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Файл:Veterinary and sanitary examination of meat and meat products. Study aid
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81
CHAPTER 9. VETERINARY AND SANITARY EXAMINATION
OF SAUSAGE PRODUCTS
Sausages are meat products made from minced meat, enclosed in a casing (or
without it) and subjected to heat treatment or fermentation until ready for
consumption.
Rules for sampling sausage products for research
When sampling, 10 % of the loaves of the batch are inspected and average
samples are taken from the inspected products from different places in the batch in an
amount of no more than 1 %, but not less than 2 units of the product, from which spot
samples are taken.
First, using a sterile knife, 2 samples 15 cm long are cut from the edges of two
different units of production for microbiological research. Then samples are taken for
organoleptic evaluation — 400–500 g each, for physical and chemical tests —
200–250 g each, also from two different sausage loaves.
Two spot samples from different units of production are combined into
combined samples, each of which is packaged separately in a polymer film;
combined samples for microbiological studies are placed in sterile containers.
Organoleptic examination of sausages
During the organoleptic examination of sausages, the following indicators are
determined:
- appearance (shape, size, knitting of loaves, color and condition of the shell —
cleanliness, dryness or moisture, presence of dirt, mold and mucus) — visually;
- consistency — by pressing, cutting, chewing;
- color and pattern of minced meat on a cut, structure and distribution of
ingredients (lard, spices) — visually;
- smell, aroma of spices;
- taste — by testing thin slices of the product.
A fresh, high-quality sausage product must have the following organoleptic
characteristics:
- appearance: a loaf with a clean, dry surface, without slips, overflows of minced
meat over the shell, the shell fits tightly to the minced meat; the shape, dimensions,
knitting of the loaf comply with the requirements of the standard;
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- consistency: from elastic to dense, depending on the type of product;
- color and pattern of the minced meat on the cut: the minced meat is well
mixed, from pale pink to dark red (depending on the type of product); pieces of bacon
of a certain size, white or white with a pinkish tint, are evenly distributed in it;
- the smell is specific, pleasant; the aroma of spices is well expressed;
- the taste is specific, pleasant, moderately salty or brackish, moderately spicy,
typical for this type of product.
A sausage product of questionable freshness has the following organoleptic
characteristics:
- appearance: the shell of the product is wet, sticky, there may be mold. The
shell is easily separated from the minced meat, but does not tear;
- consistency: in the surface layers of the loaf, the minced meat is slightly
softened;
- color on the cut: on a cross-section along the periphery of the loaf a dark gray
rim is revealed, the rest of the loaf retains its natural color. Yellowing of the bacon in
the surface layer of the loaf is possible;
- smell: slightly sour, musty, moldy; The aroma of spices is weak.
A stale sausage product has organoleptic characteristics:
- appearance: the shell is wet, sticky, spontaneously lags behind the minced
meat and breaks easily;
- consistency: the minced meat of the product is softened, loose;
- color on the cut: in the surface layers of the loaf the minced meat is gray or
greenish in color, in the deep layers gray or green areas are found, the bacon is
yellowed;
- strong unpleasant smell (musty, rancid, sour, putrid); There is no spice aroma.
Biochemical and microscopic studies of sausages for freshness
Determination of the pH value of minced sausage
The lard is removed from the minced sausage, then the minced meat is ground
in a meat mincer. A 10 g sample of crushed minced meat is placed in a conical flask,
40 cm3 of the mass is poured in and left for 30 minutes, periodically stirring the
contents of the flask. The resulting extract is filtered through a paper filter.
Further research is similar to determining the pH of meat (pp. 20–22 of this
book).
The pH of fresh sausages is 5.0–6.8, those of questionable freshness are
6.9–7.0, those of stale sausages are 7.1 or more.
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Qualitative reaction to ammonia according to Ebert
The reaction is based on the interaction of ammonia, which is one of the
products of protein breakdown and formed during the spoilage of sausages, with
hydrochloric acid, which is part of Ebert's reagent. As a result of the reaction,
ammonia is formed, which can be detected visually.
Analysis procedure.
Approximately 1 cm3 of Ebert's reagent (1 part concentrated hydrochloric acid,
1 part ether, 3 parts ethyl alcohol) is poured into a wide test tube. The test tube is
shaken and closed with a stopper and a wire hook, on which a small piece of the
sausage product under study is attached. The distance between the piece of sausage
and the surface of the reagent should be approximately 1 cm. In the presence of
ammonia gas, a white cloud of ammonia appears in the test tube. The cloud is most
noticeable when the sausage hook moves up and down, especially when removing it
from the test tube.
