Available online at: Received 24 th November 2015, revised 29 th December 2015, accepted 30 th January 2016

Transcription

1 International Research Journal of Biological Sciences E-ISSN Evaluation of Physico-Chemical Properties and Detection of Adulterants of UHT Milk Samples Available in Bangladesh Awal Md. Shihabul 1*, Amin Md. Ruhul 2, Haque Md. Raihanul 3, Kamal Md. Murtuza 4 and Hasan S.M. Kamrul 4 1 Department of Food Science and Nutrition, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh 2 Department of Agricultural and Industrial Engineering, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh 3 Department of Food Engineering and Technology, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh 4 Department of Food Processing and Preservation, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh shihab_fpe06@yahoo.com Available online at: Received 24 th November 2015, revised 29 th December 2015, accepted 30 th January 2016 Abstract In this research, four brands of UHT milk available in Bangladesh were analyzed for physico-chemical properties and adulterants used. Maximum amount of protein (3.43%) and fat (3.50%) were observed in S 3 sample, whereas minimum protein (3.2%) and fat (3.13%) were resulted in S 2 and S 1 sample respectively. The UHT milk sample S 2 showed the highest acidity (0.19%), whereas the S 1 sample showed the lowest value (0.17%). Significant (p<0.05) differences in physico- for solids not fat chemical compositions of UHT milk samples were resulted and all samples failed to maintain standards (SNF) of UHT milk recommended by BSTI. However, all UHT milk samples were proved to be fresh based on COB and alcohol test. Except added water, adulterant was not found in selected UHT milk samples. The statistical analysis showed that S 3 sample was significantly (p<0.05) superior and nutritionally most accepted than other UHT milk samples available in Bangladesh. Keywords: UHT milk, Physico-chemical property, Adulterant, Clot on Boiling (COB), Alcohol test. Introduction Milk is a complete food, which can be easily digested and absorbed in human body. Milk plays important role in regulating body process by supplying nutrients to body. Beside this, milk is good source of calcium and essential amino acids, which are essential for proper growth of infants and to prevent osteoporosis in adult stage 1,2. In Bangladesh, cow milk is more popular than any other milk and mostly come from small scale farms. In urban area of Bangladesh, pasteurize and ultra-heat treatment (UHT) milk are commonly used to meet the demand the fresh milk. Usually, milk is transported from production area to collection center or processing area by middlemen. Most of the time, middlemen cannot maintain hygienic condition during transportation and they use chemicals or adulterants to prolong shelf-life of milk. From ancient time food adulteration has been seen but it is becoming concern to all. Dairy or dairy products are most targets for adding adulterants like starch, flour, urea, sugar, vegetable oils, detergents and even lethal chemical formalin 3,4. A group of unscrupulous producers are also using harmful chemicals in milks and dairy products intentionally for extra financial benefits 5. These used adulterants, chemicals or preservatives in raw or processed milk causing various dangerous diseases 6. Urea, hydrogen peroxide, antibiotics, caustic soda, carbonates and bicarbonates adulterated milks are also very harmful for adolescent girls and pregnant women 7. Milk is highly perishable and spoiled within five hours after milking by bacterial contaminationn from different sources like milker, utensils, water supply, hands, cloths of milker, air, floor etc 8. Contaminated milk is good source of various foods borne pathogens 9. Without adding preservative, UHT is best method to prolong the shelf-life or keeping quality of milk. Moreover, adulteration leads to great economicc losses, quality deterioration