β-amylase is best described as which type of enzyme with respect to site of action and functional role in starch hydrolysis?

Introduction:
Starch-degrading enzymes differ in mode of action. Distinguishing endo- from exo-acting amylases is essential for predicting product profiles (maltose, dextrins) and selecting enzymes for brewing, baking, and sweetener manufacture. This question evaluates correct classification of β-amylase.

Given Data / Assumptions:

• Substrate: starch (amylose/amylopectin).
• Goal: define β-amylase action pattern.
• Context: industrial saccharification to maltose.

Concept / Approach:
β-amylase cleaves α-1,4 glycosidic bonds from the non-reducing ends of starch chains, releasing maltose units stepwise. Because it acts from the chain end, it is exo-acting. Its primary function is saccharification, generating fermentable sugars, hence it is termed a saccharifying enzyme.

Step-by-Step Solution:
Step 1: Identify site of action: chain ends rather than internal bonds.Step 2: Classify as exoenzyme due to terminal attack pattern.Step 3: Recognize functional role: substantial production of maltose = saccharifying activity.Step 4: Select combined option reflecting both truths.

Verification / Alternative check:
Technical datasheets and textbooks describe β-amylase as exo-acting and maltose-releasing, widely used in mashing and starch saccharification processes.

Why Other Options Are Wrong:

• endoenzyme: Describes enzymes like α-amylase that attack internal bonds.
• exoenzyme: True but incomplete alone.
• saccharifying enzyme: True but incomplete alone.
• transferase: Not the correct enzyme class for β-amylase's hydrolytic action.

Common Pitfalls:
Confusing β-amylase with α-amylase; assuming all amylases act identically regardless of endo/exo specificity.

Final Answer:
both (b) and (c)