Accounting for reaction:
- fresh sausage — negative reaction (no ammonia cloud is formed);
- a product of questionable freshness — a weakly positive reaction (a quickly
disappearing cloud that appears when a piece of sausage is removed from a test tube);
- stale product — positive reaction (a persistent cloud that appears a few
seconds after placing a piece of sausage in a test tube).
Qualitative reaction to hydrogen sulfide
Hydrogen sulfide is one of the end products of protein breakdown and
accumulates in meat products when they spoil.
Analysis procedure.
3–5 g of chopped sausage mince is loosely placed in a test tube. It is closed
with a stopper, and a strip of filter paper with a drop of 10 % solution of lead acetate
previously applied to it is clamped between the neck of the test tube and the stopper.
A strip of paper with a drop of reagent applied should hang down about halfway
inside the test tube.
The test tube is placed for 15 minutes in a water bath at a temperature of
50–55 °C, after which the reaction results are taken into account.
A fresh sausage product gives a negative reaction (the filter paper at the site
where a drop of lead acetate solution is applied is not colored or turns light brown); a
product of questionable freshness gives a weakly positive reaction — (the paper at
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the site where the reagent is applied turns brown); a stale product has a positive
reaction (the paper at the site where the reagent is applied turns dark brown).
Microscopic examination of sausages
Imprint smears are prepared from under the shell (from its inside) after
separating it from the loaf and from the middle of the sausage product after cutting it
with a sterile (flamed) knife or scalpel. If the sausage product is without a casing,
then before preparing the print, its top layer is cut off by 1–2 mm from the surface
layer of the product with sterile (flamed) scissors.
The prepared prints are fixed over the flame of an alcohol lamp and stained
according to Gram (see pp. 26–27 of this publication).
The stained fingerprint smears are microscopically examined at a microscope
magnification of × 900 using immersion oil. During microscopy, the morphology of
the detected microflora and the number of microbial bodies in the field of view of the
microscope are determined by calculating the arithmetic mean value of the indicator
after counting the number of microbes in 25 random fields of view of the microscope.
The results of the study are assessed as follows:
- fresh product: in the center of the loaf — single microbes, in the surface
layer — up to 20 microbial bodies in the field of view of the microscope;
- a product of questionable freshness: in the center of the loaf — 10–20, in the
surface layer — 20–30 microbes in the field of view of the microscope;
- stale product: in the center of the loaf — 20–30, under the shell — more than
30 microorganisms in the field of view of the microscope.
Technochemical testing of sausages
During technochemical testing of sausage products, indicators that are
regulated by the relevant regulatory and technical documentation (GOST, OST, TU,
etc.) are determined.
Determination of the mass fraction of moisture in sausages
A sample of the product weighing 2–3 g, crushed in a meat grinder, is placed in
a flask with sand (5–8 g) and a glass rod, pre-dried at a temperature of 150 ± 2 °C for
30 minutes and weighed to the nearest 0.01 g. The contents of the bottle are
thoroughly mixed with a glass rod, and the bottle is re-weighed.
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The bottle is dried in an oven at a temperature of 150 ± 2 °C for an hour,
cooled in a desiccator and weighed again.
The mass fraction of moisture in the product is determined by formula (6):
(м1 — м2)
Х = × 100 , (6)
(м1 — м0)
where:
X is the mass fraction of moisture in the product, %;
м
0
— mass of a bottle with sand and a stick, g;
м
1
— mass of a bottle with sand, a stick and a sample of product before drying, g;
м
2
— mass of a bottle with sand, a stick and a sample of product after drying, g;
100 is the conversion factor to percentage.
The arithmetic mean of the results of two parallel tests is taken as the final
result of the study.
The mass fraction of moisture in sausages should be no more than the value
established by the relevant standard (in raw smoked sausages — no more than
25–30 %, in cooked-smoked sausages — no more than 38 %, in semi-smoked
sausages — no more than 43–53 %, depending from their name).
Determination of the mass fraction of table salt in sausages
A sample of the product weighing 5 g minced in a meat grinder, weighed to the
nearest 0.01 g, is placed in a beaker and 100 cm3 of distilled water is added to it. After
40 minutes of infusion (with periodic stirring with a glass rod), the extract is filtered
through a paper filter.
