H. Ghazali - Academia.edu (original) (raw)
Papers by H. Ghazali
ASEAN Food Journal
Solvent-extracted Moringa oleifera seed oil was transesterified using immobilized lipase (Lipozym... more Solvent-extracted Moringa oleifera seed oil was transesterified using immobilized lipase (Lipozyme IM 60) (Novozymes Bagsvaerd Denmark) at 1% (w/w) concentration, shaken at 60 o C and 200 rpm for up to 24h. After transesterification, the oil was fractionated with acetone at -18 o C and without acetone at 10 o C to obtain two fractions, stearin and olein fractions. Incubation of the transesterified oil at 10 o C for 24 h resulted in the formation of fat crystals, which settled at the bottom of the flask in sample transesterified for 24 h, while the control (0 h) sample became rather viscous with fat crystals in suspension. Transesterification resulted in a change in the triacylglycerol (TAG) profile of the oil, which in turn affected its solid fat content (SFC) and thermal behavior. The SFC value at 0 o C after 24 h of reaction was 10.35% and significantly (P
Food Chemistry, 2015
Ikan pekasam is a fermented fish product produced in Malaysia and is usually made from freshwater... more Ikan pekasam is a fermented fish product produced in Malaysia and is usually made from freshwater fish with ground roasted uncooked rice as the main source of carbohydrate. In this study, the amino acid, biogenic amine, and trans- and cis-urocanic acid (UCA) contents of fifteen commercial samples of Ikan pekasam made from Javanese carp and black tilapia, that had undergone either natural or acid-assisted fermentation, were quantified. The latter includes either tamarind (Tamarindus indica) pulp or dried slices of Garcinia atroviridis fruit in the fermentation process. Results showed that there are no significant differences in most of the biogenic amines including histamine, while there are significant differences in total UCA content, and trans- and cis-UCA contents between the two samples. Differences in the amino acid contents were largely fish-dependent.
SSRN Electronic Journal, 2000
Roasting of whole-kernels is an important step in the production of pistachio paste. The effect o... more Roasting of whole-kernels is an important step in the production of pistachio paste. The effect of hot air roasting temperatures (90-190°C) and times (5-65 min) on the hardness, moisture content and colour attributes ('L', 'a' and 'b' values and yellowness index) of both whole-kernel and ground-state were investigated using response surface methodology (RSM). Increases in roasting temperature and time caused a decrease in all the responses except for 'a' value of ground-state. The interaction and quadratic models sufficiently described the changes in the hardness and colour values, respectively. The result of RSM analysis showed that hardness and colour attributes ('L' and 'b' values, yellowness index) of kernels and 'a' value of ground-state could be used to monitor the roasting quality of whole-kernels. This study showed that the recommended range of roasting temperature and time of whole-kernel for the production of pistachio paste were 130-140°C and 30-40 min, respectively.
Journal of Agricultural Science, 2011
This review discusses the performance of existing dryers for pistachio drying process, which is a... more This review discusses the performance of existing dryers for pistachio drying process, which is available in the literature. It encompasses sun drying, solar dryer, bin dryer, vertical continuous dryer, funnel cylindrical dryer, vertical cylindrical dryer, continuous mobile and steady tray dryer, drum dryer and continuous belt conveyor dryer. The split nut and shell appearance of pistachio nuts are significantly influenced by the drying methods. The types of dryer used for drying pistachio nuts are critical to the final quality of the product. Although sun drying has a good effect on the final product quality, the negative climatic and environmental conditions must be considered. A combination of bin dryer and sun drying or combination of bin dryer and solar dryer, are recommended as effective drying techniques to prevent adverse quality effect on pistachio nut.
Journal of Food Lipids, 2001
The effect of different fat sources used in the preparation of ice cream emulsions was investigat... more The effect of different fat sources used in the preparation of ice cream emulsions was investigated. Anhydrous milk fat (AMF), a mixture of unmodified palm kernel olein (PKO) and AMF (70:30, w/w) mixture were used in the preparation of the emulsions. Transesterijication was catalyzed by mycelium-bound lipase from Rhizomucor rniehei. Rheological and viscoelastic properties measured were the creep compliance, controlled-stress steady state flow and frequency sweep profiles. Results indicate that emulsion prepared using transesterified PK0:AMF (TE-PKO:AMF} exhibited a different rheological behavior from that of AMF alone, and the unmodified PK0:AMF (70:30} blend. Frequency sweep projiles showed that the G = values of both AMF and TE-PK0:AMF emulsions were higher than their G at values, indicating that these emulsions were dominated by the elastic I Corresponding author; TEL: (603) 89486101 ext 3420; FAX: (603) 89423552; E-mail: hasanah@fsb.upm.edu .my Journal of Food Lipids 8 (2001) 131-146. All Righrs Reserved. Vopyright 2001 by Food & Nutrition Press, Inc.. Trumbull, Connecticut. 131 132 M.Y.B. LIEW ETAL. component over all frequencies measured. On the other hand, the PK0:AMF emulsion was dominated by viscous components at low frequency. A plot of viscosity versus log shear rate illustrated that the ice cream emulsion made from TE-PK0:AMF was more viscous than those of unmodified PK0:AMF and AMF. The lower creep compliance showed a stronger emulsion in the TE-PK0:AMF than that of the unmod9ed PK0:AMF. Since high viscosity and greater strength are some of the desired properties in ice cream emulsion, this suggests that transesterification of PK0:AMF (70:30, w/w) can be used to produce a fat that is suitable for use in the preparation of ice cream emulsions.
