Subramani Sellappan | The University of Georgia (original) (raw)
Papers by Subramani Sellappan
Cyta - Journal of Food, 2010
Growing conditions appear to influence the nutritional composition of different types of fruit. G... more Growing conditions appear to influence the nutritional composition of different types of fruit. Grape contains a large amount of phenolic compounds in the skin, pulp, and seeds. In this research work, a comparison of the phenolic composition and antioxidant activity between red grapes (Vitis vinifera) var “Monastrell” obtained from organic and conventional cultures has been studied. The identification and quantification of phenolic compounds (anthocyanins, flavonols, and hidroxycinnamic acids) have been realized by high pressure liquid chromatography (HPLC) and analysis of antioxidant activity using the DPPH· radical. No differences were found in the total phenolic composition as well as in the antioxidant activity in both types of grapes (organic and conventional).Las condiciones de cultivo parecen influir en la composición nutricional de diferentes tipos de fruta. La uva contiene una gran cantidad de compuestos fenólicos en la piel, la pulpa y las semillas. En el presente trabajo se ha realizado la identificación y cuantificación de compuestos fenólicos (antocianos, derivados hidroxicinámicos y flavonoles) por cromatografía de alta presión (HPLC) y el análisis de la actividad antioxidante utilizando el radical DPPH· en uva tinta de la variedad Monastell obtenida por técnicas de cultivo ecológico y tradicional. No se han encontrado diferencias en la composición fenólica total en ambos tipos de uva (ecológica y tradicional), así como tampoco en la actividad antioxidante de las mismas.
Applied Biochemistry and Biotechnology, 1996
The stability of invertase was studied under various conditions, including at 75°C, in presence o... more The stability of invertase was studied under various conditions, including at 75°C, in presence of stabilizers (sorbitol and glycerol) at 75°C, and in the presence of denaturants (urea and trichloroacetic acid) at 37°C in reverse micelles. Stability of the invertase in reverse micelles was found to be improved over that of the enzyme in bulk aqueous solution. Sorbitol could enhance enzyme stability as it does in the bulk aqueous system. The stabilizing effect of glycerol was reduced in reverse micelles. The denaturation pattern of urea remains unaltered. However, the denaturation effect of trichloroacetic acid has been reduced in reverse micelles.
Applied Biochemistry and Biotechnology, 1997
α-amylase (3.2.1.1) was solubilized in reverse micelles formed by Triton X-100 in xylene. Althoug... more α-amylase (3.2.1.1) was solubilized in reverse micelles formed by Triton X-100 in xylene. Although the enzyme shows decrease in specific activity in reverse micellar medium, it possesses significantly high stability in comparison to bulk aqueous medium. Water/Surfactant ratio (Wo) was found to play a crucial role in both activity and stability of the enzyme. The optimum water/surfactant ratio for the catalytic function of an enzyme in reverse micelles is 36, while the enzyme is stable at Wo 12 for a considerably long period, and at Wo above 20 the enzyme gets inactivated within a day. Glycerol and CaCl2 improve the stability in both aqueous and reverse micellar medium. Thus the interior of the reverse micelles acts as a microreactor and provides favorable environment for the enzyme activity and stability.
Process Biochemistry, 2000
Amyloglucosidase (EC 3.2. 1.3) was entrapped into reverse micelles of Triton X-100xylenehexanol... more Amyloglucosidase (EC 3.2. 1.3) was entrapped into reverse micelles of Triton X-100xylenehexanol. The observed activity in reverse micelles was influenced by the water content. Activity was studied at different watersurfactant ratios (Wo) and pH. The effects of Wo, ...
Journal of Food Lipids, 2002
The effect of acetone on structured lipid synthesis by Lipozyme IM60 in n-hexane was studied. Tra... more The effect of acetone on structured lipid synthesis by Lipozyme IM60 in n-hexane was studied. Transesterification of tristearin with capric, lauric, myristic, palmitic and oleic acids was performed individually and in combinations at equal mole ratios. Higher incorporation of oleic acid was observed with the addition of acetone when compared to other fatty acids. Incorporation of capric acid decreased with increase in acetone concentration. The overall activity of enzyme decreased in acetone compared to n-hexane.
