Improved microbial quality of buckwheat using antimicrobial solutions in a fluidized bed

Area of Science:

• Agricultural Science
• Food Science
• Microbiology

Background:

• Buckwheat (Fagopyrum esculentum) offers significant nutritional and health benefits.
• High microbial loads on buckwheat seeds restrict its use in functional foods and international trade.
• Developing effective, safe disinfection methods is crucial for expanding buckwheat applications.

Purpose of the Study:

• To evaluate the efficacy of various antimicrobial treatments for buckwheat seed disinfection.
• To assess the impact of treatments on microbial load, specifically aerobic plate count (APC) and yeast and mold count (YMC).
• To determine the optimal treatment conditions balancing microbial reduction and potential seed quality changes.

Main Methods:

• Antimicrobial treatments evaluated included ozone gas, ozonated water, acetic acid (AA), acidic calcium sulfate (ACS), and combinations.
• Liquid treatments were applied to buckwheat grain using a fluidized bed system.
• Microbial analysis involved quantifying aerobic plate counts (APC) and yeast and mold counts (YMC).
• Scanning electron microscopy was used to investigate microbial shielding on seed surfaces.

Main Results:

• Ozone gas and ozonated water showed limited effectiveness in reducing microbial load.
• Acetic acid combined with ozonated water demonstrated low effectiveness.
• Acidic calcium sulfate (50 mL/L) was the most effective, achieving a 3.9-log10 reduction in APC and eliminating YMC.
• Microbial shielding by the seed hull's rough surface and crevices limited ozone efficacy.
• Moisture content limitations in the industry also impacted treatment effectiveness.
• Acidic calcium sulfate treatment at 50 mL/L caused undesirable bleaching and increased redness in buckwheat.

Conclusions:

• Acidic calcium sulfate is a highly effective antimicrobial treatment for buckwheat disinfection.
• Optimizing ACS concentration can achieve sufficient microbial reduction while minimizing negative effects on buckwheat color.
• Further research should focus on lower ACS concentrations to preserve buckwheat quality for food applications.