High-yield diacylglycerol formation by solid-phase enzymatic glycerolysis of hydrogenated beef tallow

Diglyceride (DG) was prepared by reaction of hydrogenated beef tallow and glycerol in the presence of aPsesudomonas lipase. The yield of DG depended strongly on the reaction temperature. After initial incubation at 60°C for 2 h, followed by the first temperature shift down to 55°C for 4 h and then the second shift down to 48°C for up to 3 d, the reaction mixture became solid and a yield of approximately 90% DG was obtained. About 95% of total DG was 1,3-DG. The yield of DG was also dependent on the glycerol (GL) to triglyceride (TG) molar ratio. At the molar ratio of 1∶2 (GL/TG), the enzyme-catalyzed reaction was highly efficient and utilized essentially all of the glycerol. The free fatty acid (FFA) content at equilibrium depended on the water concentration in the glycerol phase. The initial rate of FFA formation was low and was hardly affected by the moisture content between 0.5 and 4%, but, at higher water content (4–6.7%), there was a small increase in the rate.     

Continuous Flow Atmospheric Pressure Laser Desorption/Ionization Using a 6–7-μm-Band Mid-Infrared Tunable Laser for Biomolecular Mass Spectrometry

A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6–7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6–7-µm wavelength region corresponds to the characteristic absorption bands of various molecular vibration modes, including O–H, C=O, CH₃ and C–N bonds. Consequently, many organic compounds and solvents, including water, have characteristic absorption peaks in this region. This ion source requires no additional matrix, and utilizes water or acetonitrile as the solvent matrix at several absorption peak wavelengths (6.05 and 7.27 µm, respectively). The distribution of multiply-charged peptide ions is extremely sensitive to the temperature of the heated capillary, which is the inlet of the mass spectrometer. This ionization technique has potential for the interface of liquid chromatography/mass spectrometry (LC/MS).