International Conference: Postharvest Unlimited, 2003
Lycopene is responsible for the red colour in tomato although other pigments are also present in ... more Lycopene is responsible for the red colour in tomato although other pigments are also present in ripening fruits such as phytoene (colourless) and ζ-carotene (pale yellow), β-carotene (orange); and xanthophylls (yellow). Colorimeter measurements were used to trace pigment synthesis and to investigate the effect of some growth regulators on ripening under two different temperature regimes. mature green (MG) fruits (cv. Tommy; 3 replicates of 30 fruits each) were dipped for 30 minutes in a solution of either 1000 ppm gibberellic acid or ethephon [(2-chloroethyl) phosponic acid] and pure water (control) and stored at 20 and 12 °C for 18 and 32 days respectively. Colour was periodically measured (Minolta Chromameter CR-300) and recorded as the average of 4 different points from each fruit. L* values were not affected by treatments and only the a* and b* values were analysed. Analysis of the chromatic parameters suggests that synthesis of yellow(ish) pigments precede that of red(ish) ones. It is possible that these yellow tones were the expression of colourless (phytoene) and pale-yellow (ζ-carotene) precursors before the masking effect of the massive accumulation of lycopene (red) and β-carotene (orange) took place. Low temperature (12 °C) probably inhibited lycopene synthesis (at least partially), but β-carotene synthesis still progressed yielding pale red fruits. Ethephon immersed fruits had the highest a* values. At both temperatures ethephon accelerated carotenoid synthesis while gibberellins delayed it.
The onion is a major export crop in Argentina and obtaining consistent quality is a matter of con... more The onion is a major export crop in Argentina and obtaining consistent quality is a matter of concern to remain competitive internationally. Grading is generally done according to Mercosur standards but quality assurance programs are necessary at the packinghouse level. The objective of this study was to develop a first approach for characterizing sorting and sizing efficiency. During the 1998 season five onion packinghouses located in the Valle Bonaerense del Río Colorado (Buenos Aires Province, Argentina) were randomly selected. In all of them, variables measured were: sorting table width, bulb transport and rotation speed as well as number of bulbs/sorter/hour. Before and after sorting, samples of 100 bulbs of each size category were randomly taken and closely inspected and their diameters were measured. Sizing efficiency was determined and a Chi-square test was performed to compare observed frequencies of defects with the expected ones within each category. All the studied packi...
Las atmósferas controladas alargan la vida en estante del tomate, permitiendo su cosecha en estad... more Las atmósferas controladas alargan la vida en estante del tomate, permitiendo su cosecha en estados de madurez más avanzados y a su vez afectando su calidad. El objetivo de este experimento fue estudiar los efectos que atmósferas controladas con bajas concentraciones de oxígeno y libres de dióxido de carbono y etileno, producen sobre el color, la firmeza y los principales componentes del sabor de frutos de tomate cultivar Diva. Durante abril de 1998, frutos cosechados con grado de color 3 (USDA) en INTA Balcarce (Argentina) fueron almacenados en frascos herméticos de 3 L a 12°C durante 36 días. El diseño fue completamente aleatorizado con tres repeticiones. Cada frasco poseía cuatro frutos, los que constituyeron la unidad experimental. Los tratamientos fueron cuatro, consistiendo en un flujo continuo de: a) 1%, b) 3%, c) 5% y d) 21% de O2 (testigo) completando con N2 hasta 100%. El color, medido con un colorímetro, evolucionó más lentamente y la firmeza se retuvo por más tiempo a me...