10 cm3 of the filtrate is pipetted into a conical flask and titrated from a burette
with a 0.05N solution of silver nitrate in the presence of 0.5 cm3 of potassium
chromate until a brick-red color appears.
The mass fraction of sodium chloride in the product is determined by
formula (7):
0.00292 × V × 100 × 100
Х = , (7)
V1 × М
where:
X is the mass fraction of table salt in the product, %;
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0.00292 — the amount of table salt equivalent to 1 cm3 of a 0.05N solution of
silver nitrate, g;
V is the volume of 0.05N silver nitrate solution used for titration of the tested
extract, cm3;
100 — volume of prepared extract, cm3;
100 — conversion factor to percentage;
V1 is the volume of extract taken for titration (10 cm3);
M is the mass of the product sample, g.
The arithmetic mean of the results of two parallel tests is taken as the final
result of the study.
The mass fraction of table salt in sausages should be no more than the value
established by the relevant standard (in raw smoked sausages — no more than 6 %, in
cooked smoked sausages — no more than 5 %, in semi-smoked sausages — no more
than 3.0–4,5 %, in boiled ones — no more than 2.1–3.0 %, depending on their name).
Determination of the mass fraction of sodium nitrite in sausages
The method is based on the Griess color reaction.
Preparation for analysis.
First, solutions are prepared to carry out the color reaction.
Solution 1: 0.5 g of sulfanilic acid is dissolved in 150 cm3 of 2N acetic acid
solution.
Solution 2: 0.2 g of α-naphthylamine is boiled with 20 cm3 of water, the
solution is filtered and 180 cm3 of 2N acetic acid solution is added to the filtrate. The
solution is stored in a dark bottle.
Griess reagent: mix equal volumes of solutions 1 and 2. If a pink color appears
during mixing, add zinc dust, shake and filter.
Griess reagent is prepared immediately before analysis.
Then construct a calibration graph of the dependence of the optical density of
the solution on the concentration of sodium nitrite in it.
To do this, first prepare standard solutions with different concentrations of
sodium nitrite.
1 g chemically pure sodium nitrite are transferred to a 1 000 cm3 volumetric
flask and adjusted to the mark with distilled water. Then 10 cm3 of the prepared
solution is transferred to a 500 cm3 volumetric flask and diluted with water to the
mark. Next, 5 cm3 of the last solution is transferred to a 100 cm3 volumetric flask and
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made up to the mark with water. 1 cm3 of the resulting (working) solution contains
0.001 mg of sodium nitrite.
Add 0, 2, 4 and 6 cm3 of nitrite working solution to 4 volumetric flasks per
100 cm3 (no nitrite solution is added to the first flask — comparison solution), add
5 cm3 of 3N ammonia solution to them, 10 cm3 of 0.1N hydrochloric acid solution,
dilute with water to the mark and mix.
Transfer 15 cm3 of the prepared solutions into 4 conical flasks per 100 cm3, add
15 cm3 of Griess reagent to them, and keep the flasks for 15 minutes at room
temperature and measure the optical density of the solutions (pink color intensity) on
a photoelectrocolorimeter in a 2 cm thick cuvette with a green filter (wavelength
538 nm) in relation to the reference solution.
The graph is drawn on graph paper, with the mass fraction of sodium nitrite
concentration — 2, 4 and 6 μg/cm3 — plotted on the abscissa axis, and optical
density values (device readings) on the ordinate axis. The calibration graph must pass
through the origin. An example of a calibration graph is shown in Fig. 10.
0
5
10
15
20
25
30
35
40
45
0,00 2,00 4,00 6,00
концентрация нитрита натрия, мкг/мл
оптическая плотность
Fig. 10. Example of constructing a calibration graph
Analysis procedure
A sample of the product weighing 20 g is ground in a meat grinder, placed in a
beaker, 40 cm3 of distilled water at a temperature of 55 °C is poured in and left for
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10 minutes. Then the extract is filtered through a cotton filter into a 200 cm3
volumetric flask and the volume is adjusted to the mark with distilled water.
To prepare an extract from raw smoked sausages and smoked meats, a crushed
sample weighing 20 g is poured into 200 cm3 of hot (55 °C) distilled water, left for
30 minutes and filtered through a cotton filter.
