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A A Karim - One of the best experts on this subject based on the ideXlab platform.
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characteristics of Metroxylon sagu resistant starch type iii as prebiotic substance
Journal of Food Science, 2015Co-Authors: Tan Zini, A A Karim, Ahmad Rosma, Hussin Napisah, Mintze LiongAbstract:Resistant starch type III (RS3) was produced from sago (Metroxylon sagu) and evaluated for its characteristics as a prebiotic. Two RS3 samples designated sago RS and HCl-sago RS contained 35.71% and 68.30% RS, respectively, were subjected to hydrolyses by gastric juice and digestive enzymes and to absorption. Both sago RS and HCl-sago RS were resistant to 180 min hydrolysis by gastric acidity at pH 1 to 4 with less than 0.85% hydrolyzed. Both samples were also resistant toward hydrolysis by gastrointestinal tract enzymes and intestinal absorption with 96.75% and 98.69% of RS3 were recovered respectively after 3.5 h digestion and overnight dialysis at 37 °C. Sago RS3 supported the growth of both beneficial (lactobacilli and Bifidobacteria) and pathogenic microbes (Escherichia coli, Campylobacter coli, and Clostridium perfringens) in the range of 2.60 to 3.91 log10 CFU/mL. Hence, prebiotic activity score was applied to describe the extent to which sago RS3 supports selective growth of the lactobacilli and bifidobacteria strains over pathogenic bacteria. The highest scores were obtained from Bifidobacterium sp. FTDC8943 grown on sago RS (+0.26) and HCl-sago RS (+0.24) followed by L. bulgaricus FTDC1511 grown on sago RS (+0.21). The findings had suggested that sago RS3 has the prebiotic partial characteristics and it is suggested to further assess the suitability of sago RS3 as a prebiotic material.
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physicochemical thermal and rheological properties of acid hydrolyzed sago Metroxylon sagu starch
Lwt - Food Science and Technology, 2012Co-Authors: M N Abdorreza, Marju Robal, L H Cheng, A Y Tajul, A A KarimAbstract:Abstract The effects of acid hydrolysis on physicochemical and rheological properties of sago starch were investigated. Sago starch was hydrolyzed in hydrochloric acid at 50 °C for 6, 12, 18, and 24 h. The molecular weight distribution, physicochemical, thermal, and rheological properties of acid-hydrolyzed sago starch (AHS) were determined. After 24 h of hydrolysis, molecular weight of amylopectin and amylose were decreased to 3.57 × 10 5 and 6.5 × 10 4 g/mol, respectively. Differential scanning calorimetry studies showed that the gelatinization temperature and enthalpy of AHS increased with increasing degree of hydrolysis. Hydrolyzed sago starch containing low molecular weight fractions exhibited cold water solubility up to 100%. Setting temperature of AHS decreased with increasing hydrolysis time but amylose content and gel strength increased in the first 12 h of acid hydrolysis but decreased with extended hydrolysis time. Hydrolyzed sago starch in concentrations lower than 8 g starch per 100 g water was cold water soluble and could be used to modify properties of starch for specific applications such as yogurt and concentrated milk processing.
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fermentation of Metroxylon sagu resistant starch type iii by lactobacillus sp and bifidobacterium bifidum
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Loo Siewwai, A A Karim, Tan Zini, Norziah M Hani, Ahmad RosmaAbstract:The in vitro fermentability of sago (Metroxylon sagu) resistant starch type III (RS3) by selected probiotic bacteria was investigated. Sago RS3 with 12% RS content was prepared by enzymatic debranching of native sago starch with pullulanase enzyme, followed by autoclaving, cooling, and annealing. The fermentation of sago RS3 by L. acidophilus FTCC 0291, L. bulgaricus FTCC 0411, L. casei FTCC 0442, and B. bifidum BB12 was investigated by observing the bacterial growth, carbohydrate consumption profiles, pH changes, and total short chain fatty acids (SCFA) produced in the fermentation media. Comparisons were made with commercial fructo-oligosaccharide (FOS), Hi-maize 1043, and Hi-maize 240. Submerged fermentations were conducted in 30 mL glass vials for 24 h at 37 °C in an oven without shaking. The results indicated that fermentation of sago RS3 significantly (P < 0.05) yielded the highest count of Lactobacillus sp. accompanied by the largest reduction in pH of the medium. Sago RS3 was significantly the mos...
