Kinetic analysis of non-enzymatic browning in carrot juice concentrate during storage

The effect of storage temperature, storage time and total soluble solid (TSS) on the total sugar (TS), sucrose, glucose, fructose, total amino acid (TAA), pH, 5-hydroxymethylfurfural (HMF) and browning degree (BD) in carrot juice concentrate (CJC) stored at -18, 0, 25 and 37 degrees C was studied and the relationship between HMF and BD was established. Higher temperature at 25 and 37 degrees C had a significant effect (p < 0.05) on TS, sucrose, glucose, fructose, TAA, pH, HMF and BD, while lower temperature at 0 and -18 degrees C had less effect, and the storage time and the soluble solid of CJC stored at 25 and 37 degrees C also had a significant effect on HMF formation and BD. At 25 and 37 degrees C, the formation of HMF and BD followed a first-order reaction well as a function of storage time; a good correlation between HMF formation and BD occurred. The formation of HMF could described by the total soluble solid value [TSS] and the BD value ([BD], absorbance at 420 nm) of CJC, the equation was [HMF] (content of HMF) = 1.2177 - 0.1124 x [TSS] + (2.835 + 0.3477 x [TSS]) x [BD] and [HMF] = 1.5510 - 0.4813 x [TSS] + (23.8847 + 0.7249 x [TSS]) x [BD] at 25 and 37 degrees C, respectively.