Colorimetric indicator based on zwitterionic anti-freezing hydrogel and alizarin for visual monitoring of salmon fillets freshness

Indicating hydrogels have shown the advantages of being fast, sensitive, and real-time in demonstrating the Indicating hydrogels have shown he advantages of being fast, senstive, and real time in demonstrating the freshness of aquatic products due to their noticeable color change. In this work, an anti-freezing hydrogel freshness of aquatic products due to their noticeable color hange. In this work, an anti-freezing hydrogel embedded with pH-sensitive alizarin was developed as an original colorimetric indicator for monitoring embedded with pH sensitve alizarn was developed as n orgina colorimetric indicator for monitoring the corruption of aquatic products at low temperatures. The anti-freezing hydrogel was prepared from 2-carboxyethyl acrylate, [2-(methacryoyloxy)ethyl]-trimethylammonium chloride, and 2-hydroxyethyl the corruption of aquati p oducts at low temperatu es. The anti freezing hydroge wa prepared from 2 carboxyethyl acrylate, [2 (methacryloyloxy)ethyl] trimethyl mmonum chloride and 2 hydroxyethyl methacrylate monomers with triethylene glycol dimethacrylate as cross-linking agent. The hydrogel showed excellent anti-freezing capability, whichwas further incorporated with the pH-sensitive dye alizarin to gain methacryate monomers with triehylene glycol dimethacrylate as cross-linking agent The hydrogel showed excellent anti freezing c pability, whch was further incorporated with the pH sensitve dye alizarin to gain the indicating capability. When applied in the indication of the freshness of salmon under low-temperature the indcating capability. When applied in the indication of the freshness of salmon under ow temperature storage, it was found that the color changes of the indicator corresponded with the total volatile basic nitrogen contents of salmon, the correlation coeffiiicient of which was 0.959 6. These results indicated the application storage, t was found that the color changes of he indicaor correspon ed with the total volatile basic nitrogen potential of the hydrogels as freshness indicators during low-temperature storage or cold-chain transportation. contents of salmon, the correlation coefficient of which was 0.959 6. These results indicated the applicatio 2024 ..(c) 2024 Beijing Academy of Food Sciences . Publishing services by Elsevier B.V. on behalf of KeAi Communication Co Ltd This is an open access article under the CC BY NC-ND license Communications .Co., .Ltd. This is an open access article under the CC BY-NC-ND license (http//creativecommonsorg/license/byncnd/40/) (http://creativecommonsorg/licenses/by nc nd/40/)