Advances in Science, Biotechnology and Safety of Foods
Edited by
Santos García Hugo Sergio García Galindo Guadalupe Virginia Nevárez-Moorillón
Asociación Mexicana de Ciencias de los Alimentos, A.C.
An official publication of the Asociaci贸n Mexicana de Ciencias de los Alimentos, A.C. (AMECA)
ISBN: 978-607-95455-4-3 Published by the Asociaci贸n Mexicana de Ciencia de los Alimentos, A.C. First Edition
All Rights Reserved 漏2015 Asociaci贸n Mexicana de Ciencia de los Alimentos, A.C. No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying or recording of by any information storage and retrieval systems, without written permission of the copyright owner. Printed in Mexico
Contents Foreword……………………………………………………………………………….. Preface………………………………………………………………………………...... Editors………………………………………………………………………………...... Part I Food Chemistry and Biochemistry The Wild Mexican Blackberries: Plants for Antioxidant and Human Food………....... M.B. Silva-Adame, A.T. Chávez-Bárcenas, A.E. Bárcenas-Ortega, E.F. Hernández-Valdés, R.E. Pérez-Sánchez, P.A. García-Saucedo Extraction and Characterization of Dyes from Bouganvillea glabra for Potential Use as a Food Additive…………………………………………………………………… A. Osorio-Alva, D.I. Murillo-Monroy, F. Cruz-Sosa, L. Buendía-González, J. Orozco-Villafuerte Antioxidant Properties and the Potential Hypoglycemic Effect of Lambrisco (Vauquelinia corymbosa) Leaf Extracts Obtained Under Different Solid-Liquid Extraction Conditions …………………………………………………………………. K. Rojero, E. Joya, E. Ortega-Rivas, D. Morales-Corral, S.B. Pérez-Vega, I. Salmerón Stability and Antioxidant Activity of Seed-Coat Black Beans (Phaseolus vulgaris L.) Microencapsulated by Spray Drying …………………………………………………… I.M. García-Sánchez, S.L. Martínez-Vargas, A.A. Sánchez-Colín, P.V. Martínez-Reyes, A.Y. Guadarrama-Lezama, H. Carrillo-Navas, C. Pérez-Alonso Alternative Conditions for Polyphenolics Extraction from Black Common Bean (Phaseolus vulgaris L.) Varieties …………………………………………………...... S. G. Alba-Murguia, X. Aparicio-Fernández Evaluation of Antinutritional Factor Phytic Acid on Triticale AN66 from Coahuila State (Mexico), at Different Phenological State……………………………………….... A. A. Neira Vielma, E. Nava Reyna, A. Iliná, A.J. Lozano del Rio, G. Michelena, L.G. Gaona, J.L. Martínez Hernández Protein Hydrolysates Obtained from Azufrado (sulphur yellow) Beans (Phaseolus vulgaris): ACE-Inhibitory and Antioxidative Characterization………..………………. C.I. Fuentes-Gutiérrez, L.J. Germán-Báez, R. Gutiérrez-Dorado, S. Medina-Godoy, A. Valdez-Ortiz Shelf Life of Cookies with Flour Lentil and Microcapsules of Flaxseed Oil as a Source of Polyunsaturated Fatty Acids………………..……………………………………...... J.G. Báez González, M.P. Morones Ramírez, M G Alanís Guzmán, C.T. Gallardo Rivera, M.G. Ibarra Robles, M. E. Rodríguez Huezo Free Gluten Bakery Product for Celiacs ……………………………………………...... E. Ochoa-Reyes, H. De la Garza-Toledo, X. RuelasChacón, J.F. Hernández-Ángel, C.N. Aguilar, J. de J. Ornelas-Paz Dietary Fiber- Invertase Supplement for Sucrose Intolerance Regulation…………… C. Balvantín-García, E. P. Segura-Ceniceros, J. L. Martínez-Hernández, A. Ilina Mitigating effect of calcium and magnesium on acrylamide formation in tortilla chips..
