Analytical Methods Multivariate statistical analysis treatment of DSC thermal properties for animal fat adulteration Omar Dahimi a , Alina Abdul Rahim a,⇑ , S.M. Abdulkarim b,⇑ , Mohd Sukri Hassan a , Shazamawati B.T. Zam Hashari a , A. Siti Mashitoh a , Sami Saadi b,⇑ a Institute of Halal Research and Management (IHRAM), Universiti Sains Islam Malaysia, 71800 Nilai, Negeri Sembilan, Malaysia b Department of Food Science, Universiti Putra Malaysia, 43400 UPM, Serdang, Malaysia article info Article history: Received 24 May 2013 Received in revised form 2 February 2014 Accepted 18 February 2014 Available online 28 February 2014 Keywords: Adulteration Lard Beef tallow Chicken fat DSC PCA abstract The adulteration of edible fats is a kind of fraud that impairs the physical and chemical features of the original lipid materials. It has been detected in various food, pharmaceutical and cosmeceutical products. Differential scanning calorimetry (DSC) is the robust thermo-analytical machine that permits to finger- print the primary crystallisation of triacylglycerols (TAGs) molecules and their transition behaviours. The aims of this study was to assess the cross-contamination caused by lard concentration of 0.5–5% in the mixture systems containing beef tallow (BT) and chicken fat (CF) separately. TAGs species of pure and adulterated lipids in relation to their crystallisation and melting parameters were studied using prin- cipal components analysis (PCA). The results showed that by using the heating profiles the discrimination of LD from BT and CF was very clear even at low dose of less than 1%. Same observation was depicted from the crystallisation profiles of BT adulterated by LD doses ranging from 0.1% to 1% and from 2% to 5%, respectively. Furthermore, CF adulterated with LD did not exhibit clear changes on its crystallisation pro- files. Consequently, DSC coupled with PCA is one of the techniques that might use to monitor and differ- entiate the minimum adulteration levels caused by LD in different animal fats. Ó 2014 Published by Elsevier Ltd. 1. Introduction Nowadays food quality control has attracted much attention by private and governmental companies in Malaysia. The prevention of the adulterant materials in particular, fats and oils are one of the topics of high concern, with potential of adulteration both on deliberate or accidental cross-contamination. It necessitates the use of robust analytical machines capable to differentiate these small adulterant materials, especially when they exist at low dose in the food matrix. This issue prompted the scientist in Malaysia to probe the real causes leading to this type of fraud both in food and cosmeceutical products. Differential scanning calorimetry (DSC) is a thermal analysis technique used to study the thermal behaviours of formulated pharmaceutical and food systems. It has gained much application in edible oils and fats crystallisation, that directly influenced by their chemical structure and composition of tri, di-, and mono-acylglycerols, fatty acid chain lengths, single and double hydrogen (H 2 ) bonds, symmetrical and asymmetrical triacylglyce- rols (TAGs). For instance, most TAGs have been found to exist in three forms including alpha (a), beta prime (b 0 ) and beta (b) form, which, in this order, display increasing thermodynamic stability, melting point, heat of fusion and melting dilatation. DSC has some advantages over other classical detection meth- ods, as it is rapid and does not require excess sample preparation or solvent utilization and therefore, it is an environmental friendly technique. The applications of DSC in the analysis and character- ization of oils and fats for the determination of solid fat content, crystallisation and melting profiles, enthalpy of transitions and polymorphic forms, is well known and reviewed (Marangoni & Narine, 2002; Narine & Marangoni, 2002; Sato, 1996; Sato & Ueno, 2001; Sato, Ueno, & Yano, 1999; Tang & Marangoni, 2007). The detection of adulteration of edible oils, fats, and fat-based products necessitate the use of DSC that can help to fingerprint their thermal behaviours including melting and crystallisation (Tan & Che Man, 2002). Moreover, several works had extensively studied DSC appli- cation on olive oils, also in the sector of adulteration (Chiavaro, Vittadini, Rodrigeuez-Estrada, Cerretani, & Bendini, 2008; Chiavaro et al., 2009). DSC was able to monitor the presence of pig and http://dx.doi.org/10.1016/j.foodchem.2014.02.087 0308-8146/Ó 2014 Published by Elsevier Ltd. ⇑ Corresponding authors. Tel.: +60 6 798 8236/6 798 8237; fax: +60 6 799 8699 (A.A. Rahim). Tel.: +60 3 8946 8537; fax: +60 3 8942 3552 (S.M. Abdulkarim). Tel.: +60 142331473 (S. Saadi). E-mail addresses: alina@usim.edu.my (A.A. Rahim), ak@food.upm.edu.my (S.M. Abdulkarim), saadi.sami@ymail.com, sami.saadi84@gmail.com (S. Saadi). Food Chemistry 158 (2014) 132–138 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem