Suchergebnisse

It is now well-known that n-3 polyunsaturated fatty acids (omega-3 PUFA) have beneficial effects on health but are also rapidly oxidized in potentially toxic compounds, which means that healthy food products, rich in n-3 PUFA, can become toxic for the consumer if not stored or processed appropriately. The main objective of this work was to develop new analytical tools to study markers of lipids alteration in food, in order to allow an adequate monitoring of possible toxic compounds in n-3 PUFA rich food products. The first chapter of this PhD thesis is a literature review about fatty acids, their oxidation and the different oxidation products generated. The different analytical techniques used to study the oxidative stability of polyunsaturated fatty acids and their degradation products in food are also described. Chapter 2 describes the development of a gas chromatography coupled to mass spectrometry (GC-MS) method to analyze the fatty acids in food. The method was applied to eggs and pork (both standard and n-3 enriched) submitted to various cooking processes and storage conditions. This study confirmed that the fat of standard eggs or pork from the Belgian market cannot be considered as a source ofn-3 PUFA. Indeed, in this work, we measured no n-3 PUFA in meat or only around 2 % for eggs, while the fat of both enriched eggs and pork contained about 10 % of n-3 fatty acids. After storage or cooking without culinary fat no change of the fatty acid profile was observed, in standard eggs or pork. We made the same observation for n-3 enriched products, except for some cooking processes (pan-frying and oven cooking), which induced a slight but significant loss of n-3 fatty acids in n-3 enriched eggs or pork. The fairly stable behavior of the fatty acids after various cooking and storage experiments indicates that the fatty acid profile is not a good marker of lipid alteration. As a consequence, this work was oriented to the development of analytical tools to evaluate the presence of toxic aldehydes in food and feed as secondary oxidation products coming from polyunsaturated fatty acids. Chapter 3 is dedicated to the study of the oxidative stability of linseed oil, an oil rich in n-3 fatty acids. Section 3.1 describes the development of a liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method to evaluate the aldehyde content in linseed oil. After optimisation of the extraction, derivation, detection and quantification steps, the method was validated according to guidelines from the European legislation as well as the recommendations of the AFNOR protocol NF V 03-110 (AFNOR, 2010). The evaluated parameters included specificity/selectivity, recovery, precision, accuracy, uncertainty, limits of detection and quantification, determined using the concept of accuracy profiles. When the method was applied to first pressure linseed oil stored for several days at 60 °C according to the Schaal oven test, it was shown that 4-hydroxy-2E-hexenal (4-HHE) was the most produced aldehyde. In Section 3.2, the different patterns of oxidation of linseed oil in real-time and accelerated aging assays were investigated, in order to verify the hypothesis commonly accepted for vegetal oil that one day aging at 60 °C is equivalent to one month real time aging at room temperature. Oxidation was evaluated with the peroxide value and para-anisidine value, as well as the content in conjugated dienes and aldehydes. All four indicators of oxidation showed very different kinetic behaviours at 20 and 60 °C, showing that the hypothesis (1 day at 60 °C = 1 month at 20 °C) is not valid for linseed oil. Chapter 4 describes the adaptation and the validation of a LC-MS/MS method to determine aldehydes in animal feed samples. Indeed, as animal feed is often enriched with linseed to increase the human intake of n-3 fatty acids through the consumption of food from animal origin, the study of the oxidative stability of n-3 enriched animal feed is also of interest. To achieve that goal, the LC-MS/MS method previously developed for linseed oil was adapted to include more aldehydes and was validated using the same guidelines as in section 3.1. Finally, chapter 5 presents the discussion and conclusions about the developed methods and the results obtained as well as their comparison with literature. Future prospects to improve the evaluation of and the exposure to the markers of lipid alteration in food are proposed.

Although Argyrosomus regius (Asso, 1801) counts among the most appreciated and increasingly consumed fish species in Europe, little information is available on its flesh quality. This research concerns both healthy aquatic resource diversification and good nutritional quality. It is the first study to evaluate the quality of A. regius flesh from Mediterranean aquaculture. It aims to assess the concentration of 19 trace elements and to determine the fatty acid profile of this fish farmed in the Mediterranean Sea and to discuss human exposure risks. The nutritional intake of oligoelements (selenium (Se), zinc (Zn), and chromium (Cr)) and the mean concentrations of contaminants (arsenic (As), barium (Ba), cadmium (Cd), lead (Pb), and tin (Sn)) in A. regius muscles are, respectively, above and below recommended regulatory standards set by the international legislation. Additionally, the low fat content in its muscle mass and its high level of docosahexaenoic acid (C22: 6 n-3; DHA) and, to a lesser extent, eicosapentaenoic acid (C20: 5 n-3; EPA) confers satisfying nutritional qualities. This study allowed to conclude that meager can be considered as a source of seafood with good nutritional qualities for human health. ; Peer reviewed