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physicochemical properties of starch in sago palms Metroxylon sagu at different growth stages
Starch-starke, 2008Co-Authors: A A Karim, D M A MananAbstract:This study was aimed to examine the physicochemical properties of starch extracted from two different points (base and mid heights) of the sago palms trunks (Metroxylon sagu) of different physiological growth stages namely, ‘Plawei’, ‘Bubul’, ‘Angau Muda’, ‘Angau Tua’ and ‘Late Angau Tua’ stages. The physicochemical properties of sago starch studied were the morphology of starch, amylose content, particle size and distribution profile, pasting, thermal and retrogradation profiles. The results showed significant differences in the amylose and amylopectin content as well as in the granule sizes of starch from the different growth stages. Variation was observed in the proportions of granule sizes and pasting properties of starch from base and mid heights of the different growth stages while slight or insignificant differences was observed in the thermal properties of sago starch.
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pasting and retrogradation properties of alkali treated sago Metroxylon sagu starch
Food Hydrocolloids, 2008Co-Authors: A A Karim, M Z Nadiha, F K Chen, Y P Phuah, Y M Chui, A FazilahAbstract:Abstract Sago ( Metroxylon sagu ) starch was treated with 0.1% (w/v) and 0.5% (w/v) alkali (sodium hydroxide, NaOH) for 0, 15, and 30 days at ambient temperature (30 °C). Alkali-treated starches were characterized for pasting properties, retrogradation, intrinsic viscosity, swelling power, and solubility using various physical methods. Increase in swelling power and solubility of the alkali-treated starch could be attributed to the leaching of amylose chain, probably due to the propensity of alkali to attack the amorphous regions of the granules. This was evident by the blue regions (amylose–iodine complex) which were recognizable outside the starch granules when observed using iodine staining microscopy. Partial depolymerization of starch by alkali was also evidenced by a decrease in intrinsic viscosity. Peak viscosity and breakdown of alkali-treated starch were significantly reduced, whereas pasting temperature was not significantly affected. Microscopic examination showed that the granular shape of starch was less affected by alkaline treatment, except for the roughened surface on some granules treated with 0.5% NaOH. The effect of alkali on the crystalline region was not pronounced because the X-ray diffraction pattern was not significantly altered and the birefringence of the alkali-treated starch still remained after 30 days of treatment. Data from pulsed nuclear magnetic resonance and uniaxial compression tests for starch gels stored for 7 days at 4 °C indicated that retrogradation was markedly reduced, possibly due to depolymerization of starch polymer chains. The effects of alkali on pasting and retrogradation properties were more pronounced for starch treated with 0.5% alkali and longer duration.
Ahmad Rosma - One of the best experts on this subject based on the ideXlab platform.
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characteristics of Metroxylon sagu resistant starch type iii as prebiotic substance
Journal of Food Science, 2015Co-Authors: Tan Zini, A A Karim, Ahmad Rosma, Hussin Napisah, Mintze LiongAbstract:Resistant starch type III (RS3) was produced from sago (Metroxylon sagu) and evaluated for its characteristics as a prebiotic. Two RS3 samples designated sago RS and HCl-sago RS contained 35.71% and 68.30% RS, respectively, were subjected to hydrolyses by gastric juice and digestive enzymes and to absorption. Both sago RS and HCl-sago RS were resistant to 180 min hydrolysis by gastric acidity at pH 1 to 4 with less than 0.85% hydrolyzed. Both samples were also resistant toward hydrolysis by gastrointestinal tract enzymes and intestinal absorption with 96.75% and 98.69% of RS3 were recovered respectively after 3.5 h digestion and overnight dialysis at 37 °C. Sago RS3 supported the growth of both beneficial (lactobacilli and Bifidobacteria) and pathogenic microbes (Escherichia coli, Campylobacter coli, and Clostridium perfringens) in the range of 2.60 to 3.91 log10 CFU/mL. Hence, prebiotic activity score was applied to describe the extent to which sago RS3 supports selective growth of the lactobacilli and bifidobacteria strains over pathogenic bacteria. The highest scores were obtained from Bifidobacterium sp. FTDC8943 grown on sago RS (+0.26) and HCl-sago RS (+0.24) followed by L. bulgaricus FTDC1511 grown on sago RS (+0.21). The findings had suggested that sago RS3 has the prebiotic partial characteristics and it is suggested to further assess the suitability of sago RS3 as a prebiotic material.