Journal of the American Oil Chemists’ Society, 1995
The enzymatic transesterification of palm olein was conducted in a low-moisture medium with nonsp... more The enzymatic transesterification of palm olein was conducted in a low-moisture medium with nonspecific and 1,3-specific lipases from microbial sources. The enzymes were first immobilized on Celite, ]yophilized for 4 h and then added to a reaction medium that consisted of 10% (wt/vo[) palm olein in water-saturated hexane. The catalytic performance of the enzymes was evaluated by determining the changes in triglyceride (TG) composition and concentrations by reverse-phase highperformance liquid chromatography (HPLC) and the formation of free fatty acids by titration. Studies with lipase from Candida rugosa showed that the degree of hydrolysis was reduced by drying the immobilized preparation and that the best drying time was 4 h. In all cases, the transesterification process resulted in the formation of PPP, a TG initially undetected in the oil, and increases in the concentrations of OOO (1.3-2.1-fold), OOL (1.7-4.5-fold), and OLL (1.7-4.3-fold), where P, O, and L are palmitic, oleic, and linoleic acids, respectively. SOS (where S is stearic acid), another TG not detected in the oil, was synthesized by Rhizomucor miehei and Pseudomonas lipases, with the latter producing more of this TG. There was a corresponding decrease in the concentrations of POP, PLP, POO, and POL. PPP concentration ranged from 1.9% (w/w) for Mucorjavanicus [ipase to 6.2% (w/w) for Pseudomonas lipase after 24 h. The greatest degree and fastest rate of change were caused by Pseudomonas lipase, followed by the enzymes from R. miehei and Aspergillus niger. The effects of transesterification and hydrolysis of palm olein by the various lipases resulted in changes in the overall degree of saturation of the triglyceride components. There seems to be no clear correlation between the enzyme positional specificity and the products formed. Possible mechanisms for the formation of PPP, OOL, OLL, OOO, and SOS are discussed. JAOCS 72, 633-639 (1995).
Journal of the American Oil Chemists' Society, 2002
The induction times for the crystallization, under isothermal conditions, of refined, bleached, a... more The induction times for the crystallization, under isothermal conditions, of refined, bleached, and deodorized palm oil from the melt were studied by viscometry. At temperatures below 295 K, the crystallization of palm oil was observed to occur in a two-stage process. This two-stage process was caused by the fractionation of palm oil, most probably into the stearin and olein fractions. At temperatures higher than 295 K, only a single-stage crystallization process was observed. As seen under polarized light microscopy, spherical crystals were initially formed from the first fraction at temperatures from 287 to 293 K. The diameters of these spherical crystals decreased as the temperature increased. After that, needle-shaped crystals were formed from the second fraction and continued to grow from the surface of these spherical crystals until the spherical crystals were fully enclosed, i.e., the cocrystallization of two polymorphs was observed. At temperatures higher than 293 K, the needleshaped crystals formed from a mixture of the two fractions were found to be the only polymorphs developed with the onset of crystallization. X-ray diffraction results showed that for temperatures below 295 K, the spherical crystals formed from the first fraction were in α form, whereas the needle-like crystals that nucleated later from the second fraction were in β′ form. β′ crystals were the only polymorphs formed for temperatures above 295 K. The results obtained were in good agreement with the discontinuity observed in the induction time vs. temperature curve. Activation free energies for nucleation were calculated according to the Fisher-Turnbull equation for the various polymorphic forms. Viscometry was observed to be a sensitive method for characterizing the overall crystallization process. This technique is suitable for induction time studies of palm oil crystallization, especially at lower temperatures and with viscous oil.
Journal of the American Oil Chemists' Society, 1997
Iodine value (IV) is used as a parameter in process control as well as a quality parameter in tra... more Iodine value (IV) is used as a parameter in process control as well as a quality parameter in traded palm oil products. IV measures the number of double bonds in the molecular structure of an oil. To form a double bond, carbon requires more energy (615 kJ/mol) than to form a single bond (350 kJ/mol). Therefore, the thermal behavior of an oil could reflect its iodine value. This study was conducted to demonstrate the use of a differential scanning calorimeter (DSC) to determine the IV of palm oil and its products as an attempt to reduce the use of chemicals in the analysis. The DSC thermograms of palm oil showed a clear separation of the substances that have low melting points (low-T), consisting of triunsaturated, monosaturated and disaturated triglycerides, from the high ones (high-T), consisting of trisaturated triglycerides. Regression analysis showed that the peak characteristics, namely, area and height of the low-T group and height of the high-T group in the heating thermogram and also the height of the high-T group in the cooling thermogram, can predict the IV of palm oil with R 2 higher than 0.99. This study concludes that DSC can be used to determine the IV of palm oil and its products. JAOCS 74, 939-942 (1997).
Journal of the American Oil Chemists’ Society, 1995
The composition of purified palm olein crystals formed at room temperature (25°C) was identified ... more The composition of purified palm olein crystals formed at room temperature (25°C) was identified in this study. Two peaks were obtained when the crystals were analyzed by reverse-phase high-performance liquid chromatography (RP-HPLC). The retention times of these peaks suggested that they were not triglycerides. Gas-liquid chromatography of fatty acid methyl ester analysis of the crystals showed the presence of C16, C18:0, and C18:1 fatty acids. Further analysis by gas-liquid chromatography of carbon number, after collecting the fractions from RP-HPLC, concluded that the major peak A was 1,3dipalmito-glycerol. The minor peak B was tentatively identified as 1-pa[mito-3-stearo-glycerol and/or 1-palmito-3-oleo-glycerol due to unavailability of respective standard glycerides. The differential scanning calorimetry thermogram of the crystals show that A and B were indeed the high melting glycerides, with melting and crystallization points of 70.4 and 53.8°C, respectively. JAOCS 72, 343-347 (1995).
