Volatile methoxybenzene compounds in grains with off-odors

Area of Science:

• Agricultural Chemistry
• Analytical Chemistry
• Food Science

Background:

• Grain quality is crucial for food and feed industries.
• Off-odors in grains can significantly reduce market value and consumer acceptance.
• Identification of volatile organic compounds (VOCs) is key to understanding grain spoilage and contamination.

Purpose of the Study:

• To identify and quantify volatile methoxybenzene compounds in various grain samples.
• To correlate the presence of specific methoxybenzenes with distinct off-odors in corn, sorghum, soybean, and wheat.
• To investigate potential origins of these compounds, including insect secretions and microbial activity.

Main Methods:

• Gas chromatography-mass spectrometry (GC-MS) was employed for separation and identification of volatile compounds.
• An autosampler was used to purge volatiles from whole grain at 80°C onto a Tenax adsorbent.
• Thermal desorption and infrared detection aided in the identification of compounds, particularly isomers.

Main Results:

• Over 20 volatile methoxybenzene compounds were detected in 745 grain samples.
• Specific methoxybenzenes were associated with insect-like odors (e.g., 1,4-dimethoxybenzene derivatives) and musty/sour/smoke odors (e.g., methoxybenzene, dimethoxybenzenes).
• Correlations between compound levels and odor types suggest their role as indicators of grain quality issues.

Conclusions:

• Methoxybenzene compounds are significant contributors to off-odors in stored grains.
• The identified compounds can serve as biomarkers for insect infestation or spoilage processes.
• Further research into the biosynthetic pathways and precise origins of these methoxybenzenes is warranted.