The utilisation of β-carotene in food and beverage products is limited due to their poor water so... more The utilisation of β-carotene in food and beverage products is limited due to their poor water solubility, chemical instability and low bioavailability. Microemulsions are of particular interest as colloidal delivery systems because of the possibility of enhancing the solubility and improving the bioavailability of hydrophobic compounds. However, these systems have not been widely used in the food industry because of the difficulties in their formulation using edible oils and surfactants. The purpose of this study was to compare the pseudo-ternary phase diagram of β-carotene microemulsion prepared using long chain length fatty acids (vegetable oils) and medium chain length fatty acids (Caprylic/Capric triglyceride). The solubility of β-carotene was measured by reversed-phase liquid chromatography (HPLC). The solubility of β-carotene in long chain triglycerides was higher than medium chain triglyceride. Among Tweens that were screened, Tween 80 exhibited the highest solubilizing pote...
The aim of this study was to gain an in-depth understanding of the effect of pulsed electric fiel... more The aim of this study was to gain an in-depth understanding of the effect of pulsed electric fields (PEF) on the microstructure of potato tubers. The effect of peeling prior to PEF was also studied. Whole potato tubers were subjected to PEF at a constant frequency of 50 Hz, over a range of electric field strengths (0.2 to 1.1 kV/cm) and energy levels (1 to 10 kJ/kg). To determine the uniformity of the PEF effect across the potato tuber, cell viability was assessed using tetrazolium salt staining. To evaluate the effectiveness of PEF processing the leakage of ionic species from the tubers was measured using atomic absorption spectrophotometry and FESEM-EDS analysis. In addition the influence of PEF on cell disruption and microstructural damage was assessed using scanning electron microscopy (Cryo-SEM). As the electric field strength and energy increased potassium ion leakage and electrical conductivity of the medium increased. The orientation of the tuber towards the electrodes and the presence of the skin greatly affected the impact of PEF on cell disruption and viability. At electric field strengths of 0.3 kV/cm and above, potato cells located in the pith (inner medulla) showed more damage and had a higher proportion of cell death compared to cells located in the outer medulla. This is the first study to provide visual evidence that the application of electric fields to solid, living foods, such as potato tubers, results in an uneven distribution of cell damage and death owing to the presence of vascular bundles and cells that vary in their resistance to electric fields.
The objective of this study was to evaluate the cytotoxicity of microemulsions prepared from glyc... more The objective of this study was to evaluate the cytotoxicity of microemulsions prepared from glycerol monocaprylocaprate (Capmul MCM), non-ionic surfactant (Tween 80), and phosphate buffer loaded with β-carotene extracted from carrot pomace, to human intestinal epithelial (Caco-2) cells and to determine if non-cytotoxic concentrations of the natural β-carotene loaded microemulsion could protect Caco-2 cells from oxidative damage caused by exposure to H2O2. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and lactate dehydrogenase assays were used to determine mitochondria functionality and cell membrane integrity, respectively, both of which are commonly used to evaluate cell viability. In addition nitride oxide level was measured as a general indicator of cellular disruption and inflammation. Cytotoxicity of the formulations significantly decreased when lowering the microemulsion concentration. Increasing the cytotoxicity of microemulsions at concentrations higher than 0.0313% (Tween 80 concentration of 0.006%) might be the result of Tween 80 precipitation on the cell culture monolayer, and β-carotene loaded in the microemulsion did not appear to protect cells from Tween 80 associated damage. However, a β-carotene loaded microemulsion concentration of 0.0313% gave bioprotection to cells suffering oxidative damage caused by H2O2. These results show the potential of using natural β-carotene microemulsion as a delivery system at a safe level of Tween 80 for application in pharmaceutical and food sciences.
