Pectin methyl esterase in orange juice has a D value at 85^∘ C of 8.3 min. and the z value is 1

step 1 So, in this question, D value will represent the time required to achieve 90 percent reduction t

Pectin methyl esterase in orange juice has a D value at 85^∘...

Pectin methyl esterase in orange juice has a D value at $85^{\circ} \mathrm{C}$ of $8.3 \mathrm{~min}$. and the $\mathrm{z}$ value is $14^{\circ} \mathrm{C}$. Calculate the target juice temperature for pasteurization such that at least $99 \%$ of the enzyme will be inactivated after a 1-minute hold time followed by immediate cooling.

Key Concepts

Thermal inactivation kinetics

Thermal inactivation kinetics describes the rate at which heat treatment inactivates enzymes or microorganisms, typically modeled as a first?order reaction. This approach uses parameters like the D and z values to predict the necessary time and temperature conditions that achieve the required reduction in activity during pasteurization.

Log reduction

Log reduction is a measure used to express the extent of inactivation of microorganisms or enzyme activity. A 1 log reduction corresponds to a 90% decrease, while a 2 log reduction corresponds to a 99% decrease. This concept is essential in designing pasteurization processes to ensure that a target level of inactivation is achieved.

z value

The z value represents the temperature change required to change the D value by a factor of ten. In other words, it is the number of degrees of temperature increase needed to reduce the D value to one-tenth of its original value, thus indicating the sensitivity of the organism or enzyme to temperature changes.

D value

The D value is the time required at a specific temperature to reduce the concentration or activity of an organism or enzyme by 90% (or 1 log cycle) following first?order inactivation kinetics. It is a measure of thermal resistance and helps determine how long a product must be held at a given temperature to achieve desired levels of inactivation.

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