In soy processing, which enzyme application targets the removal of beany or grassy off flavours predominantly associated with reactive aldehydes such as hexanal?

Introduction:
Soy products may exhibit beany or grassy notes, often traced to aldehydes generated by lipid oxidation, particularly hexanal. Managing these volatiles is critical for producing neutral-tasting isolates, beverages, and meat analogues. Enzymatic oxidation can transform odour-active aldehydes into less impactful acids or alcohols.

Given Data / Assumptions:

• Primary off flavour compounds: aliphatic aldehydes (for example, hexanal).
• Goal: reduce aldehyde concentration or convert to less odour-active species.
• Process: food-grade enzymatic treatment under mild conditions.

Concept / Approach:
Aldehyde oxidase catalyses the conversion of aldehydes to carboxylic acids using oxygen and cofactors. The resulting acids generally have higher odour thresholds and different sensory profiles, reducing beany perception. This approach complements upstream control of lipoxygenase activity and oxygen exposure.

Step-by-Step Solution:

Verification / Alternative check:
Comparative volatile profiles before and after treatment show decreased hexanal and related aldehydes. Sensory panels typically report reduced beany notes, validating the biochemical conversion pathway.

Why Other Options Are Wrong:

• Diacetyl reductase: Targets diacetyl in beer, not soy aldehydes.
• β-Amylase: Produces maltose from starch; unrelated to aldehyde off flavours.
• Protease: Modifies proteins and bitterness but does not directly neutralize aldehydes.

Common Pitfalls:
Ignoring oxygen management can regenerate aldehydes downstream. Over-processing may affect desirable aroma. Combine enzymatic treatment with rapid cooling and inert gas blanketing where feasible.

Final Answer:
aldehyde oxidase