Micro- and macro-structure of cow, buffalo and mixed milk rasogolla: a comparative scanning electron and light microscope study

Abstract

Summary - Scanning electron and Iight-microscopic studies were carried out to provide information on the micro- and macro-structural differences between cow, buffalo and mixed milk rasogolla (a local Indian milk product obtained via acid coaqulation followed by cooking in sugar syrup). Scanning electron microscopy of cow milk rasogolla revealed a loese, porous protein matrix with coa!esced casein micelles forming a thread-Iike structure,.while buffalo milk rasogolla had agglomerated casein micelles which were large and compact, and formed a scale- or layer-type structure. Casein micelles in mixed milk rasogolla formed a combination of thread- and scale-type structures. Fat globules collapsed and the membrane shrank noticeably in ail the 3 sampi es: Larger fat globules were ~;'ost affected, while Iittle or no effect was observed in small fat globules. Ught microscopic investigation showed that cow milk rasogolla had smooth, small oval-shaped pores, whereas buffalo milk rasogolla had rough-edged. irregularly-shaped large pores. Mixed milk rasogolla had a heterogenous structure. The Instron and sensory texturai examination agreed weil with the composition and' structural characteristics of rasogolla.