Difficulty: Easy
Correct Answer: Aspergillus oryzae
Explanation:
Introduction / Context:Sake brewing relies on koji molds to generate a suite of enzymes that saccharify starch and modulate protein-derived haze and flavour. Understanding the enzyme source helps technologists select safe, GRAS organisms and optimize process conditions.
Given Data / Assumptions:
Concept / Approach:Aspergillus oryzae is a domesticated koji mold, long recognized for producing amylases, proteases, and other hydrolases under controlled solid-state cultivation. It is GRAS and central to East Asian fermentations. A. flavus is aflatoxigenic and unsuitable; Bacillus cereus is a foodborne pathogen; A. niger is widely used for other enzyme preparations but is not the canonical source for sake koji proteases.
Step-by-Step Solution:Identify the GRAS koji mold used in sake: A. oryzae.Relate protease function to haze reduction and flavour development.Exclude unsafe or non-standard organisms.
Verification / Alternative check:Brewing texts and enzyme supplier catalogs list A. oryzae-derived proteases for beverage clarification and flavor optimization.
Why Other Options Are Wrong:A. flavus poses aflatoxin risk; B. cereus is unsuitable; A. niger is valuable industrially but not the classic koji protease source for sake.
Common Pitfalls:Assuming all Aspergillus species are interchangeable; safety and tradition strongly favor A. oryzae in sake.
Final Answer:Aspergillus oryzae.
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