Using isoconversional methods to study the effect of antioxidants on oxidation kinetics of milk fat

Document Type

Abstract

Publication Date

2019

Location

2019 American Dairy Science Association Annual Meeting: Cincinnati, Ohio

Publisher

American Dairy Science Association

Journal

Journal of Dairy Science

Volume

102

Issue

Suppl.1

Pages

39-40

Language

en.

Keywords

differential scanning calorimetry (DSC), isoconversional method, antioxidants

Abstract

Milk fat has been used as an ingredient because of its nutritional value, functionality, and flavor. During processing and storage, milk fat may 40 J. Dairy Sci. Vol. 102, Suppl. 1 undergo oxidation which results in many undesirable changes such as unpleasant flavor and aroma, and formation of toxic compounds. A common practice to prevent the oxidation of milk fat is by the addition of antioxidants. It is worth to mention that little is known on the effect of antioxidants on the oxidation kinetics. In this work, the effect of selected antioxidants on the oxidation kinetics of anhydrous milk fat (AMF) under non-isothermal conditions was investigated. AMF with an addition of either α-Tocopherol (α-Toc), butylated hydroxytoluene (BHT), or β-carotene (β-Car) at 4 different concentrations (0.02, 0.07, 0.2, and 0.4%) were oxidized using differential scanning calorimetry (DSC) at different constant heating rates (3, 6, 9, and 12°C min−1) in a temperature range of 100–400°C. DSC spectra were analyzed according to the Kissinger-Akahira-Sunose (KAS) method, from which the pre-exponential factor (A) and the apparent activation energy (Ea) were obtained. In general, the type of antioxidant, as well as its concentration, resulted in higher onset temperature of oxidation (Ton). For instance, the Ton increased from 173.8 ± 0.8, 175.5 ± 0.5, 176.4 ± 0.7, and 182.4 ± 0.4°C for AMF, BHT, β-Car, and α-Toc, respectively. The Ea values were 82.73 ± 5.51, 93.14 ± 6.24, 68.06 ± 3.52, and 58.51 ± 7.51 kJ mol−1 for AMF, BHT, β-Car, and α-Toc, respectively. Remarkably, the addition of 0.2% of α-Toc inhibited the oxidation reaction by 9-fold judging the constant rate. The obtained kinetic parameters were interpreted in term of oxidation mechanism. The implications of this study may enable off-line simulation and development of a databank.

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