Extractive stripping voltammetry at a glassy carbon paste electrode for analysis of cow's milk and cream

Granit Jashari,Michaela Frühbauerová,Milan Sýs,Libor Červenka

doi:10.5219/1299

Granit Jashari, Michaela Frühbauerová + Show 2 more

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https://doi.org/10.5219/1299

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Abstract

In this paper, a procedure based on extractive accumulation of milk fat globules (MFGs) into a pasting liquid (lipophilic binder) of glassy carbon paste electrode (GCPE) with subsequent electrochemical detection by square-wave voltammetry (SWV) in 0.1 mol L-1 Britton-Robinson buffer of pH 4.0 has been tested to find out whether it can be utilized as a simple screening analytical method for cow's milk and cream nutrition control. Since there is assumption that the necessary alkaline hydrolysis of cow's milk and subsequent extraction of lipophilic vitamins into an organic solvent could be avoided, several GCPEs differing in type (atactic polypropylene, paraffin oil, paraffin wax, silicone oil, and vaseline) and content (5, 10, 15, 20, and 25%; w/w) of pasting liquid used were tested as part of complex optimization. The obtained results show that MFGs contain predominantly vitamin A (carotenoids and retinoids), especially all-trans-retinol, which could serve as significant marker of the fat content. However, their individual forms were not possible to distinguish due to the considerable anodic peak broadening (overlapping).

Highlights

In the mammary glands, milk fat globules (MFGs), ranging in size from 0.1 to 15 μm in diameter (Logan et al, 2014), originate as fat droplets composed largely (>98%) of triacylglycerols (TCGs)
In this paper, a procedure based on extractive accumulation of milk fat globules (MFGs) into a pasting liquid of glassy carbon paste electrode (GCPE) with subsequent electrochemical detection by square-wave voltammetry (SWV) in 0.1 mol L-1 Britton-Robinson buffer of pH 4.0 has been tested to find out whether it can be utilized as a simple screening analytical method for cow's milk and cream nutrition control
Since there is assumption that the necessary alkaline hydrolysis of cow's milk and subsequent extraction of lipophilic vitamins into an organic solvent could be avoided, several GCPEs differing in type and content (5, 10, 15, 20, and 25%; w/w) of pasting liquid used were tested as part of complex optimization

Summary

Introduction

Milk fat globules (MFGs), ranging in size from 0.1 to 15 μm in diameter (Logan et al, 2014), originate as fat droplets composed largely (>98%) of triacylglycerols (TCGs). These fat droplets are evenly emulsified throughout the volume and contain lipophilic (fat-soluble) vitamins dissolved in them (Heid and Keenan, 2005). Losses of naturally occurring lipophilic vitamins are significant after mechanical separating the milk fat (cream) from the raw milk. Obtained skimmed milk is homogenized that is a process of breaking down the large fat droplets under high pressure so that they stay together and do not separate as cream. A gravimetric method (EN 1211) is used to determine milk fat content

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