• Evolution of the bovine milk fatty acid profile – From colostrum to milk five days post parturition

      O'Callaghan, Tom; O'Donovan, Michael; Murphy, John; Sugrue, Katie; Mannion, David; McCarthy, William P.; Timlin, Mark; Kilcawley, Kieran; Hickey, Rita M.; Tobin, John T. (Elsevier BV, 2020-05)
      Milk was collected from each of 18 cows (presenting an even spread of 1st, 2nd and 3rd lactation): colostrum on the day of calving and subsequent morning milk 1–5 days post parturition. Days post parturition significantly affected the fatty acid profile of colostrum and transition milk samples. The colostrum fatty acid profile was distinctly different from that of mature milk, with significantly higher levels of polyunsaturated and saturated fatty acids. Parity of the cow had a significant effect on the fatty acid profile of colostrum and transition milk samples; conjugated linoleic acid was significantly higher in cows entering their 1st lactation than in those in their 3rd lactation, while multiparous cows produced significantly higher concentrations of C16:0. The changing composition of the fatty acid profile can be classed into three distinct phases: colostrum (D0), transition milk (D1 and D2 post parturition) and mature milk (D3–D5).
    • Influence of chaperone-like activity of caseinomacropeptide on the gelation behaviour of whey proteins at pH 6.4 and 7.2.

      Gaspard, Sophie J.; Sharma, Prateek; Fitzgerald, Ciarán; Tobin, John T.; O’Mahony, James A.; Kelly, Alan L.; Brodkorb, Andre; Dairy Research Ireland; Teagasc Walsh Fellowship Programme; European Union; et al. (Elsevier, 2020-08-15)
      The effect of caseinomacropeptide (CMP) on the heat-induced denaturation and gelation of whey proteins (2.5–10%, w/v) at pH 6.4 and 7.2, at a whey protein:CMP ratio of 1:0.9 (w/w), was investigated using differential scanning calorimetry (DSC), oscillatory rheology (90 °C for 20 min) and confocal microscopy. Greater frequency-dependence in the presence of CMP suggested that the repulsive interactions between CMP and the whey proteins affected the network generated by the non-heated whey protein samples. At pH 6.4 or 7.2, CMP increased the temperature of denaturation of β-lactoglobulin by up to 3 °C and increased the gelation temperature by up to 7 °C. The inclusion of CMP strongly affected the structure of the heat-induced whey protein gels, resulting in a finer stranded structure at pH 6.4 and 7.2. The presence of CMP combined with a lower heating rate (2 °C/min) prevented the formation of a solid gel of whey proteins after heating for 20 min at 90 °C and at pH 7.2. These results show the potential of CMP for control of whey protein denaturation and gelation.