The impact of oil type and fatty acid chain length on the development of food-grade microemulsion... more The impact of oil type and fatty acid chain length on the development of food-grade microemulsions for the entrapment of β-carotene was investigated. The microemulsion region of a ternary phase diagram containing short chain monoglycerides was larger than for di- and triglycerides when Tween 80 was used as surfactant. The cytotoxicity of microemulsions composed of a 30% monoglyceride oil, 20% Tween 80 and 50% aqueous buffer were evaluated using an in vitro cell culture model (human epithelial colorectal adenocarcinoma, Caco-2). The cytotoxicity test showed that the viability of Caco-2 cells against β-carotene microemulsions at concentrations of 0.03125% (v/v) was higher than 90%. This study suggests that short chain monoglycerides could be used with Tween 80 to prepare transparent β-carotene-encapsulated O/W microemulsions in the particle size range of 12-100 nm.
International Journal of Food Science & Technology
The purpose of this research was to study the effect of electric field strength (0.1–1 kV cm1) an... more The purpose of this research was to study the effect of electric field strength (0.1–1 kV cm1) and frequency (5–75 Hz) during pulsed electric field (PEF) processing on the extractability of carotenoids in carrots, which was examined using different vegetable oils. Increasing electric field strengths up to 1 kV cm1
at 5 Hz significantly (P < 0.05) increased the extraction of carotenoids from carrot pomace. Increasing frequency above 10 Hz at 1 kV cm 1 did not improve the carotenoids extraction. The yield of carotenoids extracted was dependent on the vegetable oils. Sunflower and soya bean oils had the highest carotenoid extractability, and peanut oil was the lowest for carrot pomace treated at 0.6 kV cm 1 and 5 Hz, but no significant difference was observed among vegetable oils for carrot pomace treated at 50 Hz. This study suggests that PEF can improve the carotenoids extractability of carrots depending on the electric field strength and frequency used.
Thermodynamically stable microemulsions were used to extract β-carotene from pulsed electric fiel... more Thermodynamically stable microemulsions were used to extract β-carotene from pulsed electric field (PEF)-treated carrot pomace. In this study, a three-level Box–Behnken design was used to predict the effect of extraction time (10–110 min), extraction temperature (30–70 °C) and carrot/microemulsion ratio (1:30–1:90 w/w) on the β-carotene content, polydispersity index (PDI) and particle size of the microemulsions. The β-carotene extracted from PEF-treated carrot pomace using microemulsions was higher than untreated carrot pomace. The extraction efficiency of β-carotene using microemulsions was higher compared to 100 % hexane or 100 % glycerol monocaprylocaprate oil. A mathematical model was developed to predict the optimal extraction conditions using transparent microemulsions with high loading of β-carotene, low PDI and small microemulsion particle size. The model predicted that an extraction time of 49.4 min, temperature of 52.2 °C and carrot/microemulsion ratio of 1:70 (w/w) would result in microemulsions with β-carotene loading of 19.6 μg/g, PDI of 0.27 and particle size of 74 nm. This study demonstrates the potential of using oil-in-water microemulsions as extraction media for β-carotene.
A crude plasmin extract was prepared from milk by ultracentrifugation and was partially purified ... more A crude plasmin extract was prepared from milk by ultracentrifugation and was partially purified using ammonium sulfate precipitation. Isothermal and high-pressure inactivation of this plasmin system at pH 6.7 could be described by a first-order kinetic model. As expected, the plasmin system displayed a high thermostability. High-pressure treatments were conducted in the 300- to 800-MPa pressure range, combined with temperatures from 25 to 65 degrees C. The plasmin system was very pressure stable at room temperature, but inactivation occurred with combined high-pressure/temperature-treatments. The influence of temperature at different constant pressures on the inactivation rate constant was quantified using the Arrhenius equation. At all temperatures studied, a synergistic effect of temperature and high pressure was observed in the 300- to 600-MPa pressure range. However, an antagonistic effect of temperature and pressure appeared at pressures above 600 MPa.
