AGRICULTURAL RESEARCH COMMUNICATION CENTRE www.arccjournals.com / indianjournals.com J. Dairying, Foods & H.S., 29 (1) : 8 - 14, 2010 VALIDATION OF ULTRA-VIOLET AND VISIBLE SPECTROSCOPIC METHODS FOR DETECTION OF MILK FAT ADULTERATION Arun Kumar 1 , Amit Kumar 2 Darshan Lal*, Raman Seth and Vivek Sharma Dairy Chemistry Division, National Dairy Research Institute, Karnal-132 001, India. ABSTRACT An investigation was carried out to explore the possibility of using ultra-violet and visible spectroscopy in the detection of adulteration of milk fat with cheaper oils and fats (vegetable oils and fats, and animal body fats). No characteristic differences were observed in the absorption behavior of different oils and fats including milk fat when scanned in the ultra violet (200-320 nm) and visible (400-800 nm) region and therefore ultraviolet and visible spectroscopy failed to give any conclusive evidence of detection of adulteration in ghee with vegetable oils, body fats and vanaspati. Key Words: Adulteration, UV and visible spectroscopy, Body fats, Vegetable oils Milk fat. INTRODUCTION Lipids form one of the most important constituents of milk and milk products. Major part of milk lipids is comprised of triglycerides (generally called fats). Minor components of milk lipids include partial glycerides (mono- and di- glycerides), phospholipids, fat soluble vitamins, cholesterol, squalene, waxes, etc. In India, milk fat is mostly consumed in the form of ghee (clarified butterfat). However, its supply falls short of demand particularly in the lean (summer) season. Further, due to its short supply and more demand, expensiveness (costing 3 to 4 times as much as edible vegetable oils) and variable chemical composition, ghee falls prey to adulteration with vegetable oils and fats, and animal body fats by the unscrupulous traders in the market. Extensive survey of the literature reveals that several methods have been developed in the past based on parameters like fatty acid composition and the physico-chemical constants to detect the adulteration in ghee. But very few attempts have been made to detect the adulteration on the basis of interaction of radiation. Therefore, techniques of Ultra-Violet and Visible spectroscopy have been explored in the present investigation. MATERIALS AND METHODS 1. Collection of milk and preparation of butter Milk used for the preparation of ghee samples was collected from the Institute’s cattle yard. Cow milk was a mixture of the milk obtained from the herd of Karan Swiss, Karan Fries, Sahiwal and Tharparkar breeds. Buffalo milk used was also the herd milk from Murrah breed only. Cows and buffaloes were maintained under identical conditions of feeding and management. Soon after the collection of milk, it was warmed to 40°C and separated into cream using mechanical cream separator. The cream was pasteurized at 77°C for 5 minutes, cooled to room temperature and then kept in a refrigerator (5 to 10°C) for 3 to 5 hours for ageing. Butter was prepared under standard conditions (9°C in summer and 13°C in winter) by churning the cream using hand churn. 2. Collection of adulterants The body fats (pig and goat), vegetable oils (sunflower, soy bean and ground nut) and vanaspati (hydrogenated vegetable oils) were collected from the local market. *Corresponding Author: NDRI, Karnal- 132 001, India. 1 Department of Dairy Food Science & Technology, Maharana Pratap Univ. of Agriculture & Technology, University Campus, Udaipur-313001 (Rajasthan) . 2 Dairy Chemistry Division, College of Dairy Science and Technology, GADVASU, Ludhiana -141004 (Punjab).
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AGRICULTURAL RESEARCH COMMUNICATION CENTREwww.arccjournals.com / indianjournals.com
J. Dairying, Foods & H.S., 29 (1) : 8 - 14, 2010
VALIDATION OF ULTRA-VIOLET AND VISIBLE SPECTROSCOPIC METHODSFOR DETECTION OF MILK FAT ADULTERATION
Arun Kumar1, Amit Kumar2 Darshan Lal*, Raman Seth and Vivek SharmaDairy Chemistry Division,
National Dairy Research Institute, Karnal-132 001, India.
ABSTRACTAn investigation was carried out to explore the possibility of using ultra-violet and visible
spectroscopy in the detection of adulteration of milk fat with cheaper oils and fats (vegetable oils andfats, and animal body fats). No characteristic differences were observed in the absorption behaviorof different oils and fats including milk fat when scanned in the ultra violet (200-320 nm) and visible(400-800 nm) region and therefore ultraviolet and visible spectroscopy failed to give any conclusiveevidence of detection of adulteration in ghee with vegetable oils, body fats and vanaspati.
