Gel products properties influenced by freezing in different conditions

The study objective was experimental analysis of gelatin gel freezing under differentiated, well-defined conditions to characterize the process kinetics. After thawing, the gel samples underwent the thawing drip analysis and their textural properties were evaluated. Freezing in liquid nitrogen ensures the highest freezing rate, whereas the least intensive procedure proves to be air freezing. There was stated unfavorable effect of the forced air freezing and in liquid nitrogen on thawing drip amount (water dilution, cracks of gel sample surface). The amount of thawing drip decreased with increasing gelatin mass fraction. The milk gel samples frozen in glycol (excluding 2% gelatin) showed no drip after thawing. The results of compression and penetration tests have given evidence of the influence of increasing gelatin share and gel freezing process on the gel texture characterized by maximal compression and penetration force.

► Milk and orange juice improve stability and texture of frozen gelatin gels.
► Immersion freezing in glycol is advantageous for gelatin gels.
► Freezing in liquid nitrogen (freezing rate 35.7 cm h−1) caused structure damages of gels with cracks on their surfaces.