Color in tomato is the most important external characteristic to assess ripeness and postharvest ... more Color in tomato is the most important external characteristic to assess ripeness and postharvest life, and is a major factor in the consumer's purchase decision. Degree of ripening is usually estimated by color charts. Colorimeters, on the other hand, express colors in numerical terms along the L*, a* and b* axes (from white to black, green to red and blue to yellow, respectively) within the CIELAB color sphere which are usually mathematically combined to calculate the color indexes. Color indexes and their relationship to the visual color classification of tomato fruits vine ripened were compared. L*, a* and b* data (175 observations from eleven cultivars) from visually classified fruits at harvest in six ripening stages according to the USDA were used to calculate hue, chroma, color index, color difference with pure red, a*/b* and (a*/b*)². ANOVA analysis were performed and means compared by Duncan's MRT. Color changes throughout tomato ripening were the result of signific...
Thermal processing extends the shelf life of fruit and vegetables products by inactivating microo... more Thermal processing extends the shelf life of fruit and vegetables products by inactivating microorganisms and enzymes. The effect of a pasteurization (P) treatment, 90 °C ± 2 ºC for 35 s, provided by continuous semi-industrial microwave (MW) under different conditions (high power/short time and low power/long time) or conventional pasteurization (CP) on orange-colored smoothies and their changes throughout 45 days of storage at 5 °C were investigated. Results indicated that vitamin C and antioxidant capacity (FRAP) in CP decreased dramatically in comparison with the unheated and MWP smoothies. On the contrary, all heating treatments increased the contents of total phenolic compounds (TPC) and carotenoids. Based on the sensory quality and microbial counts, the shelf life 2 of all those heated smoothies reached 45 days. No Listeria monocytogenes growth was found and all microbial counts were below the European legal limits. MWP as compared to the CP method led to a greater reduction of mesophilic bacteria after 45 days at 5 °C (3.7 log cfu g-1 for CP and 1.6 log cfu g-1 for MWP). When highest power and shortest time MWP treatments were used (3,600 W for 93 s), FRAP and vitamin C were better preserved.
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 24, 2016
The effect of a pasteurization treatment at 90 ± 2 ℃ for 35 s provided by continuous microwave un... more The effect of a pasteurization treatment at 90 ± 2 ℃ for 35 s provided by continuous microwave under different doses (low power/long time and high power/short time) or conventional pasteurization on the quality of orange-colored smoothies and their changes throughout 45 days of storage at 5 ℃ was investigated. A better color retention of the microwave pasteurization- treated smoothie using high power/short time than in conventionally processed sample was evidenced by the stability of the hue angle. The continuous microwave heating increased the viscosity of the smoothie more than the conventional pasteurization in comparison with non-treated samples. Lower residual enzyme activities from peroxidase, pectin methylesterase and polygalacturonase were obtained under microwave heating, specifically due to the use of higher power/shorter time. For this kind of smoothie, polygalacturonase was the more thermo-resistant enzyme and could be used as an indicator of pasteurization efficiency. T...
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 27, 2016
Smoothies represent an excellent and convenient alternative to promote the daily consumption of f... more Smoothies represent an excellent and convenient alternative to promote the daily consumption of fruit and vegetables in order to obtain their health-promoting benefits. Accordingly, a green fresh vegetables smoothie (77.2% cucumber, 12% broccoli and 6% spinach) rich in health-promoting compounds was developed. Soluble solids content, pH and titratable acidity of the smoothie were 4.3 ± 0.4°Bx, 4.49 ± 0.01 and 0.22 ± 0.02 mg citric acid 100(-1) g fw, respectively. Two thermal treatments to reduce microbial loads and preserve quality were assayed: T1 (3 min at 80 ℃) and T2 (45 s at 90 ℃). Fresh blended unheated samples were used as control (CTRL). The smoothie presented a viscoelastic behaviour. T1 and T2 treatments reduced initial microbial loads by 1.3-2.4 and 1.4-3.1 log units, respectively. Samples were stored in darkness at 5 and 15 ℃. Colour and physicochemical changes were reduced in thermal-treated samples throughout storage, which were better preserved at 5 ℃ rather than at 1...
