In order to increase the water solubility of chitosan and potential application to products that is good for human health. Chitosan was caried out the optimization of hydrolysis by cellulase to produce chitooligosaccharide. Chitosan with degree of deacetyl more than 80% and cellulase used in this study. Surface Response Method (RSM) - Central Composite Design (CCD) option is used to optimize the hydrolysis. Results of the study showed optimal values for hydrolysis such as 49 oC temperature, 5.9 pH, 0.76% substrate concentration, and 8.97 U/g enzyme concentration, 180 minutes hydrolysis time. More than 90% of the oligosaccharides produced were in the range less than 10 kDa. The research results are the premise for production of COS powder to water-soluble.

Introduction: The aim of this study is to determine appropriate parameters in the synthesis of syringic acid onto chitooligosaccharides (COSs) with an ascorbic acid/hydrogen peroxide redox pair in order to obtain the derivative with the highest grafting degree. Methods: In this study, syringic acid grafted COSs, catalysed by an ascorbic acid/hydrogen peroxide redox pair were investigated. The synthesis conditions were investigated, including the mass ratio between syringic acid and COSs, pH, temperature and synthesis time. Characteristics of the derivative were evaluated by Thin Layer Chromatography (TLC), Ultraviolet-Visible (UV-vis) and Fourier Transform Infrared (FT-IR) spectroscopy. The activities of COSs and derivative were evaluated by antimicrobial ability. Results: The results showed, that the best conditions for the synthesis were the mass ratio between syringic acid and COSs at 0.5:1, pH 5, temperature 27oC, for 6 hours with grafting degree at 32%. The TLC assay showed, that free ascorbic acid and syringic acid are not present in the product. The UV-vis and FT-IR data confirmed, that syringic acid was successfully conjugated onto COSs. Furthermore, the antibacterial assay showed that syringic acid grafted onto COSs had minimum inhibitory concentration against foodborne pathogenic bacteria at 1%. Conclusion: The syringic acid onto chitooligosaccharides were successfully synthesized by free radical mediated grafting method with an ascorbic acid/hydrogen peroxide redox pair. The grafting degree of syringic acid onto COSs was greatly affected by many factors, including COSs, syringic acid, pH, as well as temperature and time of reaction. Moreover, the new derivative showed enhanced antibacterial capabilities, as compare to free COSs.

In this study, the effect of Galactooligosaccharide (GOS) (0% và 2% w/v) on microencapsulated L.casei in whey protein 10% (w/v) and maltodextrin 5% (w/v) by spray dry method were investigated. The physical characterization included analysis of morphology, particle size. The viable cell counts of the microcapsule were determined during storage for 50 days at 10oC and in simulated gastric fluid (SGF) and intestinal fluid (SIF). All microcapsules with (WMG sample) or without GOS (WM sample) in this study showed similar morphology and particle size, between 3 to 11µm. There no differences between WMG and WM sample in cell viability were observed. For spray dry conditions tested in this work the cell viable yield with WM sample about 86.14% whereas for WMG sample about 86.78%. The viability of the microcapsules in WMG and WM were reduced about 0.44 and 0.63 log(CFU/g), respectively and remained > 6 log(CFU/g) after 2 hour in SGF or 4 hour in SIF incubating. Microcapsules made by spray dry method with whey protein 10% (w/v) and maltodextrin 5% (w/v) as encapsulating which enhancing L.casei survival, maltodextrin’s role not only as a wall material in microencapsulation but also as a prebiotic potential, eventually leading to added GOS was not necessary.