Key Words: Adulteration, UV and visible spectroscopy, Body fats, Vegetable oils Milk fat.
INTRODUCTIONLipids form one of the most important
constituents of milk and milk products. Major partof milk lipids is comprised of triglycerides (generallycalled fats). Minor components of milk lipids includepartial glycerides (mono- and di- glycerides),phospholipids, fat soluble vitamins, cholesterol,squalene, waxes, etc. In India, milk fat is mostlyconsumed in the form of ghee (clarified butterfat).However, its supply falls short of demand particularlyin the lean (summer) season. Further, due to its shortsupply and more demand, expensiveness (costing 3to 4 times as much as edible vegetable oils) andvariable chemical composition, ghee falls prey toadulteration with vegetable oils and fats, and animalbody fats by the unscrupulous traders in the market.Extensive survey of the literature reveals that severalmethods have been developed in the past based onparameters like fatty acid composition and thephysico-chemical constants to detect the adulterationin ghee. But very few attempts have been made todetect the adulteration on the basis of interaction ofradiation. Therefore, techniques of Ultra-Violet andVisible spectroscopy have been explored in thepresent investigation.
MATERIALS AND METHODS1. Collection of milk and preparation ofbutter
Milk used for the preparation of gheesamples was collected from the Institute’s cattleyard. Cow milk was a mixture of the milkobtained from the herd of Karan Swiss, KaranFries, Sahiwal and Tharparkar breeds. Buffalomilk used was also the herd milk from Murrahbreed only. Cows and buffaloes were maintainedunder identical condit ions of feeding andmanagement. Soon after the collection of milk, itwas warmed to 40°C and separated into creamusing mechanical cream separator. The creamwas pasteurized at 77°C for 5 minutes, cooled toroom temperature and then kept in a refrigerator(5 to 10°C) for 3 to 5 hours for ageing. Butterwas prepared under standard conditions (9°C insummer and 13°C in winter) by churning thecream using hand churn.
2. Collection of adulterantsThe body fats (pig and goat), vegetable oils
(sunflower, soy bean and ground nut) and vanaspati(hydrogenated vegetable oils) were collected fromthe local market.*Corresponding Author: NDRI, Karnal- 132 001, India.
1Department of Dairy Food Science & Technology, Maharana Pratap Univ. of Agriculture &Technology, University Campus, Udaipur-313001 (Rajasthan) .2Dairy Chemistry Division, College of Dairy Science and Technology, GADVASU, Ludhiana -141004 (Punjab).
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3. Preparation of adulterated ghee samples The adulterants described above wereadded individually to ghee (buffalo / cow) at thebutter stage on the basis of its fat content at 5%,10% and 15% level. The butter samples admixedwith the adulterants were clarified on direct flame ina stainless steel vessel under continuous stirring attemperature of 120°C/flash and finally filteredthrough Whatman No.4 filter paper. Simultaneously,pure ghee sample (control) was also prepared undersimilar conditions from the same lot of butter withoutadding any of the adulterants.
4. Ultra-violet and visible spectroscopyUltra-violet spectroscopy
Ultraviolet (UV) spectroscopy measurementswere made according to the method of Rego et al.,(1964), using double beam spectrophotometer,Model Specord 200, equipped with UV and visibleranges of Analytikjena make, Germany.
0.1 per cent solution of fat sample wasprepared in purified n-hexane and was scanned forabsorption maxima over a UV range of 200 to 320nm using a 1 cm quartz cell.Visible spectroscopy
0.1 per cent solution of fat sample wasprepared in purified n-hexane and was also scannedfor absorption maxima over a visible range of 400to 800 nm using 1 cm cell under similar conditionsas described above.
RESULTS AND DISCUSSIONSpectroscopic methods using ultra-violet
(200 to 400 nm) and visible (400 to 800 nm) regionshave been used for characterizing fats and oils. Inthe present study, samples of pure ghee (buffalo andcow), vegetable oils (soy bean, sunflower andgroundnut oil), vanaspati, animal body fats (goatand pig), and ghee samples adulterated with vegetableoils and animal body fats were scanned in theUltraviolet (200 to 320 nm) and Visible (400 to 800nm) regions. The results are presented in Figures 1to 8.