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fermentation of Metroxylon sagu resistant starch type iii by lactobacillus sp and bifidobacterium bifidum
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Loo Siewwai, A A Karim, Tan Zini, Norziah M Hani, Ahmad RosmaAbstract:The in vitro fermentability of sago (Metroxylon sagu) resistant starch type III (RS3) by selected probiotic bacteria was investigated. Sago RS3 with 12% RS content was prepared by enzymatic debranching of native sago starch with pullulanase enzyme, followed by autoclaving, cooling, and annealing. The fermentation of sago RS3 by L. acidophilus FTCC 0291, L. bulgaricus FTCC 0411, L. casei FTCC 0442, and B. bifidum BB12 was investigated by observing the bacterial growth, carbohydrate consumption profiles, pH changes, and total short chain fatty acids (SCFA) produced in the fermentation media. Comparisons were made with commercial fructo-oligosaccharide (FOS), Hi-maize 1043, and Hi-maize 240. Submerged fermentations were conducted in 30 mL glass vials for 24 h at 37 °C in an oven without shaking. The results indicated that fermentation of sago RS3 significantly (P < 0.05) yielded the highest count of Lactobacillus sp. accompanied by the largest reduction in pH of the medium. Sago RS3 was significantly the mos...
Nazamid Saari - One of the best experts on this subject based on the ideXlab platform.
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analysis of thermal inactivation kinetics of membrane bound polyphenol oxidases and peroxidases from Metroxylon sagu
Journal of Food Biochemistry, 2011Co-Authors: Galila Hassan Onsa, Jinap Selamat, Jamilah Bakar, Azizah Abdulhamid, Mohd Yazid Abd Manap, Nazamid SaariAbstract:Thermal inactivation kinetics for the purified membrane-bound polyphenol oxidases (mPPOs) and peroxidases (mPODs) isolated from Metroxylon sagu were analyzed. Each isoenzyme was treated at different time-temperature combinations in the range of 0-70min and 20-70C. Thermal inactivation rates constant (k) at 70C for mPOD-I (72.9×10 -3/min) and mPOD-II (97.9×10 -3/min) were lower than that of mPPO-I (379.7×10 -3/min) and mPPO-II (138.1×10 -3/min). The activation energy for inactivation of mPPO-I (32.94kcal/mol) and mPPO-II (40.34kcal/mol) was lower compared with mPOD-I (45.77kcal/mol) and mPOD-II (40.62kcal/mol). The enthalpy values for mPOD-I (45.08kcal/mol) and mPOD-II (39.94kcal/mol) were higher than those of mPPOs (mPPO-I, 32.26kcal/mol; mPPO-II, 39.66kcal/mol). This result implies that both mPOD-I and mPOD-II are more thermostable.