The shelf life of high quality horticultural products such as broccoli is relatively short, there... more The shelf life of high quality horticultural products such as broccoli is relatively short, thereby limiting their potential for export and long distance trade. To assess the quality and the shelf life of vegetables, a reliable, accurate and high-throughput technique is required. In this study, an approach that profiled enzyme activities and volatile mass ions was used. The possible relationship between volatile mass ions and changes in the activity of enzymes that influence quality of broccoli (i.e., peroxidase/POD and ascorbate oxidase/AAO) during post-harvest storage (25°C for 6days) was investigated. Proton Transfer Reaction Mass Spectometry (PTR-MS) was used to scan and quantify volatile mass ions in broccoli during storage, with m/z ratio of between 20 and 180. In this study, the effect of severe wounding on enzyme activities and the volatile profile was simulated by incubating crushed broccoli florets at different time intervals (2, 4 and 6h). Based on one-way ANOVA, changes ...
The objective of this study was to investigate the effects of temperature treatments (i.e. freezi... more The objective of this study was to investigate the effects of temperature treatments (i.e. freezing at -18 degrees C, cool storage at 4 degrees C and heating at 50, 70 and 100 degrees C for 10 min) on the activity of peroxidase (POD), lipoxygenase (LOX), ascorbic acid oxidase (AAO), superoxide dismutase (SOD) and catalase (CAT) in broccoli (Brassica oleracea L. italica). Volatiles released during storage at 20 degrees C for 24 h were monitored using on-line Proton Transfer Reaction Mass Spectrometry (m/z 21-180). Partial Least Square Regression (PLSR) was used to evaluate possible correlations between enzymes and volatiles released during storage. The results showed that temperature treatment had significant effect on all enzymes, except LOX. Temperature treatment at 70 degrees C resulted in at least 65% decrease in POD and AAO activity. In contrast, SOD and CAT activities generally increased during storage after temperature treatments. PLSR2 results showed that volatiles released a...
An experimental protocol to harmonize the pressure and temperature-histories of model samples tre... more An experimental protocol to harmonize the pressure and temperature-histories of model samples treated in different individual high pressure pilot units was developed. This protocol was based on the endpoint strategy. Step zero of this protocol consisted of an exploratory measurement of the pressure, temperature-history of the pressure transmitting medium in the different chambers without the use of a container. In
Broccoli contains glucosinolates, which can be hydrolysed by myrosinase (EC 3.2.1.147) after cell... more Broccoli contains glucosinolates, which can be hydrolysed by myrosinase (EC 3.2.1.147) after cell disruption, to yield a range of products, of which some have anticarcinogenic properties. Since thermal processing results in myrosinase inactivation, the use of a high pressure/temperature treatment (HP/T), which can induce cell permeabilisation at moderate conditions, can be an alternative. In this research it was investigated at
In plant matrices, folates exist largely as folylpoly-γ-glutamates requiring deglutamylation to m... more In plant matrices, folates exist largely as folylpoly-γ-glutamates requiring deglutamylation to monoglutamates prior to absorption, which might impair dietary folate bioavailability. This study investigated folylpoly-γ-glutamate stability and conversions in broccoli tissue during thermal (25–90°C, 30min) and high-pressure treatments (0.1–600MPa, 25–45°C, 30min) after vacuum packaging. Folates were analyzed based on poly-γ-glutamate side chain length by RP-HPLC. During thermal treatments, folates were
The quality of fruit and vegetables based products is affected by processing. Two important param... more The quality of fruit and vegetables based products is affected by processing. Two important parameters to consider are the structural characteristics and the nutritional value. As pectin is a major constituent of plant cell walls, pectin structure engineering can be used as a tool to affect the structural quality of plant based food products. During thermal processing, pectin characteristics are
The utilisation of β-carotene in food and beverage products is limited due to their poor water so... more The utilisation of β-carotene in food and beverage products is limited due to their poor water solubility, chemical instability and low bioavailability. Microemulsions are of particular interest as colloidal delivery systems because of the possibility of enhancing the solubility and improving the bioavailability of hydrophobic compounds. However, these systems have not been widely used in the food industry because of the difficulties in their formulation using edible oils and surfactants. The purpose of this study was to compare the pseudo-ternary phase diagram of β-carotene microemulsion prepared using long chain length fatty acids (vegetable oils) and medium chain length fatty acids (Caprylic/Capric triglyceride). The solubility of β-carotene was measured by reversed-phase liquid chromatography (HPLC). The solubility of β-carotene in long chain triglycerides was higher than medium chain triglyceride. Among Tweens that were screened, Tween 80 exhibited the highest solubilizing pote...