Journal of The American Oil Chemists Society, 1998
The physical properties of Pseudomonas and Rhizomucor miehei lipase-catalyzed transesterified ble... more The physical properties of Pseudomonas and Rhizomucor miehei lipase-catalyzed transesterified blends of palm stearin:palm kernel olein (PS:PKO), ranging from 40% palm stearin to 80% palm stearin in 10% increments, were analyzed for their slip melting points (SMP), solid fat content (SFC), melting thermograms, and polymorphic forms. The Pseudomonas lipase caused a greater decrease in SMP (15°C) in the PS:PKO (40:60)
Experimental Mycology, 1980
N-Acetyl-d-glucosamine kinase (GlcNAc kinase, EC 2.7.1.59), the specific enzyme required for the ... more N-Acetyl-d-glucosamine kinase (GlcNAc kinase, EC 2.7.1.59), the specific enzyme required for the phosphorylation ofN-acetyl-d-glucosamine (GlcNAc) toN-acetylglucosamine 6-phosphate, was found to be an inducible enzyme inCandida albicans. The pattern of ...
Food Chemistry, 2005
The physico-chemical properties of oil from Moringa oleifera seed were determined following extra... more The physico-chemical properties of oil from Moringa oleifera seed were determined following extraction either with petroleum ether or 2% Neutrase 0.8L (a neutral bacterial protease from Bacillus amyloiquefaciens, Novozyme Bagsvaerd Denmark). The enzyme was chosen following a preliminary study conducted on the enzymatic extraction of M. oleifera seed oil using four commercial enzymes that showed Neutrase to be the best enzyme with the highest oil recovery value. The enzymes used were Termamyl 120L, Type L (a-Amylase), Neutrase Ò 0.8L (Neutral protease), Celluclast Ò 1.5 L FG (Cellulase) and Pectinex Ò Ultra SP-L (Pectinase), all from Novozyme, Denmark. The fatty acid compositions of solvent and enzyme-extracted oil from M. oleifera seed were determined. Results showed that the solvent-extracted oil has 67.9% oleic acid compared to 70.0% in enzyme-extracted oil. Results obtained following analysis of extracted oil showed that the oil is highly unsaturated because of the high percentage of oleic acid. Apart from oleic acid, other prominent fatty acids were palmitic (7.8% and 6.8%), stearic (7.6% and 6.5%), and behenic (6.2% and 5.8%) acids for solvent and enzyme-extracted oils, respectively. It was liquid at room temperature and pale-yellow in colour (0.7R + 5.9Y and 0.7R + 3.0Y for solvent and enzyme-extracted oils, respectively). Electronic nose analysis showed that it had flavor similar to that of peanut oil. The melting points estimated by differential scanning calorimetry were found to be 19.0 and 18.9°C for the solvent-and enzyme-extracted oils, respectively. The oil contains 36.7% triolein as the main triacylglycerol. The extraction methods were found to slightly influence the relative amounts of the fatty acids in the oil. The oils extracted using these two methods were found to differ in the percentage composition of their fatty acids. Quality attributes such as relative percent of oleic acid, total percentage of unsaturated fatty acids, iodine value, free fatty acid and unsaponifiable matter contents and the colour of the enzymeextracted oil were better than those of the solvent-extracted oil.
Food Chemistry, 1995
Purified papaya (Carica papaya L. var. exotica) pectinesterase (EC 3.1.1.11) was investigated for... more Purified papaya (Carica papaya L. var. exotica) pectinesterase (EC 3.1.1.11) was investigated for its activity as a function of NaCl, pH and temperature, and determination of its kinetic parameters. The activity was linear up to 20 min with an enzyme concentration of up to 6.14 pg. Optimum activity was obtained with 0.25 M NaCl concentration and the optimum pH was found to be 8. The energy of activation of enzyme was 5690 cal mol-'. A Q,, of 1.29 was observed in the temperature range of 30-50°C and the optimum temperature for the enzyme activity was 65°C. The K,,, value for citrus pectin was 0.11 mgml, corresponding to a V,, value of 730 ~mole/min/mg protein. The turnover number was calculated as 23360 mole/(mole.min). Enzyme activity was found to be inhibited by the addition of polygalacturonic acid, alginic acid and sucrose in the reaction mixture and their Ki values were calculated as 0.019 mgml, 0.17 mgml and 29%, respectively. Polygalacturonic acid was found to act as a competitive inhibitor whereas alginic acid and sucrose showed a competitive-non-competitive and uncompetitive type of inhibition, respectively.
Food Chemistry, 1991
Rehydration of dry black gram seeds activated metabolic processes that ca:used changes in the che... more Rehydration of dry black gram seeds activated metabolic processes that ca:used changes in the chemical composition and allowed growth of the seeds. Further changes were recorded when germination occurred and the components that were found to be affected were the protein, fat, vitamin C, toi!al carotenoM (provitamin A) and simple sugar (glucose, fructose and sucrose) contents. The protein and fat contents decreased following germination. Vitamin C content, on the other hand, increased significantly when seeds were soaked and allowed to germinate. Although higher in value than the dry seeds, the vitamin C content decreased after germination for 1 day. The total carotenoid content of dry seeds was higher than either the soaked seeds or the sprouts. Soaking caused a substantial loss in total carotenoid but the content slowly increased upon germination. Sucrose was the major simple sugar of dry seeds. Upon imbibition of water, glucose and fructose were completely lost. Germination led to an increase in the contents oJ all three sugars.
