The use of Kikuchi lines is very familiar as a part of electron microscopic technique; it is not ... more The use of Kikuchi lines is very familiar as a part of electron microscopic technique; it is not so widely recognized that bend contours may be used in the same way. The two techniques are in fact very similar and generally complementary. The differences between the methods are examined and the advantages of each discussed. The use of bend contours has a number of advantages of convenience, especially for complicated specimens.
The effect of time and number of cycles used on yield and peeling quality of steam peeled potatoe... more The effect of time and number of cycles used on yield and peeling quality of steam peeled potatoes (Ballenera variety) and asparagus (Argentuil variety) at 158 °C was studied. Heat penetration of potatoes and peroxidase residual activity of asparagus were also assessed. Best peeling quality, acceptable heat penetration and a yield of 90% were achieved for potatoes with a peeling time of 36 s and three cycles. For asparagus (two sizes considered), best peeling quality and an acceptable yield and peroxidase residual activity were obtained with a peeling time of 20 s and one cycle. Steam peeling of asparagus followed by an adiabatic holding time after steam exhausting and before water cooling might inactivate peroxidase sufficiently so that blanching prior to freezing of asparagus would not be necessary.
Using Response Surface Methodology the effects of NaOH concentration (4–20%), process temperature... more Using Response Surface Methodology the effects of NaOH concentration (4–20%), process temperature (55–95°C) and time (1–7 min) was determined on the yield, peeling quality, unpeeled skin and total usage of NaOH. Also evaluated were titratable NaOH in the potato tissue, NaOH penetration and “heat ring” depths during one stage chemical peeling of potatoes (Huincul variety). The best peeling quality, maximum yield and minimum total usage of NaOH was obtained for the following ranges: concentration, 11–13%, time 5–5.70 min and temperature, 90–95°C. The maximum temperature for which the “heat ring” and NaOH penetration depths were equal was 72°C where, at 20% NaOH and 7 min, peeling quality was very good and “heat ring” was absent.
International Journal of Food Science and Technology, 2006
The effect of temperature (110, 120 and 130 °C), rotation speed (5, 10 and 15 r.p.m.) and headspa... more The effect of temperature (110, 120 and 130 °C), rotation speed (5, 10 and 15 r.p.m.) and headspace (4, 8 and 12 mm) on heat transfer coefficients to canned green peas during end-over-end sterilisation was studied using response surface methodology. The models developed for fluid-to-particle heat transfer coefficient, hfp, and overall heat transfer coefficient, U, were adequate, showing no significant lack of fit and satisfactory correlation coefficients. For the two responses, temperature, rotation speed and headspace have a significant effect. U, ranged between 477 and 905 W m−2 °C−1, while hfp, fluctuated between 480 and 1950 W m−2 °C−1. The highest hfp and U values are obtained at high temperatures, rotation speeds and headspaces. The verification of the prediction models was satisfactory. Dimensionless correlations were developed for hfp and U, with equations showing a good agreement with the experimental data. Heat transfer to liquids and particles was modelled using the Reynolds number, the Prandtl number and adimensional headspace.
The average retention of ascorbic acid in potato strips (10 × 10 × 80 mm) blanched in water at 50... more The average retention of ascorbic acid in potato strips (10 × 10 × 80 mm) blanched in water at 50°C and 65°C over various blanching times, with and without surface freezing pre-treatment was determined. The strips were frozen in Freon Freezant-12 for 15 sec, with the freezing front penetrating 0.4–0.5 mm. Average retention of ascorbic acid in the surface-frozen potato strips was significantly lower than that in fresh strips and lower at 65°C than at 50°C. At an equal average retention of ascorbic acid, at 50°C the fresh strips required a blanching time four times higher than that for the surface-frozen strips; at 65°C it was twice as high.
A company's Chief Information Officer (CIO) is responsible for the management an... more A company's Chief Information Officer (CIO) is responsible for the management and evolution of the enterprise information system. An approach suggested as an aid for the CIO's decision-making process is Enterprise Architecture, based on architectural models of both ...
