Single-wavelength near-infrared analysis as a rapid and field-deployable tool to determine the solid fat content in fats and oils

Abstract

The solid fat content (SFC) is responsible for the characteristics and properties of a variety of fat-based food products, since it provides information, among others, on physical appearance, organoleptic properties, spreadability, product stability mouth feeling, and plasticity. The traditional techniques to measure SFC, such as pulsed nuclear magnetic resonance and differential scanning calorimetry, require expensive instrumentation and trained personnel. Nowadays innovative techniques are needed for fast, automatic, and low-cost in situ, determination of SFC directly in the production lines to allow food quality monitoring in control industrial processes. This is very relevant for small and medium food industries that cannot afford an internal quality control laboratory. An innovative near-infrared analytical approach to measure SFC in vegetable fats and oils is herein presented. The method is based on single-wavelength (835 nm) and measures the sample optical attenuation during a thermal cycle (featuring both heating and cooling). An estimation of SFC is then made from the measured optical data. Samples were a set of 16 different vegetable fats and oils commonly used in the food industry, such as cocoa butter, refined and fractionated coconut oils, hydrogenated palm and soybean oil, as well as blends among them. The estimated temperature corresponding to an SFC of 80%, 60%, 40%, and 20%, respectively, was plotted versus the corresponding temperature resulting from DSC curves for all tested samples. The experimental results obtained with such a method agree with those provided by DSC at different temperatures (R2 > 0.9), thus reaching a good SFC estimation. This indicates that the single-wavelength near-infrared technique is promising for practical analysis in the production lines to assess the quality of vegetable fats and oils. The herein-tested analytical solution could be implemented in the form of a low-cost and portable electronic system.