Distinguishing between long-term-stored and fresh chili pepper powder through fingerprinting of volatiles by headspace capillary-gas chromatography-ion mobility spectrometry.

ABSTRACT

Long-term storage of chili pepper powder results in physicochemical and microbiological changes that decrease its commercial value; these changes occur owing to fungal growth and production of off-flavor compounds. Herein, long-term-stored chili pepper powder (LSCPP) and fresh chili pepper powder (FCPP) were analyzed using internal transcribed spacer sequencing and volatile organic compound fingerprinting by headspace capillary-gas chromatography-ion mobility spectrometry. Fungal analysis detected only Xeromyces bisporus with high accuracy in all the analyzed LSCPP samples. However, the proliferation of X. bisporus on nonspecific spots complicated the distinguishing process between the two groups based solely on fungal analysis. Therefore, nine compounds (three ketones, one alcohol, two aldehydes, one ester, one furan, and one sulfur compound) obtained by autoxidation and fungal metabolism were selected as potential markers for distinguishing LSCPP and FCPP. These above-mentioned substances, which were confirmed as off-flavor species owing to "stale" odor, emitted lipid fragrance and were used to successfully distinguish LSCPP from FCPP using principal component analysis and linear discriminant analysis. PRACTICAL APPLICATION According to the research results, it was possible to discriminate between long-term stored and fresh chili pepper powders using nine VOC markers for quality control in industry. In addition, the fungus generated from long-term storage of chili pepper powder was Xeromyces bisporus, which was confirmed to be safe for intake because it does not form secondary toxic metabolites.