Konjac Glucomannan Hydrolysates Research Articles

Enzymatic hydrolysis and biological activities of Konjac glucomannan hydrolysate in different degree of polymerisation

SummaryThe study explores the enhanced functional and bioactive properties of Konjac Glucomannan Hydrolysate (KGMH) by partially degrading Konjac Glucomannan (KGM) using β‐mannanase over 60 min. KGM concentrations (40% and 50% w/w) were treated with 200–300 U g−1 of the enzyme over 60 min. The hydrolysis of KGM was monitored by colorimetry, with DP values ranging from 4.20 to 6.16 for 40% KGM and 4.10 to 4.60 for 50% KGM. MALDI‐TOF‐MS analysis confirmed typical oligosaccharides with DP values from 2 to 9 and some acetyl substitutions. The optimal conditions of 40% KGM with 250 U g−1 enzyme and varying hydrolysis times produced KGMHs with a wide range of DPs, demonstrating in vitro antioxidant and anti‐glycation activities. The results showed significant bioactivities (P < 0.05) positively correlated with lower DP values. This study emphasises the potential of KGMH as a novel functional food ingredient, highlighting its bioactive properties and the significant impact of DPs on the biological functionality of saccharides.

Characterisation of chicken breast and soy proteins glycated with konjac glucomannan hydrolysate

SummaryThis study investigated the enhancement of food proteins through glycation with bioactive saccharides derived from Konjac glucomannan hydrolysate (KGMH) via the Maillard reaction. The focus was on how the degree of polymerisation (DP) of KGMH influences the glycation process and the properties of conjugates with chicken breast and soy proteins. KGMH samples with low, medium, and high DPs (4.20, 5.21, and 6.11, respectively) were glycated under wet‐heating conditions with varying pH levels (8, 9, and 10) at 70 °C for 15 min to 6 h. Results demonstrated that higher pH and longer reaction times significantly enhanced (P < 0.05) glycation and browning, particularly with lower DP saccharides. The optimal conjugates markedly improved protein solubility (1.3 to 1.9 times), heat stability (1.1 to 2.4 times), and emulsification properties (1.2 to 1.5 times), with the highest DP showing the strongest correlation. Additionally, these conjugates exhibited significantly enhanced in vitro bioaccessibility (58.69% to 66.65%) and antioxidant activity (P < 0.05). This study highlights the novel potential of KGMH‐protein conjugation through the Maillard reaction for developing functional food ingredients with superior quality.

Enhancing encapsulation efficiency: Konjac glucomannan hydrolysate as a novel coating material for flavone derivatives in rice leaves extract

This study aimed to develop a novel coating material from Konjac Glucomannan Hydrolysate (KGMH) to flavone derivates from rice leaves extract (RLE). A suitable process for producing KGMH solution with different degrees of polymerization (DP) by enzymatic treatment was developed. Mannanase enzyme (250 and 150 units/g) were used in the hydrolysis process to obtain KGMH with lower (DP4 – 7) and higher DP (DP7 – 10), respectively. The solution was then used as a coating material in spray drying with an inlet air temperature of 190 °C, and the powder characteristics were assessed. The results showed that although the KGMH produced a lower production yield (64%–66%) compared to gum Arabic (72.45% ± 0.74%), KGMH was superior in terms of encapsulation efficiency of bioactive compounds (85%–95%) and antioxidant activity retention (90%–100%). FTIR spectra and X-ray diffraction confirmed the success of encapsulation by KGMH in the spray drying process. KGMH DP7-10 has successfully improved the bioaccessibility of Tricin O-glycoside after digestion. Furthermore, adding RLE encapsulated with KGMH enhanced and preserved tea products' bioactive compound content and antioxidant activity (3%–10% lower than after 24 days of storage).

Enhancing probiotic encapsulation with konjac glucomannan hydrolysate

SummaryFeasibility of using konjac glucomannan hydrolysate (KGMH) as prebiotics and wall material for encapsulating probiotics was investigated. Prebiotic activity scores (PASs) were determined for KGMH, inulin, fructooligosaccharides and konjac glucomannan to assess their effectiveness in promoting growth of probiotics and inhibiting enteric mixture. Thermal tolerances of probiotics were also assessed. Lactobacillus rhamnosus L34 and L. acidophilus LA5 exhibited higher PASs and thermal tolerances and were selected for encapsulation; freeze drying and spray drying were used to form and dry encapsulated probiotics. Maltodextrin (MD), soy protein isolate (SPI) and KGMH, either individually or in combination, were comparatively used as wall materials. Freeze drying with SPI and KGMH resulted in highest survival rates for L. rhamnosus L34 (97.92%) and L. acidophilus LA5 (88.94%). In case of spray drying, MD, KGMH and combination of MD and KGMH resulted in drying yields of 55–71%; SPI‐containing formula resulted in lower yields (20–23%). Spray‐dried probiotics exhibited lower survival rates compared to their freeze‐dried counterpart. KGMH, particularly in combination with SPI, emerged as promising material for enhancing probiotics survival during encapsulation.