20 cm3 of the extract is placed in a volumetric flask with a capacity of 100 cm3,
10 cm3 of 0.1N sodium hydroxide solution and 40 cm3 of 0.045 % zinc sulfate
solution are added to precipitate proteins. The mixture is heated for 7 minutes in a
boiling water bath, cooled, brought to the mark with water, mixed and filtered
through a paper filter.
Add 5 cm3 of protein-free filtrate, 1 cm3 of 3N ammonia solution, 2 cm3 of
0.1N hydrochloric acid solution, 2 cm3 of distilled water and, to enhance the color,
2.5 cm3 of a standard solution of sodium nitrite with a concentration of 2 µg/cm3 into
a conical flask. Then 15 cm3 of Griess reagent is poured into the flask and after
15 minutes the optical density of the photoelectric colorimeter solution with a green
light filter (wavelength 538 nm) is determined in a 2 cm thick cuvette in relation to
the reference solution.
The mass fraction of sodium nitrite in the product in percent (X) is determined
by formula (8):
М × 200 × 100 × 100 × 30
Х = , (8)
m × 20 × 5 × 10
6
where:
M is the mass concentration of sodium nitrite, found from the calibration curve,
μg/cm
3
;
m is the mass of the product sample, g (20 g);
106 is the conversion factor to grams.
The final result of the study is taken as the arithmetic mean of the results of
two parallel tests, calculated with an accuracy of 0.0001 %.
The maximum content of residual sodium nitrite in raw smoked sausages
should not exceed 0.003 %, in other sausages — 0.005 %.
Determination of the presence of starch in sausages
Lugol's solution is applied dropwise to the surface of a fresh cut of minced
sausage. The appearance of a blue or black-blue color indicates the presence of
starch.
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The presence of starch is allowed in minced sausage products, in the recipe of
which it is provided for by regulatory documentation.
Rationale for veterinary and sanitary assessment of sausages depending
on the results of the examination
Fresh sausage products that meet the standards for all regulated indicators are
produced for free sale.
Products that do not meet the standards for at least one regulated indicator, as
well as sausages of questionable freshness, are subject to industrial processing into
lower grades, provided that the results of their laboratory tests are satisfactory.
Stale sausages are subject to technical disposal, as well as products if foreign
impurities, insect larvae, rodent droppings, etc. are detected in them.
Test questions and assignments
1. Describe the rules for sampling sausage products.
2. What indicators are determined during organoleptic examination of
sausages?
3. What laboratory methods are used when testing sausages for freshness?
4. What is the pH value of minced sausages of varying degrees of freshness?
5. What indicators are determined during technochemical testing of sausages?
6. What do you do with sausage of questionable freshness?
7. What is done with sausage that does not meet the requirements of the NTD
for the mass fraction of moisture?
90
CHAPTER 10. VETERINARY AND SANITARY EXAMINATION
OF PRODUCTS FROM SLAUGHTERED ANIMALS’ MEAT
Meat products (products) are large-piece products prepared from parts of meat
carcasses, cut up in a certain way, salted, heat-treated and ready for consumption.
This is a large group of meat products, many of which are considered gourmet.
Rules for sampling products from meat
of slaughtered animals for research
To control the appearance of the product, a sample of 10 % of the product units
of the batch is taken.
For all types of research, the following are selected from the inspected products:
- 2 samples for all types of tests, if the mass of one product is more than 2 kg;
- 2 samples for each type of test, if the weight of one product is not more than 2 kg.
First, samples are taken for microbiological studies — point samples are cut
from two units of product along the entire thickness of the product, at least 10 cm
long (with a sterile instrument).
Then, in the transverse direction, at a distance of at least 5 cm from the edge,
spot samples for organoleptic studies weighing 400–500 g and for chemical studies
weighing 200–250 g are cut from two units of the product, from which combined
samples are then made.
The samples include adipose tissue and skin, if available.
Selected pooled samples are packaged separately in film or parchment paper,
and samples for microbiological examination are packaged separately in sterile
parchment paper or dishes. All samples are numbered.
Samples are placed in a common bag, box, jar, which is sealed.
The samples are accompanied by a document (sampling report), which
indicates the name of the product, the name of the manufacturer, production date
(shift, hour), batch size, place and date of sampling, purpose of testing, full name and
the position of the persons taking the samples, their signatures.
Organoleptic examination of products from meat
of slaughtered animals
During organoleptic examination of meat products, the following is
determined:
- appearance, shape — visually;
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