Phenolic compounds are phytochemicals with high health-promoting properties. Carrot is a vegetabl... more Phenolic compounds are phytochemicals with high health-promoting properties. Carrot is a vegetable highly worldwide consumed although its phenolic content is low compared to other plant products. The aim of this work was to evaluate changes in phenolic compounds in carrots caused by abiotic stresses. The phenylalanine ammonia-lyase (PAL) activity, phenolic compounds and total antioxidant capacity (TAC) changes during storage up to 72 h at 15 °C after wounding (shredding), 9 kJ UV-C m(-2) pretreatment and hyperoxia (80 kPa) conditions of carrots were studied. Shredding and hyperoxia storage induced the highest phenolic compounds and TAC enhancements. Accumulation of phenolic compounds in shredded carrots could be structured in the following phases: 1st phase (<24 h): unchanged phenolic compounds levels with minimum PAL activity; 2nd phase (24-48 h): moderate phenolic increases (≈600-700 mg CAE kg(-1) accumulated in 24 h) concurring with the greatest increase of PAL activity; 3nd phase (48-72 h): high phenolic increases (≈1600-2700 mg CAE kg(-1), accumulated in 24 h) while a moderate increment of PAL activity was registered. Although UV-C pretreatment of shreds reduced phenolic accumulation, 600 % increments were still registered in those samples stored under hyperoxia conditions for 72 h. However, the contents of chlorogenic acid at 72 h were 1.4-fold higher in irradiated shreds under hyperoxia compared to the same samples under air conditions.
The kinetics of polyphenol oxidase (PPO, EC 1.14.18.1) with respect to oxygen concentrations from... more The kinetics of polyphenol oxidase (PPO, EC 1.14.18.1) with respect to oxygen concentrations from 5 to 100% using chlorogenic acid (CGA) as substrate was examined. In vitro mushroom PPO activity was determined by measuring the consumption of oxygen during the oxidation reaction. A differential Michaelis-Menten model was fitted to the obtained total depletion curves. The product concentration as well as the concentration of oxygen had a clear inhibitory effect on the reaction rate. However, the inhibitory effect of oxygen was more evident at low product concentration. A linear mixed inhibition model that considered both the product (oxidised CGA) and oxygen as inhibitors was developed. A model with the product as a competitive inhibitor and oxygen as an uncompetitive inhibitor was the most appropriate to explain the reaction kinetics. The values of the inhibition constants calculated from the model were 0.0032 mmol L −1 for K m (Michaelis-Menten constant related to oxygen), 0.023 mmol L −1 for K mc (constant for competitive inhibition due to the product), 1.630 mmol L −1 for K mu (constant for uncompetitive inhibition due to oxygen) and 1.77 × 10 −4 mmol L −1 s −1 for V max (maximum reaction rate). The results indicate that superatmospheric oxygen concentrations could be effective in preventing enzymatic browning by PPO.
... mínimamente procesados o de la cuarta gama Francisco Artés-Calero, Encarna Aguayo, Perla Góme... more ... mínimamente procesados o de la cuarta gama Francisco Artés-Calero, Encarna Aguayo, Perla Gómez, Francisco Artés Hernandez ... Artés-Hernández, F., Rivera-Cabrera, F., Kader, AA 2007. ... Rodríguez-Hidalgo, S., Artés-Hernández, F., Gómez, P., Fernández JA, Artés, F. 2009. ...
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 18, 2016
There is a growing demand for food supplements containing high amounts of vitamins, phenolic comp... more There is a growing demand for food supplements containing high amounts of vitamins, phenolic compounds and mineral content that provide health benefits. Those functional compounds have different solubility properties, and the maintenance of their compounds and the guarantee of their homogenic properties need the application of novel technologies. The quality of different drinkable functional foods after thermal processing (0.1 MPa) or high-pressure homogenization under two different conditions (80 MPa, 33 ℃ and 120 MPa, 43 ℃) was studied. Physicochemical characteristics and sensory qualities were evaluated throughout the six months of accelerated storage at 40 ℃ and 75% relative humidity (RH). Aroma and color were better maintained in high-pressure homogenization-treated samples than the thermally treated ones, which contributed significantly to extending their shelf life. The small particle size obtained after high-pressure homogenization treatments caused differences in turbidity ...