Diversely regio-oxidative degradation of konjac glucomannan by lytic polysaccharide monooxygenase AA10 and generating antibacterial hydrolysate

Konjac glucomannan (KGM) hydrolysate exhibit various biological activities and health-promoting effects. Lytic polysaccharide monooxygenases (LPMOs) play an important role on enzymatic degradation of recalcitrant polysaccharides to obtain fermentable sugars. It is generally accepted that LPMOs exhibits high substrate specificity and oxidation regioselectivity. Here, a bacteria-derived SmAA10A, with chitin-active with strict C1 oxidation, was used to catalyse KGM degradation. Through ethanol precipitation, two hydrolysed KGM components (4 kDa (KGM-1) and 5 kDa (KGM-2)) were obtained that exhibited antibacterial activity against Staphylococcus aureus. In natural KGM, KGM-1, and KGM-2, the molar ratios of mannose to glucose were 1:2.19, 1:3.05, and 1:2.87, respectively, indicating that SmAA10A preferentially degrades mannose in KGM. Fourier-transform infrared spectroscopy and scanning electron microscopy imaging revealed the breakage of glycosylic bonds during enzymatic catalysis. The regioselectivity of SmAA10A for KGM degradation was determined based on the fragmentation behaviour of the KGM-1 and KGM-2 oligosaccharides and their NaBD4-reduced forms. SmAA10A exhibited diverse oxidation degradation of KGM and generated single C1-, single C4-, and C1/C4-double oxidised oligosaccharide forms. This study provides an alternative method for obtaining KGM degradation components with antibacterial functions and expands the substrate specificity and oxidation regioselectivity of bacterial LPMOs.

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.

Enhanced konjac glucomannan hydrolysis by lytic polysaccharide monooxygenases and generating prebiotic oligosaccharides

Konjac glucomannan (KGM) hydrolysate is a potentially valuable prebiotic that could improve gastrointestinal health by modulating the growth of probiotic bacteria and by promoting the production of short-chain fatty acids (SCFAs). In this study, we used lytic polysaccharide monooxygenases (LPMOs) to produce oligosaccharides from KGM and studied their prebiotic functions. The LPMO from Pleurotus ostreatus (PoLPMO9D) was shown to efficiently depolymerize KGM and produce a broad range of small oligomers. PoLPMO9D showed maximal activities at 50–60 °C and pH 4.0. When KGM-depolymerizing products produced by PoLPMO9D were employed as the carbon source instead of untreated KGM polymers, the growth of faecal microbiota was 2.76 times higher, a significant increase in the genus Lactococcus was observed, and the production of SCFAs increased by 14.6-fold with a significant pH decrease. This study shows that LPMOs may be a promising alternative enzyme for depolymerizing polysaccharide to prepare prebiotics from KGM.

Functional Role of Probiotics and Prebiotics on Skin Health and Disease

Scientific and commercial interest of probiotics, prebiotics and their effect on human health and disease has increased in the last decade. The aim of this review article is to evaluate the role of pro- and prebiotics on the normal function of healthy skin as well as their role in the prevention and therapy of skin disease. Lactobacilli and Bifidobacterium are the most commonly used probiotics and thought to mediate skin inflammation, treat atopic dermatitis (AD) and prevent allergic contact dermatitis (ACD). Probiotics are shown to decolonise skin pathogens (e.g., P. aeruginosa, S. aureus, A. Vulgaris, etc.) while kefir is also shown to support the immunity of the skin and treat skin pathogens through the production of antimicrobial substances and prebiotics. Finally, prebiotics (e.g., Fructo-oligosaccharides, galacto-oligosaccharides and konjac glucomannan hydrolysates) can contribute to the treatment of diseases including ACD, acne and photo aging primarily by enhancing the growth of probiotics.

Metagenomic Mining and Functional Characterization of a Novel KG51 Bifunctional Cellulase/Hemicellulase from Black Goat Rumen.

