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Abstract
7. SUMMARY
A total of two hundreds and sixty milk samples were collected randomly of both cow’s and buffaloe’s milk including governmental dairy farms (thirty samples for each type), dairy shops, as well as, street vendors (sixty samples for cow’s milk and forty samples for buffaloe’s milk) in Assiut governorate. These samples were physically and chemically examined in order to determine whether they were adulterated or not and to detect the type of adulteration.
The results obtained were summarized as follow :
7.1. Physical and chemical examination :
The results of specific gravity, fat content, milk solids not fat percentages, total solids percentages, moisture content and added water of examined milk samples collected from different sources are compared with the Egyptian Standards recorded in the following Tables : legal and illegal
7.1.1. Cow’s milk :
Source of milk Specific gravity Fat (%) MSNF (%) T.S (%) Moisture content Add water
L.% I.L.% L. % I.L.% L. % I.L.% L. % I.L.% L. % I.L.% L. % I.L.%
Dairy farms 96.7 3.3 96.7 3.3 100.0 - 100.0 - 100.0 - 100.0 -
Dairy shops 50.0 50.0 43.3 56.7 46.7 53.3 35.0 65.0 35.0 65.0 46.7 53.3
Street vendors 38.3 61.7 35.0 65.0 30.0 70.0 23.4 76.6 23.4 76.6 30.0 70.0
L. = Legal I.L. = Illegal
7.1.2. Buffaloe’s milk :
Source of milk Specific gravity Fat (%) MSNF (%) T.S (%) Moisture content Add water
L.% I.L.% L. % I.L.% L. % I.L.% L. % I.L.% L. % I.L.% L. % I.L.%
Dairy farms 90.0 10.0 90.0 10.0 100.0 - 100.0 - 100.0 - 100.0 -
Dairy shops 42.5 57.5 32.5 67.5 62.5 37.5 50.0 50.0 50.0 50.0 62.5 37.5
Street vendors 25.0 75.0 17.5 82.5 55.0 45.0 25.0 75.0 25.0 75.0 55.0 45.0
L. = Legal I.L. = Illegal
Comparing these results by Egyptian Standards, it is cleared that street vendors dairy and shops samples of both cow’s and buffaloe’s milk were subjected to both types of adulteration Partial skimming and/or addition of water and was the worst type, while, the dairy farms milk samples were the best one and less liable to adulteration.
7.2. Detection of inhibitory substances and preservatives :
7.2.1. Cow’s milk :
7.2.1.1. General test :
The obtained results indicated that 5 (16.7%), 29 (48.3%) and 30 (50%) out of examined dairy farms, dairy shops and street vendors milk samples, respectively, were positive for inhibitory substances.
7.2.1.2. Specific tests for detection of preservatives :
It is evident from the reported results of dairy farms milk samples that all samples were free from formalin, salicylic acid, boric acid & borax, carbonate & bi-carbonate and nitrate. On the other hand, 1 (3.3%) sample was contained hydrogen peroxide.
Moreover, all milk samples of dairy shops were free from formalin and salicylic acid. On the other hand, 2 (3.3%), 3 (5%), 3 (5%) and 11 (18.3%) of samples were contained hydrogen peroxide, boric acid & borax, carbonate & bi-carbonate and nitrate, respectively.
Furthermore, all milk samples of street vendors were free from formalin, salicylic acid and hydrogen peroxide. While, 1 (1.7%), 4 (6.7%) and 13 (21.7%) of samples were contained boric acid & borax, carbonate & bi-carbonate and nitrate, respectively.
7.2.2. Buffaloe’s milk :
7.2.2.1. General test :
The obtained results indicated that 3 (10%), 14 (35%) and 16 (40%) out of examined dairy farms, dairy shops and street vendors milk samples, respectively were positive for inhibitory substances.
7.2.2.2. Specific tests for detection of preservatives :
It is evident from the reported results of milk samples collected from dairy farms that all samples were free from salicylic acid, boric acid & borax, carbonate & bi-carbonate and nitrate. On the other hand, 1 (3.3%) and 1 (3.3%) of samples were contained formalin and hydrogen peroxide.
Moreover, all milk samples of dairy shops were free from formalin and salicylic acid. On the other hand, 1 (2.5%), 1 (2.5%), 5 (12.5%) and 5 (12.5%) of samples contained hydrogen peroxide, boric acid & borax, carbonate & bi-carbonate and nitrate, respectively.
Furthermore, all milk samples of street vendors were free from formalin, salicylic acid and hydrogen peroxide. While, 2 (5%), 4 (10%) and 7 (17.5%) of samples were contained boric acid & borax, carbonate & bi-carbonate and nitrate, respectively.
7.3. Detection of common commercial additives :
Obtained results indicated that all examined milk samples of dairy farms, dairy shops and street vendors of both cow’s and buffaloe’s milk were free from any addition of starch & cereal flour, gelatin and skim milk powder.
7.4. Detection of heat treatment :
7.4.1. Cow’s milk :
It is clearly evident that all examined dairy farms milk samples (30 samples) were in raw state.
whereas, dairy shops examined milk samples showed that 9 (15%) out of 60 samples proved to be heat treated.
Moreover, 16 (26.7%) out of examined milk samples collected from street vendors proved to be heat treated.
7.4.2. Buffaloe’s milk :
Summarized data revealed that all examined dairy farms milk samples (30 samples) were in a raw state. whereas, dairy shops examined milk samples showed that 3 (7.5%) out of 40 examined milk samples were heat treated. Moreover, 9 (22.5%) out of examined street vendors milk samples proved to be heat treated.
from obvious summarized results, it’s clearly evident that milk marketed by dairy shops, as well as, street vendors in Assiut Governorate more liable to adulteration than dairy farms.
Also, street vendors milk samples were the worst to be adulterated followed by dairy shops milk samples, whereas, the dairy farms milk samples were the best one.
Likewise, the buffaloe’s milk samples were subjected to adulteration by partial skimming more than cow’s milk as it is rich in fat content while, the cow’s milk was more liable to adulteration by addition of water as well as inhibitory substances and heat treatment as it is more available in markets and of low demand than buffaloe’s milk.
Furthermore, adulteration of milk is a complex problem due to high economic costs as well as inhabiting the utilization of useful constituents of milk as fat, fat soluble vitamins, protein, lactose, antibodies which are very important for the biological processes and normal growth of body.