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 11, 2016
The effect of postharvest vapor heat treatments at 95℃ (4, 7, and 10 s) regarding a conventional ... more The effect of postharvest vapor heat treatments at 95℃ (4, 7, and 10 s) regarding a conventional sanitizing treatment with 100 mg NaClO l(-1) on enzyme activities (phenylalanine ammonia lyase, polyphenol oxidase, and peroxidase), phenolic content, and total antioxidant capacity of fresh-cut pomegranates arils throughout 18 days at 5℃ was studied. Furthermore, the effect of two sustained deficit irrigation (SDI) strategies, compared to a standardly irrigated control (CTRL), was also studied on such quality parameters throughout storage. Arils from CTRL-irrigated fruit registered phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase initial activities of 60.6, 382, and 14.4 U g(-1) fw, respectively. Arils from sustained deficit irrigation fruit registered 46-58% lower phenylalanine ammonia lyase values while polyphenol oxidase and peroxidase activities did not register great variants (<9%) among both sustained deficit irrigation treatments. Postharvest vapor heat treatmen...
Food Science and Technology International Ciencia Y Tecnologia De Alimentos Internacional, Jun 1, 2007
Minimally fresh processed (MFP) or fresh-cut fruits and vegetables is currently the fastest growi... more Minimally fresh processed (MFP) or fresh-cut fruits and vegetables is currently the fastest growing sub-sector of the food industry with still a high potential of growth world wide. The practical advantages and convenience they provide to consumers undoubtedly favour this fact. However, because of their specific ways of preparation, MFP plant foods are highly perishable. To minimise this, they must
Ready-to-eat pomegranate seeds were prepared and their quality attributes and appearance was foll... more Ready-to-eat pomegranate seeds were prepared and their quality attributes and appearance was followed during storage for 7 d under different conditions. Quality attributes, titratable acidity, total soluble solids, L* values, absorbance at 510 nm (anthocyanin content) and absorbance at 446 nm (brown metabolites) were analysed. Respiratory activity, appearance of the seeds (shriveling and browning), and weight loss were also evaluated. The influence of different washing treatments, storage temperatures (8, 4 and 1 °C) and actively or passively modified atmosphere packaging on the quality of the minimally processed pomegranate seeds was studied. Washing the seeds with chlorine and chlorine followed by ascorbic and citric acid were selected, and storage at 1 °C led to the best quality preservation. The best overall results were obtained for seeds washed with chlorine (100 mg/kg) plus antioxidants (5 g/L ascorbic acid and 5 g/L citric acid), and sealed in oriented polypropylene film using an initial atmosphere actively modified to 20 mL/L O 2 and 0 mL/L CO 2 . Under these conditions, minimally processed pomegranate seeds maintained good quality and appearance for 7 d of storage at 1 °C without fungal attacks or off-flavour development.
Two fresh red vegetables smoothies based on tomato, carrots, pepper and broccoli and rich in heal... more Two fresh red vegetables smoothies based on tomato, carrots, pepper and broccoli and rich in health-promoting compounds were developed. The smoothies showed a viscoelastic behaviour. According to sensory analyses, a shelf life of 28 days at 5 °C for fresh blended smoothies was established while thermally-treated ones (3 min, 80 °C) reached up to 40 days at 20 °C and 58 days at 5 °C. For those mild heat treated smoothies, total vitamin C degradation was 2-fold reduced during storage at 5 °C compared to samples stored at 20 °C while the initial total carotenoids, lycopene and total chlorophylls contents were not greatly affected. A 250-g portion of such smoothies covers in a great extend the established recommended daily nutrient intakes for dietary fibre, minerals and vitamin C of different population groups. As main conclusion, a mild thermal treatment and low temperature storage greatly increased the shelf life of red fresh vegetables smoothies and reduced total vitamin C degradation.