A novel KG51 gene was isolated from a metagenomic library of Korean black goat rumen and its recombinant protein was characterized as a bifunctional enzyme (cellulase/hemicellulase). In silico sequence and domain analyses revealed that the KG51 gene encodes a novel carbohydrate-active enzyme that possesses a salad-bowl-like shaped glycosyl hydrolase family 5 (GH5) catalytic domain but, at best, 41% sequence identity with other homologous GH5 proteins. Enzymatic profiles (optimum pH values and temperatures, as well as pH and thermal stabilities) of the recombinant KG51 bifunctional enzyme were also determined. On the basis of the substrate specificity data, the KG51 enzyme exhibited relatively strong cellulase (endo-β-1,4-glucanase [EC 3.2.1.4]) and hemicellulase (mannan endo-β-1,4-mannosidase [EC 3.2.1.78] and endo-β-1,4-xylanase [EC 3.2.1.8]) activities, but no exo-β-1,4-glucanase (EC 3.2.1.74), exo-β-1,4-glucan cellobiohydrolase (EC 3.2.1.91), and exo-1,4-β-xylosidase (EC 3.2.1.37) activities. Finally, the potential industrial applicability of the KG51 enzyme was tested in the preparation of prebiotic konjac glucomannan hydrolysates.

Molecular weight distribution and fermentation of mechanically pre-treated konjac enzymatic hydrolysates

There is interest in novel fibers as potential prebiotics for new and reformulated food products. Two konjac glucomannan (KGM) hydrolysates were developed by enzymatic hydrolysis with (KGMH I) or without (KGMH II) mechanical shear pre-treatment. These were characterized and evaluated as fermentation substrates using five lactobacilli and three bifidobacteria. Enzymatic treatment of native KGM reduced the average molecular weights of supernatant and pellet by ∼3-fold. Additional mechanical shear pre-treatment further reduced supernatant and pellet molecular weights by 5% and 35%, respectively. We postulated that pulverized and depolymerized short-chain KGM would better promote the growth of lactobacilli and bifidobacteria. Most lactobacilli fermented KGM hydrolysates. Lactobacillus acidophilus and Lactobacillus plantarum fermented KGMH I and II better than they fermented inulin. Overall, bifidobacteria were not strong fermenters of KGM hydrolysates. Both pulverization and enzymatic depolymerization significantly affected KGM molecular weight, suggesting that human gastrointestinal bacteria can utilize KGM hydrolysates with reduced weights.

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.

Tolerance and nutritional therapy of dietary fibre from konjac glucomannan hydrolysates for patients with inflammatory bowel disease (IBD)

Carbohydrates may provide an alternative therapeutic approach for a number of digestive health disorders such as inflammatory bowel disease (IBD). The aim of this work was to characterise the tolerance and efficacy of low and high molecular weight konjac glucomannan hydrolysates within healthy volunteers and patients suffering from IBD and associated gut conditions. These conditions included constipation, Crohn's disease and ulcerative colitis. For general tolerance, fourteen patients participated whilst for the digestive disorder trial, there were twenty. Scores of taste/texture of the product, bowel movement, stool consistency, diarrhoea, existence/absence of blood in the faeces, abdominal pains, flatulence, vomiting, fever, improvement of life style after use, willingness to use in the future and clinician's statements about each patient's conditions before and after use were recorded. The results showed that the hydrolysates were tolerated well for patients with diarrhoea and had a significant improvement on bowel movement, stool consistency, abdominal pain and flatulence after ten days. With respect to effects on IBD, there was a significant health benefit after fourteen days of consumption for bowel movement, stool consistency, diarrhoea, existence/absence of blood in the faeces, abdominal pain, flatulence and vomiting. Most patients declared an improvement of their life style after consuming the hydrolysates. The use of konjac glucomannan hydrolysates as a therapeutic agent or adjunct to standard treatments could prove a successful tool for the treatment of a range of disorders; although large scale studies are required to characterise further the role of the carbohydrates.

