sliding angle is called the coefficient of friction. The 
value of these indicators depends on the type of fish, its size and condition. 
In large fish, the sliding angle and friction coefficient are smaller than in 
small fish of the same type; in live and completely fresh sleeping fish - less than in 
kept ones. On a surface wet with water or salt water, fish move better than dry. The 
sliding angle and friction coefficient of mackerel on tin plate are 10.5 °C and 
0.186, 16 °C and 0.286 for galvanized iron, and 63 °C and 1.971 for rubber, 
respectively. The sliding angle of sardinella, horse mackerel, and carp on the 
inclined surface of irrigated fish is 5-10 °C lower than that of non-irrigated fish. 
Capacitance and thermal conductivity. During cooling and heat treatment of fish 
(cooling, freezing, thawing, boiling, drying, frying, sterilization) it is necessary to 
know the thermophysical parameters describing some characteristics of fish. as 
heat capacity and thermal conductivity. Heat capacity is the amount of heat that 
must be transferred to or removed from a fish to raise or lower its temperature by 
1°C. Heat capacity is measured in kJ/(kgK), it kcal/(kg-°C). It depends on the 
chemical composition of the fish. Heat capacity of fatty fish (eel, herring) 0.70-
0.75 kcal/(kg'°C), lean fish (cod, halibut, pike perch) 0 ,80-0,85, and the heat 
capacity of frozen fish is much less. - 0.38-0.43 kcal/(kg-°C). This is because the 
heat capacity of ice is twice that of water. heat die The coefficient of thermal 
conductivity describes the ability of the fish body to conduct heat when heated or 
cooled. The coefficient of thermal conductivity for fresh fish is about 0.5, and for 
frozen fish it is 1.6 W/ (m2, K). The electrical resistance of fish is an indicator that 
you need to know when using new methods of fish processing - electric smoking, 
heating and defrosting using high-frequency currents. Among the electrical 
properties of fish, electrical resistance is the most studied, and its value depends on 
the type of fish, its chemical composition, structure, and physiological state. Live 
or freshly sleeping fish meat has a very high electrical resistance. As the 
postmortem changes in the fish continue, it is significantly reduced. electrical 
resistance, also depends on the frequency of applied current and temperature. With 
an increase in the frequency of the current passing through the body of the fish, as 
well as with an increase in the temperature of the fish before the start of protein 
coagulation, the electrical resistance decreases. In addition, fresh fish tissue has a 
higher electrical resistance than tissue that has been subjected to freezing and 
thawing. 

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The consistency of fish meat from the sea is an important indicator of fish 
quality and is determined by a combination of its physical and mechanical 
properties (elasticity, viscosity and firmness). These features are related to the level 
of development of individual structural elements that make up the muscle tissue of 
fish and the adhesion forces between them. They also depend on the chemical 
composition of fish meat - its fat content and the ratio between the amount of water 
and proteins. During the storage of fresh fish, the non-tissue structure changes 
significantly, and therefore the structural and mechanical parameters change 
significantly. During rigor mortis, the muscle fibers become denser, as a result of 
which the fish the elasticity and firmness of the splint increases and it becomes 
difficult to touch it. Autolysis and spoilage of fish are accompanied by relaxation 
of muscle tissue, and then its destruction, as a result of which the elasticity and 
strength of muscle tissue is significantly reduced, the meat is softer, softer and 
stained to the touch. ladi In industrial and commercial practice, the consistency of 
fish meat is usually evaluated by the organoleptic method - it is determined 
according to the result of feeling the body of the fish and rubbing the meat between 
the fingers. will be soft and dirty to the touch. In industrial and commercial 
practice, the consistency of fish meat is usually evaluated by the organoleptic 
method - it is determined according to the result of feeling the body of the fish and 
rubbing the meat between the fingers. will be soft and dirty to the touch. In 
industrial and commercial practice, the consistency of fish meat is usually 
evaluated by the organoleptic method - it is determined according to the result of 
feeling the body of the fish and rubbing the meat between the fingers.