Evaluation of sterols as markers of fungal spoilage in red pepper powder

Abstract

Red pepper powder (RPP) made from ground dried red pepper (Capsicum annuum L.) is prone to adulteration with fungal-spoiled RPP to gain unfair profits in Korea. This study aimed to investigate the effects of fungal infection on the ergosterol and phytosterol content of RPP and evaluate the potential of the sterol content as a marker for identifying fungal-spoiled RPP. Ergosterol was detected only in fungal-spoiled RPP and not in unspoiled RPP [<LOD (2.3 mg/kg)], making it a reliable marker for fungal spoilage. The ergosterol content [<LOQ (7.07 mg/kg)–87.4 mg/kg] in commercial RPP samples suggested contamination levels of 0.2–28.9 w/w% by fungal-spoiled RPP, depending on the fungal species. Despite elevated levels of campesterol, stigmasterol, and β-sitosterol and high stigmasterol-to-β-sitosterol ratios in fungal-spoiled RPP compared to unspoiled RPP, these parameters were not reliable markers due to natural variations of these compounds in RPP, not specific to fungal influence.