of finished products and safety issue 10. However, off flavor and denaturation of protein may be resulted during UHT. This is also a big problem in UHT milk industry 11. Milk Vita, PRAN, Aarong Dairy, Rangpur Dairy and FARM FRESH MILK are common brands of pasteurized or UHT milk in Bangladesh. But people don t show their interest to purchase UHT milk because of using adulterants in processed milk. Therefore, it is very important for the processed milk industry to maintain the quality of processed milk and ensure that UHT milk is adulterant free. So far, one or two researches have been carried out on quality evaluation of UHT milk available in Bangladesh. From the above point of view, the research was undertaken to analyze the physico-chemical properties as well as the adulterants in the UHT milk samples. International Science Community Association 1

2 Materials and Methods Collection of sample: In this study, UHT milk of four different brands was purchased from local grocery shop at Basherhat, Dinajpur. The milk samples were then stored at room temperature in laboratory under the faculty of Engineering, Hajee Mohammad Danesh Science and Technology University for further analysis. Physico-chemical analysis of UHT milk samples: Protein content of milk was determined by titrimetric method described by Davide 12. Protein content was calculated by following equation: % Protein = mlof 0.1N NaOHrequiredto neutralize10mlmilk 1.7 Fat content was determined according to Gerber method described by Kleyn et al. 13. Titratable acidity was measured by titrimetric method reported by O Mahoney 14. The ph of milk was measured using a digital ph meter (HI 8314, Hanna Instruments, Italy) calibrated with ph 4 and 7 buffer following the method of Pearson 15. Corrected lactometer reading (CLR) indicates the density of milk that was measured by lactometer according to method described by Aggarwal and Sharma 16. Specific gravity of milk was determined according to the procedure of Aggarwal and Sharma 16. Specific gravity was CLR calculated as: Specific gravity of milk = Solids not fat (SNF) of milk was determined by lactometric method 17 and calculated following equation: Fat % CLR SNF = Total solids of milk were measured according to Ling 18 and CLR calculated as: TS = ( Fat% 1.2) Clot on boiling test (COB) was observed by following the method described by Tessema and Tibbo 19. Alcohol test was conducted by the method of Tessema and Tibbo 19 where equal amount of milk and 68% ethanol solution were mixed in a test tube to know the good quality of milk. Detection of adulterants in UHT milk: Added water in UHT milk was determined by simple equation described by Ibrahim et al. 20 and given as below: Water added (%) = Legal milk solid not fat Milk solids not fat of sample Legal milk solids not fat x 100 Hydrogen peroxide in milk sample was determined according to the procedure of Faraz et al. 21. Soda test of milk was performed by the method of Kamthania et al. 22, carried out by mixing 5ml of alcohol with 5ml of milk followed by 2-3 drops of rosolic acid. Formaldehyde in UHT milk was studied by Hehner test according to the method Kamthania et al. 22. Starch in UHT milk was perceived by starch-iodite test following the method of Kamthania et al. 22 where one drop of iodine solution was added to 3ml of UHT milk and mixed properly to notice the color change. Cane sugar test was performed by following method of Kamthania et al. 22 to detect the added sugar in milk. The presence of carbonate in milk was detected by the method described by Faraz et al. 21. Skim milk powder content in milk was measured according to method of Awan et al. 23, carried out by adding few drops of nitric acid to milk sample. Method described by Awan et al. 23 was used to measure the sodium chloride content in milk where 2 to 3 drops of 1% potassium dichromate was added to 1ml of UHT milk sample. Pulverized soap in milk sample was examined