Mannans as stabilizers of oil-in-water beverage emulsions

The stabilizing effect of spruce galactoglucomannan (GGM) on a model beverage emulsion system was studied and compared to that of guar gum and locust bean gum galactomannans, konjac glucomannan, and corn arabinoxylan. In addition, guar gum was enzymatically modified in order to examine the effect of the degree of polymerization and the degree of substitution of galactomannans on emulsion stability. Use of GGM increased the turbidity of emulsions both immediately after preparation and after storage of up to 14 days at room temperature. GGM emulsions had higher turbidity than the emulsions containing other mannans. The initial turbidity increased with increasing GGM content, but after 14 days storage at room temperature, the turbidity was the highest for GGM/oil ratio of 0.10:1 when ethanol-precipitated GGM was used. Increasing the storage temperature to +45 °C led to rapid emulsion breakdown, but a decrease in storage temperature increased emulsion stability after 14 days. Confocal microscopy showed that the average particle size in the bottom part of GGM emulsions stored for 14 days was smaller than 1 μm. A low degree of polymerization and a high degree of substitution of the modified galactomannans were associated with a decrease in emulsion turbidity.     

Synergistic effects between κ-carrageenan and locust bean gum on physicochemical properties of edible films made thereof

The development of mixed systems, formed by locust bean gum (LBG), and κ-carrageenan (κ-car) can offer new interesting applications such as the development of edible films with particular properties. κ-car/LBG blend films with different ratios were developed, and their effects on films’ physical properties were assessed. Thermogravimetric analysis (TGA), X-ray diffraction (XRD) patterns, dynamic mechanical analysis (DMA) and Fourier-transform infrared (FTIR) spectroscopy techniques were used to highlight the interactions between the two polysaccharides. The addition of κ-car to LBG improved the barrier properties of the films leading to a decrease of water vapor permeability (WVP). Improved values of elongation-at-break (EB) were registered when the ratio of κ-car/LBG was 80/20 or 40/60 (% w/w). Moreover, the κ-car/LBG blend films enhance the tensile strength (TS) compared to κ-car and LBG films. FTIR results suggested that hydrogen bonds interactions between κ-car and LBG have a great influence in films’ properties e.g. moisture content, WVP. Therefore, different κ-car/LBG ratios can be used to tailor edible films with enhanced barrier and mechanical properties.     

Effect of chymotrypsin digestion followed by polysaccharide conjugation or transglutaminase treatment on functional properties of millet proteins

Millet protein was solubilized by chymotrypsin; the soluble protein was conjugated to galactomannan under controlled conditions (60 °C, 76% RH) or polymerised by transglutaminase (TGase). SDS–PAGE patterns showed that the conjugated and polymerised proteins had higher molecular mass bands above the stacking gel. SDS–PAGE patterns also indicated that the digest was conjugated to galactomannan and polymerised by TGase. The free amino groups (OD₃₄₀) of the conjugated and polymerised digest were greatly reduced. Although the chymotrypsin digest was considerably insoluble between pH 2.0 and 5.0, galactomannan conjugate was completely soluble at all levels of pH. TGase polymer was slightly insoluble at pH 4.0. Galactomannan conjugate resisted heat-induced aggregation, even after heating at 90 °C for 20 min, while TGase polymer resisted heat-induced aggregation up to 70 °C, after which its solubility started to decline. The emulsifying properties of the conjugate and the polymerized proteins were greatly improved, compared to the native and chymotrypsin digests.     

Effects of tropical fruit pulps and partially hydrolysed galactomannan from Caesalpinia pulcherrima seeds on the dietary fibre content,probiotic viability,texture and sensory features of goat dairy beverages

The use of cheese whey and probiotic cultures in the production of dairy beverages has been highly attractive; nonetheless, whey-based goat beverages tend to be poor and watery when compared to fermented milks. The addition of fruits and fibre ingredients might improve texture and mouthfeel of this kind of product. Fermented whey-based goat beverages prepared using Streptococcus thermophilus TA-40 as starter culture, with added guava or soursop pulps, and with or without addition of partially hydrolysed galactomannan from Caesalpinia pulcherrima seeds (PHGM), showed to be good vehicles for Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus Lr-32, maintaining their viability above 7 log CFU/ml during 21 days. PHGM increased the dietary fibre content and enhanced the instrumental texture and sensory features of both guava and soursop dairy beverages, especially texture, appearance, and overall acceptability. The PHGM might be recommended to improve nutritional and sensory quality of fermented probiotic beverages produced with goat milk and cheese whey.     

食品级胡芦巴胶及其降血糖功效的研究

本文研究了胡芦巴种子中提取食物级胡芦巴胶的工艺技术，并就食品级胡芦巴胶对体内血糖水平的作用进行了动物实验，食品级胡芦巴胶对Ⅱ型糖尿病鼠有显著的降血糖作用，其降血糖功效比胡芦巴种子提高10倍以上。     

Galactomannan esters—A simple, cost-effective method of preparation and characterization

Acetate, succinate and octenylsuccinate derivatives of galactomannans were prepared in anhydrous reaction conditions carried out at slightly elevated temperature (40–60 °C) using solid NaHCO₃ as a mild base catalyst. Prior surface wetting of the reactants with 5% absolute ethyl alcohol gave derivatives with a higher degree of substitution, although it decreased the slurry viscosity. Use of NaHCO₃ significantly minimized high pH-induced degradative reactions, and its quantitative removal later was easily accomplished by repeated washings with aqueous ethyl alcohol. FT-IR, ¹³C-NMR, HPSEC and SEM data provided additional structural information. These derivatives are useful as functional food ingredients.     

Characterization of Galactomannan Stabilised Yogurt Drink Using Dynamic Rheology

A stabilised yogurt drink (SYD) was produced by mixing yogurt and water with the galactomannans guar (GG) and locust bean (LBG) gum at concentrations of 0.02, 0.06, 0.10, 0.14, and 0.20 g/100 g. The resulting colloid mixtures' viscous behaviour and stability was investigated. Rheological characterization using oscillatory methodology revealed that dynamic properties of elastic (G′), viscous (G″) modules and complex viscosity (η*) appreciably increased with increasing addition of both gums. Changing shear stress demonstrated complex flow behaviour and revealed the shear dependency of the SYD's flow behaviour. Syneresis decreased with increasing viscosity giving 93% improvement at 0.2 g/100 g gum addition.     

Physicochemical and functional characterization of the galactomannan obtained from mesquite seeds (<Emphasis Type="Italic">Prosopis</Emphasis> <Emphasis Type="Italic">pallida</Emphasis>)

The aim of this work was to carry out the physicochemical and functional characterization of the purified galactomannan obtained from mesquite seed’s endosperm (MSG). From the seeds, a MSG content of 13/100 g with a purity of 94/100 g was determined. The dispersions of MSG samples (up to 5 g/100 mL) exhibited a shear thinning non-Newtonian behavior, with 35.68 mPa.s of viscosity, and surface tension values between 43.5 and 61.06 dynes/cm. The chromatographic analysis revealed a 1.1:1 mannose/galactose ratio, with a molecular weight between 900,000 and 1,000,000 Da. The calorimetric analysis showed a specific vitreous transition temperature of 52.92 °C. The values of apparent viscosity were superior to those of commercial galactomannans, which indicates that MSG can be used too as a thickening agent. The obtained results provide information, which contribute to a better knowledge of MSG, in order to consider its sustainable exploitation in a future.