Development of Indirect Quantitative Methods for 3-MCPD Fatty Acid Esters (3-MCPDEs) and Glycidyl Fatty Acid Esters (GEs) in Thermally Processed Foodstuffs.

For indirect determination of 3-chloro-1,2-propanediol fatty acid esters (3-MCPDEs) and glycidyl fatty acid esters (GEs) in thermally processed foodstuffs distributed in Japan, we modified two published methods, an enzymatic method (later approved as JOCS Standard Method for the Analysis of Fats, Oils, and Related Materials 2.4.14-2016 and Joint JOCS/AOCS Official Method Cd 29d-19) and EFSA method developed by the Joint Research Centre of the European Commission. The performance of these methods was demonstrated to be satisfactory. The partially modified enzymatic method showed mean recoveries of 93.7-98.5% for 3-MCPDEs, 94.4-98.4% for GEs, and HorRat(r) values of 0.06-0.78 in analyses of 6 types of foods including Japanese specific foods (fried rice cracker, fried instant noodle, biscuit, karinto, vegetable tempura, and frozen deep-fried chicken) spiked with 3-MCPD dioleate and glycidyl oleate at 0.02-0.04 mg/kg or 0.2-0.4 mg/kg. The partially modified EFSA method showed mean recoveries of 96.6-99.4% for 3-MCPDEs, 95.7-100.1% for GEs, and HorRat(r) values of 0.14-1.05 in analyses of 5 types of foods (not including karinto) spiked simultaneously with 3-MCPD dioleate and glycidyl oleate at either 0.02-0.04 mg/kg or 0.2-0.4 mg/kg. The results of analyses of 9 samples (fried rice cracker, biscuit, 2 potato crisps, fried potato snack, baked cracker, cracker dough, seafood tempura, and frozen deep-fried chicken) using these 2 methods were comparable. The 95% confidence intervals determined with weighted Deming regression analysis between the results of 3-MCPDEs or GEs in the same samples analyzed by the 2 methods showed: the slope around 1 (3-MCPDEs, 0.982-1.025; GEs, 0.887-1.078); and intercept close to 0 (3-MCPDEs, －0.002-0.003; GEs, －0.011-0.015). These data confirmed that the concentrations of 3-MCPDEs and GEs in food samples determined by 2 independent analytical methods were equivalent.

Bone-like tissue formation by three-dimensional culture of MG63 osteosarcoma cells in gelatin hydrogels using calcium-enriched medium.

The aim of this study was to investigate the effect of Ca(2+) concentration in culture medium on the promotion of osteogenesis by MG63 osteoblast-like cells and to prepare bone-like tissues by supplying Ca(2+)-enriched medium to MG63 cells immobilized in three-dimensional gelatin hydrogels. Human osteosarcoma MG63 cells were cultured on tissue culture dish under various Ca(2+) concentrations to evaluate the effect of Ca(2+) concentration on calcium deposition. When Ca(2+) concentration was 8 mM, the maximum calcium deposition was obtained at day 28. Then MG63 cells were entrapped in gelatin hydrogels cross-linked by transglutaminase and cultured for 28 days, either in a standard culture medium or in medium containing 8 mM Ca(2+). Effects of Ca(2+)-enriched medium on osteoblastic phenotype of MG63 cells in gelatin hydrogels were analyzed in terms of cell number, calcium deposition content, and alkaline phosphatase (ALP) activity. The characteristics of calcified gelatin hydrogels were evaluated by x-ray diffraction (XRD), histological analysis, and scanning electron microscopy (SEM). After 28 days of culture, no significant difference in cell numbers was found between the different culture conditions. However, calcium content of gelatin hydrogels with cells cultured in Ca(2+)-enriched media was significantly higher than that of hydrogels with cells cultured in standard Ca(2+) concentration medium. After 14 days of culture, ALP activity of cells cultured in Ca(2+)-enriched media was down-regulated compared with that of cells cultured in standard Ca(2+) concentration media. XRD analysis indicated the formation of hydroxyapatite in gelatin hydrogels cultured in the Ca(2+)-enriched media at day 14, and the XRD pattern of the composite at day 21 was almost similar to that of mouse tibia. Moreover, histological analysis and SEM analysis revealed that cross-sections of hydrogels cultured in Ca(2+)-enriched media had an organic/mineral layer structure analogous to that of mouse tibia.