Effect of fat content and homogenization under conventional or ultra-high-pressure conditions on interactions between proteins in rennet curds.
The objective of this study was to investigate the influence of conventional and ultra-high-pressure homogenization on interactions between proteins within drained rennet curds. The effect of fat content of milk (0.0, 1.8, or 3.6%) and homogenization treatment on dissociation of proteins by different chemical agents was thus studied. Increasing the fat content of raw milk increased levels of unbound whey proteins and calcium-bonded caseins in curds; in contrast, hydrophobic interactions and hydrogen bonds were inhibited. Both homogenization treatments triggered the incorporation of unbound whey proteins in the curd, and of caseins through ionic bonds involving calcium salts. Conventional homogenization-pasteurization enhanced interactions between caseins through hydrogen bonds and hydrophobic interactions. In contrast, ultra-high-pressure homogenization impaired hydrogen bonding, led to the incorporation of both whey proteins and caseins through hydrophobic interactions and increased the amount of unbound caseins. Thus, both homogenization treatments provoked changes in the protein interactions within rennet curds; however, the nature of the changes depended on the homogenization conditions.
CERPTA, XaRTA, XiT, MALTA Consolider Group, Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
A
A
Zamora
CERPTA, XaRTA, XiT, MALTA Consolider Group, Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
A J
AJ
Trujillo
School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
E
E
Armaforte
School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
D S
DS
Waldron
School of Food and Nutritional Sciences, University College Cork, Cork, Ireland. Electronic address: a.kelly@ucc.ie.
A L
AL
Kelly
D000818:Animals; D002417:Cattle; D012085:Chymosin / Q000378:metabolism*; D005223:Fats / Q000032:analysis*; D006860:Hydrogen Bonding; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D008894:Milk Proteins / Q000032:analysis / Q000378:metabolism*; D061352:Pasteurization / Q000379:methods*; D011312:Pressure; D000067816:Whey Proteins
D005223:Fats; D008894:Milk Proteins; D000067816:Whey Proteins; C025350:rennet; D012085:Chymosin