The aim of this study was to gain an in-depth understanding of the effect of pulsed electric fiel... more The aim of this study was to gain an in-depth understanding of the effect of pulsed electric fields (PEF) on the microstructure of potato tubers. The effect of peeling prior to PEF was also studied. Whole potato tubers were subjected to PEF at a constant frequency of 50 Hz, over a range of electric field strengths (0.2 to 1.1 kV/cm) and energy levels (1 to 10 kJ/kg). To determine the uniformity of the PEF effect across the potato tuber, cell viability was assessed using tetrazolium salt staining. To evaluate the effectiveness of PEF processing the leakage of ionic species from the tubers was measured using atomic absorption spectrophotometry and FESEM-EDS analysis. In addition the influence of PEF on cell disruption and microstructural damage was assessed using scanning electron microscopy (Cryo-SEM). As the electric field strength and energy increased potassium ion leakage and electrical conductivity of the medium increased. The orientation of the tuber towards the electrodes and the presence of the skin greatly affected the impact of PEF on cell disruption and viability. At electric field strengths of 0.3 kV/cm and above, potato cells located in the pith (inner medulla) showed more damage and had a higher proportion of cell death compared to cells located in the outer medulla. This is the first study to provide visual evidence that the application of electric fields to solid, living foods, such as potato tubers, results in an uneven distribution of cell damage and death owing to the presence of vascular bundles and cells that vary in their resistance to electric fields.
The objective of this study was to evaluate the cytotoxicity of microemulsions prepared from glyc... more The objective of this study was to evaluate the cytotoxicity of microemulsions prepared from glycerol monocaprylocaprate (Capmul MCM), non-ionic surfactant (Tween 80), and phosphate buffer loaded with β-carotene extracted from carrot pomace, to human intestinal epithelial (Caco-2) cells and to determine if non-cytotoxic concentrations of the natural β-carotene loaded microemulsion could protect Caco-2 cells from oxidative damage caused by exposure to H2O2. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and lactate dehydrogenase assays were used to determine mitochondria functionality and cell membrane integrity, respectively, both of which are commonly used to evaluate cell viability. In addition nitride oxide level was measured as a general indicator of cellular disruption and inflammation. Cytotoxicity of the formulations significantly decreased when lowering the microemulsion concentration. Increasing the cytotoxicity of microemulsions at concentrations higher than 0.0313% (Tween 80 concentration of 0.006%) might be the result of Tween 80 precipitation on the cell culture monolayer, and β-carotene loaded in the microemulsion did not appear to protect cells from Tween 80 associated damage. However, a β-carotene loaded microemulsion concentration of 0.0313% gave bioprotection to cells suffering oxidative damage caused by H2O2. These results show the potential of using natural β-carotene microemulsion as a delivery system at a safe level of Tween 80 for application in pharmaceutical and food sciences.
The impact of oil type and fatty acid chain length on the development of food-grade microemulsion... more The impact of oil type and fatty acid chain length on the development of food-grade microemulsions for the entrapment of β-carotene was investigated. The microemulsion region of a ternary phase diagram containing short chain monoglycerides was larger than for di- and triglycerides when Tween 80 was used as surfactant. The cytotoxicity of microemulsions composed of a 30% monoglyceride oil, 20% Tween 80 and 50% aqueous buffer were evaluated using an in vitro cell culture model (human epithelial colorectal adenocarcinoma, Caco-2). The cytotoxicity test showed that the viability of Caco-2 cells against β-carotene microemulsions at concentrations of 0.03125% (v/v) was higher than 90%. This study suggests that short chain monoglycerides could be used with Tween 80 to prepare transparent β-carotene-encapsulated O/W microemulsions in the particle size range of 12-100 nm.