Food Chemistry, 1987
Polygalacturonase ( PGase ) was extracted and partially purified from ripe starfruit (Averrhoa ca... more Polygalacturonase ( PGase ) was extracted and partially purified from ripe starfruit (Averrhoa carambola, L.). 2.3-and 7.8-fold purifications were obtained following purification by Amicon ultrafiltration and Sephadex G-100 filtration, respectively. The apparent pH optimum of PGase in the Amicon concentrate and gel filtrate (combined fractions 6-8) was 5.2. Viscometric and reductometric analyses, on PGase in the gel filtrate and paper chromatographic analysis on the enzyme reaction mixture, were carried out to ascertain the mode of action. The results obtained indicated that exoPGase was the only PGase enzyme present in ripe starfruit.
Food Chemistry, 2007
The performance of the high-oleic Moringa oleifera seed oil (MoO) in deep-frying was evaluated by... more The performance of the high-oleic Moringa oleifera seed oil (MoO) in deep-frying was evaluated by comparing its frying stability with other conventional frying oils [canola (CLO), soybean (SBO), and palm olein (PO)]. The oils were used as a frying media to fry potato chips for 6 h a day up to a maximum of 5 days. Standard methods for the determination of used frying oil deterioration such as changes in color, viscosity, free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), iodine value (IV), specific extinction ðE p p % cm 233 and 269 nm) and total polar compounds (TPC) were used to evaluate the oils. At the end of the frying period, the change in percent FFA from the initial to final day of frying were as follows SBO (60.0%), PSO (65.0%), MoO (66.6%) and CLO (71.4%) and the change in p-AV and TOTOX value of MoO were found to be significantly lower (P < 0.05) than the rest of the oils tested, followed by PO, with the highest values obtained in CLO and SBO. The levels of conjugated dienes and trienes ðE p p % cm at 233 and 269 nm) throughout the frying period were lowest in MoO and PO followed CLO, with highest levels found in SBO. The rate of darkening and increase in viscosity were proportional to the frying time for all the oils. PO darkened earlier followed by CLO. At the end of frying period, TPC was significantly (P < 0.05) lower in MoO (20.78%) and PSO (21.23%), as compared to CLO (28.73%) and SBO (31.82%).
Food Chemistry, 2001
The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1:... more The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1: 1 by weight) blend was compared with its control (physical mixture or no enzyme added) and a commercial plastic frying shortening (CS). The samples were used as deep-...
Food Chemistry, 1995
Stability studies were carned out on the purilied papaya (Curiro pupqa L. var. UM~UI) pectincster... more Stability studies were carned out on the purilied papaya (Curiro pupqa L. var. UM~UI) pectincsterase (EC 3.1. I. I1 1. The enzyme preparation was stabk at 4'C in 0-02~ sodium phosphate butTer (pH 7.5) solution containing 0.2~ N&l and O-O% sodium azide and the loss in activity was less than 5% after storage (or I year. The thermoslability studia showed that enzyme was more heat-stable at pH 7-5 thao at pH 4. After heating al 60°C for 5 min. 65 6 and 82% activity still remained at pH 4 and pH 7-5. respectively. Ii war completely inactivated by heating for 5 mitt at 70 and 75°C al pH 4 and pH 7.5, respectively. The D values (time to inactivate W%, or the enzyme) at 55.60, 65 and 70°C at pH 4.0 were estimated 10 bo 112.14. 23.78.8.33 and I.71 min. respectively. Lower inactivalion rates were ohscrvcd for pH 7.5. whh lhe D values ranging from 143.27 to I.67 min for tcmper4tures between 60 and 7W. The 2 values, which indicate lhc rise in temperature necessary *o obarvc a IO-times faster rdte of heat-inaclivdtion. were estimated lo he 7%'C and S,38'C at pH 7.5 and pH 40. respectively. The inactivation energies and Qlo values were calculated as 256.9 W/m01 and 15.59 at pH 4.0 and 284.76 kllmol and 19.21 at pH 7 5. respectively. pH stability arudics showed that the enzyme was stable from pH Cl I abler exposure of ihe enzyme LO these pHs far 24 h at 3WC. More than 85% of the activity was retained in all of these casts. However. at pH I and 12. the enzyme was unstable
Food Chemistry, 2007
The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition o... more The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition of palm oil (PO), palm kernel oil (PKO) and their binary blends at 3:1, 1:1 and 1:3 (w/w) ratios, using both 1,3 specific Rhizomucor miehei, (Lipozyme™) and non-specific Pseudomonas sp. lipases were evaluated. IE of the native PO and PKO showed very distinct chemical composition changes. Catalysis of
Food Chemistry, 2000
The physical characteristics of a palm stearin:anhydrous milkfat (40:60) mixture, enzymatically t... more The physical characteristics of a palm stearin:anhydrous milkfat (40:60) mixture, enzymatically transesteri®ed in a solvent-free system, was investigated by monitoring changes in the slip melting point (SMP), solid fat content (SFC) and melting characteristics. The enzymes used were 1,3-speci®c lipases from Aspergillus niger, Rhizomucor miehei, Rhizopus javanicus, Rhizopus niveus, Alcaligenes sp. and non-speci®c lipases from Pseudomonas sp. and Candida rugosa. Results indicated that Pseudomonas lipase-catalyzed mixtures produced the highest degree of transesteri®cation (33.9%) and rate of transesteri®cation (50.0/h), followed by R. miehei lipase at 32.3% and 27.1/h. The highest % free fatty acid (FFA) liberated was also from the reaction mixture catalyzed by Pseudomonas (2.6 1%) lipase followed by Alcaligenes (2.56%) and R. miehei (2.88%) lipases. The SMP of all the transesteri®ed PS:AMF mixtures underwent only slight reductions, ranging from 0.5 to 2.5 C with reactions catalyzed by Pseudomonas and R. miehei lipases, producing the biggest drop in SMP values. #
ASEAN Food Journal
