Hafiza Saima Ghaffar (2009-VA-230)

Comparative Quality Evaluation Of Raw And Pasteurized Milk - 2016. - 217p.;

This particular project was designed to evaluate the overall quality of raw and pasteurized milk available at different areas of Lahore. The parameter which was checked includes microbiological analysis, adulterants, physicochemical properties and the effect of temperature on vitamin C in milk samples. Raw samples were collected from ten different towns of Lahore, whereas pasteurized milk samples belong to ten different brands. Ten samples were collected under control conditions from animals in sterilized containers.
For microbiological analysis four parameters were selected including total plate count (TPC), total coliform count (TCC), total psychrotrophic count (TPSC) and total yeast and mold count (TYMC) whereas, different adulterants like adulteration test was done such as urea, starch, hydrogen peroxide, detergent or soap, sorbitol, quaternary ammonium compound, boric acid, cane sugar, sodium chloride, formalin and hypochlorite were checked by using the milk adulteration kit in QOL. Milk contains casein and whey proteins. Whey protein being added in the milk to increase its density which is considers being an adulterant. In this project whey protein was estimated in all milk samples by titration method. Physicochemical characteristics of milk are an important parameter to judge the quality of milk. These physicochemical properties include fat%, SNF%, density kg/m3, lactose%, solid/ash, protein% and pH. Physicochemical properties were evaluated mechanically by Milkoscan. Heat treatment is an important method to reduce the microbiological contamination of milk. These treatments may include pasteurization and UHT etc. During the heat treatment some of the micronutrients may deteriorate thus compromising the quality of milk. Vitamin C is among those heat labile micronutrients. Vitamin C was checked quantitatively in market and self-collected samples by using titration method.
It was concluded that total plate count TPC, TCC, TPSC and TYMC of raw milk samples were above the standard value indicating the poor quality of the milk. As far as the pasteurized milk samples were concerned ninety percent of the samples showing higher values for TCC, TPSC and TYMC. Total plate counts of all self-collected raw milk from a healthy animal were found within the standard value. Counts were in range of 3.8x 103 – 8.9x103 CFU/mL of all milk samples. TPC of all self-collected raw milk from a healthy animal were found within the standard TCC were found within permissible value (102 CFU/mL .TPSC were negative for all milk samples. TYMC were in range of 2.6x101 -7.2x101 CFU/mL. Among milk samples (n=10), three samples (30%) were positive for TYMC were while remaining samples (70%) were negative and showed no growth.
Physicochemical factor show that 50 percent of raw milk have low nutritional value as compared to the standards which are buffalo and cow milk contains 7.6, 4.5% fat, 3.8, 3.8 % protein, 5.1, 4.9% lactose, 0.78, 0.72% ash and 17.0, 13.9% total solid respectively. In raw milk mean of fat (%), solid not fat (%), lactose (%), Solid/ash (0%), protein(%) and pH were 4.50±0.03, 7.915±0.06, 23.05±0.055, 3.893±0.06, 3.85±0.05, and6.9±0.0.02 respectively. In pasteurized milk mean value for fat, SNF, lactose, ash, protein and pH were 3.48 ±0.13, 7.24±0.10, 3.60±0.05,0.5 ±0.06, 2.82±0.05, 7.2±0.20 respectively. Pasteurized milk is good for consumption.
Different adulterant such as urea, starch, hydrogen peroxide, Sorbitol, QAC, Boric acid, Cane sugar, NaCl, Carbonate, Formalin, hypochlorite, whey protein, Added water and soap /detergents were evaluated in all milk samples. Among these adulterant water (66%) was found in majority of milk samples, followed by whey protein (15%), starch (13%), (10%) NaCl and
(8%) cane sugar were detected in raw milk samples. n Pasteurized milk samples only added water (49%) and whey protein (31%) was detected.
Among the raw milk samples the maximum and minimum concentration of vitamin C was observed 0.33±0.02 and 3.33 ±0.02 mg/100ml and for pasteurized milk maximum and minimum concentration of vitamin C was observed 2.54mg/100ml and 0.32 ±0.02 mg/100ml respectively. In self- collected samples the minimum and maximum concentration of vitamin C was observed 5.25±0.02 and 8.34 ±0.04 mg/100ml respectively and after pasteurization in laboratory minimum and maximum concentration of vitamin C was observed 3.48±0.04 and 5.83 ±0.02 mg/100ml respectively. These observations had showed that pasteurization treatment decreased Vitamin C quantity.

Department of Microbiology


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