This review aims to give an insight into the main hazards currently found in smoked meat and fish products. Literature research was carried out on international databases such as Access to Global Online Research in Agriculture (AGORA) database, Science direct, and Google scholar to collect and select 92 relevant publications included in this review. The smoking process was described and five hazards mostly found in smoked fish and meat were presented. The heat-induced compounds such as polycyclic aromatic hydrocarbons, heterocyclic amines, and nitrosamines were found in smoked fish and meat. Other hazards such as biogenic amines and heavy metals were also present in smoked fish and meat. The levels of these hazards reported from the literature exceeded the maximal limits of European Union. A brief description of risk assessment methodology applicable to such toxic compounds and risk assessment examples was also presented in this review. As most of the hazards reported in this review are toxic and even carcinogenic to humans, actions should be addressed to reduce their presence in food to protect consumer health and to prevent public health issue.

This review aims to give an insight into the main hazards currently found in smoked meat and fish products. Literature research was carried out on international databases such as Access to Global Online Research in Agriculture (AGORA) database, Science direct, and Google scholar to collect and select 92 relevant publications included in this review. The smoking process was described and five hazards mostly found in smoked fish and meat were presented. The heat-induced compounds such as polycyclic aromatic hydrocarbons, heterocyclic amines, and nitrosamines were found in smoked fish and meat. Other hazards such as biogenic amines and heavy metals were also present in smoked fish and meat. The levels of these hazards reported from the literature exceeded the maximal limits of European Union. A brief description of risk assessment methodology applicable to such toxic compounds and risk assessment examples was also presented in this review. As most of the hazards reported in this review are toxic and even carcinogenic to humans, actions should be addressed to reduce their presence in food to protect consumer health and to prevent public health issue.

Production of kilichi, a grilled meat of West Africa, is a common method of meat preservation in Niger. Thirty samples of condiments‐coated kilichi and uncoated kilichi collected in Niger, were analyzed for microbiological contamination, as well as NaCl, protein and lipid contents, using standard methods. Contamination with Polycyclic Aromatic Hydrocarbons (PAHs) was also assessed using a HPLC–FLD technique. Highly significant differences (p < .001) were observed between coated kilichi and uncoated kilichi, for NaCl content (2.56% and 1.40%), for proteins (51% and 72%) and lipids (18% and 13%), respectively. Water activity was low in both kilichi, showing a potential microbial stability. Among the 15 European Union (EU) priority PAHs, 12 were detected in the samples. About 56.3% of coated kilichi samples exceeded the EU maximal limit for BaP, and 75% exceeded the EU maximal limit for the sum of 4 PAHs (PAH4). For uncoated kilichi, 28.6% of samples did not meet the standards for BaP and PAH4. About 6% of coated kilichi samples were not compliant with standards related to Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, and 31%, 50% for yeasts and fungi, respectively. Escherichia coli and Enterobacteria were below the detection limit in both kilichi, but Salmonella and Bacillus cereus were detected only in one coated kilichi. The noncompliant samples of uncoated kilichi were in the proportions varying between 7% –86% for S. aureus, C. perfringens, yeasts, and fungi. This study showed potential risks associated with the consumption of traditionally produced kilichi in Niger due to both PAHs and pathogen bacteria contamination.

Production of kilichi, a grilled meat of West Africa, is a common method of meat preservation in Niger. Thirty samples of condiments‐coated kilichi and uncoated kilichi collected in Niger, were analyzed for microbiological contamination, as well as NaCl,protein and lipid contents, using standard methods. Contamination with Polycyclic Aromatic Hydrocarbons (PAHs) was also assessed using a HPLC–FLD technique. Highly significant differences (p < .001) were observed between coated kilichi and uncoated kilichi, for NaCl content (2.56% and 1.40%), for proteins (51% and 72%) and lipids (18% and 13%), respectively. Water activity was low in both kilichi, showing a potential microbial stability. Among the 15 European Union (EU) priority PAHs, 12 were detected in the samples. About 56.3% of coated kilichi samples exceeded the EU maximal limit for BaP, and 75% exceeded the EU maximal limit for the sum of 4 PAHs (PAH4). For uncoated kilichi, 28.6% of samples did not meet the standards for BaP and PAH4. About 6% of coated kilichi samples were not compliant with standards related to Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, and 31%,50% for yeasts and fungi, respectively. Escherichia coli and Enterobacteria were below the detection limit in both kilichi, but Salmonella and Bacillus cereus were detected only in one coated kilichi. The noncompliant samples of uncoated kilichi were in the proportions varying between 7% –86% for S. aureus, C. perfringens, yeasts, and fungi. This study showed potential risks associated with the consumption of traditionally produced kilichi in Niger due to both PAHs and pathogen bacteria contamination.