The Use of Konjac Glucomannan Hydrolysates (GMH) to Improve the Health of the Skin and Reduce Acne Vulgaris

Gluco mannan hydrolysates (GM H) have been shown to have positive prebiotic properties and when ingested have been shown to have a positive but indirect impact on the skin. However, d irect in vivo topical benefits have not been established. The aim of this work was to establish how effective GMH is with respect to improving skin health especially the reduction of infection due to acne vulgaris.Twenty six female volunteers aged between 18 to 39 years with active lesions of acne vulgaris were included in this study. Patients were assigned randomly into two groups to receive either a standard treatment or a spray formu lation containing GMH at a concentration of 5% (w/v). Before and during treat ment, the skin was evaluated according to the acne severity index (A SI). The results showed that there was a significant (P< 0.001) imp rovement of the skin health at the second (20 days) and third clinical evaluation (40 days) for established (e.g. antibiotics) and GM H treatments. Overall these data indicate that the GM H could be used as a prophylactic or novel topical therapeutic product for acne vulgaris and to imp rove skin health more generally.

The synbiotic effects of konjac glucomannan hydrolysates (GMH) and lactobacilli on the growth of Staphylococcus aureus and Salmonella typhimurium

PurposeThe purpose of this paper is to investigate how synbiotic combinations of lactobacilli with konjac glucomannan hydrolysate (GMH) may be used to reduce Staphylococcus aureus (S. aureus) and Salmonella typhimurium (S. typhimurium) growth in vitro.Design/methodology/approachGrowth of S. aureus and S. typhimurium was assessed individually and when mixed with L. acidophilus in modified media supplemented with two per cent GMH. The effect of the GMH and the Lactobacillus strain on S. aureus growth was also investigated using the well diffusion test on Muller‐Hinton agar medium.FindingsThe results showed that L. acidophilus “out grew” the pathogens S. aureus and S. typhimurium in the presence of konjac glucomannan in the mixed cultures.Originality/valueThe paper demonstrates that konjac glucomannan hydrolysates combined with probiotic bacteria, may be used to inhibit the growth of pathogenic bacteria such as S. aureus and S. typhimurium. These data support the development of an alternative approach to reduce infections and promote consumer health.

The use of konjac glucomannan hydrolysates to recover healthy microbiota in infected vaginas treated with an antifungal agent

The aim of this study was to evaluate how konjac glucomannan hydrolysates (GMH) could support the healthy re-colonisation of vaginal microflora post infections. A total of 26 female patients (12 controls and 14 treatments) aged 18 to 25 suffering from vaginal infection were recruited for this study. Patients were assigned randomly into two groups to receive a standard antifungal treatment or a standard antifungal treatment plus pessary capsules containing 200 mg GMH (twice a week for thirty days). Patients were assessed on day zero, sixteen and thirty of the trial. Several parameters were determined including yeast and bacterial counts, the KOH test, pH, Gram staining and wet mount microscopic observations. The results showed that the counts of Candida were diminished completely with antifungal treatment for both groups. However, the total bacterial counts increased with time in the GMH pessary group unlike the control. The normalised average KOH scores were reduced sharply with time in both groups although in the control group scores started to increase after sixteen days. The normalised average white blood cell scores also decreased with time for both groups. Epithelial cell scores decreased only for the GMH pessary group while clue cells and yeast-like fungi decreased with time for both control and GMH pessary groups. These results indicate the improvement of vaginal health recovery (post antifungal treatment for Candida infection) and especially the presence of healthy microflora due to the introduction of GMH in the vagina. The data indicate that it would be worth examining further the health benefits of GMH in a vaginal health format with a view to employing the material as a prophylactic or therapeutic agent. It provides an alternative approach to reducing vaginal infections and promoting consumer health.

A preliminary study of the synbiotic effects of konjac glucomannan hydrolysates (GMH) and lactobacilli on the growth of the oral bacterium Streptococcus mutans

PurposeThe purpose of this paper is to determine the effect of synbiotic combination of lactobacilli with konjac glucomannan hydrolysate (GMH) to reduce Streptococcus mutans growth in vitro with the intention of characterising its efficacy as a new approach for oral hygiene.Design/methodology/approachStrains of Lactobacillus acidophilus and S. mutans were grown individually or in combination in modified Columbia base broth supplemented with 2 per cent GMH. Following incubation, the samples were plated on De Man, Rogosa and Sharpe and Columbia blood agar and growth of both strains was assessed.FindingsThe probiotic bacteria L. acidophilus was able to “out grow” S. mutans in the presence of konjac glucomannan in the mixed cultures.Originality/valueThe results indicate that consumption of prebiotic and probiotic combinations may play a role as potential prophylactic or therapeutic agents for reducing the presence of organisms in the mouth associated with tooth decay. In order to confirm a beneficial effect of GMH further in vivo in this concept, studies involving healthy human volunteers should be considered.

