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VISCOSIMETRIC STUDY OF MULTIFLORAL HONEYS
WITH SPECIFIC GUARANTEE «MIEL DE GALICIA»
Gómez-Díaz, D.; Navaza, J. M.*; Quintáns-Riveiro, L. C.
Departamento de Ingeniería Química. ETSI. Universidad de Santiago de Compostela. Lope Gómez de Marzoa s/n. E-15706. Santiago de Compostela. España.
Volume 4, Number 4, pp 234-239
Abstract
The present paper shows experimental results about the viscosimetric characterization of multifloral honeys included in the specific guarantee "miel de Galicia" (Galician honey). The characterization carried out in the present paper consist in the classification of these honeys in the different kinds of fluids and comparison with honeys of other origins. Also, several empirical models have been employed to fit the experimental data of viscosity / shear rate and viscosity / temperature. © 2004 Altaga. All rights reserved.
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SENSORY EVALUATION AND ASCORBIC ACID OF FROZEN AND FRESH VEGETABLES
Borges Marques, R. M.; von Atzingen, M. C.; Machado Pinto e Silva, M. E.*
Departamento de Nutrição - Faculdade de Saúde Pública - Universidade de São Paulo. Av. Dr. Arnaldo, 715, Cerqueira César. 01246-904 São Paulo, Brasil
*Autor para la correspondencia. E-Mail: mmachado@usp.br
Volume 4, Number 4, pp 240-245
Abstract
To evaluate the sensory characteristics and the ascorbic acid content of frozen and fresh broccoli and cauliflower after different cooking methods. The vegetables were cooked in boiling water, steaming and microwave. The sensory evaluation was by the Simple Ranking Test. The vitamin C content was determined by spectrophotometry. There were found significant differences (p?0.05) among the samples regarding color, flavor and texture, but there were not found significant differences (p?0.05) on the global preference. The vitamin C content of the fresh vegetables was significantly higher (p?0.05) than the content of the frozen. Frozen vegetables cooked in boiling water resulted in a higher loss of the vitamin C. Frozen vegetables tend to lose more vitamin C after cooking than the fresh vegetables. Controlling the time of cooking and volume of water reduces losses in the content of ascorbic acid and in the sensory characteristics after cooking.
© 2004 Altaga. All rights reserved.
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EFFECT OF FAT CONTENT ON THE SENSORY CHARACTERISTICS OF A VANILLA-FLAVOURED MILK
Carrapiso, M. R.; Aguayo, C.;. Carrapiso, A. I.*
Tecnología de Alimentos, Escuela de Ingenierías Agrarias, Universidad de Extremadura,
Ctra. de Cáceres 06071, Badajoz, España
*Autor para la correspondencia: acarrapi@unex.es
Volume 4, Number 4, pp 246-250
Abstract
The objective of this work was to determine the effect of varying fat content on the most important sensory characteristics of a vanilla-flavoured milk. By using a descriptive method for the sensory analysis, milk solutions with the same concentration of vanilla flavouring and different concentration of fat were researched. Varying the fat content of solutions caused significant differences in perceived viscosity, sweet taste and flavour intensity. The sensory differences found for viscosity are related to expected differences in the instrumental viscosity of samples. However, differences in sweet taste and flavour intensity can not be related to changes in the concentration of the compounds directly involved in the perception of those characteristics. These differences confirm that fat plays multiple and complex functions in food, including in vanilla-flavoured milk. © 2004 Altaga. All rights reserved.
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EFFECT OF PLASTICIZER, pH AND HYDRATION ON THE
MECHANICAL AND BARRIER PROPERTIES OF ZEIN AND ETHYLCELLULOSE FILMS
Romero-Bastida, C.A.1*; Martin-Polo, M.O.2; Velazquez, G.3; Torres, J.A.3
1Depto. de Desarrollo Tecnológico, Centro de Desarrollo de Productos Bióticos. Carr. Yautpec-Jojutla Km. 8.5, Col. San Isidro, Yautepec, Morelos, México. C. P. 62731
2Departamento de Investigación y Posgrado en Alimentos. Universidad Autónoma de Querétaro, Querétaro, México
3Department of Food Science & Technology. Oregon State University, 100 Wiegand Hall, Corvallis OR, 97330.
Volume 4, Number 4, pp 251-256
Abstract
Edible barrier films complement modified atmosphere in preserving food quality and extending shelf life. The effects of plasticizer (stearic acid or propylene glycol), pH (4.4 or 9.4) and degree of hydration (58 or 84% RH) on the water vapor permeability, tensile strength and percent elongation at breakpoint were determined for zein and ethylcellulose films. Zein film hydration increased water permeability and elongation at breakpoint for both plasticizers while tensile strength decreased. Hydration of ethylcellulose films had no effect on their barrier properties.© 2004 Altaga. All rights reserved.
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CHANGES IN THE NUTRITIONAL VALUE OF POTATOES DURING DIFFERENT CULINARY PROCESSES
Suárez Hernández, P.; Rodríguez Rodríguez, E.M.; Díaz Romero, C*
??rea de Nutrición y Bromatología. Departamento de Química Analítica, Nutrición y Bromatología. Universidad de La Laguna. Santa Cruz de Tenerife.