Solvent-extracted Moringa oleifera seed oil was transesterified using immobilized lipase (Lipozym... more Solvent-extracted Moringa oleifera seed oil was transesterified using immobilized lipase (Lipozyme IM 60) (Novozymes Bagsvaerd Denmark) at 1% (w/w) concentration, shaken at 60 o C and 200 rpm for up to 24h. After transesterification, the oil was fractionated with acetone at -18 o C and without acetone at 10 o C to obtain two fractions, stearin and olein fractions. Incubation of the transesterified oil at 10 o C for 24 h resulted in the formation of fat crystals, which settled at the bottom of the flask in sample transesterified for 24 h, while the control (0 h) sample became rather viscous with fat crystals in suspension. Transesterification resulted in a change in the triacylglycerol (TAG) profile of the oil, which in turn affected its solid fat content (SFC) and thermal behavior. The SFC value at 0 o C after 24 h of reaction was 10.35% and significantly (P
Food Chemistry, 2015
Ikan pekasam is a fermented fish product produced in Malaysia and is usually made from freshwater... more Ikan pekasam is a fermented fish product produced in Malaysia and is usually made from freshwater fish with ground roasted uncooked rice as the main source of carbohydrate. In this study, the amino acid, biogenic amine, and trans- and cis-urocanic acid (UCA) contents of fifteen commercial samples of Ikan pekasam made from Javanese carp and black tilapia, that had undergone either natural or acid-assisted fermentation, were quantified. The latter includes either tamarind (Tamarindus indica) pulp or dried slices of Garcinia atroviridis fruit in the fermentation process. Results showed that there are no significant differences in most of the biogenic amines including histamine, while there are significant differences in total UCA content, and trans- and cis-UCA contents between the two samples. Differences in the amino acid contents were largely fish-dependent.
SSRN Electronic Journal, 2000
Roasting of whole-kernels is an important step in the production of pistachio paste. The effect o... more Roasting of whole-kernels is an important step in the production of pistachio paste. The effect of hot air roasting temperatures (90-190°C) and times (5-65 min) on the hardness, moisture content and colour attributes ('L', 'a' and 'b' values and yellowness index) of both whole-kernel and ground-state were investigated using response surface methodology (RSM). Increases in roasting temperature and time caused a decrease in all the responses except for 'a' value of ground-state. The interaction and quadratic models sufficiently described the changes in the hardness and colour values, respectively. The result of RSM analysis showed that hardness and colour attributes ('L' and 'b' values, yellowness index) of kernels and 'a' value of ground-state could be used to monitor the roasting quality of whole-kernels. This study showed that the recommended range of roasting temperature and time of whole-kernel for the production of pistachio paste were 130-140°C and 30-40 min, respectively.
Journal of Agricultural Science, 2011
This review discusses the performance of existing dryers for pistachio drying process, which is a... more This review discusses the performance of existing dryers for pistachio drying process, which is available in the literature. It encompasses sun drying, solar dryer, bin dryer, vertical continuous dryer, funnel cylindrical dryer, vertical cylindrical dryer, continuous mobile and steady tray dryer, drum dryer and continuous belt conveyor dryer. The split nut and shell appearance of pistachio nuts are significantly influenced by the drying methods. The types of dryer used for drying pistachio nuts are critical to the final quality of the product. Although sun drying has a good effect on the final product quality, the negative climatic and environmental conditions must be considered. A combination of bin dryer and sun drying or combination of bin dryer and solar dryer, are recommended as effective drying techniques to prevent adverse quality effect on pistachio nut.
Journal of Food Lipids, 2001
The effect of different fat sources used in the preparation of ice cream emulsions was investigat... more The effect of different fat sources used in the preparation of ice cream emulsions was investigated. Anhydrous milk fat (AMF), a mixture of unmodified palm kernel olein (PKO) and AMF (70:30, w/w) mixture were used in the preparation of the emulsions. Transesterijication was catalyzed by mycelium-bound lipase from Rhizomucor rniehei. Rheological and viscoelastic properties measured were the creep compliance, controlled-stress steady state flow and frequency sweep profiles. Results indicate that emulsion prepared using transesterified PK0:AMF (TE-PKO:AMF} exhibited a different rheological behavior from that of AMF alone, and the unmodified PK0:AMF (70:30} blend. Frequency sweep projiles showed that the G = values of both AMF and TE-PK0:AMF emulsions were higher than their G at values, indicating that these emulsions were dominated by the elastic I Corresponding author; TEL: (603) 89486101 ext 3420; FAX: (603) 89423552; E-mail: hasanah@fsb.upm.edu .my Journal of Food Lipids 8 (2001) 131-146. All Righrs Reserved. Vopyright 2001 by Food & Nutrition Press, Inc.. Trumbull, Connecticut. 131 132 M.Y.B. LIEW ETAL. component over all frequencies measured. On the other hand, the PK0:AMF emulsion was dominated by viscous components at low frequency. A plot of viscosity versus log shear rate illustrated that the ice cream emulsion made from TE-PK0:AMF was more viscous than those of unmodified PK0:AMF and AMF. The lower creep compliance showed a stronger emulsion in the TE-PK0:AMF than that of the unmod9ed PK0:AMF. Since high viscosity and greater strength are some of the desired properties in ice cream emulsion, this suggests that transesterification of PK0:AMF (70:30, w/w) can be used to produce a fat that is suitable for use in the preparation of ice cream emulsions.
