Changes of Physicochemical Properties and Rheology during the Thawing Period of Frozen Condensed Milk

This study analyzed the physicochemical properties and rheology of frozen condensed skim milk during thawing at 5 room temperature (20°C). The viscosity of the condensed milk was 80 cps (21.5°C) immediately after manufacture, and this value was decreased to 0 cps (21.5°C) during storage at day 7. The particle sizes of the condensed skim milk were 0.128 mm just after manufacture, and 0.522 and 0.818 mm at days 3 and 5 of thawing at 20°C, respectively. Condensed skim milk with no temperature abuse had lower acidity than those stored at room temperature on the 3rd and 7th days. Additionally, a sandy texture was observed as the thawing period increased. Based on the comprehensive results of this study, when frozen condensed skim milk is added to a product as a raw material, the longer the thawing period at room temperature, the longer the ice crystals inside melt and become water drips. Quality defects, such as weight loss, decreased pH, protein denaturation, and texture deterioration, are expected to occur.