.

.

.

🌾 Wheat Enzymes: A Technical Insight into α‑Amylase Activity and Its Impact

۱٫ Effect of Milling and Thermal Processing

Milling conditions and heat treatments significantly alter the activity of endogenous wheat enzymes, particularly α‑amylase, which plays a crucial role in flour functionality and baking quality.

2. Why α‑Amylase Activity Increases

• Preharvest Sprouting (PHS): Rainfall before harvest can induce germination, leading to a spike in α‑amylase levels, especially in the aleurone and germ layers of the grain.

• Late Maturity α‑Amylase (LMA): In certain wheat cultivars, exposure to temperature fluctuations during grain filling triggers α‑amylase synthesis, even in the absence of visible sprouting.

3. Impact on Falling Number (FN)

The Falling Number (FN) test, as defined by ICC and AACC methods, measures the liquefaction rate of a starch gel due to enzymatic activity.

• A low FN (<250–۳۰۰ seconds) indicates high α‑amylase activity.

• PHS or LMA both reduce FN, but their effects on baking quality may differ.

4. Effects on Baking Quality

• PHS-induced high α‑amylase typically causes dough stickiness, weak gluten structure, and results in collapsed, gummy baked goods.

• However, LMA-related α‑amylase may not adversely affect bread quality, even at high activity levels. In some cases, it may enhance loaf volume due to increased sugar availability.

• In commercial baking, exogenous α‑amylase (e.g., from Aspergillus oryzae) is often added to improve gas retention and loaf height, simulating the effect of controlled enzymatic action.

5. Practical Implications for Millers & Bakers

• Managing harvest timing and grain moisture levels is essential to reduce the risk of PHS.

• Proper milling techniques can help eliminate sprouted kernels and moderate α‑amylase levels.

• Relying solely on FN may be misleading; measuring direct α‑amylase activity (AACC 22-02) is advised to distinguish PHS from LMA.

✅ Summary & Key Takeaways

• A low FN doesn’t always indicate poor flour — context matters (PHS vs LMA).
• Direct α‑amylase tests provide more accurate insights into flour quality than FN alone.
• Optimizing harvest, storage, and milling conditions can significantly improve final product performance.

📚 References & Further Reading:

• “Falling Number Test – Importance & Limitations”, ICC Standard 107/1.
• Mares, D. J., & Mrva, K. (2008). Late maturity α‑amylase: Low Falling Number in wheat in the absence of preharvest sprouting. Journal of Cereal Science.
• AACC International Approved Methods, Method 22-02.01 (α‑Amylase Activity in Wheat and Flour).
• Every, D. et al. (2006). Effects of elevated α‑amylase on baking quality: Comparison between PHS and LMA. Cereal Chemistry Journal.
• grainar