Journal of Agricultural and Food Chemistry, 2002
Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia,... more Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia, Georgia, were analyzed for flavonoid content. A high-performance liquid chromatographic (HPLC) method with photodiode array detection was used for quantification. Compounds were analyzed as aglycons after acid hydrolysis with 1.2 M HCl. Identification of each compound was based on comparison of its retention time and UV spectra with those of pure commercial standards. Three major flavonoids, kaempferol, myricetin, and quercetin, were identified and quantified. Quercetin was the major flavonoid (7.70-46.32 mg/100 g fresh weight, FW) present in all varieties, followed by myricetin (2.77-4.13 mg/100 g FW). Minor quantities of kaempferol (1.10-1.98 mg/100 g FW) were also detected. The total polyphenols and Trolox equivalent antioxidant capacity (TEAC) ranged from 73.33 to 180.84 mg/100 g FW and 0.92-1.56 microM TEAC/g FW, respectively. A positive but weaker correlation was obtained for total polyphenols versus antioxidant capacity. Nevertheless, a stronger correlation (r(2) = 0.34) was obtained between flavonoid content versus antioxidant capacity. The data indicate that Vidalia onions are a rich source of quercetin, and they also contain myricetin and kaempferol.
Journal of Agricultural and Food Chemistry, 2003
Fruits of 10 cultivars of muscadine grapes (five bronze skin and five purple skin) grown in south... more Fruits of 10 cultivars of muscadine grapes (five bronze skin and five purple skin) grown in southern Georgia were separated into skin, seed, and pulp. Each fruit part and the leaves from the corresponding varieties were extracted for HPLC analysis of major phenolics. Total phenolics were determined colorimetrically using Folin-Ciocalteu reagent. Total anthocyanins were determined according to a pH-differential method, using a UV-visible spectrophotometer. Antioxidant capacity was determined by the Trolox equivalent antioxidant capacity (TEAC) assay. Gallic acid, (+)-catechin, and epicatechin were the major phenolics in seeds, with average values of 6.9, 558.4, and 1299.4 mg/100 g of fresh weight (FW), respectively. In the skins, ellagic acid, myricetin, quercetin, kaempferol, and trans-resveratrol were the major phenolics, with respective average values of 16.5, 8.4, 1.8, 0.6, and 0.1 mg/100 g of FW. Contrary to previous results, ellagic acid and not resveratrol was the major phenolic in muscadine grapes. The HPLC solvent system used coupled with fluorescence detection allowed separation of ellagic acid from resveratrol and detection of resveratrol. Reported here for the first time are the phenolic content and antioxidant capacity of muscadine leaves. Major phenolics in muscadine leaves were myricetin, ellagic acid, kaempferol, quercetin, and gallic acid, with average concentrations of 157.6, 66.7, 8.9, 9.8, and 8.6, respectively. Average total phenolics were 2178.8, 374.6, 23.8, and 351.6 mg/g gallic acid equivalent in seed, skin, pulp, and leaves, respectively. Total anthocyanin contents were 2.1 and 132.1 mg/100 g of FW in the skins of bronze and purple grapes, respectively, and 4.3 and 4.6 mg/100 g of FW in seeds and pulps, in that order. Antioxidant capacity values were, on average, 2.4, 12.8, 281.3, and 236.1 microM TEAC/g of FW for pulps, skins, seeds, and leaves, respectively.
Journal of Agricultural and Food Chemistry, 2005
Total phenolics, ascorbic acid, and betalain contents of differently colored cactus pear clones (... more Total phenolics, ascorbic acid, and betalain contents of differently colored cactus pear clones (nine Opuntia ficus-indica [L.] Mill. clones and one O. robusta Wendl. clone) were investigated and related to their respective antioxidant potential assessed by Trolox-equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) assays. TEAC and ORAC values were very highly correlated with each other and also with values for total phenolics, betalain contents, and ascorbic acid concentrations. Total phenolics had the greatest contribution to ORAC and TEAC values. Highperformance liquid chromatography (HPLC)-diode array detector (DAD)-tandem mass spectrometry (MS/MS) measurements of cactus pear juices permitted the differentiation of the clones based on variations in pigment patterns and betalain concentrations. The red and yellow betalains were absent in lime green colored cactus fruits. The ratio and concentration of these pigments were responsible for the yellow, orange, red, and purple colors in the other clones. Progeny of purple and lime green colored parents were characterized by 12% and 88% of plants bearing lime green and purple fruit, respectively. This implies that the genes for betalain production were lacking in the lime green fruits but could be provided by a parent with a complete set of genes, that is, purple fruits. Besides known pigments typical of Cactaceae, two unexpected betalains were identified. Whereas gomphrenin I was found for the first time in tissues of cactus plants, methionine-betaxanthin has never been described before as a genuine betalain. In addition to their alleged health-promoting properties, various combinations of yellow betaxanthins and red-purple betacyanins may allow the development of new food products without using artificial colorants.
