Formation of Nε-Carboxymethyl-Lysine and Nε-Carboxyethyl-Lysine in Pacific Oyster (Crassostrea gigas) Induced by Thermal Processing Methods

Abstract

Advanced glycation end products (AGEs) are important endogenous hazardous substances produced during the thermal processing of foods, which have attracted much attention due to the potential health risks. The current research first investigated the effect of different thermal processing methods (steaming, boiling, sous vide (SV), and sterilizing) on the formation of two typical markers of AGEs, including Nε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL), in Pacific oyster (Crassostrea gigas). The compositions, lipid oxidation, di-carbonyl compounds, and AGEs in 12 kinds of processed oysters were detected, and the Index values (total Z-score) were calculated. The SV treatment at 70°C caused higher processing yield and lower CEL level while sterilizing in oil at 121°C greatly resulted in the formation of CML. The Index value of SV-treated oysters was much lower than steamed, boiled, and sterilized ones. Correlation analysis showed that the CML and CEL levels were positively correlated with fat content, a* and b* value (p < 0.05), and negatively correlated with moisture content and L* value (p < 0.05). Besides, thiobarbituric acid reactive substances had a negative correlation with CML (r = −0.63, p < 0.05) while no significant correlation with CEL (p > 0.05), suggesting that lipid oxidation had a greater effect on the formation of CML but less on the formation of CEL. In summary, SV treatment at 70°C within 15 min was a recommended thermal processing method to reduce the formation of AGEs in oysters.

Investigations of the Polycyclic Aromatic Hydrocarbon and Elemental Profile of Smoked Fish

“…Since tuna is an umbrella species, a proximate composite of sub-tuna species differs from each other. In this study, the proximate composition of Atlantic bluefin tuna (T. thynnus) was determined as moisture (63.9%), total lipid (10.7%), crude protein (21.9%), and ash (2.1%) which is in accordance with previous research that indicated that the proximate composition of farmed and wild Atlantic bluefin tuna consisted of the following: lipid rate (11.04–12.85%), protein rate (20.96–21.09%) and moisture rate (61.03–63.28%) [ 26 ]. The proximal values of Atlantic bonito were determined as: protein (14.3%), fat (17.8%), moisture (68.2%), and ash (1.8%) ( Table 1 ), which were in agreement with results reported by Koral et al [ 38 ] who indicated the protein, lipid and moisture levels as 14.55, 12.87 and 67.71%, respectively.…”

“…The samples were analyzed in triplicate. The processing yield was determined according to Zhou et al [ 26 ]. The processing yield was calculated as the ratio of the weight of each fillet before salting to its weight after the smoking process, and was expressed as a percentage.…”

Effects of Baking and Frying on the Protein Oxidation of Wheat Dough

“…Protein oxidation occurs all the time during the process of food farm to table, especially in the process of processing, which changes the structure, sensory characteristics, and nutritional value of the protein. Reactive oxygen species (ROS) or oxidation products produced by foods under thermal processing directly or indirectly induce covalent modification of proteins to form protein oxidation/amino acid products [1,2], such as carbonyl [3,4], free sulfhydryl (SH) [5], dityrosine [6,7], and advanced glycation end products (AGEs) [8,9]. The intake of foods high in these oxidation products can lead to the accumulation of these substances in the body, which is closely related to obesity, diabetes, cardiovascular disease, and aging-related diseases (such as neurodegeneration, osteoporosis, and cataracts) [10].…”