Microstructure and chemical composition of camel and cow milk powders’ surface

Ahmed Zouari (1, 2) , Pierre Schuck (1) , Frederic Gaucheron (1) , Mehdi Triki (2) , Guillaume Delaplace (3) , Claire Gauzelin-Gaiani (4) , Christelle Lopez (1) , Hamadi Attia (2) , Mohamed Ali Ayadi (5)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 Valuation, Security and Food Analysis Laboratory, National Engineering School of Sfax
3 UMET - Unité Matériaux et Transformations - UMR 8207
4 LIBio - Laboratoire d'Ingénierie des Biomolécules
5 Sfax University - Valuation, Security and Food Analysis Laboratory, National Engineering School of Sfax

This study aimed at investigating the chemical composition and microstructure of spray dried camel and cow milk powders' surfaces with two different milk-fat contents (1 and 20g 100 g−1). The SEM (Scanning Electron Microscopy) micrographs showed that spherical particles with a ‘brain’-type surface for both milk powders were produced. The surface roughness (Ra) of whole (WDMP) and skimmed (SDMP) camel milk powders (Ra=7.6 ± 0.4 nm and 5.6 ± 0.7 nm, respectively) were significantly lower as compared with the partially skimmed (PSCMP) and skimmed (SCMP) cow milk powders. The XPS (X-ray Photoelectron Spectroscopy) analysis highlighted that the surface of skimmed camel milk powders contained twice the lactose amount (17.7 ± 0.8%) as compared to cow milk powders (8.7 ± 0.4%). Furthermore, both milk powders showed the overexposure of proteins and fats at their surfaces regardless of the fat content. The CLSM (Confocal Laser Scattering Microscopy) micrographs highlighted that most of the camel milk fat globules were encapsulated by the proteins near the powder surface. Camel milk fat behavior during particle formation was attributed to their lower size distribution and their higher crystallization temperature.

Mots clés: lait de chamelle; lait de vache; poudre d lait; microstructure; composition chimique; surface; spectroscopie; camel milk; cow milk; spectrometry; crystallization; x ray; milk fat globules

Mots clés: lait de chamelle; lait de vache; poudre de lait; spectrométrie; microstructure des aliments; composition chimique du lait; cristallisation; rayon x; spectroscopie xps; procédé de séchage; matière grasse du lait

Domaines: Alimentation et Nutrition; Ingénierie des aliments

Ahmed Zouari, Pierre Schuck, Frederic Gaucheron, Mehdi Triki, Guillaume Delaplace, et al.. Microstructure and chemical composition of camel and cow milk powders’ surface. LWT - Food Science and Technology, 2020, 117, pp.108693. ⟨10.1016/j.lwt.2019.108693⟩. ⟨hal-02306145⟩