Journal of The American Oil Chemists Society, 2000
Triacylglycerols with potential for coating application were prepared by acidolysis of tristearin... more Triacylglycerols with potential for coating application were prepared by acidolysis of tristearin with lauric and oleic acids using Lipozyme IM60 lipase in n-hexane. The effects of reaction parameters such as time, temperature, substrate mole ratio, water content, enzyme load, and enzyme reuse were studied. Five-gram scale synthesis was carried out to obtain the melting profile of products by differential scanning calorimetry (DSC). An acceptable melting profile was obtained for the product obtained with a 1∶4∶1 (tristearin/lauric acid/oleic acid) mole ratio of reactants. The DSC melting peak for this product was 31.4°C. Synthesis of 1200 g of this product was carried out at a 1∶4∶1 substrate ratio in a stirred tank batch reactor under optimal conditions. The reaction product, purified by short-path distillation, was coated onto crackers and studied for its moisture inhibition ability, under water vapor-saturated atmosphere, in a desiccator over different time intervals. The effectiveness of the synthesized lipid as a coating material was compared against uncoated crackers as a control and with cocoa butter-coated crackers. The synthesized lipid was better in preventing moisture absorption than cocoa butter.
Journal of Agricultural and Food Chemistry, 2002
Phenolic compounds and antioxidant activities of four mango varieties cultivated in Brazil were a... more Phenolic compounds and antioxidant activities of four mango varieties cultivated in Brazil were analyzed. The profile of flavonol-Oglycosides and xanthone-C-glycosides was characterized in pulps from Haden, Tommy Atkins, Palmer, and Ubá cultivars and in the agro-industrial residues from Ubá variety by LC-ESI-MS analysis. The first three varieties were collected from conventional production, whereas Ubá was obtained from organic production. The total phenolic content of the peels and seed kernel extracts was analyzed utilizing Folin-Ciocalteu's reagent. The aqueous-methanolic extracts of pulp, peel and seed kernels were analyzed for antioxidant activity (AA) by free radical-scavenging and reducing power. A total of 12 flavonoids and xanthones were identified in the pulps, peels and seed kernels, with larger amounts of these compounds being present in the organically grown Ubá variety. The Ubá mango pulp presented higher AA and the peel and seed kernel extracts showed higher AA than did a commercial standard.
Journal of Agricultural and Food Chemistry, 2001
Structured lipids (SL) containing caprylic, stearic, and linoleic acids were synthesized by enzym... more Structured lipids (SL) containing caprylic, stearic, and linoleic acids were synthesized by enzymatic transesterification using Lipozyme IM60. Pure trilinolein and free fatty acids were used as substrates. Incorporation of stearic acid was higher than that of caprylic acid in all parameters. Highest incorporations of both acids were achieved at 32 h, mole ratio of 1:4:4 (trilinolein/caprylic/stearic acids), water content of 1% (wt %), temperature of 55 degrees C, and 10% (wt %) enzyme load. The maximal incorporations of caprylic and stearic acids were 23.73 and 62.46 mol %, respectively. Reaction time, water content, and enzyme load had major influences on the reaction, whereas substrate mole ratio and temperature showed less influence. Lipozyme showed good stability over six reuses. Differential scanning calorimetric analysis of SL gave a melting profile with a very low melting peak of 0-3.3 degrees C and a solid fat content of 25.21% at 0 degrees C. The melting profile and solid fat content of SL were compared with those of fats extracted from commercially available solid and liquid margarine products. The data suggest that enzymatically produced SL could be used in liquid margarine products.
Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of... more Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of esters formed from glycerol and long-chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. The many applications of lipases include speciality organic syntheses, hydrolysis of fats and oils, modification of fats, flavor enhancement in food processing, resolution of racemic mixtures, and chemical analyses. This article discusses the production, recovery, and use of microbial lipases. Issues of enzyme kinetics, thermostability, and bioactivity are addressed. Production of recombinant lipases is detailed. Immobilized preparations of lipases are discussed. In view of the increasing understanding of lipases and their many applications in high-value syntheses and as bulk enzymes, these enzymes are having an increasing impact on bioprocessing. D
Cyta - Journal of Food, 2010
Growing conditions appear to influence the nutritional composition of different types of fruit. G... more Growing conditions appear to influence the nutritional composition of different types of fruit. Grape contains a large amount of phenolic compounds in the skin, pulp, and seeds. In this research work, a comparison of the phenolic composition and antioxidant activity between red grapes (Vitis vinifera) var “Monastrell” obtained from organic and conventional cultures has been studied. The identification and quantification of phenolic compounds (anthocyanins, flavonols, and hidroxycinnamic acids) have been realized by high pressure liquid chromatography (HPLC) and analysis of antioxidant activity using the DPPH· radical. No differences were found in the total phenolic composition as well as in the antioxidant activity in both types of grapes (organic and conventional).Las condiciones de cultivo parecen influir en la composición nutricional de diferentes tipos de fruta. La uva contiene una gran cantidad de compuestos fenólicos en la piel, la pulpa y las semillas. En el presente trabajo se ha realizado la identificación y cuantificación de compuestos fenólicos (antocianos, derivados hidroxicinámicos y flavonoles) por cromatografía de alta presión (HPLC) y el análisis de la actividad antioxidante utilizando el radical DPPH· en uva tinta de la variedad Monastell obtenida por técnicas de cultivo ecológico y tradicional. No se han encontrado diferencias en la composición fenólica total en ambos tipos de uva (ecológica y tradicional), así como tampoco en la actividad antioxidante de las mismas.
Applied Biochemistry and Biotechnology, 1996
The stability of invertase was studied under various conditions, including at 75°C, in presence o... more The stability of invertase was studied under various conditions, including at 75°C, in presence of stabilizers (sorbitol and glycerol) at 75°C, and in the presence of denaturants (urea and trichloroacetic acid) at 37°C in reverse micelles. Stability of the invertase in reverse micelles was found to be improved over that of the enzyme in bulk aqueous solution. Sorbitol could enhance enzyme stability as it does in the bulk aqueous system. The stabilizing effect of glycerol was reduced in reverse micelles. The denaturation pattern of urea remains unaltered. However, the denaturation effect of trichloroacetic acid has been reduced in reverse micelles.
Applied Biochemistry and Biotechnology, 1997
α-amylase (3.2.1.1) was solubilized in reverse micelles formed by Triton X-100 in xylene. Althoug... more α-amylase (3.2.1.1) was solubilized in reverse micelles formed by Triton X-100 in xylene. Although the enzyme shows decrease in specific activity in reverse micellar medium, it possesses significantly high stability in comparison to bulk aqueous medium. Water/Surfactant ratio (Wo) was found to play a crucial role in both activity and stability of the enzyme. The optimum water/surfactant ratio for the catalytic function of an enzyme in reverse micelles is 36, while the enzyme is stable at Wo 12 for a considerably long period, and at Wo above 20 the enzyme gets inactivated within a day. Glycerol and CaCl2 improve the stability in both aqueous and reverse micellar medium. Thus the interior of the reverse micelles acts as a microreactor and provides favorable environment for the enzyme activity and stability.
Process Biochemistry, 2000
Amyloglucosidase (EC 3.2. 1.3) was entrapped into reverse micelles of Triton X-100xylenehexanol... more Amyloglucosidase (EC 3.2. 1.3) was entrapped into reverse micelles of Triton X-100xylenehexanol. The observed activity in reverse micelles was influenced by the water content. Activity was studied at different watersurfactant ratios (Wo) and pH. The effects of Wo, ...
Journal of Food Lipids, 2002
The effect of acetone on structured lipid synthesis by Lipozyme IM60 in n-hexane was studied. Tra... more The effect of acetone on structured lipid synthesis by Lipozyme IM60 in n-hexane was studied. Transesterification of tristearin with capric, lauric, myristic, palmitic and oleic acids was performed individually and in combinations at equal mole ratios. Higher incorporation of oleic acid was observed with the addition of acetone when compared to other fatty acids. Incorporation of capric acid decreased with increase in acetone concentration. The overall activity of enzyme decreased in acetone compared to n-hexane.
