Cholesterol Oxidation in Fish and Fish Products

Lipid Peroxidation in Muscle Foods: Impact on Quality, Safety and Human Health

The issue of lipid changes in muscle foods under the action of atmospheric oxygen has captured the attention of researchers for over a century. Lipid oxidative processes initiate during the slaughtering of animals and persist throughout subsequent technological processing and storage of the finished product. The oxidation of lipids in muscle foods is a phenomenon extensively deliberated in the scientific community, acknowledged as one of the pivotal factors affecting their quality, safety, and human health. This review delves into the nature of lipid oxidation in muscle foods, highlighting mechanisms of free radical initiation and the propagation of oxidative processes. Special attention is given to the natural antioxidant protective system and dietary factors influencing the stability of muscle lipids. The review traces mechanisms inhibiting oxidative processes, exploring how changes in lipid oxidative substrates, prooxidant activity, and the antioxidant protective system play a role. A critical review of the oxidative stability and safety of meat products is provided. The impact of oxidative processes on the quality of muscle foods, including flavour, aroma, taste, colour, and texture, is scrutinised. Additionally, the review monitors the effect of oxidised muscle foods on human health, particularly in relation to the autooxidation of cholesterol. Associations with coronary cardiovascular disease, brain stroke, and carcinogenesis linked to oxidative stress, and various infections are discussed. Further studies are also needed to formulate appropriate technological solutions to reduce the risk of chemical hazards caused by the initiation and development of lipid peroxidation processes in muscle foods.

Effect of lipid oxidation on quality attributes and control technologies in dried aquatic animal products: a critical review

Aquatic animals are viewed as a good source of healthy lipids. Although drying is an effective method for the preservation of aquatic animal products (AAPs), the whole process is accompanied by lipid oxidation. This article reviews the main mechanism of lipid oxidation in the drying process. It also summarizes the effects of lipid oxidation on the quality of dried aquatic animal products (DAAPs), including nutrients, color, flavor, and hazard components, especially for those harmful aldehydes and heterocyclic amines. In addition, it concluded that moderate lipid oxidation contributes to improving the quality of products. Still, excessive lipid oxidation produces hazardous substances and induces health risks. Hence, to obtain high-quality DAAPs, some effective control technologies to promote/prevent lipid oxidation are introduced and deeply discussed, including salting, high-pressure processing, irradiation, non-thermal plasma technology, defatting treatments, antioxidants, and edible coating. A systematic review of the effect of lipid oxidation on quality attributes and control technologies in DAAPs is presented, and some perspectives are made for future research.

Polycyclic Aromatic Hydrocarbons in Foods: Biological Effects, Legislation, Occurrence, Analytical Methods, and Strategies to Reduce Their Formation

Polycyclic aromatic hydrocarbons (PAHs) are chemical compounds comprised of carbon and hydrogen molecules in a cyclic arrangement. PAHs are associated with risks to human health, especially carcinogenesis. One form of exposure to these compounds is through ingestion of contaminated food, which can occur during preparation and processing involving high temperatures (e.g., grilling, smoking, toasting, roasting, and frying) as well as through PAHs present in the soil, air, and water (i.e., environmental pollution). Differently from changes caused by microbiological characteristics and lipid oxidation, consumers cannot sensorially perceive PAH contamination in food products, thereby hindering their ability to reject these foods. Herein, the occurrence and biological effects of PAHs were comprehensively explored, as well as analytical methods to monitor their levels, legislations, and strategies to reduce their generation in food products. This review updates the current knowledge and addresses recent regulation changes concerning the widespread PAHs contamination in several types of food, often surpassing the concentration limits deemed acceptable by current legislations. Therefore, effective measures involving different food processing strategies are needed to prevent and reduce PAHs contamination, thereby decreasing human exposure and detrimental health effects. Furthermore, gaps in literature have been addressed to provide a basis for future studies.

Lipid profile and high contents of cholesterol oxidation products (COPs) in different commercial brands of canned tuna

Canned fish is submitted to processes that may degrade its lipids and form harmful compounds called cholesterol oxidation products (COPs). Samples of Brazilian commercial canned tuna were analyzed to evaluate the influence of different liquid mediums (oil and brine) on the fatty acid composition and formation of COPs. The exchange between fish lipids and the constituents of the covering liquid was highlighted by the high levels of linoleic acid found in tuna conserved in oil. High amounts of COPs were found. However, higher contents of COPs were found in tuna in brine (933.14 to 1914.23 µg/g) than in oil (698.24 to 1167.88 µg/g). This result was mainly promoted by the presence of pro-oxidant elements such as salt, as well as greater heat transfer in brine than in oil. This study showed that canned tuna is a potential source of exogenous COPs, indicating the role of liquid mediums in oxidative processes.

