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Summary: Deep‐frying oil featuring total polar compound (TPC) has been found to be unhealthy. However, little information is available regarding the impact of TPC on the lipid digestion behaviour. In this study, three typical edible oils (palm oil, PO; high oleic acid peanut oil, HOA; and high linoleic acid sunflower oil, HLA) were selected to investigate the effect of deep‐frying on the lipid digestion. Digestion behaviour was monitored by pH‐Stat method in vitro. Digestibility rate analysis showed that free fatty acids release rate of all TPC groups was the slowest among corresponding fresh oils and deep‐frying oils, indicating deep‐frying decreased lipid digestion rate. Lipid droplet analysis uncovered that deep‐frying could increase lipid particle size. Correlation analysis showed the polymers in TPC are negatively correlated with digestion rate and particle size, suggesting the digestion behaviour of deep‐frying oil is related to TPC constitution. In conclusion, this study highlights that deep‐frying weaken the lipid digestion capacity, and the multiplicity of TPC distribution which vary in terms of FAs type contribute to differences of digestion behaviour in deep‐frying oils. [ABSTRACT FROM AUTHOR]

New food processing technology is required for food production with high quality and healthfulness. In this study, a novel application was developed to extract lard from pig fatback, a by-product of the slaughter plant, by an aqueous enzymatic extraction method (AEE). Various proteases with different properties including Alcalase 2.4 L, Neutrase 1.5 MG, Flavourzyme 1000 L, and Protamex were evaluated for their efficiency in oil release and lard qualities. Alcalase 2.4 L was more effective for oil extraction with a yield of 95.19%. A high quality of lard was produced by AEE in comparison with lards produced by conventional extraction methods in aspects of color, acid value, peroxide value, phospholipids, cholesterol, and oxidation stability. A further refinement to reduce cholesterol from lard by β-cyclodextrin (β-CD) was developed and the optimal conditions were established. The optimal conditions were 7% β-CD addition (w/w) to a mixture of equal amount of lard and distilled water at reaction temperature 50°C for about 60 min. The cholesterol content of lard from this refinement process was about 3.2 mg/100 g which was about 93.7% reduction from 51.2 mg/100 g. This simple process by AEE and cholesterol reduction did not affect the composition of fatty acids and construction of triglyceride. Factors that were components of lard or produced during the lard extraction processes were evaluated for their influence on the cholesterol removal. Phospholipids could slightly enhance cholesterol removal, while free fatty acids with saturated or unsaturated aliphatic chains would have inhibitory effects because of their competition with cholesterol for β-CD. Practical applications: An excellent quality of lard was produced by a novel application of an aqueous enzymatic extraction method (AEE). This lard could be further refined by β-cyclodextrin for cholesterol reduction. This procedure would be a promising technology to obtain healthy lard and explore animal by-products for the food industry. This lard with high nutrients could have very broad applications such as in baking, cooking, deep fat frying in food industry. Lard obtained by combination of aqueous enzymatic extraction and β-cyclodextrin treatment presented high quality and very low cholesterol. [ABSTRACT FROM AUTHOR]

• Epoxy group weakened the digestion capacity of triglyceride. • Epoxy group increased the mean particle diameter of triglyceride. • Epoxy group decreased binding capacity of triglycerides to salt ions in digestive juice. • Epoxy group enhanced the flexibility of lipase. The digestion behavior of epoxy triglyceride, the main cytotoxic product of deep-frying oil, remains unknown, which may affect its biosafety. In this study, epoxy triglyceride (EGT) and triglyceride (GT) were used to reveal the effect of epoxy group on digestion. Digestibility rate analysis showed that the free fatty acids release rate of EGT was slower. To clarify this phenomenon, binding ability with salt ions in digestive juice and particle size were also been studied. Cluster size analysis indicated that epoxy group increased triglyceride particle size, resulting in smaller contact area between EGT and lipase. Interface behaviors displayed EGT decreased binding ability with salt ions in digestive juice. Spectroscopic analysis showed EGT caused the red shift of lipase peak, indicating that epoxy group changed lipase structure. Molecular dynamics simulation suggested EGT leads to loosen lipase structure. In conclusion, this study highlights that epoxy group could weaken the triglyceride digestion. [ABSTRACT FROM AUTHOR]