Molecular brewing: Molecular structural effects involved in barley malting and mashing

Area of Science:

• Agricultural Science
• Food Science
• Biochemistry

Background:

• Malting and mashing are crucial processes in brewing, converting barley starches into fermentable sugars.
• Understanding the molecular interplay between barley starch and proteins is key to optimizing these processes.
• Current selection criteria for malting barley primarily focus on protein content, potentially overlooking other critical factors.

Purpose of the Study:

• To investigate the molecular effects of barley starch and starch-protein interactions on malting and mashing performance.
• To elucidate the underlying mechanisms influencing fermentable sugar production.
• To identify novel criteria for selecting high-quality malting barley.

Main Methods:

• Analysis of ten barley samples with varied protein content.
• Malting and mashing experiments to assess performance.
• Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) for starch granular analysis.
• Size-exclusion chromatography (SEC) to determine the molecular fine structures of amylose and amylopectin.

Main Results:

• Hydrolysis of both amylose and amylopectin polymers occurred concurrently during malting.
• A significant negative correlation was observed between protein and amylose content (in both unmalted and malted barley) and fermentable sugar content post-mashing.
• Starch molecular structure provides valuable insights into fermentable sugar release, beyond protein content.

Conclusions:

• Barley starch molecular structure is a critical factor influencing fermentable sugar yield during malting and mashing.
• Relying solely on protein content for malting barley selection may be insufficient.
• Incorporating starch structural analysis offers brewers new, effective methods for selecting optimal malting barley varieties.