43 Brix sucrose = 43 gram sucrose in 100 gram total aqueous solution. According to this definition, Brix is independent of temperature. Thus, 43 Brix sucrose at 50 C can be made by dissolving 43 g sucrose (dry matter) in 57 g water in a sealed bottle at any temperature of choice and store this at 50 C in a stove or water bath.

Would add an extra information to the asnwer from Peter.

The reading of the Brix of a sucrose solution by its refractive index ( through brixmeter ) will require a correction in function of the temperature of the reading.

Please check

https://www.oiml.org/fr/files/pdf_r/r108-f93.pdf

the correction tables have been initially published in 1978 by ICUMSA.

Good luck.