Influence of the Colloidal Structure of Dairy Gels on Milk Fat Fusion Behavior: Quantification of the Liquid Fat Content by In Situ Quantitative Proton Nuclear Magnetic Resonance Spectroscopy (isq 1H NMR)

Bouteille, Romain; Perez, J.; Khifer, Farid; Bouveresse, Delphine Jouan-Rimbaud; Lecanu, B.; This, Hervé

doi:10.1111/1750-3841.12072

Cited by 5 publications

(1 citation statement)

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“…The formation of dairy gels (e.g., yoghurt) has been investigated by NMR, and an increase in lactate was observed in real time as the microbes fermented the milk, suggesting that the technique may prove useful in the evaluation of new bacterial strains for dairy products [19]. These authors have also demonstrated the utility of NMR for monitoring the changes in liquid fat content in dairy gels, again demonstrating the utility of NMR in understanding complex processes in food processing and production [20]. …”

Section: 1h Nmr Studiesmentioning

confidence: 99%

Applications of NMR in Dairy Research

Maher¹,

Rochfort

2014

Metabolites

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NMR is a robust analytical technique that has been employed to investigate the properties of many substances of agricultural relevance. NMR was first used to investigate the properties of milk in the 1950s and has since been employed in a wide range of studies; including properties analysis of specific milk proteins to metabolomics techniques used to monitor the health of dairy cows. In this brief review, we highlight the different uses of NMR in the dairy industry.

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Section: 1h Nmr Studiesmentioning

confidence: 99%

Applications of NMR in Dairy Research

Maher¹,

Rochfort

2014

Metabolites

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Solution to Hollandaise challenge

This

2016

Anal Bioanal Chem

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SolutionCan one recover a failed Hollandaise sauce by adding cold water? Let us first try to understand the production of this sauce before examining how it can fail and be recovered. First, egg yolks are mainly composed of approximately 50 % water, 15 % proteins, and 35 % lipids, including phospholipids and triglycerides, Belitz and Grosch [1]. Butter is made of about 82 % triglycerides of many varieties (which explains why the melting point of butter begins at -10°C and finishes at +55°C), a maximum of 16 % of water, including some lactose and proteins, Bouteille et al. [2], Lopez and Ollivon [3].The processes that occur during the first step of thermal processing of the mixture of egg and an aqueous solution depend on the temperature, as egg proteins can denature, aggregate, and even coagulate as soon as the temperature reaches 61°C, This, 2009 [4]. At the same time, air bubbles are introduced by the whisk, which can be observed simply from the whitening of the sauce or by microscopic optical examination (Fig. 1).When melted butter is added, the liquid fat is dispersed in the water phase, making a more complex physical system: the final sauce is a suspension (of egg proteins aggregates), an emulsion (of melted fat droplets), and a foam (of air bubbles) at the same time. The disperse system formalism of such a system can be described as (G+O+S)/W, where G stands for the gas bubbles, O for the oil droplets, S for the protein aggregates, solidus / for the random dispersion, and solid protein for the continuous water phase, This, 2012 [5].What happens when heating is too strong or too long, particularly when the finished sauce is kept on mild heat until it is served? There are many possibilities, but the most obvious is a phase separation, Thakur et al, 2007 [6] because of an insufficient quantity of water: for an emulsion to subsist, approximately 5 % water is needed and, indeed, this limit is breached when water evaporates during the sauce preparation. It is useful to remember that the water quantity can be small in the sauce. A typical recipe would contain 20-30 % water before heating.Is it true that water can help to recover a smooth system? Indeed, and one can easily perform the experiment. In one of Fig. 1 Microscopic view of the Hollandaise sauce. One can see the oil droplets (smaller white disks) and the air bubbles (bigger disks, with a dark edge). The egg aggregates appear with difficulty at this magnification (the diameter of the largest air bubbles is about 0.1 mm).

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