Formation of Cholesterol Oxidation Products, Cholesterol Dimers and Cholestadienes After Thermal Processing of Cholesterol Standards and Butter

Abstract

The aim of the study is to compare the transformation cholesterol standard and cholesterol present in a food matrix (butter) during thermal treatment at 150 and 180 °C for 1 h, which results in the formation of cholesterol oxidation products (0.5–189.3 mg g−1 of unheated standard and 0.044–0.063 mg g−1 of unheated butter) and cholesterol dimers (72.3–120.3 mg g−1 of unheated standard and 0.208 mg g−1 of unheated butter). The presence of cholesta‐3,5‐diene is investigated, especially in free cholesterol and cholesteryl palmitate unheated samples (105.3–116.4 mg g−1), as well as in thermally processed butter (0.009 mg g−1). Moreover, the processes of the extensive degradation of cholesterol are observed in standards samples (34.7–98.8% losses) compared to butter samples (25.5–73.5% losses). The qualitative and quantitative analyses of the above mentioned compounds are performed with the use of solid‐phase extraction, gas chromatography coupled with mass spectrometry and gel permeation chromatography. In conclusion, the thermal processing of butter and products containing cholesterol should be performed at mild temperatures, for example, 150 °C, because fewer negative components (e.g., oxysterols, cholesterol dimers) are formed in those conditions compared to heat processing at higher temperatures. Practical Application: The methods described in this study may be useful for the determination of sterols, oxysterols, cholesterol dimers, and cholesta‐3,5‐diene in standard cholesterol samples and cholesterol present in food products. The presented results data are crucial for the assessment of cholesterol changes during processing, especially the observation that some of the components have adverse effects on the human metabolism of oxysterols or cholesterol dimers. The investigations show that the thermal processing of products containing cholesterol should be performed at the lowest possible temperatures, for example, 150 °C, because this protects cholesterol from dimerization, oxidation, and degradation. Thermal processing of cholesterol can lead to the formation of cholesterol dimers, cholesterol oxidation products or cholestadienes, which can have adverse effect of the human health.

Dietary cholesterol oxidation products: Perspectives linking food processing and storage with health implications

“…Cholesterol and COPs in foods are often present dissolved in lipids, so the lipids need to be extracted from the sample before detection. Organic solvents, such as cyclohexane, n ‐hexane, and diethyl ether, were used for lipids extraction from foods (Derewiaka, 2019; Pikul et al., 2013; Risso et al., 2021). Since COPs contain amphiphilic groups, nonpolar solvents or single solvents are not suitable for extraction of COPs, and a mixture of organic solvents should be used for the extraction (Boselli et al., 2002; Cardenia et al., 2012; Folch et al., 1957; Soto‐Rodriguez et al., 2008).…”

“…The solid model system involves heating crystalline cholesterol alone or mixed with other components in organic solvents in a glass container. It is mainly used to study the mechanism of cholesterol oxidation and the main oxidation products (especially volatile substances) (Derewiaka, 2019; Derewiaka & Molinska, 2015). The aqueous and lipid models can be used to simulate the COPs formation in the food matrix and the influence of other components and the environmental factors on cholesterol oxidation.…”

“…Given the complexity of food composition, studies on COPs in different food matrices provide insights into the formation and mechanism of COPs. Derewiaka (2019) heated 0.8 g butter (about 2 mg cholesterol in it) and 2 mg cholesterol standard in glass ampoules at 150°C or 180°C for 60 min. The COPs content in cholesterol after thermal treatment at 150°C and 180°C for 60 min were 155.5 and 76.9 mg/g cholesterol, respectively.…”

“…The following sections will discuss several researches related to COPs formation based on these model systems. Derewiaka (2019) reported that with the temperature increased from 150 • C to 180 • C, heating cholesterol for 1 h leads to cholesterol loss from 64.1% to 90.5%. However, the yield of COPs (4α/β-HC, 6α/β-HC, 7α/β-HC, 5α,6α-/5β,6β-EC, Triol, and 7-KC) was reduced from 15.6% to 7.69%, as the temperature rose from 150 • C to 180 • C. Similar results were also reported by Min et al (2015).…”

Current Trends of Food Analysis, Safety, and Packaging

“…Moreover, standard samples (34.7-98.8% losses) relative to butter samples (25.5-73.5% losses) observe the processes of extensive cholesterol degradation. Research indicates that cholesterol-containing materials' thermal processing should be carried out at the lowest possible temperatures, e.g., 150°C, which prevents cholesterol from dimerization, oxidation, and degradation [ 112 ].…”