In industrial vinegar production using submerged fermentation, which special fermenter designs are employed for rapid acetification under aerated conditions?

Introduction / Context:
Vinegar is produced by Acetobacter and related acetic acid bacteria that oxidize ethanol to acetic acid. Two broad process routes exist: surface (trickling) fermentation using packed generators and submerged fermentation using specially designed, highly aerated fermenters. This question checks awareness of the correct vessel types used for submerged acetification.

Given Data / Assumptions:

• We are focusing on submerged (not surface) vinegar fermentation.
• Options list different equipment names, some specific to submerged technology.
• Goal is to identify which designs match submerged systems.

Concept / Approach:
Submerged acetification requires intense aeration and efficient heat removal because the ethanol to acetic acid conversion is exothermic and oxygen-demanding. Classic submerged fermenters include the Frings acetator and the cavitator (and related designs), which maximize oxygen transfer (kLa) via turbines, air sparging, draft tubes, and sometimes mechanical foam control.

Step-by-Step Solution:
Recognize acetator → canonical submerged vinegar fermenter engineered for high oxygen transfer. Recognize cavitator → another submerged design leveraging intense mixing and aeration. Identify packed vinegar generator → belongs to surface/trickle processes, not submerged. Therefore, submerged fermentation employs acetator and cavitator → choose both (a) and (b).

Verification / Alternative check:
Textbook classifications of vinegar plants split into packed generators (Orleans/quick process) and submerged fermenters (acetator/cavitator). Industrial case studies confirm the latter for high throughput.

Why Other Options Are Wrong:
Packed vinegar generator: surface culture; does not represent submerged acetification. “None of these” contradicts established practice.

Common Pitfalls:
Confusing process types; assuming all vinegar systems use packed beds. Submerged units differ by agitation, aeration, and foam handling.

Final Answer:
Both (a) and (b).