by the method of Awan et al. 23. Statistical analysis: The data for the quality parameters of the present study were statistically analyzed using SPSS (verson- 20). One way analysis of variance (ANOVA) for different quality parameters was performed and means were compared by the Duncan s Multiple Range Test (DMRT) with 5% significance level. Results and Discussion Protein and fat content: The protein and fat content of different brands of UHT milk samples are presented in Figure-1. The highest amount of protein was found for S 3 (3.43%) and followed by S 1 (3.37%), S 4 (3.26%) and S 2 (3.2%) sample. UHT milk sample of S 4 and S 2 were found to meet the minimum requirement for protein content of UHT milk (3.3%) recommended by BSTI 24. In a previous study, Hossain et al. 25 observed highest protein content (3.68%) followed by 3.52% and 3.43% protein in three UHT milk samples available in Bangladesh. The protein content of UHT milk is mostly affected by heating and subsequent storage condition 26. Figure-1 shows a range of fat content from 3.2 to 3.5% in UHT milk samples studied in this research work. One of UHT milk sample failed to fulfill the minimum fat content requirement (3.4%) set by BSTI 24. However, all UHT milk samples satisfied the minimum fat content requirement (3.25%) for fluid whole milk set by Food and Drug Administration (FDA). In contrast, very low fat content (3.09%) was observed in a UHT milk sample 25 that failed to satisfy the minimum fat requirement for whole milk fixed by BSTI. Preference of UHT milk depends on fat content largely and for that reason, consumers don t show same interest to all UHT milk samples available in Bangladesh. ph and Acidity Content: Figure-2 shows the ph and acidity of UHT milk samples studied in this research. The ph content of UHT milk samples varied from 6.1 to 6.3 where highest was found for S 1 sample and lowest for S 2 sample. Acidity of milk is a good measure of it s freshness. In this study, acidity of UHT milk samples differed from 0.17% to 0.19% (Figure-2) where maximum acidity (0.15%) is allowed for UHT milk 24. This International Science Congress Association 2

3 range was slight higher than the range of acidity (0.14% to 0.16%) was reported for UHT milk in a previous study 25. Variation in acidity content of UHT milk may be occurred because of longer storage period and different storage conditions. Sour flavor in milk starts to develop at acidity 0.3%, whereas clear sour taste is sensible at acidity 0.4% and precipitates at 0.6% 26. Physical parameters: Physical parameters of UHT milk samples are presented in Table-1. There was no significant (p>0.05) difference in specific gravity among UHT milk samples. The range of specific gravity of UHT milk samples was within the standard range (1.028 to 1.033) recommended for UHT milk by FAO. The specific gravity (1.028) is considered as standard value for UHT milk in Bangladesh 25. Solids not fat (SNF) were not same in all milk samples. Highest SNF (7.86%) was recorded for S3 sample, whereas S 1 sample was found with least SNF (7.74%) Protein 3.5 Fat Amount (%) S1 S2 S3 S UHT Milk Figure-1 Protein and Fat content in UHT milk samples ph Acidity (%) Amount S S S3 S UHT Milk ph Figure-2 and Acidity content in UHT milk samples International Science Congress Association 3

4 Table-1 Physico-chemical parameters of UHT milk samples (*) Parameters S 1 S 2 S 3 S 4 Specific Gravity 1.027±0.05 a 1.028±0.04 a 1.028±0.05 a 1.028±0.04 a Solids not fat (%) 7.74±0.06 ab 7.79±0.03 ab 7.86±0.09 a 7.83±0.07 a Total solids (%) 10.88±0.12 b 11.31±0.29 a 11.36±0.12 a 11.33±0.10 a Corrected lactometer reading 27.90±0.21 a 27.87±0.24 ab 28.10±0.37 a 27.97±0.29 a *Mean values with standard deviation; values with different superscripts within a column are significantly (p<0.05) different None of UHT milk samples maintained the standards for SNF of 8% and 8.25% fixed by BSTI 24. In earlier, a higher range of SNF (7.91% to 