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ANALYSIS OF THERMAL INACTIVATION KINETICS OF MEMBRANE‐BOUND POLYPHENOL OXIDASES AND PEROXIDASES FROM Metroxylon SAGU
Journal of Food Biochemistry, 2011Co-Authors: Galila Hassan Onsa, Jinap Selamat, Jamilah Bakar, Mohd Yazid Abd Manap, Azizah Abdul-hamid, Nazamid SaariAbstract:Thermal inactivation kinetics for the purified membrane-bound polyphenol oxidases (mPPOs) and peroxidases (mPODs) isolated from Metroxylon sagu were analyzed. Each isoenzyme was treated at different time-temperature combinations in the range of 0-70min and 20-70C. Thermal inactivation rates constant (k) at 70C for mPOD-I (72.9×10 -3/min) and mPOD-II (97.9×10 -3/min) were lower than that of mPPO-I (379.7×10 -3/min) and mPPO-II (138.1×10 -3/min). The activation energy for inactivation of mPPO-I (32.94kcal/mol) and mPPO-II (40.34kcal/mol) was lower compared with mPOD-I (45.77kcal/mol) and mPOD-II (40.62kcal/mol). The enthalpy values for mPOD-I (45.08kcal/mol) and mPOD-II (39.94kcal/mol) were higher than those of mPPOs (mPPO-I, 32.26kcal/mol; mPPO-II, 39.66kcal/mol). This result implies that both mPOD-I and mPOD-II are more thermostable.
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histochemical localization of polyphenol oxidase and peroxidase from Metroxylon sagu
2007Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah Bakar, Abdulkarim Sabo Mohammed, Shamsul BahriAbstract:Polyphenol oxidase (PPO) and peroxidase (POD) activities were visualized histochemically at the cellular level of a young and a mature tree of Metroxylon sagu employing histochemical technique. In the mature tree, intense PPO activity was observed in the cell wall of the parenchyma and xylem cells when visualized under light microscope. Pith collected from the young tree showed PPO activity in the amyloplast and mitochondria inner membrane and to some extent in the golgi complex and endoplasmic reticulum. Whereas, a positive POD reaction product was visualized in the cell wall, peroxisomes and to some extent in the cytoplasm and the vacuole. The localization of PPO activity in the amyloplast and being adsorbed by the starch granules is in line with the general view that enzyme is involved in the browning of sago starch.
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enzymatic production of linear long chain dextrin from sago Metroxylon sagu starch
Food Chemistry, 2007Co-Authors: Chen Wai Wong, Nazamid Saari, Sharifah Kharidah Syed Muhammad, M H Dzulkifly, Hasanah Mohd GhazaliAbstract:Pullulanase (EC.3.2.1.41) was used to generate more linear-chain dextrin from sago starch (24.9% amylose) such that the resulting product could act as a high amylose starch. A starch suspension of 5.0% (w/v) sago starch was heated at 100 °C for 45 min and, after cooling, the gelatinized sago starch was hydrolyzed with 2.0% (v/dry weight starch) pullulanase (Promozyme 400L, Novozymes A/S, Denmark) for 24 h. The linear long-chain dextrin (LLD) content of the hydrolysate after drying, was then compared with the initial LLD content. The surface morphology of the starch granules was observed with a scanning electron microscope (SEM). The effects of gelatinization, time of reaction, pretreatment with different strengths of hydrochloric acid prior to enzyme hydrolysis, and starch and enzyme concentrations were studied. Raw sago starch was resistant to the action of pullulanase, but caused an increase in the LLD of that sago starch from an initial concentration of 24.9–33.2% following gelatinization. The best conditions to maximize the amount of LLD were 5.0% (w/v) sago starch, 2.0% (v/w) enzyme and 12 h reaction time. Acid pretreatment of the sago starch did not cause greater improvement in the accessibility and susceptibility of pullulanase as the LLD content, following pullulanase action did not change significantly. Shrinkage on the surface of the starch granules was observed with the SEM.
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purification and characterization of membrane bound peroxidases from Metroxylon sagu
Food Chemistry, 2004Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah BakarAbstract:Two membrane-bound peroxidases, mPOD-I and mPOD-II, have been isolated and purified from Metroxylon sagu, using a combination of temperature-induced phase partitioning, DEAE-Toyopearl 650M, CM-Toyopearl 650 M and gel filtration. The mPOD-I and mPOD-II had molecular mass of 51.2 and 43.8 kDa, respectively, as determined by SDS–PAGE. Both enzymes showed high efficiency of interaction with the substrates. The isoenzymes were highly inhibited by ascorbic acid, metabisulfite, l-cysteine and p-coumaric acid. The inhibition mode of action and inhibition rate constant (Ki) values for these inhibitors were determined. Their activities were highly enhanced by Al3+, Ca2+ and Fe3+ but they were moderately inhibited by Zn2+.