The use of Kikuchi lines is very familiar as a part of electron microscopic technique; it is not ... more The use of Kikuchi lines is very familiar as a part of electron microscopic technique; it is not so widely recognized that bend contours may be used in the same way. The two techniques are in fact very similar and generally complementary. The differences between the methods are examined and the advantages of each discussed. The use of bend contours has a number of advantages of convenience, especially for complicated specimens.
The effect of time and number of cycles used on yield and peeling quality of steam peeled potatoe... more The effect of time and number of cycles used on yield and peeling quality of steam peeled potatoes (Ballenera variety) and asparagus (Argentuil variety) at 158 °C was studied. Heat penetration of potatoes and peroxidase residual activity of asparagus were also assessed. Best peeling quality, acceptable heat penetration and a yield of 90% were achieved for potatoes with a peeling time of 36 s and three cycles. For asparagus (two sizes considered), best peeling quality and an acceptable yield and peroxidase residual activity were obtained with a peeling time of 20 s and one cycle. Steam peeling of asparagus followed by an adiabatic holding time after steam exhausting and before water cooling might inactivate peroxidase sufficiently so that blanching prior to freezing of asparagus would not be necessary.
Using Response Surface Methodology the effects of NaOH concentration (4–20%), process temperature... more Using Response Surface Methodology the effects of NaOH concentration (4–20%), process temperature (55–95°C) and time (1–7 min) was determined on the yield, peeling quality, unpeeled skin and total usage of NaOH. Also evaluated were titratable NaOH in the potato tissue, NaOH penetration and “heat ring” depths during one stage chemical peeling of potatoes (Huincul variety). The best peeling quality, maximum yield and minimum total usage of NaOH was obtained for the following ranges: concentration, 11–13%, time 5–5.70 min and temperature, 90–95°C. The maximum temperature for which the “heat ring” and NaOH penetration depths were equal was 72°C where, at 20% NaOH and 7 min, peeling quality was very good and “heat ring” was absent.
International Journal of Food Science and Technology, 2006
The effect of temperature (110, 120 and 130 °C), rotation speed (5, 10 and 15 r.p.m.) and headspa... more The effect of temperature (110, 120 and 130 °C), rotation speed (5, 10 and 15 r.p.m.) and headspace (4, 8 and 12 mm) on heat transfer coefficients to canned green peas during end-over-end sterilisation was studied using response surface methodology. The models developed for fluid-to-particle heat transfer coefficient, hfp, and overall heat transfer coefficient, U, were adequate, showing no significant lack of fit and satisfactory correlation coefficients. For the two responses, temperature, rotation speed and headspace have a significant effect. U, ranged between 477 and 905 W m−2 °C−1, while hfp, fluctuated between 480 and 1950 W m−2 °C−1. The highest hfp and U values are obtained at high temperatures, rotation speeds and headspaces. The verification of the prediction models was satisfactory. Dimensionless correlations were developed for hfp and U, with equations showing a good agreement with the experimental data. Heat transfer to liquids and particles was modelled using the Reynolds number, the Prandtl number and adimensional headspace.
The average retention of ascorbic acid in potato strips (10 × 10 × 80 mm) blanched in water at 50... more The average retention of ascorbic acid in potato strips (10 × 10 × 80 mm) blanched in water at 50°C and 65°C over various blanching times, with and without surface freezing pre-treatment was determined. The strips were frozen in Freon Freezant-12 for 15 sec, with the freezing front penetrating 0.4–0.5 mm. Average retention of ascorbic acid in the surface-frozen potato strips was significantly lower than that in fresh strips and lower at 65°C than at 50°C. At an equal average retention of ascorbic acid, at 50°C the fresh strips required a blanching time four times higher than that for the surface-frozen strips; at 65°C it was twice as high.
A company's Chief Information Officer (CIO) is responsible for the management an... more A company's Chief Information Officer (CIO) is responsible for the management and evolution of the enterprise information system. An approach suggested as an aid for the CIO's decision-making process is Enterprise Architecture, based on architectural models of both ...
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Papers by Enrique Silva