Influence of different pasteurization conditions with equivalent pasteurization units on chemical, physical, and sensory properties of cloudy apple juice

Pasteurization is the prevalent method for stabilizing cloudy apple juice and prolonging its shelf life, but can also impair quality. Therefore, it is necessary to investigate and quantify the chemical, physical and sensory effects of this treatment. In this study, cloudy apple juice was treated at different time-temperature combinations with equivalent microbial lethality with 161.6 PU. These can be categorized as low temperature/long time (LTLT with 70°C and 80°C) or high temperature/short time (HTST with 90°C, 100°C and 105°C) treatments. The results were compared to those of untreated juice. HTST treatment had significantly less impact on the juice compared to LTLT treatment. LTLT-treated juices were characterized by different sensory attributes, such as raisin and caramel odor and bitter taste. In contrast, the untreated and HTST-treated juices exhibited odors like pear and lemon. There were also significant differences in turbidity, sugar composition, viscosity and a heightened 5-(hydroxymethyl)furfural (HMF) content with LTLT treatment. In summary, HTST-treated juices are more similar to the untreated juices and are rated higher in terms of quality characteristics. The lowest pasteurization temperature of 70°C results in the greatest deterioration of juice quality. It can be concluded that different pasteurization conditions showed different effects on juice quality, despite having the same microbiological lethality of 161.6 PU. Results can be considered when designing pasteurization processes.