Jamilah Bakar - One of the best experts on this subject based on the ideXlab platform.
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analysis of thermal inactivation kinetics of membrane bound polyphenol oxidases and peroxidases from Metroxylon sagu
Journal of Food Biochemistry, 2011Co-Authors: Galila Hassan Onsa, Jinap Selamat, Jamilah Bakar, Azizah Abdulhamid, Mohd Yazid Abd Manap, Nazamid SaariAbstract:Thermal inactivation kinetics for the purified membrane-bound polyphenol oxidases (mPPOs) and peroxidases (mPODs) isolated from Metroxylon sagu were analyzed. Each isoenzyme was treated at different time-temperature combinations in the range of 0-70min and 20-70C. Thermal inactivation rates constant (k) at 70C for mPOD-I (72.9×10 -3/min) and mPOD-II (97.9×10 -3/min) were lower than that of mPPO-I (379.7×10 -3/min) and mPPO-II (138.1×10 -3/min). The activation energy for inactivation of mPPO-I (32.94kcal/mol) and mPPO-II (40.34kcal/mol) was lower compared with mPOD-I (45.77kcal/mol) and mPOD-II (40.62kcal/mol). The enthalpy values for mPOD-I (45.08kcal/mol) and mPOD-II (39.94kcal/mol) were higher than those of mPPOs (mPPO-I, 32.26kcal/mol; mPPO-II, 39.66kcal/mol). This result implies that both mPOD-I and mPOD-II are more thermostable.
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ANALYSIS OF THERMAL INACTIVATION KINETICS OF MEMBRANE‐BOUND POLYPHENOL OXIDASES AND PEROXIDASES FROM Metroxylon SAGU
Journal of Food Biochemistry, 2011Co-Authors: Galila Hassan Onsa, Jinap Selamat, Jamilah Bakar, Mohd Yazid Abd Manap, Azizah Abdul-hamid, Nazamid SaariAbstract:Thermal inactivation kinetics for the purified membrane-bound polyphenol oxidases (mPPOs) and peroxidases (mPODs) isolated from Metroxylon sagu were analyzed. Each isoenzyme was treated at different time-temperature combinations in the range of 0-70min and 20-70C. Thermal inactivation rates constant (k) at 70C for mPOD-I (72.9×10 -3/min) and mPOD-II (97.9×10 -3/min) were lower than that of mPPO-I (379.7×10 -3/min) and mPPO-II (138.1×10 -3/min). The activation energy for inactivation of mPPO-I (32.94kcal/mol) and mPPO-II (40.34kcal/mol) was lower compared with mPOD-I (45.77kcal/mol) and mPOD-II (40.62kcal/mol). The enthalpy values for mPOD-I (45.08kcal/mol) and mPOD-II (39.94kcal/mol) were higher than those of mPPOs (mPPO-I, 32.26kcal/mol; mPPO-II, 39.66kcal/mol). This result implies that both mPOD-I and mPOD-II are more thermostable.
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histochemical localization of polyphenol oxidase and peroxidase from Metroxylon sagu
2007Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah Bakar, Abdulkarim Sabo Mohammed, Shamsul BahriAbstract:Polyphenol oxidase (PPO) and peroxidase (POD) activities were visualized histochemically at the cellular level of a young and a mature tree of Metroxylon sagu employing histochemical technique. In the mature tree, intense PPO activity was observed in the cell wall of the parenchyma and xylem cells when visualized under light microscope. Pith collected from the young tree showed PPO activity in the amyloplast and mitochondria inner membrane and to some extent in the golgi complex and endoplasmic reticulum. Whereas, a positive POD reaction product was visualized in the cell wall, peroxisomes and to some extent in the cytoplasm and the vacuole. The localization of PPO activity in the amyloplast and being adsorbed by the starch granules is in line with the general view that enzyme is involved in the browning of sago starch.