8.56%) was observed in UHT milk samples available in Bangladesh 25. Table-1 shows the significant (p<0.05) difference in total solids of UHT milk samples. A range of total solids from to 11.36% was observed in this research. This range of total solids was more or less than the results reported by Hossain et al. 25. Variation in total solids may be resulted due to addition of water in milk. Corrected lactometer reading (CLR) of UHT milk samples varied from to (Table-1). A range of 28.0 to 30.0 is considered standard CLR for milk 27. Only S 3 milk sample fulfilled the standard of CLR, whereas other samples were almost near to the minimum value of Clot on boiling (COB) and Alcohol test: Table-2 shows the results of clot on boiling (COB) and alcohol test of four UHT milk samples. All of four milk samples showed negative results on both COB and alcohol test that were symbols of good quality milk. Both of tests are important in milk processing for identification of abnormal milk, developed acidity and mineral balance in milk. It is interesting to note that there is no published research paper regarding COB and alcohol test of UHT milk available in Bangladesh. Table-2 COB and Alcohol for UHT Milk Milk Sample COB Test Alcohol Test S 1 S 2 S 3 S 4 + = Positive and =Negative Adulteration in Milk: Results of presence of various adulterants namely, added water, hydrogen peroxide soda, formaldehyde, starch, cane sugar, carbonate, skim milk powder, sodium chloride and pulverized soap in UHT milk are shown in Table-3. Table-3 Results of adulteration test of UHT milk samples Adulterants Milk Sample S 1 S 2 S 3 S 4 Added water Hydrogen per oxide Rosolic acid Formaldehyde Starch Cane sugar Carbonates Skim milk powder Sodium chloride + = Positive and =Negative Results indicated the presence of added water in all UHT milk samples. Adding water in milk is common practice in Bangladesh especially in raw milk. Addition of milk in raw milk is usually practiced by unscrupulous producers for extra profit. This result was in line with the finding of Hossain et al. 25 who also observed added water in UHT milk available in Bangladesh. However, hydrogen per oxide, rosolic acid, formaldehyde, starch, cane sugar, carbonates, skim milk powder and sodium chloride were not found in UHT milk samples analyzed in this study. In contrast, Hossain et al. 25 reported the presence of sucrose in UHT milks sold in local market of Bangladesh. Conclusion Milk is usually considered as complete food because of it s nutritional compositions. Due to high perish ability of milk, it is International Science Congress Association 4

5 urgent to process after milking. Milk is processed by ultra-heat treatment (UHT) with integrated aseptic packaging to increase the shelf life with sound quality. Ultra heat treatment (UHT) has been proved to be potential heat treatment process. BSTI standards for UHT milk were not followed properly in UHT milk processing industries. However, no harmful adulterant except added water was not found in UHT milk samples. A few years ago, UHT milk was not preferred like fresh milk because of misconception but the demand of UHT milk is gradually increasing in Bangladesh. Therefore, legal authority should be aware regarding the standards of BSTI for UHT milk. References 1. Neumann C.G., Harris D.M. and Rogers L.M. (2002). Contribution of Animal Source Foods in Improving Diet Quality and Function in Children in the Developing World. Nutr. Res., 22, Espinosa M.P., Sigman M., Neumann C.G., Bwibo N.O. and McDonald M.A. (1992). Playground Behaviors of School-Age Children in Relation to Nutrition, Schooling and Family Characteristics. Dev. Psychol., 28, Karouri R. and Baedemaeker J. (2007). A Review of The Analytical Methods Coupled with Chemometric Tools for the Determination of the Quality and Identity of Dairy Products. Food Chemistry, 102(3), El-Loly M.M., Mansour A.I.A and Ahmed R.O. (2013). Evaluation of Raw Milk for Common Commercial Additives and Heat Treatments. Internet Journal of Food Safety, 15, Nicolaou N, Xu Y and Goodacre R. (2011). MALDI-MS and Multivariate Analysis for the Detection and Quantification of Different Milk Species. Anal Bioanal Chem., 399, Afzal A, Mahmood M.S., Hussain I. and Akhtar M. (2011). Adulteration and Microbiological Quality of Milk. A Review. Pakistan J. Nutrition, 10(12), Tariq M.A. (2011). Subject: A close look at diatery paterns. htm. 8. Ensminger M.E., Ensminger A.H., Konlande J.E. and Robson J.R.K. (1994). Foods and Nutrition Encyclopedia. 