Validation of a Simple and Robust Liebermann-Burchard Colorimetric Method for the Assay of Cholesterol in Selected Milk Products in Ghana.

Joseph K Adu,Cedric D K Amengor,Stella Abla Gameli Patamia,Bernice Korkor Okrah,Emmanuel Orman,Naomi Kabiri

doi:10.1155/2019/9045938

Abstract

Cholesterol plays a key role in the synthesis of bile acids and steroid hormones in the human body. However, excessively high levels are usually implicated in cardiovascular diseases. For this reason, it is essential to monitor exposure to high levels of it in products meant for human consumption, and this calls for the need to develop analytical methods to detect them. The use of Liebermann–Burchard reaction in this study has been explored to develop a simple, reliable, and robust quantitative colorimetric method to assay cholesterol, and hence provide a good alternative to chromatographic methods. The developed method was validated and used to determine the contents of cholesterol in selected dairy products on the Kumasi Metropolis market. The method demonstrated a good linearity (R2 = 0.996) over concentration range of 0.01–0.08 mg/ml. It was also shown to be precise and robust. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.00430 mg/ml and 0.01304 mg/ml, respectively. Ten selected brands of canned milk (B1–B5) and fresh yoghurt products (A1–A5) were then assayed using the developed method. The results showed that three products from each category had cholesterol contents above the allowable content of 5 mg/100 g in dairy products. The study thus has proposed a simple colorimetric method that can be adopted by dairy products manufacturing facilities to rapidly determine cholesterol contents during manufacturing in order to monitor the safe consumption of their products, and eliminate or minimize possible future health hazards.

Highlights

Phytosterols constitute an important class of natural products that have been explored for their medicinal importance
Principle of the Colorimetric Assay. e colorimetric method developed for the assay of cholesterol in the dairy products was based on the ability of cholesterol, a weakly UV absorbing compound, to be derivatized into a strongly absorbing moiety at a wavelength of approximately 420 nm [15] (Figure 1), void of sample matrix interferences in a reaction known as the Liebermann–Burchard Reaction [20]
Liebermann–Burchard reagent (LBR), containing acetic anhydride and concentrated sulphuric acid, provided the necessary conditions for the reaction to proceed. e quantitative conversion of all cholesterol to Liebermann–Burchard product (LBP) provided the basis for the colorimetric estimation of its content

Summary

Introduction

Phytosterols constitute an important class of natural products that have been explored for their medicinal importance. Cholesterol, stigmasterol, and sitosterol are examples of phytosterols of which cholesterol is the most abundant in animals. Cholesterol is mostly found in animal fat such as milk, eggs, and cheese whilst stigmasterol and sitosterol are ubiquitous in plants. Dairy product consumption has been a daily routine for most people in both developed and developing nations usually as part of their diet. Milk consumption is associated with a reduced risk of noncommunicable diseases (NCDs) such as osteoporosis, colorectal cancer, and type 2 diabetes [4]. Concern has been raised about possible association between high diary consumption and cardiovascular related diseases because of their cholesterol contents [5,6,7]

Methods

Results

Conclusion