International Journal of Food Science & Technology
The purpose of this research was to study the effect of electric field strength (0.1–1 kV cm1) an... more The purpose of this research was to study the effect of electric field strength (0.1–1 kV cm1) and frequency (5–75 Hz) during pulsed electric field (PEF) processing on the extractability of carotenoids in carrots, which was examined using different vegetable oils. Increasing electric field strengths up to 1 kV cm1
at 5 Hz significantly (P < 0.05) increased the extraction of carotenoids from carrot pomace. Increasing frequency above 10 Hz at 1 kV cm 1 did not improve the carotenoids extraction. The yield of carotenoids extracted was dependent on the vegetable oils. Sunflower and soya bean oils had the highest carotenoid extractability, and peanut oil was the lowest for carrot pomace treated at 0.6 kV cm 1 and 5 Hz, but no significant difference was observed among vegetable oils for carrot pomace treated at 50 Hz. This study suggests that PEF can improve the carotenoids extractability of carrots depending on the electric field strength and frequency used.
Thermodynamically stable microemulsions were used to extract β-carotene from pulsed electric fiel... more Thermodynamically stable microemulsions were used to extract β-carotene from pulsed electric field (PEF)-treated carrot pomace. In this study, a three-level Box–Behnken design was used to predict the effect of extraction time (10–110 min), extraction temperature (30–70 °C) and carrot/microemulsion ratio (1:30–1:90 w/w) on the β-carotene content, polydispersity index (PDI) and particle size of the microemulsions. The β-carotene extracted from PEF-treated carrot pomace using microemulsions was higher than untreated carrot pomace. The extraction efficiency of β-carotene using microemulsions was higher compared to 100 % hexane or 100 % glycerol monocaprylocaprate oil. A mathematical model was developed to predict the optimal extraction conditions using transparent microemulsions with high loading of β-carotene, low PDI and small microemulsion particle size. The model predicted that an extraction time of 49.4 min, temperature of 52.2 °C and carrot/microemulsion ratio of 1:70 (w/w) would result in microemulsions with β-carotene loading of 19.6 μg/g, PDI of 0.27 and particle size of 74 nm. This study demonstrates the potential of using oil-in-water microemulsions as extraction media for β-carotene.
A crude plasmin extract was prepared from milk by ultracentrifugation and was partially purified ... more A crude plasmin extract was prepared from milk by ultracentrifugation and was partially purified using ammonium sulfate precipitation. Isothermal and high-pressure inactivation of this plasmin system at pH 6.7 could be described by a first-order kinetic model. As expected, the plasmin system displayed a high thermostability. High-pressure treatments were conducted in the 300- to 800-MPa pressure range, combined with temperatures from 25 to 65 degrees C. The plasmin system was very pressure stable at room temperature, but inactivation occurred with combined high-pressure/temperature-treatments. The influence of temperature at different constant pressures on the inactivation rate constant was quantified using the Arrhenius equation. At all temperatures studied, a synergistic effect of temperature and high pressure was observed in the 300- to 600-MPa pressure range. However, an antagonistic effect of temperature and pressure appeared at pressures above 600 MPa.
The shelf life of high quality horticultural products such as broccoli is relatively short, there... more The shelf life of high quality horticultural products such as broccoli is relatively short, thereby limiting their potential for export and long distance trade. To assess the quality and the shelf life of vegetables, a reliable, accurate and high-throughput technique is required. In this study, an approach that profiled enzyme activities and volatile mass ions was used. The possible relationship between volatile mass ions and changes in the activity of enzymes that influence quality of broccoli (i.e., peroxidase/POD and ascorbate oxidase/AAO) during post-harvest storage (25°C for 6days) was investigated. Proton Transfer Reaction Mass Spectometry (PTR-MS) was used to scan and quantify volatile mass ions in broccoli during storage, with m/z ratio of between 20 and 180. In this study, the effect of severe wounding on enzyme activities and the volatile profile was simulated by incubating crushed broccoli florets at different time intervals (2, 4 and 6h). Based on one-way ANOVA, changes ...