*Autor para la correspondencia. E-mail: cdiaz@ull.es
Volume 4, Number 4, pp 257-261
Abstract
The contents of moisture, ash, protein, fat, starch and ascorbic acid present in Cara potatoes, before and after to apply the following culinary processes: fried, boiled, baked and wrinkled («arrugado»), were determined in order to know the real contribution of these nutrients for its consumption. The frying is the culinary treatment that produces a higher water loss, being replaced partly by oil, which representing the 20.2% of dry weight. In the other three forms of preparation, lower water losses were observed. The starch and ascorbic acid contents decreased with the culinary processes applied, except during frying. In relation to the protein and ash contents, the fried and baked potatoes were, respectively, the richest in these nutrients. This is due to the dehydration and starch loss that takes place in the frying and baked respectively. The boiled potatoes showed, in contrast, the smallest protein and ash concentrations, which is the result of leaching into the cooking water.When the results were expressed in dry weight, the starch, ash and ascorbic acid contents decreased and the protein contents increased with the culinary processes applied. The baked potatoes were those that showed higher and lower contents of protein and ascorbic acid respectively. The boiled potatoes had the lowest ash content, which is probably due to dissolution processes, and the wrinkled («arrugado») and baked potatoes presented the lowest contents of starch. © 2004 Altaga. All rights reserved.
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MICROENCAPSULATION OF BARLEY GREEN JUICE BY SPRAY DRYING
García-Gutiérrez, C.1*; González-Maldonado, M. B.1; Ochoa-Martínez, L. A.2 ; Medrano-Roldán, H.2
1CIIDIR-COFAA-IPN. Unidad Durango. Sigma s/n Fracc. 20 de Nov. II. C. P. 34220. Durango, Dgo. México. E-mail: garciacipriano@hotmail.com
2InstitutoTecnológico de Durango. Av. Felipe Pescador No. 1830 Ote. C. P. 34080.
Durango, Dgo. México.
Volume 4, Number 4, pp 262-266
Abstract
The barley green (BG) Hordeum vulgare L. is a plant with a high nutritive value. Spray drying (SD) has been used as a technique to encapsulate food materials, keeping its nutritional properties. The objective of this work was to evaluate the SD operation conditions to obtain microencapsulate BG powder. Parameters such as moisture content, color, proteins, sugars, minerals and, rehydration properties were determined. Juice from BG was obtained and maltodextrin was added as microencapsulating agent. The SD operation conditions were: inlet air temperature: 120, 140, and 160°C; maltodextrin concentration: 1, 3 and 5%, feed rate: 9, 11, and 13 ml/min; outlet air temperature ranged from 70 to 80°C. L*, a* and b* parameters in BG powder had significant differences with respect to juice. Due to inlet air temperatures statistical differences (p£0.5, F=395.98), while the maltodextrin concentration and feed rate did not have statistical differences with respect to microencapsulate nutritive properties (p³0.05). Statistical differences were found between treatments with respect to rehydratation properties, moisture content and temperature, so these were the most influencing parameters. © 2004 Altaga. All rights reserved.
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CHARACTERIZATION OF POLYPHENOL OXIDASE OF SOURSOP (Annona muricata L.) FRUIT AND A COMPARATIVE STUDY OF ITS INHIBITION IN ENZYME EXTRACT AND IN PULP
Bora, P. S.1*; Holschuh, H. J.1; da Silva Vasconcelos, M. A.2
1Departamento de Tecnologia Química e de Alimentos, Universidade Federal da Paraíba, João Pessoa, 58059-900 Brazil.
2Departamento de Nutrição, Universidade Federal de Pernambuco, Recife, Brazil.
* Autor para la correspondencia. E-mail: Pradesh@uol.com.br
Volume 4, Number 4, pp 267-273
Abstract
Crude enzyme extract containing polyphenoloxidase (PPO) was obtained from ripe soursop (Annona muricata L.) fruit by extraction with 0.2 M phosphate buffer (pH 7.5) containing 0.5 M NaCl, followed by precipitation with 20, 40, 60 and 80% saturation of ammonium sulfate and dialysis against distilled water at 4ºC. The maximum PPO activity was observed in the protein fraction obtained with 60% ammonium sulphate saturation. The effect of pH (3 to 8.8), temperature (20 to 60ºC) and chemical inhibitors (ascorbic acid, EDTA and SO2) at several concentrations on the PPO activity was studied. The optimum pH and temperature for PPO activity were 7.5 and 32ºC, respectively. Among chemical inhibitors, ascorbic acid and SO2 were almost equally effective, but EDTA showed very small inhibitory effect. 61.9 and 71.5% inhibition of PPO was achieved using 0.28 mM and 0.84 mM concentrations of ascorbic acid, while for 55.4 and 70.2% inhibition 0.78 mM and 2.34 mM concentrations of SO2 were needed. Heating the enzyme extract at 70, 80, 90 and 95ºC for 6 s reduced 15.2, 49.5, 84.8 and 95.1% PPO activity, respectively. At the natural pH of pulp (4.3), SO2 at concentration of 3.9 mM reduced specific activity of PPO from about 60 to about 8.4 U/mg protein in partially-purified enzyme extract (PPEE), while the specific activity of 22.5 U/mg protein was retained in the pulp. Heating PPEE at 80ºC at pH 4.3 (natural pH of pulp) for about 14 s decreased specific enzyme activity from 60.0 to about 11.0 U/mg and heating during 8 min decreased to 9.0 U/mg protein. © 2004 Altaga. All rights reserved.
