Which of the following is an intrinsic factor that directly influences microbial growth in food?[Fill in the blank]

Question

BlackTom AI · Accepted Answer

Water activity (aw) measures the amount of free, unbound water in a food that microorganisms can use for growth, so it is an intrinsic property that directly controls microbial proliferation.

1) Relevant knowledge points and concepts
- Intrinsic factors are properties inherent to the food itself (pH, water activity, nutrient content, antimicrobial constituents, redox potential, physical structure).
- Extrinsic factors are environmental/storage conditions (temperature, time, relative humidity, atmosphere/oxygen).
- Water activity (aw) ranges from 0 to 1 and directly limits which microorganisms can grow: most bacteria require aw ≥ ~0.91, most yeasts ≥ ~0.88, and many molds can grow at aw as low as ~0.80.

2) Step-by-step reasoning
- Examine each option and classify it as intrinsic or extrinsic.
  A. Storage temperature — this is an environmental/storage condition (extrinsic).
  B. Time between processing and consumption — this is a handling/storage/time factor (extrinsic).
  C. Oxygen availability in storage — this describes the storage atmosphere (extrinsic).
  D. Water activity (aw) — this is a physicochemical property of the food itself (intrinsic).

3) Numerical/illustrative steps
- Example values: fresh meat aw ≈ 0.99 (supports bacterial growth); dried fruit aw ≈ 0.60 (inhibits bacteria). Reducing aw from 0.99 to 0.85 prevents growth of most bacteria (because 0.85 < 0.91 threshold), illustrating direct control.

4) Why the correct answer is correct
- Water activity is inherent to the food composition (moisture bound vs free) and directly determines whether microorganisms can metabolize and multiply. Because aw is a characteristic of the food matrix, it is classified as an intrinsic factor.

5) Why the other options are incorrect
- A (storage temperature): influences microbial growth but is extrinsic (external condition).
- B (time between processing and consumption): a temporal/handling variable, not an inherent food property.
- C (oxygen availability in storage): relates to storage atmosphere (extrinsic).

Conclusion: Water activity (aw) is the intrinsic factor that directly influences microbial growth in food; therefore the correct answer is D.

Which of the following is an intrinsic factor that directly influences microbial growth in food?[Fill in the blank]单项选择题

类似问题

High-sugar foods such as jams inhibit bacterial growth but may still support mould growth because:[Fill in the blank]

Which of the following is an intrinsic factor that directly influences microbial growth in food?[Fill in the blank]

Which of the following foods has the highest water activity (Aw)?[Fill in the blank]

A food with water activity above 0.8 is:[Fill in the blank]

Which food has the most available moisture for bacteria to grow?

Most fresh foods, such as fresh meat, vegetables and fruits, have water activity values close to the optimum growth level of most microorganisms.

Based on water activity (Aw) alone, which of the following food items is the most likely to support microbial growth?

Drying preserves food by:

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单