Phytase activity in brown rice during steeping and sprouting.

Area of Science:

• Agricultural Science
• Food Science
• Biochemistry

Background:

• Phytase is crucial for nutrient bioavailability in grains.
• Seed germination activates and accumulates phytase in brown rice.
• Understanding phytase activity changes during germination is key for food processing.

Purpose of the Study:

• To investigate the impact of steeping and sprouting conditions on phytase activity in brown rice.
• To determine optimal pre-treatment and sprouting parameters for maximizing phytase activation.

Main Methods:

• Studied phytase activity changes during two germination stages: steeping and sprouting.
• Varied steeping conditions (temperature, medium composition, pH) and sprouting conditions (time, temperature).
• Analyzed phytase activity using standard assays and compared results based on pre-treatment.

Main Results:

• Steeping significantly decreased phytase activity, with lowest levels observed under specific conditions (20°C, 24h in demineralized water, CaCl2, or H2O2).
• Phytase activity increased during sprouting, reaching stable levels and showing temperature dependence (15-25°C).
• Pre-steeping with CaCl2 or H2O2 delayed then accelerated phytase activation during sprouting compared to control.

Conclusions:

• Steeping conditions critically influence subsequent phytase activation during sprouting.
• Neutral pH (6.8) demineralized water is the optimal pre-treatment for maximizing phytase activation before sprouting at 25°C.
• Extreme pH conditions during steeping inhibit phytase activation and negatively affect brown rice kernel appearance.