Ultra-violet SpectroscopyPure ghee (buffalo and cow), animal body
fats (goat and pig), vegetable oils (soy bean,sunflower and groundnut oil) and vanaspati samplesdissolved in n-hexane and scanned on double beamspectrophotometer, between 200 to 320 nm showedfirst absorption maxima between 220 and 230 nm
(Figures 1 to 4). All these oils and fats showed secondabsorption maxima at around 270 to 280 nm, exceptvanaspati which showed no such second maxima(Figure 3B). Thus, it is apparent from the resultsthat the ghee, animal body fats, vegetable oils andvanaspati behaved in almost similar fashion.Therefore, it can be inferred from the above findingsthat Ultra-violet (UV) spectroscopic examination offats and oils did not give any indication fordemonstrating the adulteration in ghee.Consequently, ghee samples adulterated with bodyfats or vegetable oils or vanaspati, individually or incombinations at 5, 10 and 15 percent levels also didnot show any difference from pure ghee in terms offirst or second absorption maxima.
The results obtained in the presentinvestigation are in full agreement with those ofSinghal (1973) and Sharma (1989) who also opinedthat UV spectroscopy did not offer any help indetecting adulteration in milk fat.
Visible SpectroscopyPure ghee (buffalo and cow), body fats (goat
and pig), vegetable oils (soybean, sunflower andgroundnut oil) and vanaspati samples dissolved inn-hexane were also scanned for visible spectrumbetween 400 to 800 nm and showed no positiveabsorption maxima, rather showed somewhatincreasing absorption on the negative side (Figures5 to 8). However, buffalo and cow pure ghee samplesshowed some sign of positive absorption in the regionof 430 to 440 nm and 400 to 500 nm, respectively.Thus, like UV spectroscopic scanning, visiblespectroscopic examination could not be used indetecting adulteration of ghee as adulterated gheesamples also showed similar behaviour in visible(400 to 800 nm) region studied.
Jha (1981) also used visible spectroscopyfor the detection of Cheuri (Madhuca butyracia) fatin ghee, a common adulterant of ghee in Nepal, in anarrow visible region of 600 to 700 nm, and reportedthat pure ghee showed no absorption band whereasCheuri fat showed an absorption band with maximabetween 640 and 680 nm. Using this technique, aslow as 5 percent Cheuri fat added to ghee wasdetectable. On the other hand, vegetable oils andfats used as an adulterant in the present study didnot show the similar kind of absorption behaviouras has been reported for Cheuri fat.
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Fig. 2: UV absorption spectra of sunflower oil (A) and soy bean oil (B).
A - Sunflower oil
B - Soy bean oil
Fig. 1: UV absorption spectra of pure buffalo ghee (A) and pure cow ghee (B).
A - Pure buffalo ghee
B - Pure cow ghee
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Fig. 3: UV absorption spectra of groundnut oil (A) and vanaspati (B).
A - Groundnut oil
B - Vanaspati
Fig. 4: UV absorption spectra of pig body fat (A) and goat body fat (B).
A - Pig body fat
B - Goat body fat
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Fig. 5: Visible spectra of pure buffalo ghee (A) and pure cow ghee (B).
A - Pure buffalo ghee
B - Pure cow ghee
Fig. 6: Visible spectra of sunflower oil (A) and soy bean oil (B).
A - Sunflower oil
B - Soy bean oil
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Fig. 7: Visible spectra of groundnut oil (A) and vanaspati (B).
A - Groundnut oil
B - Vanaspati
A - Pig body fat
B - Goat body fat
Fig. 8: Visible spectra of pig body fat (A) and goat body fat (B).
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CONCLUSIONThe study revealed that the UV and Visible
spectroscopy did not offer any help in detectingthe adulteration in ghee because no characteristicdifferences were observed in the absorptionbehaviour of different oils and fats including milkfat studied in the UV (200-400 nm) and visible(400-800 nm) region, indicating that there are
common functional groups present in all these oilsand fats.
ACKNOWLEDGEMENTThe first author thanks Indian Council of
Agricultural Research and National DairyResearch Institute for the award of SeniorResearch Fellowship during the course of thisstudy.
REFERENCESArun Kumar et al ( 2002). Indian J. Dairy Sci. 55(6):319-330.Jha,J.S.(1981). J. Amer. Oil Chem. Soc. 58: 843-845.Rego, M.D. et al (1964). Ann. Bromat., 16: 455 460.Sharma, S.K. (1989). Ph.D. Thesis , National Dairy Research Institute (Deemed University), Karnal, India.Singhal, O.P. (1973). Ph.D. Thesis, Punjab University, Chandigarh.
