Valorization of Spent Grains from Beer Production through ß-Glucan Extraction.

Brewers' spent grains (BSG) are the major byproduct of the brewing industry. Recently, it has been found that ß-glucan, which can be used as a food supplement, can be extracted from BSG and offers the greatest added value. This study aimed to investigate the effects of temperature (45-90 °C) and time (30-120 min) on ß-glucan extraction efficiency when using hot water extraction. ß-glucan was precipitated upon 80% ethanol addition. The chemical compositions were examined. The highest ß-glucan concentration and yield were obtained at a temperature and time of 60 °C and 90 min, respectively. The functional properties of the extracted ß-glucan were analyzed and compared with other commercial stabilizers such as sodium carboxymethyl cellulose (CMC), xanthan gum, gum arabic, and oat ß-glucan. All stabilizers exhibited non-Newtonian flow behavior, except for gum arabic, which exhibited Newtonian flow behavior. The water holding capacity of BSG ß-glucan was 6.82 g/g and the creaming index of the emulsions stabilized with BSG ß-glucan was 89.05%. BSG ß-glucan improved the color and stability of orange juice by reducing the precipitation of orange pulp. This study illustrated that BSG ß-glucan can be used as a stabilizer and viscosity enhancer in foods, depending on the concentration, which can be applied to a variety of foods.

Influence of Degree of Polymerization of Low-Molecular-Weight Chitosan Oligosaccharides on the α-Glucosidase Inhibition.

Chitosan oligosaccharide (COS) is a bioactive compound derived from marine by-products. COS consumption has been demonstrated to lower the risk of diabetes. However, there are limited data on the inhibitory effect of low-molecular-weight COSs with different degrees of polymerization (DP) on α-glucosidase. This study investigates the α-glucosidase inhibitory activity of two low-molecular-weight COSs, i.e., S-TU-COS with DP2−4 and L-TU-COS with DP2−5, both of which have different molecular weight distributions. The inhibition constants of the inhibitors binding to free enzymes (Ki) and an enzyme−substrate complex (Kii) were investigated to elucidate the inhibitory mechanism of COSs with different chain lengths. The kinetic inhibition model of S-TU-COS showed non-completive inhibition results which are close to the uncompetitive inhibition results with Ki and Kii values of 3.34 mM and 2.94 mM, respectively. In contrast, L-TU-COS showed uncompetitive inhibition with a Kii value of 5.84 mM. With this behavior, the IC50 values of S-TU-COS and L-TU-COS decreased from 12.54 to 11.84 mM and 20.42 to 17.75 mM, respectively, with an increasing substrate concentration from 0.075 to 0.3 mM. This suggests that S-TU-COS is a more potent inhibitor, and the different DP of COS may cause significantly different inhibition (p < 0.05) on the α-glucosidase activity. This research may provide new insights into the production of a COS with a suitable profile for antidiabetic activity.

Synthesis and cytotoxicity study of magnesium ferrite-gold core-shell nanoparticles.

In this work, the core-magnesium ferrite (MgFe2O4) nanoparticles were prepared by hydrothermal technique. Completed gold (Au) shell coating on the surfaces of MgFe2O4 nanoparticles was obtained by varying core/shell ratios via a reduction method. Phase identification, morphological evolution, optical properties, magnetic properties and cytotoxicity to mammalian cells of these MgFe2O4 core coated with Au nanoparticles were examined by using a combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, UV-visible spectroscopy (UV-vis), vibrating sample magnetometry and resazurin microplate assay techniques. In general, TEM images revealed different sizes of the core-shell nanoparticles generated from various core/shell ratios and confirmed the completed Au shell coating on MgFe2O4 core nanoparticles via suitable core/shell ratio with particle size less than 100 nm. The core-shell nanoparticle size and the quality of coating influence the optical properties of the products. The UV-vis spectra of complete coated MgFe2O4-Au core-shell nanoparticles exhibit the absorption bands in the near-Infrared (NIR) region indicating high potential for therapeutic applications. Based on the magnetic property measurement, it was found that the obtained MgFe2O4-Au core-shell nanoparticles still exhibit superparamagnetism with lower saturation magnetization value, compared with MgFe2O4 core. Both of MgFe2O4 and MgFe2O4-Au core-shell also showed in vitro non-cytotoxicity to mouse areola fibroblast (L-929) cell line.