2 nd edition, 1, Oliver S.P., Jayarao B.M. and Almeida R.A. (2005). Foodborne Pathogens in Milk and the Dairy Farm Environment: Food Safety and Public Health Implications. Foodborne Pathogen and Diseases, 2(2), Mabrook M.F. and Petty M.C. (2003). A Novel Technique for the Detection of Added Water to Full Fat Milk Using Single Frequency Admittance Measurements. Sensors and Actuators B: Chemical, 96 (1 2), Mansour A.I., El-Shobery M.A., El-Esheery M.I. (2007). Sensory and Microbiological Evaluation of Shelf-Life for Pasteurized and UHT Milk. Al-Azhar J. Res., 45(2), Davide C.L. (1997). Laboratory guide in dairy chemistry practicals. FAO Regional Dairy Development Centre for Asia and the Pacific. Dairy Training and Research Institute, UPLB, Laguna, Philippines. 13. Kleyn D.H., Lynch J.M., Barbano D.M., Bloom M.J. and Mitchell M.W. (2001). Determination of Fat in Raw and Processed Milks by the Gerber. Method: Collaborative Study. Journal of AOAC international, 84(5). 14. O Mahoney F. (1988). Rural dairy technology- Experiences in Ethiopia. ILCA Manual No. 4. Dairy Technology Unit. ILCA, Addis Ababa, Ethiopia, 3(8), Pearson D. (1977). The Chemical Analysis of Food., 7 th Ed., Chemical Publishers Co., New York, Aggarwal A.C. and Sharma R.M. (1961). A laboratory manual of milk inspection printed in India. 4 th Ed. Asia publishing house, Bombay, India. 17. Ramsey J.A. and Swartzel K.R. (1984). Effect of UHT Processing and Storage Conditions on Rates of Sedimentation and Fat Separation of Aseptically Packaged Milk, J. Food Sci., 49, Ling T.R. (1963). Textbook of dairy chemistry. 3 rd Ed, Chapman and Hall, London II, Tessema A. and Tibbo M. (2009). Technical Bulletin No. 2, Milk Quality Control. International Center for Agricultural Researchin the Dry Areas, Ethiopia. 20. Ibrahim A., Mansour A., Mansour M. El-Loly and Ahmed R.O. (2012). A Preliminary Detection of Physical and Chemical Properties, Inhibitory Substances and Preservatives in Raw Milk, Internet Journal of Food Safety, 14, Faraz A., Lateef M., Mustafa M.I., Akhtar P., Yaqoob M. and Rehman S. (2013). Detection of Adulteration, Chemical Composition and Hygienic Status of Milk Supplied to Various Canteens of Educational Institutes and Public Places in Faisalabad. The Journal of Animal and Plant Sciences, 23(1), Kamthania M., Saxena J., Saxna K. and Sharma D.K. (2014). Milk Adultration: Methods of Detection and Remedial Measures. National Conference on Synergetic Trends in engineering and Technology. 23. Awan A., Naseer M., Iqbal A., Ali M., Iqbal R. and Iqbal F. (2013). A Study on Chemical Composition and Detection of Chemical Adulteration in Tetra Pack Milk Samples Commercially Available in Multan, International Science Congress Association 5

6 Pakistan.Journal of pharmaceutical science, 27(1), BSTI (2002). BDS 1702: Bangladesh Standard: Specification for Pasteurized Milk. Bangladesh Standards and Testing Institution, Tejgaon Industrial Area, Dhaka, Hossain T.J., Alam M.K. and Sikdar D. (2011). Chemical and Microbiological Quality Assessment of Raw and Processed Liquid Market Milks of Bangladesh. Continental J. Food Science and Technology, 5(2), Fox P.F. and Mc Sweeney P.L.H. (1998). Dairy Chemistry and Biochemistry. Kluwer Academic Publisher, New York, Sukumar D. (2005). Outlines of Dairy Technology. Oxford University Press, New Delhi, International Science Congress Association 6