In this study, the effects of diglyceride (DAG) content, baking temperature, addition of salt and baking duration on the contents of 3-monochloropropane-1,2-diol esters (3-MCPDE), glycidyl esters (GE), hardness and gumminess of soda biscuit prepared with diglyceride-rich olive oil were evaluated. The results showed that the highest contents of 3-MCPDE and GE in soda biscuit were 1.05 and 0.37 mg/kg, respectively. Moreover, it was found that the content of 3-MCPDE was positively correlated with the baking temperature and salt addition, and GE content increased with increasing baking temperature up to 170 ℃. However, the production of 3-MCPDE and GE were not significantly (P > 0.05) related to the content of DAG and baking duration. In conclusion, diglyceride-rich olive oil can be safely used in soda biscuit and can improve its texture. In addition, controlling baking temperature and salt addition can reduce the contents of 3-MCPDE and GE in soda biscuit.

Diacylglycerol microcapsule is a new type of functional food ingredient. In order to accurately determine the oil content, peroxide value, diacylglycerol content and other physical and chemical indexes of diacylglycerol microcapsule, the optimal extraction method for the oil components should be established. In this study, four methods of acid hydrolysis, alkali hydrolysis, ultrasonic treatment and bromelain hydrolysis were used for wall-breaking pretreatment of flaxseed diacylglycerol microcapsule. The effects of the different pretreatment methods on the extraction of fats and oils from the microcapsules were compared. In other words, the extraction rate of the fats and oils and the peroxide value of the them were investigated, and the glyceride composition of the extracted fats and oils was analyzed by high performance liquid chromatography. The results show that: the diacylglycerol obtained by the bromelain hydrolysis method has the least loss and the lowest peroxide value; the diacylglycerol obtained by acid hydrolysis and ultrasonic treatment has higher extraction rate, but acid hydrolysis results in the greatest loss of diacylglycerol content and ultrasonic treatment results in the highest peroxide values; and the alkali hydrolysis treatment leads to the lowest oil extraction rate. On the basis of the single factor experiment of enzyme hydrolysis, orthogonal optimization test was performed to explore the effect of enzyme addition, temperature and time on oil extraction rate, and the extraction solvent after enzymatic digestion was also optimized. The results show that when the dosage of bromelain is 12000 U/g, the enzymatic hydrolysis temperature is 55 ℃, and the enzymatic hydrolysis time is 5 min, the oil extraction rate of the diacylglycerol microcapsules can reach (98.60±0.78)%, and the peroxide value of the extracted oil is (0.037±0.001) g/100 g. The optimal extraction system after enzymatic hydrolysis is ethanol-diethyl ether-petroleum ether (2:5:5, in volume ratio). This method has high oil extraction rate and little impact on oil quality, providing theoretical basis for the detection of physicochemical properties of diacylglycerol microcapsules.

The in vitro digestion models mimicking the gastrointestinal (GI) tract of general population and lipid indigestion patients (with lower levels of bile salts or pancreatic lipase) were selected to investigate whether diacylglycerols (DAGs) are potential good lipid sources for these patients. Linseed oil-based DAG (LD) and linseed oil (LT) were selected. LD-based emulsion ((83.74 ± 1.23)%) had higher lipolysis degree than LT-based emulsion ((74.47 ± 1.16)%) when monitoring the GI tract of normal population as previously reported. Indigestion conditions seriously decreased the digestive degree of LT-based emulsion ((40.23 ± 2.48)%–(66.50 ± 3.70)%) while showed less influence on LD-based emulsion ((64.18 ± 2.41)%–(81.85 ± 3.45)%). As opposed to LT-based emulsion, LD-based emulsion exhibited preference for releasing unsaturated fatty acids (especially oleic acid and α-linolenic acid) due to their different glycerolipid compositions. LD-based emulsion showed potential for providing lipids and nutrients (including essential fatty acids) for lipid indigestion patients.