Antioxidant Activities of Konjac Glucomannan Hydrolysates of Different Molecular Weights at Different Values of pH.

Konjac glucomannan (KGM) is a high-molecular-weight polysaccharide that was originally extracted from the corms (underground storage organs) of Amorphophallus konjac. KGM and its oligomers have been reported as dietary fibers that exhibit an array of health benefits. The depolymerization of KGM via enzymatic hydrolysis at different conditions gives products of low viscosity and can be used for coating materials in microencapsulation. In the present study, konjac glucomannan hydrolysates (KGMHs) were produced by enzymatic hydrolysis using commercial mannanase at pH 4.5 at 70 °C for 5-120 min, then KGMHs' molecular weight (Mw), Degree of Polymerization (DP) and their bioactivities were determined. A longer hydrolysis time resulted in KGMH of a lower DP. Oligoglucomannans (Mw < 10,000) could be obtained after hydrolysis for 20 min. The DP of KGMH rapidly decreased during an early stage of the hydrolysis (first 40 min); DP reached around 7 at the end of the hydrolysis. Antioxidant activities were determined by the DPPH radical scavenging and FRAP assays of KGMHs prepared at pH 4.5 and evaluated at pH 2.0-8.0 depending on pH. KGMH having lower Mw exhibited higher antioxidant activities. KGMHs having the smallest molecular weight (Mw = 419) exhibited the highest DPPH radical scavenging activity. Mw and pH have a greater impact on KGMHs' bioactivities which can be useful information for KGMHs as functional ingredients.

Tapioca Resistant Maltodextrin as a Carbohydrate Source of Oral Nutrition Supplement (ONS) on Metabolic Indicators: A Clinical Trial.

Tapioca resistant maltodextrin (TRM) is a novel non-viscous soluble resistant starch that can be utilized in oral nutrition supplements (ONS). This study aims to evaluate acute and long-term metabolic responses and the safe use of ONS containing TRM. This study comprised of two phases: In Phase I, a randomized-cross over control study involving 17 healthy adults was conducted to evaluate three ONS formulations: original (tapioca maltodextrin), TRM15 (15% TRM replacement), and TRM30 (30% TRM replacement). Plasma glucose, serum insulin, and subjective appetite were evaluated postprandially over 180 min. In Phase II, 22 participants consumed one serving/day of ONS for 12 weeks. Blood glucose, insulin, lipid profile, and body composition were evaluated. Gastrointestinal tolerability was evaluated in both the acute and long-term period. During phase I, TRM30 decreased in area under the curve of serum insulin by 33.12%, compared to the original formula (2320.71 ± 570.76 uIU × min/mL vs. 3470.12 ± 531.87 uIU × min/mL, p = 0.043). In Phase II, 12-week TRM30 supplementation decreased HbA1C in participants (from 5.5 ± 0.07% to 5.2 ± 0.07%, p < 0.001), without any significant effect on fasting glucose, insulin, lipid profile, and body composition. The ONS was well-tolerated in both studies. TRM is therefore, a beneficial functional fiber for various food industries.

Effect of post-harvest drying process on chlorogenic acids, antioxidant activities and CIE-Lab color of Thai Arabica green coffee beans.

Drying process affected the qualitative indicators of green coffees; chlorogenic acid (CGAs), total phenolic content (TPC), antioxidant activities and CIE-lab color to varying degrees. Sun drying and heat pump drying resulted in comparable levels of CGAs and antioxidant activities in green coffees; however, color parameters, especially lightness (L*), differed. Correlation analyses indicated a relationship between specific CGAs, antioxidant activities and color parameters among coffees. PLS analysis revealed that the high contents of 5-caffeoylquinic acid in green coffees did not correlate with antioxidant activities. Results from CGAs contents and PCA analysis provided a linkage to previous research relating important components and quality indices of both green and roasted coffees as affected by postharvest drying. Results indicated that heat pump drying at 50 °C is a viable alternative and possibly superior to sun drying for preserving certain desirable chemical and physical characteristics of green coffee.