International Conference: Postharvest Unlimited, 2003
Lycopene is responsible for the red colour in tomato although other pigments are also present in ... more Lycopene is responsible for the red colour in tomato although other pigments are also present in ripening fruits such as phytoene (colourless) and ζ-carotene (pale yellow), β-carotene (orange); and xanthophylls (yellow). Colorimeter measurements were used to trace pigment synthesis and to investigate the effect of some growth regulators on ripening under two different temperature regimes. mature green (MG) fruits (cv. Tommy; 3 replicates of 30 fruits each) were dipped for 30 minutes in a solution of either 1000 ppm gibberellic acid or ethephon [(2-chloroethyl) phosponic acid] and pure water (control) and stored at 20 and 12 °C for 18 and 32 days respectively. Colour was periodically measured (Minolta Chromameter CR-300) and recorded as the average of 4 different points from each fruit. L* values were not affected by treatments and only the a* and b* values were analysed. Analysis of the chromatic parameters suggests that synthesis of yellow(ish) pigments precede that of red(ish) ones. It is possible that these yellow tones were the expression of colourless (phytoene) and pale-yellow (ζ-carotene) precursors before the masking effect of the massive accumulation of lycopene (red) and β-carotene (orange) took place. Low temperature (12 °C) probably inhibited lycopene synthesis (at least partially), but β-carotene synthesis still progressed yielding pale red fruits. Ethephon immersed fruits had the highest a* values. At both temperatures ethephon accelerated carotenoid synthesis while gibberellins delayed it.
The onion is a major export crop in Argentina and obtaining consistent quality is a matter of con... more The onion is a major export crop in Argentina and obtaining consistent quality is a matter of concern to remain competitive internationally. Grading is generally done according to Mercosur standards but quality assurance programs are necessary at the packinghouse level. The objective of this study was to develop a first approach for characterizing sorting and sizing efficiency. During the 1998 season five onion packinghouses located in the Valle Bonaerense del Río Colorado (Buenos Aires Province, Argentina) were randomly selected. In all of them, variables measured were: sorting table width, bulb transport and rotation speed as well as number of bulbs/sorter/hour. Before and after sorting, samples of 100 bulbs of each size category were randomly taken and closely inspected and their diameters were measured. Sizing efficiency was determined and a Chi-square test was performed to compare observed frequencies of defects with the expected ones within each category. All the studied packi...
Las atmósferas controladas alargan la vida en estante del tomate, permitiendo su cosecha en estad... more Las atmósferas controladas alargan la vida en estante del tomate, permitiendo su cosecha en estados de madurez más avanzados y a su vez afectando su calidad. El objetivo de este experimento fue estudiar los efectos que atmósferas controladas con bajas concentraciones de oxígeno y libres de dióxido de carbono y etileno, producen sobre el color, la firmeza y los principales componentes del sabor de frutos de tomate cultivar Diva. Durante abril de 1998, frutos cosechados con grado de color 3 (USDA) en INTA Balcarce (Argentina) fueron almacenados en frascos herméticos de 3 L a 12°C durante 36 días. El diseño fue completamente aleatorizado con tres repeticiones. Cada frasco poseía cuatro frutos, los que constituyeron la unidad experimental. Los tratamientos fueron cuatro, consistiendo en un flujo continuo de: a) 1%, b) 3%, c) 5% y d) 21% de O2 (testigo) completando con N2 hasta 100%. El color, medido con un colorímetro, evolucionó más lentamente y la firmeza se retuvo por más tiempo a me...
Color in tomato is the most important external characteristic to assess ripeness and postharvest ... more Color in tomato is the most important external characteristic to assess ripeness and postharvest life, and is a major factor in the consumer's purchase decision. Degree of ripening is usually estimated by color charts. Colorimeters, on the other hand, express colors in numerical terms along the L*, a* and b* axes (from white to black, green to red and blue to yellow, respectively) within the CIELAB color sphere which are usually mathematically combined to calculate the color indexes. Color indexes and their relationship to the visual color classification of tomato fruits vine ripened were compared. L*, a* and b* data (175 observations from eleven cultivars) from visually classified fruits at harvest in six ripening stages according to the USDA were used to calculate hue, chroma, color index, color difference with pure red, a*/b* and (a*/b*)². ANOVA analysis were performed and means compared by Duncan's MRT. Color changes throughout tomato ripening were the result of signific...