Konjac glucomannan hydrolysate beneficially modulates bacterial composition and activity within the faecal microbiota

The prebiotic potential of a konjac glucomannan hydrolysate (GMH) was investigated in vitro using batch cultures inoculated with human faeces. Bacterial enumeration was carried out using the culture independent technique, fluorescent in situ hybridisation (FISH), and short chain fatty acid (SCFA) production was monitored by gas chromatography. The populations of Bifidobacterium genus, Lactobacillus– Enterococcus group and the Atopobium group all significantly increased after GMH and inulin fermentation. The Bacteroides– Prevotella group had a lower end population after GMH fermentation while inulin gave an increase, although these differences were not significant. No significant differences in SCFA concentrations were observed between inulin and GMH. As with inulin, GMH produced selective stimulation of beneficial gut microbiota and a favourable SCFA profile. In order to confirm a beneficial effect of GMH further in vivo studies involving healthy human volunteers should be considered.

Effect of konjac glucomannan hydrolysates and probiotics on the growth of the skin bacterium Propionibacterium acnes in vitro

The synbiotic ability of probiotic bacteria and konjac glucomannan hydrolysates (GMH) to inhibit acne-inducing bacterium, Propionibacterium acnes growth was studied in vitro. All probiotic bacteria strains tested were able to inhibit the growth of this species of skin bacterium where the inhibition was significantly (P < 0.01) enhanced by the presence of the GMH prebiotic. As the current treatment of acne is based on topical or systemic drugs, it is worth examining further the biotherapeutic activities of the GMH and selected probiotics with a view to future use as prophylactic or therapeutic synbiotics for treating acne infections.

Preparation and Characterization of Enzyme-Modified Konjac Glucomannan/Xanthan Blend Films

Enzyme-modified konjac glucomannan (KGM) and xanthan blend films have been prepared and characterized. Enzymatic hydrolysis of purified KGM by β-mannanase yielded samples of various weight-average molecular weight (M w) that were determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS) and calculated using the established Mark–Houwink–Sakurada equation [η] = 4.07 × 10−4 M w 0.733. KGM degradation products were blended with xanthan for preparation of films that were used in orthogonal-designed experiments. These films were characterized in terms of their structures, thermal stability, crystallinities and mechanical properties. The results of Fourier transform infrared spectroscopy indicated that, after blending, there was strong intermolecular interaction caused by hydrogen bonds between xanthan and KGM hydrolysates. This phenomenon was more marked at lower M w of KGM. The thermal stability of the blend films determined by differential scanning calorimetry was higher with increasing KGM molecular weight. The degrees of crystallinity characterized by X-ray diffraction (XRD) decreased with the increasing content of non-degraded KGM. Mechanical properties of the polymer blends including the tensile strength and elongation rate were also correlated to M w of KGM. The tensile strength achieved a maximum at 10.25 MPa with KGM of M w = 4.25 × 105 and the elongation rate reached a maximum value of 89.5% with KGM of M w = 8.95 × 105. These results were directly attributed to intermolecular interactions between xanthan and KGM, and this synergistic behavior led to good physicochemical and mechanical performance of the blended films.

Effects of konjac glucomannan hydrolysates on the gut microflora of mice

PurposeThe aim of this study is to determine the effects of depolymerised mannans and specifically konjac glucomannan hydrolysates (GMH) on the colonic microflora of mice. Blood glucose and cholesterol were also measured.Design/methodology/approachTwo groups (n = 20) of 12‐week old Wister mice were used for a period of 14 weeks. One group (treatment group) were fed diets containing 5 per cent konjac GMH dissolved in drinking water in addition to the control (group) standard diet. Faecal microflora, feed consumption, body weight, blood glucose and cholesterol were determined.FindingsThe GMH promoted the growth of anaerobes and lactobacilli in the treatment group where this was statistically, highly significant (P &lt; 0.001). Also, the hydrolysate was able to reduce highly significantly (P &lt; 0.001) faecal Clostridium perfringens and Escherichia coli counts. A significant increase in average daily feed consumption (P &lt; 0.05) and weekly body weight (P &lt; 0.001) was found for the treatment group. The mean ± SD (mmol/l) of blood glucose and cholesterol was lower in the treatment group.Originality/valueIn addition to modulating the gut microflora, GMH seems to lower the blood glucose and cholesterol in mice. Although this needs to be verified by further studies, GMH could also be a candidate for possible treatment of subjects with high cholesterol and for diabetics.