Bioaccessibility and antioxidant activity of phenolic acids, flavonoids, and anthocyanins of encapsulated Thai rice bran extracts during in vitro gastrointestinal digestion.

Encapsulation technique was applied to improve the stability of bioactive compounds in bran extracts from Thai rice cultivars (Khao Dawk Mali 105, Kiaw Ngu, Hom Nil, and Leum Pua), using three carriers including gelatin, gum Arabic, and the mixture of gelatin and gum Arabic. The microcapsules obtained using gelatin provided a higher production yield of 76.08, 85.63, 85.63 and 85.59%, respectively. A greater encapsulation efficiency was also observed in the extracts encapsulated with gelatin (93.45, 95.91, 91.19 and 95.09%, respectively). After simulated gastric and intestinal digestion, the microcapsules formed by using gelatin exhibited the higher release of bioactive compounds and antioxidant activity than unencapsulated extracts. However, the extracts encapsulated using gelatin and gum Arabic complex yielded the lowest release of bioactive compounds and their antioxidant activity after simulated digestion. The overall results showed that gelatin was an appropriate carrier that could protect bioactive compounds from the digestion conditions.

A novel approach to develop spray-dried encapsulated curcumin powder from oil-in-water emulsions stabilized by combined surfactants and chitosan.

In this study, a novel approach to prepare spray-dried encapsulated curcumin powder was investigated. The effects of surfactants viz. Tween 80 (at 0.25 to 0.75% wt) and lecithin (at 1% wt) and of a stabilizer viz. chitosan (at 0 to 0.375% wt) on the characteristics of curcumin-based emulsions as well as on physicochemical properties of the resulting spray-dried encapsulated powder were determined. The optimal emulsion was noted to be the one formulated with 0.50 and 0.25% wt, respectively, of Tween 80 and chitosan (T0.50/C0.25). Spray-dried powder prepared from the optimal emulsion was compared to that prepared from an emulsion with 0.5% Tween 80 and 0% chitosan (T0.50/C0.00), as well as that from an emulsion with 0.25% Tween 80 and 0.25% chitosan (T0.25/C0.25). Physical properties of all powders were not significantly different. However, the encapsulation efficiency of T0.50/C0.25 powder (72.28%) was significantly higher than those of T0.50/C0.00 (47.19%) and T0.25/C0.25 powder (51.61%). Ferric reducing antioxidant powers of T0.50/C0.25 and T0.25/C0.25 powders were comparable but significantly higher than that of T0.50/C0.00 powder. After reconstitution, the mean particle sizes of T0.50/C0.25 and T0.25/C0.25 remained unchanged due to the protection by chitosan. T0.50/C0.00 powder was noted to exhibit the highest bioaccessibility (89.32%) in the simulated gastrointestinal tract. PRACTICAL APPLICATION: The results of this study can be used as a guideline to develop a stable formulation of curcumin feed emulsion that can later be transformed into an encapsulated powdery form via spray drying. Such a guideline should prove useful for a company looking for a way to produce high-quality functional ingredients and/or products from curcumin.

Synbiotic edible film from konjac glucomannan composed of Lactobacillus casei-01® and Orafti®GR, and its application as coating on bread buns.

