Changes in organosulfur compounds in garlic cloves during storage

Area of Science:

• Food Chemistry
• Agricultural Science
• Biochemistry

Background:

• Garlic's bioactive compounds, including gamma-glutamyl peptides and sulfoxides, are crucial for its quality and health benefits.
• Understanding the stability of these compounds during storage is essential for preserving garlic's properties.

Purpose of the Study:

• To investigate the changes in gamma-glutamyl peptides and sulfoxides in garlic during cold storage.
• To elucidate the chemical conversion pathways between these compounds at different temperatures.

Main Methods:

• High-performance liquid chromatography (HPLC) was used to quantify three gamma-glutamyl peptides and four sulfoxides.
• Garlic cloves were stored at -3, 4, and 23 degrees C for 150 days.
• Chemical conversion kinetics of isoalliin to cycloalliin were studied in buffer solutions and garlic cloves at varying temperatures.

Main Results:

• Storage at 4 degrees C led to the conversion of gamma-glutamyl peptides to alliin and isoalliin.
• Storage at 23 degrees C resulted in a decrease of gamma-glutamyl peptides and an increase in cycloalliin, not isoalliin.
• Isoalliin was found to be enzymatically produced from gamma-glutamyl peptides and chemically converted to cycloalliin, a process accelerated at higher temperatures.

Conclusions:

• Garlic storage temperature significantly impacts the transformation of key bioactive compounds.
• The conversion of isoalliin to cycloalliin is a temperature-dependent chemical process.
• These findings are valuable for managing garlic quality and its associated biological activities during storage and processing.