Journal of the American Oil Chemists’ Society, 1995
The enzymatic transesterification of palm olein was conducted in a low-moisture medium with nonsp... more The enzymatic transesterification of palm olein was conducted in a low-moisture medium with nonspecific and 1,3-specific lipases from microbial sources. The enzymes were first immobilized on Celite, ]yophilized for 4 h and then added to a reaction medium that consisted of 10% (wt/vo[) palm olein in water-saturated hexane. The catalytic performance of the enzymes was evaluated by determining the changes in triglyceride (TG) composition and concentrations by reverse-phase highperformance liquid chromatography (HPLC) and the formation of free fatty acids by titration. Studies with lipase from Candida rugosa showed that the degree of hydrolysis was reduced by drying the immobilized preparation and that the best drying time was 4 h. In all cases, the transesterification process resulted in the formation of PPP, a TG initially undetected in the oil, and increases in the concentrations of OOO (1.3-2.1-fold), OOL (1.7-4.5-fold), and OLL (1.7-4.3-fold), where P, O, and L are palmitic, oleic, and linoleic acids, respectively. SOS (where S is stearic acid), another TG not detected in the oil, was synthesized by Rhizomucor miehei and Pseudomonas lipases, with the latter producing more of this TG. There was a corresponding decrease in the concentrations of POP, PLP, POO, and POL. PPP concentration ranged from 1.9% (w/w) for Mucorjavanicus [ipase to 6.2% (w/w) for Pseudomonas lipase after 24 h. The greatest degree and fastest rate of change were caused by Pseudomonas lipase, followed by the enzymes from R. miehei and Aspergillus niger. The effects of transesterification and hydrolysis of palm olein by the various lipases resulted in changes in the overall degree of saturation of the triglyceride components. There seems to be no clear correlation between the enzyme positional specificity and the products formed. Possible mechanisms for the formation of PPP, OOL, OLL, OOO, and SOS are discussed. JAOCS 72, 633-639 (1995).
Journal of the American Oil Chemists' Society, 2002
The induction times for the crystallization, under isothermal conditions, of refined, bleached, a... more The induction times for the crystallization, under isothermal conditions, of refined, bleached, and deodorized palm oil from the melt were studied by viscometry. At temperatures below 295 K, the crystallization of palm oil was observed to occur in a two-stage process. This two-stage process was caused by the fractionation of palm oil, most probably into the stearin and olein fractions. At temperatures higher than 295 K, only a single-stage crystallization process was observed. As seen under polarized light microscopy, spherical crystals were initially formed from the first fraction at temperatures from 287 to 293 K. The diameters of these spherical crystals decreased as the temperature increased. After that, needle-shaped crystals were formed from the second fraction and continued to grow from the surface of these spherical crystals until the spherical crystals were fully enclosed, i.e., the cocrystallization of two polymorphs was observed. At temperatures higher than 293 K, the needleshaped crystals formed from a mixture of the two fractions were found to be the only polymorphs developed with the onset of crystallization. X-ray diffraction results showed that for temperatures below 295 K, the spherical crystals formed from the first fraction were in α form, whereas the needle-like crystals that nucleated later from the second fraction were in β′ form. β′ crystals were the only polymorphs formed for temperatures above 295 K. The results obtained were in good agreement with the discontinuity observed in the induction time vs. temperature curve. Activation free energies for nucleation were calculated according to the Fisher-Turnbull equation for the various polymorphic forms. Viscometry was observed to be a sensitive method for characterizing the overall crystallization process. This technique is suitable for induction time studies of palm oil crystallization, especially at lower temperatures and with viscous oil.
Journal of the American Oil Chemists' Society, 1997
Iodine value (IV) is used as a parameter in process control as well as a quality parameter in tra... more Iodine value (IV) is used as a parameter in process control as well as a quality parameter in traded palm oil products. IV measures the number of double bonds in the molecular structure of an oil. To form a double bond, carbon requires more energy (615 kJ/mol) than to form a single bond (350 kJ/mol). Therefore, the thermal behavior of an oil could reflect its iodine value. This study was conducted to demonstrate the use of a differential scanning calorimeter (DSC) to determine the IV of palm oil and its products as an attempt to reduce the use of chemicals in the analysis. The DSC thermograms of palm oil showed a clear separation of the substances that have low melting points (low-T), consisting of triunsaturated, monosaturated and disaturated triglycerides, from the high ones (high-T), consisting of trisaturated triglycerides. Regression analysis showed that the peak characteristics, namely, area and height of the low-T group and height of the high-T group in the heating thermogram and also the height of the high-T group in the cooling thermogram, can predict the IV of palm oil with R 2 higher than 0.99. This study concludes that DSC can be used to determine the IV of palm oil and its products. JAOCS 74, 939-942 (1997).
Journal of the American Oil Chemists’ Society, 1995
The composition of purified palm olein crystals formed at room temperature (25°C) was identified ... more The composition of purified palm olein crystals formed at room temperature (25°C) was identified in this study. Two peaks were obtained when the crystals were analyzed by reverse-phase high-performance liquid chromatography (RP-HPLC). The retention times of these peaks suggested that they were not triglycerides. Gas-liquid chromatography of fatty acid methyl ester analysis of the crystals showed the presence of C16, C18:0, and C18:1 fatty acids. Further analysis by gas-liquid chromatography of carbon number, after collecting the fractions from RP-HPLC, concluded that the major peak A was 1,3dipalmito-glycerol. The minor peak B was tentatively identified as 1-pa[mito-3-stearo-glycerol and/or 1-palmito-3-oleo-glycerol due to unavailability of respective standard glycerides. The differential scanning calorimetry thermogram of the crystals show that A and B were indeed the high melting glycerides, with melting and crystallization points of 70.4 and 53.8°C, respectively. JAOCS 72, 343-347 (1995).
