title: Rennet-induced coagulation of raw and heated camel and cow milk gels determined by instrumental techniques: effects of added calcium and phosphate.
abstract: BACKGROUND
  The potentiality of the front-face fluorescence spectroscopy and rheological measurements combined with chemometric tools to characterise the structure evolution during coagulation of raw and preheated camel and cow milk at 50 and 70 °C with/without added calcium and phosphate was evaluated. Tryptophan and vitamin A fluorescence spectra were collected during the gelation of milk at 0, 10, 20, 30, 40, and 45 min after the addition of rennet-induced coagulation. In parallel, the storage modulus (G'), loss modulus (G″) and tan delta (tan δ) were determined using low amplitude oscillation shear analysis.
  
  
  RESULTS
  The principal component analysis (PCA) applied to the normalised tryptophan spectra allowed the gels made with camel milk to be differentiated from those of cow milk on the one hand, and to monitor protein structure modifications during the gelation, on the other hand. The common components and specific weights analysis (CCSWA) applied jointly to the fluorescence and rheological data sets permitted a clear separation of raw milk gels from those preheated at 50 and 70 °C.
  
  
  CONCLUSIONS
  The front-face fluorescence spectroscopy method coupled with multi-variate statistical analyses showed a high capacity for studying changes in the micelle structure throughout the rennet-induced coagulation process. © 2017 Society of Chemical Industry.
authors.affiliation: Univ. Artois, EA 7394, Institut Charles Violette, Lens, France.|ISA Lille, EA 7394, Institut Charles Violette, Lille, France.|Ulco, EA 7394, Institut Charles Violette, Boulogne sur Mer, France.|Univ. Lille, EA 7394, Institut Charles Violette, Lille, France.
authors.forename: Romdhane
authors.initials: R
authors.lastname: Karoui
authors.affiliation: Univ. Artois, EA 7394, Institut Charles Violette, Lens, France.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Kamal
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis*; D002162:Camelus; D002417:Cattle; D012085:Chymosin / Q000737:chemistry*; D003296:Cooking; D005260:Female; D005503:Food Additives / Q000737:chemistry*; D005511:Food Handling / Q000295:instrumentation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry*; D010710:Phosphates / Q000032:analysis*
chemical_list: D005503:Food Additives; D010710:Phosphates; C025350:rennet; D012085:Chymosin; D002118:Calcium
keywords: chemometric; coagulation; fluorescence; milk; rheology