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Научни трудове на Съюза на учените в България-Пловдив. Серия В. Техника и технологии, естествен ии хуманитарни науки, том XVI., Съюз на учените сесия "Международна конференция на младите учени" 13-15 юни 2013. Scientific research of the Union of Scientists in Bulgaria-Plovdiv, series C. Natural Sciences and Humanities, Vol. XVI, ISSN 1311-9192, Union of Scientists, International Conference of Young Scientists, 13 - 15 June 2013, Plovdiv.
ASSESSMENT (EVALUATION) OF BIOCHEMICAL AND MICROBIOLOGICAL QUALITIES OF RAW MILK "VITA"
Domniku.R1, Hajdini.S2, Salihu.D2
1. Devolli Group - Dairy " Vita" Istog, Kosovo 2. Department of Food Technology, Faculty of Geoscience, University of
Prishtina, Kosovo
INTRODUCTION
Milk is a specific product of mammary glands that is produced by mammals after calving, that serving for the nourishment of their young (Z.Ndoja). Milk contains all essential substances such as: water, fats, carbohydrates, proteins, minerals and vitamins. From this specific composition, indicates that milk has high nutritional value and therefore it is individualized as basic food in human life (R.Troja).
Milk is opaque white color liquid with nice light taste and characteristic aroma.
Microorganisms occurring in our environment find in milk ideal substrate for their development, because that fulfills nutritional requirements of many microbial species (S.Cvejanovic, M.Caric, S.Milanovic, R.Radovanovic). Level of contamination of this product from the milking process to the consumer, grows up and is proportional to the storage time and the temperature of the environment which is stored.
Fresh milk from a healthy cow is practically free from bacteria, but immediately after milking they can fall in milk from the surrounding environment (N.Striceviq). Therefore when it emerges from the breast milk temperature is 38°C, exists all conditions that this micro flora multiply within a short time. That's why it is recommended immediate cooling of milk after milking at a temperature of 4-10°C (A. Myftiu).
Customer demands to have food product of high and safe quality are growing. Today aims is that unprepared food products undergo the technological process, before it is used for consumption in order to increase the quality and safety of food product for consumption. Processes such as pasteurization, sterilization is very common today because they increase food product safety.
MATERIALS AND METHODS
Our study is set in the factory "Vita ". Their production capacity goes up to 150 000 liters (daily). For milk testing is used raw material which has not been subject to technological processing. Tests that we decided to include in the study are able to determine the chemical-biological qualities of milk that will stand out in the market.
Methods used for determining the freshness, fat, acidity, density and total count are standard
methods, and to determination the protein we used EKOMILK (by which are determined almost all biochemical parameters and in particular the determination of proteins which do not have the opportunity to define with standard method).
All samples were initially tested for their organoleptic quality and also for the situation of freshness. This would allow for a rapid selection of poor milk quality at the point of collection. Freshness test principle is supported by the loss of proteins stability in milk when the level of acidity is increased. This fact can be evident when we add alcohol in milk.
Testing features of quantitative indicators (such as fat and milk proteins) as well as qualitative indicators (such as acidity and specific weight of milk) were strictly conducted and observed in every step of the test, after the results of these tests are related acknowledging the price of milk (ILAC Manual No.4).
In term of bacterial milk control we took into account the fact that samples for analysis should in advance to be diluted so we have the possibility to count with naked eye microbial colonies formed in the ground feeder.
For dilution of samples we used physiological water or buffer solution in dilutions 10-1, 10-2, 10-3, etc. Bacteriological test results were taken after 18-24hours (K.Sini, B.Bijo).
Results obtained on a series platp nlnntpH with v^inn« dilatation. Counting of colonies developed on the planted plates is calc ¡¡PC =-—-
ICi™,) + GUiHaflHi
• XC= number of all counted colonies
• n1= the number of plates used in the thinning of the first counting
• n2 = the number of plates used in the second thinning
• d= dilution factor of the concentrated dilution.
RESULTS AND DISCUSSION
Results of chemical analysis
As we introduced at the beginning of this paper all laboratory work is carried out in the factory "Vita", in its respective laboratory for measuring organoleptic indicators, quantitative, qualitative and microbiological fresh milk.
Table. 1 we have grouped the results that have to deal with values of measurement of quantitative and qualitative characteristics of the milk. Now we explain that every sample was evaluated through three parallel measurements and from these measurements is extracted an average score.
Table. 1 - Results of qualitative and quantitative indicators:
First measurement Second measurement The third measurement
% fat 3.9 3.9 3.9
% protein 3.0 2.98 3.0
Density 1.030 1.030 1.030
pH value 6.64 6.63 6.63
Acidity °SH 6.4 6.4 6.4
From simple analysis of all results of Table No. 1, we can say that testing samples of raw milk represent us in all cases the values which correspond to the state standard for cow milk.
If we want to analyze one by one, all indicators, we could comment only minimum value
of fresh milk protein concentration, which apparently relates the way of feeding the cows. It is known that during the spring, summer and autumn cows feed with moistening, which reduces the level of protein concentration, but although keep this value within standard. Results of microbiological analyses
Milk because of its chemical composition represents a very good cultural ground for growth of microorganism. Development in this environment causes a series of chemical modifications that give us motive to alterative processes that cause valuable changes and that lead us to the preparation of food products, as it is in case of fermented milk and cheese.
Milk which destination is human consumption should have following microbiological parameters (EU Directive 92/46):
• Content of total microflora 100.000/ml (this value is calculated as geometric average for two months period with at least 2 test per month)
Based on EU Directive quoted above we could say that situation in Kosovo is still far away from these indicators, which forces us to accept milk with microbiological indicators far from EU reality.
Table 2 - Test results in total micro fresh milk.
First measurement Second measurement The third measurement
Total count 550 000 530 000 520 000
Thermal operating treatment provides not only the destruction of all vegetative forms of microbes but also spore forms.
CONCLUSIONS
• Milk that come for processing in the factory "Vita" meets satisfactory level quantitative and qualitative indicators of characteristics defined in Kosovo state standard.
• Milk as a raw material has high total microbial load indicator, which is reflected in table. 2. This high microbial load is indicative of a low level of hygienic milk handling until it arrives at the factory. On the other hand this charge carries with it the potential risk that the milk may also have pathogenic bacteria that pose a danger to the health of consumer.
• UHT thermal treatment guarantees total destruction of micro flora which is present in raw milk.
• Respect to correct technology is a guarantee for the product and for customer.
• Factory respects and performs regularly standardized tests, and that increase its own reputation in dairy market in Kosovo and widely.
REFERENCES
1. A. Myftiu (translators) - republished 2003 -Dairy processing handbook - Tetra Pak -Tirana, Albania
2. Prof.as Kristag Sini, Prof.as. Bizena Bijo - 2003 - Manual of food microbiology and hygiene - Tirana, Albania
3. S.Cvejanovic, M.Caric, S.Milanovic, R.Radovanovic - 1998 Food Technology -Belgrade, Serbia
4. N. Striceviq - Recognition goods technology - Pristina, Kosovo
5. Rozana Troja - 2005-Chemistry and food technology - Tirana, Albania
6. Dr.Sc. Z.Ndoja, eng. Xh.Ramadani - 1996-Technology of livestock products / Practicum - Pristina, Kosovo
7. ILAC Manual No.4, Rural Dairy Technology. Experiences from Ethiopia.