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EFFECT OF TUMBLING OR MARINATION WITH CALCIUM CHLORIDE
ON BOVINE MEAT TEXTURE
1Instituto de Ciencias Agropecuarias, Universidad Autónoma del Estado de Hidalgo en Tulancingo, Hidalgo, México.
2Departamento de Higiene y Tecnología de Alimentos, Universidad de León, León, España.
3Laboratorio de Alimentos, Tecnológico de Estudios Superiores de Ecatepec, Ecatepec, México.
4Departamento de Biotecnología, Universidad Autónoma Metropolitana Iztapalapa, Ciudad de México, México.
*Autor para la correspondencia: rtenotio@uaeh.reduaeh.mx
Volume 4, Number 4, pp 274-277
Abstract
In meat industry, meat marination could be employed to preserve and enhance the value of fresh cuts considered as hard with low commercialization and added value. The objective of this work was to determine the use of calcium chloride marinating in a vacuum tumbling system in order to increase meat tenderness, determined the texture (as shear force) and the final calcium concentration. Marinating conditions were established in four tumbling levels (turns per minute, TPM): 1000, 2000, 3000 and 4000. Control was a sample without tumbling and marinated by immersion 48h at 4°C in same calcium chloride solution (150 mM). Results shown that the number of TPM had no significantly effect (P>0.05) on the studied variables, but the samples treated in vacuum tumbling were more tender (lower shear force values), improving the mechanical characteristics of the lower commercial value meat cuts. © 2004 Altaga. All rights reserved.
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TOLERANCE OF Oenococcus oeni RS1 TO STRESS ENVIRONMENTAL CONDITIONS
OF WINE
Mesas, J. M.1*; Rodríguez, M. C.2; Alegre, M. T.3
1Departamento de Química Analítica, Nutrición y Bromatología (??rea de Tecnología de Alimentos). Escuela Politécnica Superior. Universidad de Santiago de Compostela. 27002 Lugo. España.
2Departamento de Fisiología Vegetal. Escuela Politécnica Superior. Universidad de Santiago de Compostela. 27002 Lugo. España.
3Departamento de Microbiología y Parasitología. Escuela Politécnica Superior. Universidad de Santiago de Compostela. 27002 Lugo. España.
*Autor para la correspondencia: E-mail: jmesas@lugo.usc.es
Volume 4, Number 4, pp 278-282
Abstract
The tolerance of Oenococcus oeni RS1 to different stress conditions of the wine, its natural habitat, has been studied. The results obtained indicate that, in our assay conditions, the O. oeni RS1 strain exhibit high tolerance to the adverse environmental conditions given by the wine (temperature, high acidity, presence of SO2, ethanol, aromas and metals). In the other hand, when the RS1 strain, who carries the plasmid pRS1, is compared with the RS1C7 strain, who lacks it, the implication of the plasmid pRS1 on the resistance mechanism to the stress conditions gave by antioxidant compounds as SO2 and geraniol can be concluded. © 2004 Altaga. All rights reserved.
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EVALUATION OF HEMICELLULOSIC SUGARS FROM VINE-TRIMMING WASTES AND VINIFICATION LEES AS A NUTRITIONAL MEDIUM FOR LACTIC ACID PRODUCTION BY LACTOBACILLUS PENTOSUS
Bustos, G.*; De la Torre, N.; Martínez, M.; Casares, A.; Domarco, Y.
Departamento de Ingeniería Química, Universidad de Vigo (Campus Ourense), As Lagoas s/n, 32004 Ourense, España
*Autor para la correspondecia. E-mail: gbvazquez@uvigo.es
Volume 4, Number 4, pp 283-291
Abstract
Lees coming from the white and red wine making technology were used in different concentrations (10, 20, 30 or 40 g/L) as an economic nutrient, in both synthetic broths or using trimmings of vineshoots as a carbon source. In this last case, trimmings were hydrolyzed under a prehydrolysis process with 3 % H2SO4 during 15 min. The results were compared with those obtained when using the general broth of Lactobacillus. With the purpose of not diluting the hydrolysates, lees were freeze-dried. When using lees coming from the white wine making technology, the lactic acid concentrations were similar or even higher than those achieved when the general broth of Lactobacillus was used. Yields in these fermentations oscillated between 0.43 and 0.59 g/g. The volumetric productivities of these fermentations, calculated after 33 h, show also similar values. © 2004 Altaga. All rights reserved.
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