Thermal processing extends the shelf life of fruit and vegetables products by inactivating microo... more Thermal processing extends the shelf life of fruit and vegetables products by inactivating microorganisms and enzymes. The effect of a pasteurization (P) treatment, 90 °C ± 2 ºC for 35 s, provided by continuous semi-industrial microwave (MW) under different conditions (high power/short time and low power/long time) or conventional pasteurization (CP) on orange-colored smoothies and their changes throughout 45 days of storage at 5 °C were investigated. Results indicated that vitamin C and antioxidant capacity (FRAP) in CP decreased dramatically in comparison with the unheated and MWP smoothies. On the contrary, all heating treatments increased the contents of total phenolic compounds (TPC) and carotenoids. Based on the sensory quality and microbial counts, the shelf life 2 of all those heated smoothies reached 45 days. No Listeria monocytogenes growth was found and all microbial counts were below the European legal limits. MWP as compared to the CP method led to a greater reduction of mesophilic bacteria after 45 days at 5 °C (3.7 log cfu g-1 for CP and 1.6 log cfu g-1 for MWP). When highest power and shortest time MWP treatments were used (3,600 W for 93 s), FRAP and vitamin C were better preserved.
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 24, 2016
The effect of a pasteurization treatment at 90 ± 2 ℃ for 35 s provided by continuous microwave un... more The effect of a pasteurization treatment at 90 ± 2 ℃ for 35 s provided by continuous microwave under different doses (low power/long time and high power/short time) or conventional pasteurization on the quality of orange-colored smoothies and their changes throughout 45 days of storage at 5 ℃ was investigated. A better color retention of the microwave pasteurization- treated smoothie using high power/short time than in conventionally processed sample was evidenced by the stability of the hue angle. The continuous microwave heating increased the viscosity of the smoothie more than the conventional pasteurization in comparison with non-treated samples. Lower residual enzyme activities from peroxidase, pectin methylesterase and polygalacturonase were obtained under microwave heating, specifically due to the use of higher power/shorter time. For this kind of smoothie, polygalacturonase was the more thermo-resistant enzyme and could be used as an indicator of pasteurization efficiency. T...
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 27, 2016
Smoothies represent an excellent and convenient alternative to promote the daily consumption of f... more Smoothies represent an excellent and convenient alternative to promote the daily consumption of fruit and vegetables in order to obtain their health-promoting benefits. Accordingly, a green fresh vegetables smoothie (77.2% cucumber, 12% broccoli and 6% spinach) rich in health-promoting compounds was developed. Soluble solids content, pH and titratable acidity of the smoothie were 4.3 ± 0.4°Bx, 4.49 ± 0.01 and 0.22 ± 0.02 mg citric acid 100(-1) g fw, respectively. Two thermal treatments to reduce microbial loads and preserve quality were assayed: T1 (3 min at 80 ℃) and T2 (45 s at 90 ℃). Fresh blended unheated samples were used as control (CTRL). The smoothie presented a viscoelastic behaviour. T1 and T2 treatments reduced initial microbial loads by 1.3-2.4 and 1.4-3.1 log units, respectively. Samples were stored in darkness at 5 and 15 ℃. Colour and physicochemical changes were reduced in thermal-treated samples throughout storage, which were better preserved at 5 ℃ rather than at 1...