Quantification of Cooking Method Effect on COP Content in Meat Types Using Triple Quadrupole GC-MS/MS

A diet containing cholesterol is an essential component of biological function; however, cholesterol oxidation products (COPs) remain a major public health concern. This study investigated the effects of cooking methods (boiling and frying) on the production levels of COPs in processed foods. Samples, as represented by minced beef, chicken sausages, and fish fillets, were subjected to different cooking methods followed by COP extraction using a saponification method. Then, six common COPs, 5α-cholest, α-epoxy, β-epoxy, 25-HC, triol, and 7-keto, were quantified by triple quadrupole gas chromatography-mass spectrometry (GS-MS/MS). A significantly high number of COPs were detected in minced meat, of which 7-keto and triol were detected as major oxidation products, followed by chicken sausages and fish fillets (p ≤ 0.05). Compared to boiling, frying generated significantly more COPs, specifically triol (0.001-0.004 mg/kg) and 7-keto (0.001-0.200 mg/kg), in all samples. Interestingly, cholesterol level was found to be slightly (but not significantly) decreased in heat-treated samples due to oxidation during cooking, producing a higher number of COPs. Notably, the fish fillets were found to produce the fewest COPs due to the presence of a low amount of cholesterol and unsaturated fatty acids. In conclusion, adapting boiling as a way of cooking and choosing the right type of meat could serve to reduce COPs in processed foods.

Mutagenicity of 7-ketocholesterol in CHO cells: The role of lipid peroxidation

As an important cholesterol oxide, 7-ketocholesterol plays a deleterious role in the occurrence of cancer. Although the fact had been proved that 7-ketocholesterol could induce several biological phenomena, including apoptosis, DNA damage, et al., this issue whether 7-ketocholesterol led to mutagenesis in mammalian cells remains largely unexplored. Here, we investigated the major role of lipid peroxidation in the genotoxic response to 7-ketocholesterol in chinese hamster ovary (CHO) cells. The results showed that 7-ketocholesterol induced gene mutation and DNA double-strand breaks (DSBs) in concentration- and time-dependent manner. After CHO cells were treated with 25 μM 7-ketocholesterol for 48 h, the mutation frequency at hprt gene loci and the level of γ-H2AX protein were both significantly increased. Exposure to 7-ketocholesterol resulted in a concentration-dependent increase in the apoptotic rate and the protein expression of cleaved caspase-3 and -7 in CHO cells. Moreover, a significant increase of superoxide dismutase (SOD) activity and content of malondialdehyde (MDA) was also observed. Using a inhibitor of lipid peroxidation (butylated hydroxytoluene), it was found to remarkably inhibit the genotoxicity and MDA levels caused by 7-ketocholesterol. These findings indicated that lipid peroxidation was involved in the mutagenic process of 7-ketocholesterol in CHO cells.

Optimization of mass spectrometry settings for steroidomic analysis in young and old killifish

Steroids are essential structural components of cell membranes that organize lipid rafts and modulate membrane fluidity. They can also act as signalling molecules that work through nuclear and G protein–coupled receptors to impact health and disease. Notably, changes in steroid levels have been implicated in metabolic, cardiovascular and neurodegenerative diseases, but how alterations in the steroid pool affect ageing is less well understood. One of the major challenges in steroidomic analysis is the ability to simultaneously detect and distinguish various steroids due to low in vivo concentrations and naturally occurring stereoisomers. Here, we established such a method to study the mass spectrometry behaviour of nine sterols/steroids and related molecules (cholesterol precursors: squalene, lanosterol; sterol metabolites; 7 Dehydrocholesterol, 24, 25 and 27 Hydroxycholesterol; and steroids: progesterone, testosterone, and corticosterone) during ageing in the African turquoise killifish, a new model for studying vertebrate longevity. We find that levels of all tested steroids change significantly with age in multiple tissues, suggesting that specific steroids could be used as biomarkers of ageing. These findings pave the way for use of Nothobranchius furzeri as a novel model organism to unravel the role of sterols/steroids in ageing and age-related diseases.

Phospholipid packing defects and oxysterols in atherosclerosis: Dietary prevention and the French paradox

The research literature on atherosclerosis includes findings investigating the atherosclerotic effect of oxysterols, which are the oxidation products of cholesterol; and the literature on oxysterols refers to mechanisms by which oxysterols cause phospholipid packing defects in cell membranes. This review synthesizes these two bodies of research findings to describe how oxysterols cause phospholipid packing defects within the membranes of vascular endothelial cells, potentially increasing cell permeability of low-density lipoprotein cholesterol which may lead to atheroma formation. Exogenous sources of oxysterols are provided by dietary intake of animal-based foods that contain cholesterol oxidation products. This review proposes an explanation for the anti-atherosclerotic effect of plant-based dietary patterns, which is attributed to restriction or avoidance of dietary oxysterol intake from animal-based foods. Furthermore, raw-milk cheeses play an important role in the traditional French diet-low oxysterol content in these unheated foods may contribute to the French paradox, in which reduced coronary heart disease is associated with a diet high in saturated fat and cholesterol.

CO2 Plant Extracts Reduce Cholesterol Oxidation in Fish Patties during Cooking and Storage

Cholesterol oxidation products (COPs) in foods may pose risks for human health. Suitable antioxidants can reduce the formation of COPs in industrial products. Consumer awareness of food additives has brought a need for more natural alternatives. This is the first study on the effects of supercritical CO₂ extracts of rosemary, oregano, and an antimicrobial blend of seven herbs, tested at two levels (1 and 3 g/kg fish), against cholesterol oxidation in patties made of a widely consumed fish species, Atlantic salmon (Salmo salar), during baking and storage. Cholesterol oxidation was reduced by the extracts as indicated by lowered levels of 7α-hydroxycholesterol, 7β-hydroxycholesterol, and 7-ketocholesterol, which were quantified by GC-MS. The total amount of COPs was smaller in all of the cooked samples containing the plant extracts (<1 μg/g extracted fat) than in the cooked control (14 μg/g). Furthermore, the plant extracts exhibited protective effects also during cold storage for up to 14 days.