BACKGROUND: Konjac glucomannan-based edible films formulated with Lactobacillus casei-01® and chicory-derived inulin Orafti®GR were studied for their properties, stability, and application as coatings on bread buns. RESULTS: Thickness and transparency were variable and dependent on the formulations. Alterations in color properties of all supplemented films were unnoticeable by unaided human eyes, with ΔE less than 3. Lactobacillus casei-01® and Orafti®GR were associated with higher water solubility of the films. Lactobacillus casei-01® decreased the water vapor permeability of the films while Orafti®GR promoted it. The mechanical properties in all combinations remained unchanged, although those with Orafti®GR showed profoundly reduced tensile strength. Scanning electron micrographs and Fourier transform infrared spectra of the films confirmed good homogeneity and intermolecular attraction between the prebiotic and konjac glucomannan. Cell viability in the films stored at room temperature decreased sharply, becoming less than the minimum recommended level after day 4, while viable L. casei-01® in coatings on bread buns gradually decreased, with a reduction of ca. 2 log colony-forming units (CFU) portion-1 over the 7 day storage period at room temperature. CONCLUSION: The synbiotic film and coating developed in this study are a relatively simple strategy for incorporating L. casei-01® and Orafti®GR into bread buns, which are short shelf-life foods. Bread buns with synbiotic coating could diversify functional food choices. Pretreatment, together with other technologies, is required to maintain a desirable number of active probiotic cells for longer. © 2020 Society of Chemical Industry.

Impact of drying process on chemical composition and key aroma components of Arabica coffee.

Influence of heat pump drying (HP at 40, 45 and 50 °C), tray drying (TD) and sun drying (SD) on the quality of Arabica coffee was evaluated. Drying process did not affect the caffeine content, but influenced levels of some amino acids. Sucrose content was higher in HP and TD than in SD green coffees. The perceived aroma of brewed coffee from SD was similar to HP, but differed from TD. Concentrations of 30 important odorants were compared for SD, HP (50 °C) and TD brewed coffees. 2-Furfurylthiol, a key odorant of coffee, was at the same level in SD and HP coffees and lowest in TD samples. Principal component analysis (PCA) separated SD from HP and TD, based on the concentrations of 23 odorants. Combined results of sensory and chemical analyses showed that in comparison to SD, HP was superior to TD for preserving overall flavor quality.

A soft computing tool for species classification and prediction of glucomannan content in Amorphophallus genus.

The proposed work aims at designing a classification system for automatic identification of A. muelleri species, grown as a potential cash crop in many Asian countries, from the DNA fingerprints of Amorphophallus genus. Four sets of 48 DNA fingerprints belonging to 37 species of the Amorphophallus genus, developed with the help of four different primers are considered for the experiment, with an objective to identify only the fingerprints of the species of interest. A second experimental setup deals with the automatic classification of species containing high amounts of glucomannan from the same set of DNA fingerprints of the Amorphophallus genus. For each set of 48 DNA fingerprints generated with a specific primer, the DNA fingerprints are preprocessed to extract a 42 dimensional feature vector which is used to generate a k-Nearest Neighbor based classifier based on the Leave One Out Cross Validation protocol. Final classification based on outputs from individual classifiers constructed with respect to the four different primers is performed according to a n-star consensus strategy. The n-star consensus predicts species A. muelleri with cent per cent accuracy while it predicts species containing glucomannan with a more modest accuracy of 81.25%.

Konjac glucomannan hydrolysate: A potential natural coating material for bioactive compounds in spray drying encapsulation.

This research aimed to develop a suitable coating material for encapsulating a plant bioactive compound via spray drying. A suitable process for modifying the rheological property of konjac glucomannan (KGM) solution by enzymatic treatment was developed. A plant bioactive compound, andrographolide, was selected to use as core material. Mannanase (1500 units of enzyme) was used in the treatment of KGM solution. The concentration of KGM solution was varied from 9 to 18% (w/w). It was found that 12% (w/w) was the optimum KGM concentration that could be hydrolyzed to a viscosity of <100 mPa·s. HPLC analysis of hydrolyzed solution found a fair amount of DP4-DP7 oligosaccharides (where DP is degree of polymerization) were obtained. The solution was then used as coating material in spray drying with inlet air temperature of 170°C and outlet air temperature of 85°C. It was found that 12% (w/w) konjac glucomannan hydrolysate (KGMH) was suitable for coating 2% (w/w) andrographolide. Its efficiency of encapsulation was also higher than that of KGMH combined with gamma-cyclodextrin or beta-cyclodextrin. This study revealed a great potential of using KGMH solution for pharmaceutical and food industries in the spray drying encapsulation process.