The objective of this study was to investigate the effects of temperature treatments (i.e. freezi... more The objective of this study was to investigate the effects of temperature treatments (i.e. freezing at -18 degrees C, cool storage at 4 degrees C and heating at 50, 70 and 100 degrees C for 10 min) on the activity of peroxidase (POD), lipoxygenase (LOX), ascorbic acid oxidase (AAO), superoxide dismutase (SOD) and catalase (CAT) in broccoli (Brassica oleracea L. italica). Volatiles released during storage at 20 degrees C for 24 h were monitored using on-line Proton Transfer Reaction Mass Spectrometry (m/z 21-180). Partial Least Square Regression (PLSR) was used to evaluate possible correlations between enzymes and volatiles released during storage. The results showed that temperature treatment had significant effect on all enzymes, except LOX. Temperature treatment at 70 degrees C resulted in at least 65% decrease in POD and AAO activity. In contrast, SOD and CAT activities generally increased during storage after temperature treatments. PLSR2 results showed that volatiles released a...
An experimental protocol to harmonize the pressure and temperature-histories of model samples tre... more An experimental protocol to harmonize the pressure and temperature-histories of model samples treated in different individual high pressure pilot units was developed. This protocol was based on the endpoint strategy. Step zero of this protocol consisted of an exploratory measurement of the pressure, temperature-history of the pressure transmitting medium in the different chambers without the use of a container. In
Broccoli contains glucosinolates, which can be hydrolysed by myrosinase (EC 3.2.1.147) after cell... more Broccoli contains glucosinolates, which can be hydrolysed by myrosinase (EC 3.2.1.147) after cell disruption, to yield a range of products, of which some have anticarcinogenic properties. Since thermal processing results in myrosinase inactivation, the use of a high pressure/temperature treatment (HP/T), which can induce cell permeabilisation at moderate conditions, can be an alternative. In this research it was investigated at
In plant matrices, folates exist largely as folylpoly-γ-glutamates requiring deglutamylation to m... more In plant matrices, folates exist largely as folylpoly-γ-glutamates requiring deglutamylation to monoglutamates prior to absorption, which might impair dietary folate bioavailability. This study investigated folylpoly-γ-glutamate stability and conversions in broccoli tissue during thermal (25–90°C, 30min) and high-pressure treatments (0.1–600MPa, 25–45°C, 30min) after vacuum packaging. Folates were analyzed based on poly-γ-glutamate side chain length by RP-HPLC. During thermal treatments, folates were
The quality of fruit and vegetables based products is affected by processing. Two important param... more The quality of fruit and vegetables based products is affected by processing. Two important parameters to consider are the structural characteristics and the nutritional value. As pectin is a major constituent of plant cell walls, pectin structure engineering can be used as a tool to affect the structural quality of plant based food products. During thermal processing, pectin characteristics are
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at 5 Hz significantly (P < 0.05) increased the extraction of carotenoids from carrot pomace. Increasing frequency above 10 Hz at 1 kV cm 1 did not improve the carotenoids extraction. The yield of carotenoids extracted was dependent on the vegetable oils. Sunflower and soya bean oils had the highest carotenoid extractability, and peanut oil was the lowest for carrot pomace treated at 0.6 kV cm 1 and 5 Hz, but no significant difference was observed among vegetable oils for carrot pomace treated at 50 Hz. This study suggests that PEF can improve the carotenoids extractability of carrots depending on the electric field strength and frequency used.
at 5 Hz significantly (P < 0.05) increased the extraction of carotenoids from carrot pomace. Increasing frequency above 10 Hz at 1 kV cm 1 did not improve the carotenoids extraction. The yield of carotenoids extracted was dependent on the vegetable oils. Sunflower and soya bean oils had the highest carotenoid extractability, and peanut oil was the lowest for carrot pomace treated at 0.6 kV cm 1 and 5 Hz, but no significant difference was observed among vegetable oils for carrot pomace treated at 50 Hz. This study suggests that PEF can improve the carotenoids extractability of carrots depending on the electric field strength and frequency used.