Integrated calculation of pasteurization time: A case study for thermal inactivation kinetics of a mixed fruit beverage
Prasanna P. Bhalerao, Snehasis Chakraborty
Abstract
Abstract The impact of batch thermal treatment (50–95°C/0–10 min) on various quality attributes of a mixed fruit beverage (pomegranate–amla–muskmelon juice = 57:5:38) was evaluated. The responses include microbial count (aerobic mesophiles [AM], yeast and mold [YM], psychrotrophs [PSY], and lactic acid bacteria [LAB]); enzyme activity (polyphenol oxidase [PPO] and peroxidase [POD]); and bioactive (ascorbic acid [AA], total phenolics [TPC], antioxidants [AOC], anthocyanins [TAC], and flavonoids [TFC]). Weibull model indicated a tailing behavior ( β = 0.8) for LAB, while others showed the shouldering behavior ( β > 1). YM was the most resistant microbial group. Enzyme inactivation and bioactive degradation were discussed with the n th‐order model. POD was more resistant than PPO. The corresponding activation energy ( E a ) values for PPO and POD were 61.8 and 65.1 kJ/mol, respectively. Among bioactive compounds, AA was most sensitive toward thermal stress. At 95°C, the 90% inactivation of enzyme activity ( t 90 value) was achieved after the total process time (come up + holding + cooling time) of 1.5 + 4.1 + 0.3 min. The corresponding losses (%) for AA, TPC, and AOC, at t 90 condition, were 39, 27, and 34, respectively. Practical applications The study attempts to introduce the expression for calculating the time required for 5‐log cycle reduction in resistant microbes ( t 5D value) and 90% reduction in enzyme activity ( t 90 value) of the sample. The kinetic model based on the cumulative approach of come‐up time ( t CUT ), holding time ( t HOLD ), and cooling time ( t COOL ) will undoubtedly help in designing the thermal pasteurization process of this mixed fruit juice and thereby pave the pathway for similar counterparts.