Question Bank • QB_DFE_PF_019 NAT • 2 Marks

Section 7: Dairy and Food Engineering

Preservation of Food

Subtopic: Preservation of food by cooling and freezing

Question Statement:

A gamma radiation dose of $D_{10} = 2.50\text{ kGy}$ achieves a $1\text{-log}$ ($90\%$) reduction of \textit{Salmonella} in fresh poultry meat. To achieve a $5\text{-log}$ reduction ($5 D_{10}$ safety process), the total radiation dose in $\text{kGy}$ is ________ (round off to one decimal place).

Answer Key:

12.5

Step-by-Step Solution & Explanation

Multi-Approach Solution: **Method 1: Direct D-Value Scaling** Total radiation dose required: $\text{Dose} = n \times D_{10} = 5 \times 2.50\text{ kGy} = 12.50\text{ kGy}$ **Method 2: First-Order Radiation Survival Law** $\log_{10}\left(\frac{N_0}{N}\right) = \frac{\text{Dose}}{D_{10}} \implies 5 = \frac{\text{Dose}}{2.50} \implies \text{Dose} = 12.5\text{ kGy}$
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