Journal of The American Oil Chemists Society, 1998
The physical properties of Pseudomonas and Rhizomucor miehei lipase-catalyzed transesterified ble... more The physical properties of Pseudomonas and Rhizomucor miehei lipase-catalyzed transesterified blends of palm stearin:palm kernel olein (PS:PKO), ranging from 40% palm stearin to 80% palm stearin in 10% increments, were analyzed for their slip melting points (SMP), solid fat content (SFC), melting thermograms, and polymorphic forms. The Pseudomonas lipase caused a greater decrease in SMP (15°C) in the PS:PKO (40:60)
Experimental Mycology, 1980
N-Acetyl-d-glucosamine kinase (GlcNAc kinase, EC 2.7.1.59), the specific enzyme required for the ... more N-Acetyl-d-glucosamine kinase (GlcNAc kinase, EC 2.7.1.59), the specific enzyme required for the phosphorylation ofN-acetyl-d-glucosamine (GlcNAc) toN-acetylglucosamine 6-phosphate, was found to be an inducible enzyme inCandida albicans. The pattern of ...
Food Chemistry, 2005
The physico-chemical properties of oil from Moringa oleifera seed were determined following extra... more The physico-chemical properties of oil from Moringa oleifera seed were determined following extraction either with petroleum ether or 2% Neutrase 0.8L (a neutral bacterial protease from Bacillus amyloiquefaciens, Novozyme Bagsvaerd Denmark). The enzyme was chosen following a preliminary study conducted on the enzymatic extraction of M. oleifera seed oil using four commercial enzymes that showed Neutrase to be the best enzyme with the highest oil recovery value. The enzymes used were Termamyl 120L, Type L (a-Amylase), Neutrase Ò 0.8L (Neutral protease), Celluclast Ò 1.5 L FG (Cellulase) and Pectinex Ò Ultra SP-L (Pectinase), all from Novozyme, Denmark. The fatty acid compositions of solvent and enzyme-extracted oil from M. oleifera seed were determined. Results showed that the solvent-extracted oil has 67.9% oleic acid compared to 70.0% in enzyme-extracted oil. Results obtained following analysis of extracted oil showed that the oil is highly unsaturated because of the high percentage of oleic acid. Apart from oleic acid, other prominent fatty acids were palmitic (7.8% and 6.8%), stearic (7.6% and 6.5%), and behenic (6.2% and 5.8%) acids for solvent and enzyme-extracted oils, respectively. It was liquid at room temperature and pale-yellow in colour (0.7R + 5.9Y and 0.7R + 3.0Y for solvent and enzyme-extracted oils, respectively). Electronic nose analysis showed that it had flavor similar to that of peanut oil. The melting points estimated by differential scanning calorimetry were found to be 19.0 and 18.9°C for the solvent-and enzyme-extracted oils, respectively. The oil contains 36.7% triolein as the main triacylglycerol. The extraction methods were found to slightly influence the relative amounts of the fatty acids in the oil. The oils extracted using these two methods were found to differ in the percentage composition of their fatty acids. Quality attributes such as relative percent of oleic acid, total percentage of unsaturated fatty acids, iodine value, free fatty acid and unsaponifiable matter contents and the colour of the enzymeextracted oil were better than those of the solvent-extracted oil.
Food Chemistry, 1995
Purified papaya (Carica papaya L. var. exotica) pectinesterase (EC 3.1.1.11) was investigated for... more Purified papaya (Carica papaya L. var. exotica) pectinesterase (EC 3.1.1.11) was investigated for its activity as a function of NaCl, pH and temperature, and determination of its kinetic parameters. The activity was linear up to 20 min with an enzyme concentration of up to 6.14 pg. Optimum activity was obtained with 0.25 M NaCl concentration and the optimum pH was found to be 8. The energy of activation of enzyme was 5690 cal mol-'. A Q,, of 1.29 was observed in the temperature range of 30-50°C and the optimum temperature for the enzyme activity was 65°C. The K,,, value for citrus pectin was 0.11 mgml, corresponding to a V,, value of 730 ~mole/min/mg protein. The turnover number was calculated as 23360 mole/(mole.min). Enzyme activity was found to be inhibited by the addition of polygalacturonic acid, alginic acid and sucrose in the reaction mixture and their Ki values were calculated as 0.019 mgml, 0.17 mgml and 29%, respectively. Polygalacturonic acid was found to act as a competitive inhibitor whereas alginic acid and sucrose showed a competitive-non-competitive and uncompetitive type of inhibition, respectively.
Food Chemistry, 1991
Rehydration of dry black gram seeds activated metabolic processes that ca:used changes in the che... more Rehydration of dry black gram seeds activated metabolic processes that ca:used changes in the chemical composition and allowed growth of the seeds. Further changes were recorded when germination occurred and the components that were found to be affected were the protein, fat, vitamin C, toi!al carotenoM (provitamin A) and simple sugar (glucose, fructose and sucrose) contents. The protein and fat contents decreased following germination. Vitamin C content, on the other hand, increased significantly when seeds were soaked and allowed to germinate. Although higher in value than the dry seeds, the vitamin C content decreased after germination for 1 day. The total carotenoid content of dry seeds was higher than either the soaked seeds or the sprouts. Soaking caused a substantial loss in total carotenoid but the content slowly increased upon germination. Sucrose was the major simple sugar of dry seeds. Upon imbibition of water, glucose and fructose were completely lost. Germination led to an increase in the contents oJ all three sugars.
