Quantitative Neutron Dark-Field Imaging of Milk: A Feasibility Study

Youngju Kim,Jongyul Kim,Ohsung Oh,Francois Boue,Markus Strobl,Matteo Busi,Christopher Garvey,Evelyne Lutton,Jacopo Valsecchi,Seung Wook Lee

doi:10.3390/app12020833

Abstract

Scattering studies of milk and milk products, which are highly relevant food products on the global market, are often utilized and reported in literature to investigate and understand the subtle microscopic structural differences between dairy samples. These structural features determine the physical properties and ultimately the texture of milk products and, thus, also influence the consumer’s experience. Small-angle neutron scattering is a prominent example, which enables observations of length scales, which convey proteins and fat globules in food-grade milk. In addition, deuteration enables contrast variations between the constituents of dairy products. In this study, we investigate the potential of probing small-angle neutron scattering from milk samples through quantitative neutron dark-field imaging using grating interferometry, to establish the feasibility of studying, in particular, fat globules and milk gel structures with this spatially resolved scattering technique.

Highlights

Dairy milk has a very long history of use and forms a basic part of global nutrition, which is reflected in global production in 2019 of 881 hundred million tons [1]
The most basic and main constituents of milk, apart from water, salts, and whey proteins, are casein micelles (CM) and fat in the form of fat globules (FG) with sizes ranging between 10–102 nm for CM and approximately
Attenuation contrast image (AI) images, which, in terms of contrast, do not depend on the changing experimental settings, display only minor contrast variations with respect to fat content and gelation. This is clearly different for the DFI images, where the contrast increases obviously with increasing fat content, as well as with an increasing probed correlation length, ξ. This is the first indication that the contribution of the scattering by FG dominates the scattering signal and that this scattering contrast is picked up for all samples, respectively

Summary

Introduction

Dairy milk has a very long history of use and forms a basic part of global nutrition, which is reflected in global production in 2019 of 881 hundred million tons [1]. The structure of milk during processing is of considerable commercial and consumer interest in the sense of creating a demand for new dairy products; optimizing processing; human nutrition; and oral drug delivery. The most basic and main constituents of milk, apart from water, salts, and whey proteins, are casein micelles (CM) and fat in the form of fat globules (FG) with sizes ranging between 10–102 nm for CM and approximately. The CM is a colloidal and electrostatically stabilized sol, where glycomacropeptide strands, κ-casein, decorate the CM surface in the form of brushes, providing electrostatic or steric repulsion. The repulsion can either be neutralized or, in the case of rennet gels, the brush strands can be removed by enzymes

Methods

Results

Conclusion