title: Ultrasound improves the renneting properties of milk.
abstract: The effects of ultrasound application on skim milk (10% w/w total solids at natural pH 6.7 or alkali-adjusted to pH 8.0) prior to the renneting of milk at pH 6.7 were examined. Skim milk, made by reconstituting skim milk powder, was sonicated at 20kHz and 30°C (dissipated power density 286kJkg(-1)) in an ultrasonic reactor. The rennet gelation time, curd firming rate, curd firmness, and the connectivity of the rennet gel network were improved significantly in rennet gels made from milk ultrasonicated at pH 8.0 and re-adjusted back to pH 6.7 compared to those made from milk sonicated at pH 6.7. These renneting properties were also improved in milk sonicated at pH 6.7 compared to those of the non-sonicated control milk. The improvements in renneting behavior were related to ultrasound-induced changes to the proteins in the milk. This study showed that ultrasonication has potential to be used as an intervention to manipulate the renneting properties of milk for more efficient manufacturing of cheese.
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Road, Werribee, VIC 3030, Australia; School of Applied Sciences, College of Science, Engineering and Health, RMIT University, VIC 3001, Australia.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Road, Werribee, VIC 3030, Australia.
authors.forename: Pablo
authors.initials: P
authors.lastname: Juliano
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Road, Werribee, VIC 3030, Australia.
authors.forename: Roderick P W
authors.initials: RP
authors.lastname: Williams
authors.affiliation: School of Applied Sciences, College of Science, Engineering and Health, RMIT University, VIC 3001, Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Niere
authors.affiliation: CSIRO Animal, Food and Health Sciences, 671 Sneydes Road, Werribee, VIC 3030, Australia. Electronic address: maryann.augustin@csiro.au.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Augustin
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D002850:Chromatography, Gel; D012085:Chymosin / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry / Q000378:metabolism*; D010316:Particle Size; D013010:Sonication
chemical_list: D001798:Blood Proteins; C025350:rennet; D012085:Chymosin
keywords: Cheese; Coagulation; Gelation; Milk; Rennet; Ultrasound