Color and viscosity of watermelon juice treated by high-intensity pulsed electric fields or heat

Preservation of Bioactive Compounds and Quality Parameters of Watermelon Juice Enriched with L-Citrulline through Short Thermal Treatment

“…Similar results were previously described in watermelon juices treated with thermal, ultraviolet-C, and high pressure treatments at the same temperature (60 ∘ C) where a correlation between PME activity and dynamic viscosity has been described [38]. In agreement with our results, Aguiló-Aguayo et al [36] did not observe a significant change in viscosity at day 0 between treatments, detecting a lower viscosity during the storage in samples pasteurized for 30 s with respect to 60 s, maintaining the highest viscosity values during the storage period. In previous studies, changes in color and viscosity of tomato juice were assigned to the activity of the enzymes POD, PME, and PG [19].…”

“…PWJ-40 s samples showed a residual PME activity of around 11% and PWJ-90 s of around 10% (Figure 2(b)). These values were lower than those obtained by Aguiló-Aguayo et al [36] in watermelon juice that had been thermally treated at 90 ∘ C for 60 s or 30 s, which obtained 25% and 38% of PME activity, respectively. Other results in clementine tangerine juice, after pasteurization at 74 ∘ C for 10 s, reduced the initial value of PME activity to 7% [37].…”

“…These values were lower than those obtained by Aguiló-Aguayo et al [36] in watermelon juice at 90 ∘ C for 60 s or 30 s. This author did not observe significant differences between thermally treated and nontreated juices. The incomplete reduction of PME and PG could explain the loss of stability in watermelon juice depending on the duration of the heat treatment [25].…”

“…The lowest scores in sensorial parameters were taste followed by aroma. The reduction in sensorial quality parameters has been previously described by Aguiló-Aguayo et al [36], who observed reductions in taste compounds when watermelon juice was thermally treated (90 ∘ C, 60 s) and stored for up to 56 days at 4 ∘ C.…”

“…The residual POD activity was around 26% in PWJ-40 s samples and 12% in PWJ-90 s samples (Figure 2(a)). Similarly, Aguiló-Aguayo et al [36] described a similar residual POD activity after the application of thermal treatments (90 ∘ C for 40 s or 60 s). It was rapidly reduced in the first week of storage and remained constant until day 30.…”