Analysis of Amino Acids in Fermented Food and Drinks

Significance of the Topic

Amino acids play crucial roles in the nutritional and sensory properties of fermented foods and beverages. Reliable profiling of these compounds is essential for quality control, product development, and nutritional evaluation.

Objectives and Study Overview

This study presents the application of the Shimadzu amino acid analysis system using post-column OPA fluorescence derivatization to simultaneously quantify 38 amino acids in fermented products such as soy sauce, mirin, and miso. The aim is to demonstrate method performance and practical workflows for complex food matrices.

Methodology and Instrumentation

The analysis employs a Li-type cation exchange column coupled with post-column derivatization using o-phthalaldehyde (OPA). Key instrumental parameters include:

• Column: Shim-pack Amino-Li (100 mm × 6.0 mm I.D.)
• Mobile phase: Li-type amino acid kit with gradient elution
• Column temperature: 39 °C; flow rate: 0.6 mL/min
• Reagent: OPA-based amino acid kit at 0.3 mL/min, reaction temperature 39 °C
• Detection: fluorescence (Ex 350 nm, Em 450 nm)

Sample preparation varies by product type. Soy sauce is diluted 200-fold in pH 2.2 citrate buffer; mirin is diluted tenfold; miso is extracted with water, centrifuged, and filtered before a tenfold buffer dilution.

Key Results and Discussion

Baseline separation of 38 standard amino acids was achieved within 140 minutes, including proteinogenic, non-proteinogenic, and modified residues. Application to food samples yielded clear chromatographic profiles, enabling quantification of amino acid patterns in soy sauce, mirin, and miso. Matrix interferences were effectively managed by optimized sample dilution and buffer conditions.

Benefits and Practical Applications

• High sensitivity and selectivity for both free and modified amino acids
• Simultaneous multi-analyte capability enhances throughput
• Simplified derivatization workflow improves operational efficiency
• Applicable to quality control in food and beverage industries

Future Trends and Potential Applications

Ongoing advances may include faster columns for reduced analysis time, alternative derivatization reagents for extended amino acid coverage, and integration with mass spectrometry for structural confirmation. Broader adoption in nutritional research and process monitoring is anticipated.

Conclusion

The Shimadzu amino acid analysis system with OPA post-column derivatization offers a robust, sensitive, and versatile solution for comprehensive amino acid profiling in fermented foods and beverages. Its application enhances quality assurance and supports product optimization in food analytics.