Food Chemistry, 1987
Polygalacturonase ( PGase ) was extracted and partially purified from ripe starfruit (Averrhoa ca... more Polygalacturonase ( PGase ) was extracted and partially purified from ripe starfruit (Averrhoa carambola, L.). 2.3-and 7.8-fold purifications were obtained following purification by Amicon ultrafiltration and Sephadex G-100 filtration, respectively. The apparent pH optimum of PGase in the Amicon concentrate and gel filtrate (combined fractions 6-8) was 5.2. Viscometric and reductometric analyses, on PGase in the gel filtrate and paper chromatographic analysis on the enzyme reaction mixture, were carried out to ascertain the mode of action. The results obtained indicated that exoPGase was the only PGase enzyme present in ripe starfruit.
Food Chemistry, 2007
The performance of the high-oleic Moringa oleifera seed oil (MoO) in deep-frying was evaluated by... more The performance of the high-oleic Moringa oleifera seed oil (MoO) in deep-frying was evaluated by comparing its frying stability with other conventional frying oils [canola (CLO), soybean (SBO), and palm olein (PO)]. The oils were used as a frying media to fry potato chips for 6 h a day up to a maximum of 5 days. Standard methods for the determination of used frying oil deterioration such as changes in color, viscosity, free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), iodine value (IV), specific extinction ðE p p % cm 233 and 269 nm) and total polar compounds (TPC) were used to evaluate the oils. At the end of the frying period, the change in percent FFA from the initial to final day of frying were as follows SBO (60.0%), PSO (65.0%), MoO (66.6%) and CLO (71.4%) and the change in p-AV and TOTOX value of MoO were found to be significantly lower (P < 0.05) than the rest of the oils tested, followed by PO, with the highest values obtained in CLO and SBO. The levels of conjugated dienes and trienes ðE p p % cm at 233 and 269 nm) throughout the frying period were lowest in MoO and PO followed CLO, with highest levels found in SBO. The rate of darkening and increase in viscosity were proportional to the frying time for all the oils. PO darkened earlier followed by CLO. At the end of frying period, TPC was significantly (P < 0.05) lower in MoO (20.78%) and PSO (21.23%), as compared to CLO (28.73%) and SBO (31.82%).
Food Chemistry, 2001
The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1:... more The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1: 1 by weight) blend was compared with its control (physical mixture or no enzyme added) and a commercial plastic frying shortening (CS). The samples were used as deep-...
Food Chemistry, 1995
Stability studies were carned out on the purilied papaya (Curiro pupqa L. var. UM~UI) pectincster... more Stability studies were carned out on the purilied papaya (Curiro pupqa L. var. UM~UI) pectincsterase (EC 3.1. I. I1 1. The enzyme preparation was stabk at 4'C in 0-02~ sodium phosphate butTer (pH 7.5) solution containing 0.2~ N&l and O-O% sodium azide and the loss in activity was less than 5% after storage (or I year. The thermoslability studia showed that enzyme was more heat-stable at pH 7-5 thao at pH 4. After heating al 60°C for 5 min. 65 6 and 82% activity still remained at pH 4 and pH 7-5. respectively. Ii war completely inactivated by heating for 5 mitt at 70 and 75°C al pH 4 and pH 7.5, respectively. The D values (time to inactivate W%, or the enzyme) at 55.60, 65 and 70°C at pH 4.0 were estimated 10 bo 112.14. 23.78.8.33 and I.71 min. respectively. Lower inactivalion rates were ohscrvcd for pH 7.5. whh lhe D values ranging from 143.27 to I.67 min for tcmper4tures between 60 and 7W. The 2 values, which indicate lhc rise in temperature necessary *o obarvc a IO-times faster rdte of heat-inaclivdtion. were estimated lo he 7%'C and S,38'C at pH 7.5 and pH 40. respectively. The inactivation energies and Qlo values were calculated as 256.9 W/m01 and 15.59 at pH 4.0 and 284.76 kllmol and 19.21 at pH 7 5. respectively. pH stability arudics showed that the enzyme was stable from pH Cl I abler exposure of ihe enzyme LO these pHs far 24 h at 3WC. More than 85% of the activity was retained in all of these casts. However. at pH I and 12. the enzyme was unstable
Food Chemistry, 2007
The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition o... more The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition of palm oil (PO), palm kernel oil (PKO) and their binary blends at 3:1, 1:1 and 1:3 (w/w) ratios, using both 1,3 specific Rhizomucor miehei, (Lipozyme™) and non-specific Pseudomonas sp. lipases were evaluated. IE of the native PO and PKO showed very distinct chemical composition changes. Catalysis of
Food Chemistry, 2000
The physical characteristics of a palm stearin:anhydrous milkfat (40:60) mixture, enzymatically t... more The physical characteristics of a palm stearin:anhydrous milkfat (40:60) mixture, enzymatically transesteri®ed in a solvent-free system, was investigated by monitoring changes in the slip melting point (SMP), solid fat content (SFC) and melting characteristics. The enzymes used were 1,3-speci®c lipases from Aspergillus niger, Rhizomucor miehei, Rhizopus javanicus, Rhizopus niveus, Alcaligenes sp. and non-speci®c lipases from Pseudomonas sp. and Candida rugosa. Results indicated that Pseudomonas lipase-catalyzed mixtures produced the highest degree of transesteri®cation (33.9%) and rate of transesteri®cation (50.0/h), followed by R. miehei lipase at 32.3% and 27.1/h. The highest % free fatty acid (FFA) liberated was also from the reaction mixture catalyzed by Pseudomonas (2.6 1%) lipase followed by Alcaligenes (2.56%) and R. miehei (2.88%) lipases. The SMP of all the transesteri®ed PS:AMF mixtures underwent only slight reductions, ranging from 0.5 to 2.5 C with reactions catalyzed by Pseudomonas and R. miehei lipases, producing the biggest drop in SMP values. #