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purification and characterization of membrane bound peroxidases from Metroxylon sagu
Food Chemistry, 2004Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah BakarAbstract:Two membrane-bound peroxidases, mPOD-I and mPOD-II, have been isolated and purified from Metroxylon sagu, using a combination of temperature-induced phase partitioning, DEAE-Toyopearl 650M, CM-Toyopearl 650 M and gel filtration. The mPOD-I and mPOD-II had molecular mass of 51.2 and 43.8 kDa, respectively, as determined by SDS–PAGE. Both enzymes showed high efficiency of interaction with the substrates. The isoenzymes were highly inhibited by ascorbic acid, metabisulfite, l-cysteine and p-coumaric acid. The inhibition mode of action and inhibition rate constant (Ki) values for these inhibitors were determined. Their activities were highly enhanced by Al3+, Ca2+ and Fe3+ but they were moderately inhibited by Zn2+.
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latent polyphenol oxidases from sago log Metroxylon sagu partial purification activation and some properties
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah BakarAbstract:Latent polyphenol oxidase (LPPO), an enzyme responsible for the browning reaction of sago starches during processing and storage, was investigated. The enzyme was effectively extracted and partially purified from the pith using combinations of nonionic detergents. With Triton X-114 and a temperature-induced phase partitioning method, the enzyme showed a recovery of 70% and purification of 4.1-fold. Native PAGE analysis of the partially purified LPPO revealed three activity bands when stained with catechol and two bands with pyrogallol. The molecular masses of the enzymes were estimated by SDS−PAGE to be 37, 45, and 53 kDa. The enzyme showed optimum pH values of 4.5 with 4-methylcatechol as a substrate and 7.5 with pyrogallol. The LPPO was highly reactive toward diphenols and triphenols. The activity of the enzyme was greatly enhanced in the presence of trypsin, SDS, ethanol, and linoleic acid. Keywords: Metroxylon sagu; pith; latent polyphenol oxidase; extraction; partial purification; characterization
Galila Hassan Onsa - One of the best experts on this subject based on the ideXlab platform.
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analysis of thermal inactivation kinetics of membrane bound polyphenol oxidases and peroxidases from Metroxylon sagu
Journal of Food Biochemistry, 2011Co-Authors: Galila Hassan Onsa, Jinap Selamat, Jamilah Bakar, Azizah Abdulhamid, Mohd Yazid Abd Manap, Nazamid SaariAbstract:Thermal inactivation kinetics for the purified membrane-bound polyphenol oxidases (mPPOs) and peroxidases (mPODs) isolated from Metroxylon sagu were analyzed. Each isoenzyme was treated at different time-temperature combinations in the range of 0-70min and 20-70C. Thermal inactivation rates constant (k) at 70C for mPOD-I (72.9×10 -3/min) and mPOD-II (97.9×10 -3/min) were lower than that of mPPO-I (379.7×10 -3/min) and mPPO-II (138.1×10 -3/min). The activation energy for inactivation of mPPO-I (32.94kcal/mol) and mPPO-II (40.34kcal/mol) was lower compared with mPOD-I (45.77kcal/mol) and mPOD-II (40.62kcal/mol). The enthalpy values for mPOD-I (45.08kcal/mol) and mPOD-II (39.94kcal/mol) were higher than those of mPPOs (mPPO-I, 32.26kcal/mol; mPPO-II, 39.66kcal/mol). This result implies that both mPOD-I and mPOD-II are more thermostable.
