Heat transfer characteristics of cryogenically Frozen Kulfi (A dairy dessert) Mukheshkumar G. H.1, Pushpadass Heartwin A.1,*, Emerald F. Magdaline Eljeeva1, Patel Saurabh Shankar1, Manimala K.2 1Southern Regional Station, ICAR-National Dairy Research Institute, Bengaluru-560 030, India 2Department of Information Science and Technology, Anna University, College of Engineering, Guindy Campus, Chennai-600025, India *Corresponding Author’s E-mail: heartwin1@gmail.com, p.dhass@icar.gov.in
Online published on 7 March, 2025. Abstract Kulfi was frozen from concentrated milk as well as from reconstituted dry mix with solids content of 60%. The convective heat transfer coefficients during freezing of kulfi by deep freeze and cryogenic methods were determined using one-dimensional transient heat conduction equation. The heat transfer coefficient for cryogenic freezing of kulfi from milk and dry mix concentrates was 210.57 W m-2K-1 and 216.84 W m-2K-1, respectively when compared to 8.33 W m-2K-1 for conventional deep-frozen kulfi. Freezing was achieved in 267 min in deep freeze method, while it reduced to just 185-190 s under cryogenic conditions. The freezing time was predicted using empirical equations, and the prediction accuracies were compared. Cryogenic freezing was nearly 87.66 times faster than deep freezing, and Pham’s model best-predicted the freezing time. Organoleptic evaluation using fuzzy-logic revealed that the order of ranking of quality attributes of kulfi was body and texture (highly important) > melting characteristics (highly important) > flavour and taste (highly important) > colour and appearance (important), and cryogenically frozen kulfi was statistically (p<0.05) superior to conventionally frozen kulfi. Top Keywords Cryogenic freezing, Freezing time, Prediction model, Heat transfer coefficient, Thermo-physical properties. Top |