Journal of Agricultural and Food Chemistry, 2002
Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia,... more Vidalia onion varieties Nirvana, DPS 1032, Yellow 2025, King-Midas, and SBO 133 grown at Vidalia, Georgia, were analyzed for flavonoid content. A high-performance liquid chromatographic (HPLC) method with photodiode array detection was used for quantification. Compounds were analyzed as aglycons after acid hydrolysis with 1.2 M HCl. Identification of each compound was based on comparison of its retention time and UV spectra with those of pure commercial standards. Three major flavonoids, kaempferol, myricetin, and quercetin, were identified and quantified. Quercetin was the major flavonoid (7.70-46.32 mg/100 g fresh weight, FW) present in all varieties, followed by myricetin (2.77-4.13 mg/100 g FW). Minor quantities of kaempferol (1.10-1.98 mg/100 g FW) were also detected. The total polyphenols and Trolox equivalent antioxidant capacity (TEAC) ranged from 73.33 to 180.84 mg/100 g FW and 0.92-1.56 microM TEAC/g FW, respectively. A positive but weaker correlation was obtained for total polyphenols versus antioxidant capacity. Nevertheless, a stronger correlation (r(2) = 0.34) was obtained between flavonoid content versus antioxidant capacity. The data indicate that Vidalia onions are a rich source of quercetin, and they also contain myricetin and kaempferol.
Journal of Agricultural and Food Chemistry, 2003
Fruits of 10 cultivars of muscadine grapes (five bronze skin and five purple skin) grown in south... more Fruits of 10 cultivars of muscadine grapes (five bronze skin and five purple skin) grown in southern Georgia were separated into skin, seed, and pulp. Each fruit part and the leaves from the corresponding varieties were extracted for HPLC analysis of major phenolics. Total phenolics were determined colorimetrically using Folin-Ciocalteu reagent. Total anthocyanins were determined according to a pH-differential method, using a UV-visible spectrophotometer. Antioxidant capacity was determined by the Trolox equivalent antioxidant capacity (TEAC) assay. Gallic acid, (+)-catechin, and epicatechin were the major phenolics in seeds, with average values of 6.9, 558.4, and 1299.4 mg/100 g of fresh weight (FW), respectively. In the skins, ellagic acid, myricetin, quercetin, kaempferol, and trans-resveratrol were the major phenolics, with respective average values of 16.5, 8.4, 1.8, 0.6, and 0.1 mg/100 g of FW. Contrary to previous results, ellagic acid and not resveratrol was the major phenolic in muscadine grapes. The HPLC solvent system used coupled with fluorescence detection allowed separation of ellagic acid from resveratrol and detection of resveratrol. Reported here for the first time are the phenolic content and antioxidant capacity of muscadine leaves. Major phenolics in muscadine leaves were myricetin, ellagic acid, kaempferol, quercetin, and gallic acid, with average concentrations of 157.6, 66.7, 8.9, 9.8, and 8.6, respectively. Average total phenolics were 2178.8, 374.6, 23.8, and 351.6 mg/g gallic acid equivalent in seed, skin, pulp, and leaves, respectively. Total anthocyanin contents were 2.1 and 132.1 mg/100 g of FW in the skins of bronze and purple grapes, respectively, and 4.3 and 4.6 mg/100 g of FW in seeds and pulps, in that order. Antioxidant capacity values were, on average, 2.4, 12.8, 281.3, and 236.1 microM TEAC/g of FW for pulps, skins, seeds, and leaves, respectively.
Journal of Agricultural and Food Chemistry, 2005
Total phenolics, ascorbic acid, and betalain contents of differently colored cactus pear clones (... more Total phenolics, ascorbic acid, and betalain contents of differently colored cactus pear clones (nine Opuntia ficus-indica [L.] Mill. clones and one O. robusta Wendl. clone) were investigated and related to their respective antioxidant potential assessed by Trolox-equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) assays. TEAC and ORAC values were very highly correlated with each other and also with values for total phenolics, betalain contents, and ascorbic acid concentrations. Total phenolics had the greatest contribution to ORAC and TEAC values. Highperformance liquid chromatography (HPLC)-diode array detector (DAD)-tandem mass spectrometry (MS/MS) measurements of cactus pear juices permitted the differentiation of the clones based on variations in pigment patterns and betalain concentrations. The red and yellow betalains were absent in lime green colored cactus fruits. The ratio and concentration of these pigments were responsible for the yellow, orange, red, and purple colors in the other clones. Progeny of purple and lime green colored parents were characterized by 12% and 88% of plants bearing lime green and purple fruit, respectively. This implies that the genes for betalain production were lacking in the lime green fruits but could be provided by a parent with a complete set of genes, that is, purple fruits. Besides known pigments typical of Cactaceae, two unexpected betalains were identified. Whereas gomphrenin I was found for the first time in tissues of cactus plants, methionine-betaxanthin has never been described before as a genuine betalain. In addition to their alleged health-promoting properties, various combinations of yellow betaxanthins and red-purple betacyanins may allow the development of new food products without using artificial colorants.