Production of kilichi, a grilled meat of West Africa, is a common method of meat preservation in Niger. Thirty samples of condiments‐coated kilichi and uncoated kilichi collected in Niger, were analyzed for microbiological contamination, as well as NaCl,protein and lipid contents, using standard methods. Contamination with Polycyclic Aromatic Hydrocarbons (PAHs) was also assessed using a HPLC–FLD technique. Highly significant differences (p < .001) were observed between coated kilichi and uncoated kilichi, for NaCl content (2.56% and 1.40%), for proteins (51% and 72%) and lipids (18% and 13%), respectively. Water activity was low in both kilichi, showing a potential microbial stability. Among the 15 European Union (EU) priority PAHs, 12 were detected in the samples. About 56.3% of coated kilichi samples exceeded the EU maximal limit for BaP, and 75% exceeded the EU maximal limit for the sum of 4 PAHs (PAH4). For uncoated kilichi, 28.6% of samples did not meet the standards for BaP and PAH4. About 6% of coated kilichi samples were not compliant with standards related to Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, and 31%,50% for yeasts and fungi, respectively. Escherichia coli and Enterobacteria were below the detection limit in both kilichi, but Salmonella and Bacillus cereus were detected only in one coated kilichi. The noncompliant samples of uncoated kilichi were in the proportions varying between 7% –86% for S. aureus, C. perfringens, yeasts, and fungi. This study showed potential risks associated with the consumption of traditionally produced kilichi in Niger due to both PAHs and pathogen bacteria contamination.

BACKGROUND In the traditional food sector, the smoking process and smoking-drying process are widely used to increase the shelf-life of seafood products. The smoking process and smoking-drying process are mainly performed using barrel kiln and wood as fuel in many West African countries. The present study evaluated the performances of the barrel kiln and its effects on physicochemical characteristics and safety of smoked fish (SF) and smoked-dried fish (SDF). Twelve follow-ups were conducted with three experimental processors and 24 samples of fish collected at different steps of processing were analyzed in a laboratory using standard methods. RESULTS The extreme values of combustion temperature recorded during the smoking process (456.4 °C) and smoking-drying process (482.8 °C) were higher than 450 °C, the temperature at which wood pyrolysis generates polycyclic aromatic hydrocarbons (PAHs). Smoked fish were highly contaminated with PAHs, and showed maximal levels of benzo[a]pyrene (52.7 μg kg−1) and PAH4 (i.e. sum of benzo[a]pyrene, chrysene, benzo[b]fluoranthene and benz[a]anthracene) (290.9 μg kg−1) exceeding the European Union limits by about 25-fold. After smoking of Scomber scombrus and smoking-drying of Cypselurus cyanopterus, no significant differences were recorded for lipid, protein and biogenic amine contents between fresh and processed fish, even if the histamine content of both fish exceeded the limit fixed by the European Union regulation. CONCLUSION The results obtained in the present study showed that smoked fish and smoked-dried fish produced using barrel kiln and wood fuel are highly contaminated by PAHs. Therefore, there is a need to improve the preservation practices of raw fish and smoking conditions to limit the contamination of end-products by PAHs known to be carcinogenic components for humans and to ensure consumer safety. © 2021 Society of Chemical Industry.

BACKGROUND In the traditional food sector, the smoking process and smoking-drying process are widely used to increase the shelf-life of seafood products. The smoking process and smoking-drying process are mainly performed using barrel kiln and wood as fuel in many West African countries. The present study evaluated the performances of the barrel kiln and its effects on physicochemical characteristics and safety of smoked fish (SF) and smoked-dried fish (SDF). Twelve follow-ups were conducted with three experimental processors and 24 samples of fish collected at different steps of processing were analyzed in a laboratory using standard methods. RESULTS The extreme values of combustion temperature recorded during the smoking process (456.4 °C) and smoking-drying process (482.8 °C) were higher than 450 °C, the temperature at which wood pyrolysis generates polycyclic aromatic hydrocarbons (PAHs). Smoked fish were highly contaminated with PAHs, and showed maximal levels of benzo[a]pyrene (52.7 μg kg−1) and PAH4 (i.e. sum of benzo[a]pyrene, chrysene, benzo[b]fluoranthene and benz[a]anthracene) (290.9 μg kg−1) exceeding the European Union limits by about 25-fold. After smoking of Scomber scombrus and smoking-drying of Cypselurus cyanopterus, no significant differences were recorded for lipid, protein and biogenic amine contents between fresh and processed fish, even if the histamine content of both fish exceeded the limit fixed by the European Union regulation. CONCLUSION The results obtained in the present study showed that smoked fish and smoked-dried fish produced using barrel kiln and wood fuel are highly contaminated by PAHs. Therefore, there is a need to improve the preservation practices of raw fish and smoking conditions to limit the contamination of end-products by PAHs known to be carcinogenic components for humans and to ensure consumer safety. © 2021 Society of Chemical Industry.