Continuous hydrolysis of raffinose family oligosaccharides in soymilk by fluidized bed reactor

Label-Free Quantification by Liquid Chromatography-Tandem Mass Spectrometry of the Kunitz Inhibitor of Trypsin KTI3 in Soy Products

The greater awareness of consumers regarding the sustainability of food chains has shifted part of the consumption from animal protein sources to vegetable sources. Among these, of relevance both for human food use and for animal feed, is soy. However, its high protein content is unfortunately accompanied by the presence of antinutritional factors, including Kunitz's trypsin inhibitor (KTI). Now there are few analytical methods available for its direct quantification, as the inhibitory activity against trypsin is generically measured, which however can be given by many other molecules and undergo numerous interferences. Therefore, in this work, a direct label-free liquid chromatography-mass spectrometry (LC-MS) method for the identification and quantification of trypsin Kunitz inhibitor KTI3 in soybean and derivative products has been developed. The method is based on the identification and quantification of a marker peptide, specific for the protein of interest. Quantification is achieved with an external calibration curve in the matrix, and the limit of detection and the limit of quantification of the method are 0.75 and 2.51 μg/g, respectively. The results of the LC-MS method were also compared with trypsin inhibition measured spectrophotometrically, highlighting the complementarity of these two different pieces of information.

One-pot conversions of raffinose into furfural derivatives and sugar alcohols by using heterogeneous catalysts

Inedible and/or waste biomass reserves are being strongly focused upon as a suitable new energy and chemical source. Raffinose, which is an indigestible trisaccharide composed of glucose, galactose, and fructose, is found abundantly in beet molasses, sugar cane, and seeds of many leguminous plants. Herein, we demonstrate the one-pot synthesis of furan derivatives and sugar alcohols from raffinose by using heterogeneous acid, base, and/or metal-supported catalysts. The combination of Amberlyst-15 and hydrotalcite (HT) showed a high activity (37% yield) for 5-hydroxymethyl-2-furaldehyde (HMF) through continuous hydrolysis, isomerization, and dehydration reactions. In addition, the use of a hydrotalcite-supported ruthenium catalyst (Ru/HT) successfully afforded 2,5-diformylfuran (DFF, 27% yield) from HMF produced by raffinose, directly. Moreover, the hydrogenation of hexoses obtained by raffinose hydrolysis into sugar alcohols (galactitol, mannitol, sorbitol) was also achieved in a high yield (91%) with Amberlyst-15 and Ru/HT catalysts. Thus, we suggest that raffinose has great potential for the synthesis of important industrial intermediates under mild reaction conditions.

Enzymatic hydrolysis preparation of mono-O-lauroylsucrose via a mono-O-lauroylraffinose intermediate

1'-O-Lauroylsucrose and 6'-O-lauroylsucrose were formed through hydrolysis of the C-6″ galactose group of 1'-O-lauroylraffinose and 6'-O-lauroylraffinose, respectively, in the presence of α-galactosidase. The enzymatic hydrolysis of 1'-O-lauroylraffinose and 6'-O-lauroylraffinose is discussed in detail. Acetic acid-sodium acetate was chosen as the buffer solution of the enzymatic hydrolysis reaction. The optimum conditions for the enzymatic hydrolysis reaction were as follows: buffer solution, pH 3.8; enzymatic time, 48 h; and enzymatic temperature, 37 °C. Under the optimal process conditions, the efficiency of α-galactosidase was ca. 82.6%. The isomers were fully compared in solubility, hydrophile-lipophile balance (HLB) values, critical micelle concentration (CMC), and thermal stability. The results showed that all lauroylsucrose isomers have similar solubilities in polar solvent, HLB values, CMC values, and thermal stabilities.