Gelatin Under Attack

Overview

Gelatin forms a strong three dimensional network during gelation, where protein chains trap water within a branching framework. This project investigates the biochemical effects of citric acid, sodium chloride, and sucrose on this protein network. It was hypothesized that these additives would destabilize the gelatin structure through various molecular processes. Firmness was measured by placing a 20 gram weight on gelatin for five seconds and measuring the depth of the dent. Samples were tested with varying concentrations of additives (0.5g, 1.0g, and 2.0g) against a control group. All additives reduced the firmness of gelatin compared to the control sample (no additives). Salt and citric acid had the most significant impact, with citric acid having the greatest effect at the 2.0g concentration, causing a 315% increase in dent depth. Sodium Chloride reduces firmness through ionic shielding, where ions bond to the protein chains, reducing the links available between protein chains. However, at higher concentrations (2.0g), citric acid denatures gelatin’s internal structure through electrostatic repulsion. This suggests citric acid has the stronger effect on firmness. By introducing hydrogen ions, citric acid causes electrostatic repulsion and protein denaturation, causing the network to physically push apart. Sucrose is a non-charged additive, so it had the least impact which suggests its effect is limited to molecular crowding.

Competition history

• CSEF 2026 Biochemistry/ Molecular Biology (Junior Division) · Entry J-04-14

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