You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Effects of different freezing treatments on the biogenic amine and quality changes of bighead carp (Aristichthys nobilis) heads during ice storage. The effects of different freezing treatments on the quality changes of bighead carp heads were evaluated in terms of pH value, TBARS, TVB-N, K-value, biogenic amine, total aerobic counts (TACs), drip loss, cooking loss and electrical conductivity (EC) during ice storage. Fish heads were stored at -40°C (T1), -40°C for 12h and then -18°C (T2), -18°C (T3) for 3months prior to ice storage. No significant differences were observed among T1, T2 and T3 for drip loss, cooking loss and EC (p>0.05). T2 showed lower TACs, pH value, TBARS and TVB-N than T3 did. Significant lower value of spermine and spermidine were observed in T1, T2 and T3 than those of control group (fresh) from 9th to 18th day (p<0.05). Drip loss was significantly correlated with TBARS, pH value, TVB-N, and TACs in groups T1, T2 and T3 (p<0.05).
{"Chemical": ["spermine", "spermidine", "amine"]}