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ANALYSIS OF THERMAL INACTIVATION KINETICS OF MEMBRANE‐BOUND POLYPHENOL OXIDASES AND PEROXIDASES FROM Metroxylon SAGU
Journal of Food Biochemistry, 2011Co-Authors: Galila Hassan Onsa, Jinap Selamat, Jamilah Bakar, Mohd Yazid Abd Manap, Azizah Abdul-hamid, Nazamid SaariAbstract:Thermal inactivation kinetics for the purified membrane-bound polyphenol oxidases (mPPOs) and peroxidases (mPODs) isolated from Metroxylon sagu were analyzed. Each isoenzyme was treated at different time-temperature combinations in the range of 0-70min and 20-70C. Thermal inactivation rates constant (k) at 70C for mPOD-I (72.9×10 -3/min) and mPOD-II (97.9×10 -3/min) were lower than that of mPPO-I (379.7×10 -3/min) and mPPO-II (138.1×10 -3/min). The activation energy for inactivation of mPPO-I (32.94kcal/mol) and mPPO-II (40.34kcal/mol) was lower compared with mPOD-I (45.77kcal/mol) and mPOD-II (40.62kcal/mol). The enthalpy values for mPOD-I (45.08kcal/mol) and mPOD-II (39.94kcal/mol) were higher than those of mPPOs (mPPO-I, 32.26kcal/mol; mPPO-II, 39.66kcal/mol). This result implies that both mPOD-I and mPOD-II are more thermostable.
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histochemical localization of polyphenol oxidase and peroxidase from Metroxylon sagu
2007Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah Bakar, Abdulkarim Sabo Mohammed, Shamsul BahriAbstract:Polyphenol oxidase (PPO) and peroxidase (POD) activities were visualized histochemically at the cellular level of a young and a mature tree of Metroxylon sagu employing histochemical technique. In the mature tree, intense PPO activity was observed in the cell wall of the parenchyma and xylem cells when visualized under light microscope. Pith collected from the young tree showed PPO activity in the amyloplast and mitochondria inner membrane and to some extent in the golgi complex and endoplasmic reticulum. Whereas, a positive POD reaction product was visualized in the cell wall, peroxisomes and to some extent in the cytoplasm and the vacuole. The localization of PPO activity in the amyloplast and being adsorbed by the starch granules is in line with the general view that enzyme is involved in the browning of sago starch.
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purification and characterization of membrane bound peroxidases from Metroxylon sagu
Food Chemistry, 2004Co-Authors: Galila Hassan Onsa, Nazamid Saari, Jinap Selamat, Jamilah BakarAbstract:Two membrane-bound peroxidases, mPOD-I and mPOD-II, have been isolated and purified from Metroxylon sagu, using a combination of temperature-induced phase partitioning, DEAE-Toyopearl 650M, CM-Toyopearl 650 M and gel filtration. The mPOD-I and mPOD-II had molecular mass of 51.2 and 43.8 kDa, respectively, as determined by SDS–PAGE. Both enzymes showed high efficiency of interaction with the substrates. The isoenzymes were highly inhibited by ascorbic acid, metabisulfite, l-cysteine and p-coumaric acid. The inhibition mode of action and inhibition rate constant (Ki) values for these inhibitors were determined. Their activities were highly enhanced by Al3+, Ca2+ and Fe3+ but they were moderately inhibited by Zn2+.
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Membrane-bound polyphenol oxidases and peroxidases from Metroxylon sagu: Changes in activity and isoenzyme profiles during maturation
2003Co-Authors: Galila Hassan Onsa, Azizah Osman, Shamsul BahriAbstract:Membrane-bound polyphenol oxidases (mPPO: E.C.1.10.3.2) and peroxidases (mPOD: E.C.1.11.1.7) were isolated from membrane-fractions of Metroxylon sagu employing temperature-induced phase partitioning technique using Triton X-114. The specific activities in unit activity / mg protein and their isoenzyme profile were studied during maturation. The stages of maturity are the young stage (1-2 years old), pre-mature (6-8 years old) and mature stage (9-12 years old). The highest mPPO specific activity was observed at the top log section of young stage and then decreased by 3.0 and 25-fold at premature and mature stage, respectively. On the other hand, mPOD activity was found to be constant at the early stages of maturity up to the premature stage. mPOD activity then increased by 1.5 and 2.9-fold at premature and matured stage respectively. High mPOD activity at mature stage was associated with the appearance of new isoenzymes as well as intensification of the existing one. A change in the polypeptides during maturation was also observed.