• The effect of direct and indirect heat treatment on the attributes of whey protein beverages

      Kelleher, Clodagh M.; O'Mahony, James A.; Kelly, Alan L.; O'Callaghan, Donal; Kilcawley, Kieran; McCarthy, Noel; Department of Agriculture, Food and the Marine; Teagasc Walsh Fellowship programme; 10 RD TMFRC 703 (Elsevier, 2018-06-11)
      Thermal processing of ready-to-drink high protein beverages can have a substantial impact on the physical and sensory properties of the final product for long-life milks such as extended shelf life and ultra high temperature processed products. Direct and indirect heat treatment technologies were applied to whey protein isolate (WPI) -based beverages containing 4, 6 or 8% (w/w) protein. Lower levels of protein denaturation (66–94%) were observed using direct heating compared with indirect heating (95–99%) across protein levels and heating temperatures (121 and 135 °C final heat). Direct heat treatment resulted in significantly lower viscosity and less extensive changes to the volatile profile, compared with indirect heat treatment. Overall, the application of direct and indirect heat treatment to WPI solutions resulted in significantly different final products in terms of appearance, physical characteristics and volatile profile, with direct heating resulting in many enhanced properties compared with conventional indirect heat treatment.
    • Influence of particle size on the physicochemical properties and stickiness of dairy powders

      O'Donoghue, Laura T.; Haque, Md Kamrul; Kennedy, Deirdre; Laffir, Fathima R.; Hogan, Sean A.; O'Mahony, James A.; Murphy, Eoin G.; Enterprise Ireland; TC/2014/0016 (Elsevier BV, 2019-11)
      The compositional and physicochemical properties of different whey permeate (WPP), demineralised whey (DWP) and skim milk powder (SMP) size fractions were investigated. Bulk composition of WPP and DWP was significantly (P < 0.05) influenced by powder particle size; smaller particles had higher protein and lower lactose contents. Microscopic observations showed that WPP and DWP contained both larger lactose crystals and smaller amorphous particles. Bulk composition of SMP did not vary with particle size. Surface composition of the smallest SMP fraction (<75 μm) showed significantly lower protein (−9%) and higher fat (+5%) coverage compared with non-fractionated powders. For all powders, smaller particles were more susceptible to sticking. Hygroscopicity of SMP was not affected by particle size; hygroscopicity of semi-crystalline powders was inversely related to particle size. This study provides insights into differences between size fractions of dairy powders, which can potentially impact the sticking/caking behaviour of fine particles during processing.