title: Influence of micellar calcium and phosphorus on rennet coagulation properties of cows milk.
abstract: The main requirement for milk processed in most cheese typologies is its rennet coagulation ability. Despite the increasing number of studies, the causes for abnormal coagulation of milk are not fully understood. The aim of this study was to ascertain relationships between milk characteristics and its rennet coagulation ability, focusing on the influence of calcium (Ca) and phosphorus (P). Ca and P are essential constituents of the micelles. Micellar P can be present as part of colloidal calcium phosphate (inorganic-P) or covalently bound to caseins as phosphate groups (casein-P). Eighty one herd milk samples (SCC<400 000 cell/ml) were classified as Optimal (8), Suboptimal (39) Poor (29) and Non-coagulating milk (5), according to their rennet coagulation parameters as assessed by lactodynamographic test. Samples were analysed for their chemical composition (basic composition, protein fractions, minerals and salt equilibria), physicochemical parameters (pH and titratable acidity) and rheological properties. Optimal milk was characterised by the highest contents of major constituents, protein fractions and minerals, lowest content of chloride and highest values of titratable acidity. Non-coagulating milk was characterised by the highest values of pH and the lowest of titratable acidity. At micellar level, Optimal milk showed the highest values of colloidal Ca, casein-P and colloidal Mg (g/100 g casein), while Non-coagulating milk showed the lowest values. Interestingly, there was no statistical difference regarding the content of colloidal inorganic-P (g/100 g casein) between Optimal and Non-coagulating milks. Overall, high mineralisation of the micelle (expressed as g inorganic-P/100 g casein) positively affect its rennetability. However, excessive mineralisation could lead to a reduction of the phosphate groups (g casein-P/100 g casein) available for curd formation.
authors.affiliation: Department of Food Science, University of Parma, Via del Taglio 10, I-43126 Parma, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Malacarne
authors.affiliation: Department of Food Science, University of Parma, Via del Taglio 10, I-43126 Parma, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Franceschi
authors.affiliation: Department of Food Science, University of Parma, Via del Taglio 10, I-43126 Parma, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Formaggioni
authors.affiliation: Centro Servizi per l'Agroalimentare, Via Torelli 17, I-43123 Parma, Italy.
authors.forename: Sandro
authors.initials: S
authors.lastname: Sandri
authors.affiliation: Department of Food Science, University of Parma, Via del Taglio 10, I-43126 Parma, Italy.
authors.forename: Primo
authors.initials: P
authors.lastname: Mariani
authors.affiliation: Department of Food Science, University of Parma, Via del Taglio 10, I-43126 Parma, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Summer
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis* / Q000502:physiology; D002130:Calcium Phosphates / Q000032:analysis / Q000737:chemistry; D002364:Caseins / Q000032:analysis / Q000737:chemistry; D002417:Cattle; D002611:Cheese; D055598:Chemical Phenomena; D012085:Chymosin / Q000378:metabolism*; D003102:Colloids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000032:analysis; D008823:Micelles; D008892:Milk / Q000737:chemistry / Q000187:drug effects* / Q000201:enzymology*; D008894:Milk Proteins / Q000032:analysis; D010758:Phosphorus / Q000032:analysis* / Q000502:physiology; D012212:Rheology
chemical_list: D002130:Calcium Phosphates; D002364:Caseins; D003102:Colloids; D008823:Micelles; D008894:Milk Proteins; D010758:Phosphorus; C025350:rennet; C020243:calcium phosphate; D012085:Chymosin; D008274:Magnesium; D002118:Calcium