2.3.6. Hydroxymethylfurfural (HMF)

HMF was recorded by determining the absorbance of the solutions at 284 and 336 nm, which was done using a GenesysTM10S UV-visible spectrometer (Thermo Fisher Scientific, Shanghai, China) [18]. The following equation was used to calculate the HMF content:

$$\text{HMF}(\text{mg/kg}) = (\text{A284}) - (\text{A336}) \times 149.7$$

where A284: absorbance value at 284 nm, A336: absorbance at 336 nm, and 149.7: a factor calculated by the molecular weight of HMF and the mass of the sample [12,15].