Phenolic compounds are phytochemicals with high health-promoting properties. Carrot is a vegetabl... more Phenolic compounds are phytochemicals with high health-promoting properties. Carrot is a vegetable highly worldwide consumed although its phenolic content is low compared to other plant products. The aim of this work was to evaluate changes in phenolic compounds in carrots caused by abiotic stresses. The phenylalanine ammonia-lyase (PAL) activity, phenolic compounds and total antioxidant capacity (TAC) changes during storage up to 72 h at 15 °C after wounding (shredding), 9 kJ UV-C m(-2) pretreatment and hyperoxia (80 kPa) conditions of carrots were studied. Shredding and hyperoxia storage induced the highest phenolic compounds and TAC enhancements. Accumulation of phenolic compounds in shredded carrots could be structured in the following phases: 1st phase (&lt;24 h): unchanged phenolic compounds levels with minimum PAL activity; 2nd phase (24-48 h): moderate phenolic increases (≈600-700 mg CAE kg(-1) accumulated in 24 h) concurring with the greatest increase of PAL activity; 3nd phase (48-72 h): high phenolic increases (≈1600-2700 mg CAE kg(-1), accumulated in 24 h) while a moderate increment of PAL activity was registered. Although UV-C pretreatment of shreds reduced phenolic accumulation, 600 % increments were still registered in those samples stored under hyperoxia conditions for 72 h. However, the contents of chlorogenic acid at 72 h were 1.4-fold higher in irradiated shreds under hyperoxia compared to the same samples under air conditions.
The kinetics of polyphenol oxidase (PPO, EC 1.14.18.1) with respect to oxygen concentrations from... more The kinetics of polyphenol oxidase (PPO, EC 1.14.18.1) with respect to oxygen concentrations from 5 to 100% using chlorogenic acid (CGA) as substrate was examined. In vitro mushroom PPO activity was determined by measuring the consumption of oxygen during the oxidation reaction. A differential Michaelis-Menten model was fitted to the obtained total depletion curves. The product concentration as well as the concentration of oxygen had a clear inhibitory effect on the reaction rate. However, the inhibitory effect of oxygen was more evident at low product concentration. A linear mixed inhibition model that considered both the product (oxidised CGA) and oxygen as inhibitors was developed. A model with the product as a competitive inhibitor and oxygen as an uncompetitive inhibitor was the most appropriate to explain the reaction kinetics. The values of the inhibition constants calculated from the model were 0.0032 mmol L −1 for K m (Michaelis-Menten constant related to oxygen), 0.023 mmol L −1 for K mc (constant for competitive inhibition due to the product), 1.630 mmol L −1 for K mu (constant for uncompetitive inhibition due to oxygen) and 1.77 × 10 −4 mmol L −1 s −1 for V max (maximum reaction rate). The results indicate that superatmospheric oxygen concentrations could be effective in preventing enzymatic browning by PPO.
... mínimamente procesados o de la cuarta gama Francisco Artés-Calero, Encarna Aguayo, Perla Góme... more ... mínimamente procesados o de la cuarta gama Francisco Artés-Calero, Encarna Aguayo, Perla Gómez, Francisco Artés Hernandez ... Artés-Hernández, F., Rivera-Cabrera, F., Kader, AA 2007. ... Rodríguez-Hidalgo, S., Artés-Hernández, F., Gómez, P., Fernández JA, Artés, F. 2009. ...
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 18, 2016
There is a growing demand for food supplements containing high amounts of vitamins, phenolic comp... more There is a growing demand for food supplements containing high amounts of vitamins, phenolic compounds and mineral content that provide health benefits. Those functional compounds have different solubility properties, and the maintenance of their compounds and the guarantee of their homogenic properties need the application of novel technologies. The quality of different drinkable functional foods after thermal processing (0.1 MPa) or high-pressure homogenization under two different conditions (80 MPa, 33 ℃ and 120 MPa, 43 ℃) was studied. Physicochemical characteristics and sensory qualities were evaluated throughout the six months of accelerated storage at 40 ℃ and 75% relative humidity (RH). Aroma and color were better maintained in high-pressure homogenization-treated samples than the thermally treated ones, which contributed significantly to extending their shelf life. The small particle size obtained after high-pressure homogenization treatments caused differences in turbidity ...
