Phytase-active yeasts from grain-based food and beer.

Area of Science:

• Microbiology
• Food Science
• Biotechnology

Background:

• Phytase enzymes are crucial for breaking down phytate, a compound that inhibits mineral absorption in grains.
• Yeast strains are a potential source of phytase for food applications, particularly in baking.
• Identifying yeast with high phytase activity can improve the nutritional value of grain-based foods.

Purpose of the Study:

• To screen yeast strains from grain-based foods and beer for phytase activity.
• To identify high phytase-producing yeast strains suitable for the baking industry.
• To evaluate both extracellular and intracellular phytase activities in selected yeast strains.

Main Methods:

• Yeast strains were isolated from grain-based food and beer.
• Two growth-based tests were employed for initial screening of phytase activity under bread leavening conditions (pH 5.5, 30°C).
• Extracellular and intracellular phytase activities were determined for 14 selected strains from six species, including Saccharomyces cerevisiae and Saccharomyces pastorianus.

Main Results:

• Phytase activity was detected in strains belonging to Saccharomyces cerevisiae, Saccharomyces pastorianus, Saccharomyces bayanus, Kazachstania exigua, Candida krusei, and Arxula adeninivorans.
• Saccharomyces pastorianus KVL008 (lager beer strain) exhibited the highest extracellular phytase production, followed by Saccharomyces cerevisiae KVL015 (ale beer strain) and Candida krusei P2 (sorghum beer strain).
• Intracellular phytase activities were generally low across all tested strains.

Conclusions:

• Beer-related strains of Saccharomyces pastorianus and Saccharomyces cerevisiae are reported as phytase-positive for the first time.
• The identified yeast strains with high extracellular phytase activity are promising candidates for producing wholemeal bread with enhanced mineral bioavailability.