Journal of The American Oil Chemists Society, 2000
Triacylglycerols with potential for coating application were prepared by acidolysis of tristearin... more Triacylglycerols with potential for coating application were prepared by acidolysis of tristearin with lauric and oleic acids using Lipozyme IM60 lipase in n-hexane. The effects of reaction parameters such as time, temperature, substrate mole ratio, water content, enzyme load, and enzyme reuse were studied. Five-gram scale synthesis was carried out to obtain the melting profile of products by differential scanning calorimetry (DSC). An acceptable melting profile was obtained for the product obtained with a 1∶4∶1 (tristearin/lauric acid/oleic acid) mole ratio of reactants. The DSC melting peak for this product was 31.4°C. Synthesis of 1200 g of this product was carried out at a 1∶4∶1 substrate ratio in a stirred tank batch reactor under optimal conditions. The reaction product, purified by short-path distillation, was coated onto crackers and studied for its moisture inhibition ability, under water vapor-saturated atmosphere, in a desiccator over different time intervals. The effectiveness of the synthesized lipid as a coating material was compared against uncoated crackers as a control and with cocoa butter-coated crackers. The synthesized lipid was better in preventing moisture absorption than cocoa butter.
Journal of Agricultural and Food Chemistry, 2002
Phenolic compounds and antioxidant activities of four mango varieties cultivated in Brazil were a... more Phenolic compounds and antioxidant activities of four mango varieties cultivated in Brazil were analyzed. The profile of flavonol-Oglycosides and xanthone-C-glycosides was characterized in pulps from Haden, Tommy Atkins, Palmer, and Ubá cultivars and in the agro-industrial residues from Ubá variety by LC-ESI-MS analysis. The first three varieties were collected from conventional production, whereas Ubá was obtained from organic production. The total phenolic content of the peels and seed kernel extracts was analyzed utilizing Folin-Ciocalteu's reagent. The aqueous-methanolic extracts of pulp, peel and seed kernels were analyzed for antioxidant activity (AA) by free radical-scavenging and reducing power. A total of 12 flavonoids and xanthones were identified in the pulps, peels and seed kernels, with larger amounts of these compounds being present in the organically grown Ubá variety. The Ubá mango pulp presented higher AA and the peel and seed kernel extracts showed higher AA than did a commercial standard.
Journal of Agricultural and Food Chemistry, 2001
Structured lipids (SL) containing caprylic, stearic, and linoleic acids were synthesized by enzym... more Structured lipids (SL) containing caprylic, stearic, and linoleic acids were synthesized by enzymatic transesterification using Lipozyme IM60. Pure trilinolein and free fatty acids were used as substrates. Incorporation of stearic acid was higher than that of caprylic acid in all parameters. Highest incorporations of both acids were achieved at 32 h, mole ratio of 1:4:4 (trilinolein/caprylic/stearic acids), water content of 1% (wt %), temperature of 55 degrees C, and 10% (wt %) enzyme load. The maximal incorporations of caprylic and stearic acids were 23.73 and 62.46 mol %, respectively. Reaction time, water content, and enzyme load had major influences on the reaction, whereas substrate mole ratio and temperature showed less influence. Lipozyme showed good stability over six reuses. Differential scanning calorimetric analysis of SL gave a melting profile with a very low melting peak of 0-3.3 degrees C and a solid fat content of 25.21% at 0 degrees C. The melting profile and solid fat content of SL were compared with those of fats extracted from commercially available solid and liquid margarine products. The data suggest that enzymatically produced SL could be used in liquid margarine products.
Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of... more Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of esters formed from glycerol and long-chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. The many applications of lipases include speciality organic syntheses, hydrolysis of fats and oils, modification of fats, flavor enhancement in food processing, resolution of racemic mixtures, and chemical analyses. This article discusses the production, recovery, and use of microbial lipases. Issues of enzyme kinetics, thermostability, and bioactivity are addressed. Production of recombinant lipases is detailed. Immobilized preparations of lipases are discussed. In view of the increasing understanding of lipases and their many applications in high-value syntheses and as bulk enzymes, these enzymes are having an increasing impact on bioprocessing. D