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, Jan 11, 2016
The effect of postharvest vapor heat treatments at 95℃ (4, 7, and 10 s) regarding a conventional ... more The effect of postharvest vapor heat treatments at 95℃ (4, 7, and 10 s) regarding a conventional sanitizing treatment with 100 mg NaClO l(-1) on enzyme activities (phenylalanine ammonia lyase, polyphenol oxidase, and peroxidase), phenolic content, and total antioxidant capacity of fresh-cut pomegranates arils throughout 18 days at 5℃ was studied. Furthermore, the effect of two sustained deficit irrigation (SDI) strategies, compared to a standardly irrigated control (CTRL), was also studied on such quality parameters throughout storage. Arils from CTRL-irrigated fruit registered phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase initial activities of 60.6, 382, and 14.4 U g(-1) fw, respectively. Arils from sustained deficit irrigation fruit registered 46-58% lower phenylalanine ammonia lyase values while polyphenol oxidase and peroxidase activities did not register great variants (<9%) among both sustained deficit irrigation treatments. Postharvest vapor heat treatmen...
Food Science and Technology International Ciencia Y Tecnologia De Alimentos Internacional, Jun 1, 2007
Minimally fresh processed (MFP) or fresh-cut fruits and vegetables is currently the fastest growi... more Minimally fresh processed (MFP) or fresh-cut fruits and vegetables is currently the fastest growing sub-sector of the food industry with still a high potential of growth world wide. The practical advantages and convenience they provide to consumers undoubtedly favour this fact. However, because of their specific ways of preparation, MFP plant foods are highly perishable. To minimise this, they must
Ready-to-eat pomegranate seeds were prepared and their quality attributes and appearance was foll... more Ready-to-eat pomegranate seeds were prepared and their quality attributes and appearance was followed during storage for 7 d under different conditions. Quality attributes, titratable acidity, total soluble solids, L* values, absorbance at 510 nm (anthocyanin content) and absorbance at 446 nm (brown metabolites) were analysed. Respiratory activity, appearance of the seeds (shriveling and browning), and weight loss were also evaluated. The influence of different washing treatments, storage temperatures (8, 4 and 1 °C) and actively or passively modified atmosphere packaging on the quality of the minimally processed pomegranate seeds was studied. Washing the seeds with chlorine and chlorine followed by ascorbic and citric acid were selected, and storage at 1 °C led to the best quality preservation. The best overall results were obtained for seeds washed with chlorine (100 mg/kg) plus antioxidants (5 g/L ascorbic acid and 5 g/L citric acid), and sealed in oriented polypropylene film using an initial atmosphere actively modified to 20 mL/L O 2 and 0 mL/L CO 2 . Under these conditions, minimally processed pomegranate seeds maintained good quality and appearance for 7 d of storage at 1 °C without fungal attacks or off-flavour development.
Two fresh red vegetables smoothies based on tomato, carrots, pepper and broccoli and rich in heal... more Two fresh red vegetables smoothies based on tomato, carrots, pepper and broccoli and rich in health-promoting compounds were developed. The smoothies showed a viscoelastic behaviour. According to sensory analyses, a shelf life of 28 days at 5 °C for fresh blended smoothies was established while thermally-treated ones (3 min, 80 °C) reached up to 40 days at 20 °C and 58 days at 5 °C. For those mild heat treated smoothies, total vitamin C degradation was 2-fold reduced during storage at 5 °C compared to samples stored at 20 °C while the initial total carotenoids, lycopene and total chlorophylls contents were not greatly affected. A 250-g portion of such smoothies covers in a great extend the established recommended daily nutrient intakes for dietary fibre, minerals and vitamin C of different population groups. As main conclusion, a mild thermal treatment and low temperature storage greatly increased the shelf life of red fresh vegetables smoothies and reduced total vitamin C degradation.
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