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R. Salazar, G. Arámbula-Villa, E. Gutierrez-Arias, G. Luna-Bárcenas, E. Azuara Hybrids Development of Quality Protein Maize for Highlands Valleys of Mexico: Genetic Advance in Relation to Parents Average …………………………………...... 91 G. F. Gutiérrez-Hernández, J. L. Arellano-Vázquez, J. M. Vázquez-Ramos, E. García-Ramírez, P. Vázquez-Lozano Exploration of Aroma Quality of Mezcal by Sensory Analysis and Chromatographic Analysis………………………………………………………………………………...... 97 S. E. García-Barrón, A. Gschaedler-Mathis, H. B. Escalona-Buendía, S.J. Villanueva-Rodríguez Evaluation of the Acceptance of Mixed Stabilizers in Goat Milk Ice Cream ……………… 105 L. Hernández-González, L. Isidro-Requejo, S. Fernández-Michel, M.L. Froto-Madariaga Sensory Evaluation of Marinated Beef with Chía-Base Marinator …………………...... 111 S.M. Sánchez-Chi, J.A. Vázquez-Rodríguez, A.R García-Arellano, J.G. Báez-González, M.A. Núñez-González, C.A. Amaya-Guerra
Part II Food Biotechnology Effect of Fermentation Conditions on the Production of a Pineapple Wine (Ananas comosus (L.) Merrill) …………………………………………………………..………. M. Martínez-Minaya, E. N. Aquino-Bolaños, M. López del Castillo-Lozano Sensory Evaluation of Handcrafted Corn Malt Beverages: Sendechó and Corn Beer…. M.A Romero-Medina, N.N. Cruz-Rodríguez, H.B. Escalona-Buendía, J. R Verde-Calvo Production and Partial Characterization of Lipase from Aspergillus niger Obtained by Submerged Fermentation in Conventional Media ………………………………….…. D. Y. López, Y. Osuna, A. Iliná and J.L Martínez Preliminary culture conditions for carotenoids production by Rhodotorula glutinis YB-252 in solid-state fermentation ……………………………….…………………... A.Y. Hernández-Almanza, C.G. Martínez-Ávila, J.C. Montañez-Sáenz, R. Rodríguez-Herrera, C.N. Aguilar Pectin Oligomers Obtained By Enzymatic Hydrolysis of Guava And Papaya Cell Walls ……………………………………………………………………...……………. R. Vélez-de la Rocha, R. C. Heras-Gaspar, R, J.C. Contreras-Esquivel, J. A. Sañudo- Barajas Enzymatic Activity Of Peroxidase and Catalase from Fresh Coriandrum sativum and Petroselinum crispum ………………………………………………………………… A.M. García-Frayre, Y.T. Gallardo-Navarro, M.T. Cruz-y-Victoria.
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Part III Food Processing and Engineering Use of maguey (Agave spp.) leaves as a source of functional ingredients in cooked sausages elaboration ………………………………………………….………………... 163 B.I. Castillejos-Gómez, A. Totosaus, M.L. Pérez-Chabela iv
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Glass Transition and Water Activity of Model Food Systems Analogous to Fruit Powder Composition………………………………………………………………. M. Z. Saavedra-Leos, A. Grajales-Lagunes, R. González-García, A. Toxqui-Terán, S. A. Pérez-García, M. Abud-Archila, M. Moscosa-Santillán and M. A. RuizCabrera Thermal Analysis Characterization in Apple Osmotic Dehydration…………………. M. E. Rosas-Mendoza, J. L. Arjona-Román Mass Transfer Modeling during Osmotic Dehydration of Foods Shaped as Annular Cylinders ……………………………………………………………..………………... B. Ortiz-García-Carrasco, H. Ruiz-Espinosa, M.A. García-Alvarado, I.I. Ruiz-López Modeling the Apparent Density and Shrinkage Characteristics of Fruits and Vegetables during Convective Drying ………………………………..………………. E. Molinos-Badillo, H. Ruiz-Espinosa, M.L. Luna-Guevara, I.I. Ruiz-López Water Diffusivity Determination During Osmotic Dehydration of Kiwi Fruit and Guava Chips………………………………..…………………………………………... W.N. Hernández-Díaz, F.J. Hernández-Campos, C. Gomez-Cruz, J.A. Tinoco-Alonso, O. Quiroz-Cardoso,L.A. Arau-Roffiel, M.A. Benitez. Water Adsorption Isotherms for Tascalate, A Powder Employed To Make A Traditional Beverage Of Chiapas, México …………………………...………………... L.J. Corzo-Rios, M. A. Aguilar-Méndez, M.E. Ramirez-Ortíz Ratio of the Activation Energy of the Drying Process of Aqueous Solutions of Biopolymers With the Efficiency of Microencapsulation …………………………… J.G. Báez González, C.A. Amaya Guerra; M.A. Núñez González, M.E. Rodríguez Huezo, C.T. Gallardo Rivera, E.J. Vernon Carter Physical and rheological characterization of edible coatings formulated with a BWP (biopolymer - wax - polyol) system …………………………………………………… E. Ochoa Reyes, D.G. Martínez Vázquez, E. Jimenez Regalado, H. De La Garza Toledo, J.C. Montanez, R. Rojas, J. de J. Ornelas-Paz, C.N. Aguilar Production of Nixtamalyzed Corn Flour by Continuous Ohmic Heating……………… I. Ménera-López, M. Gaytán-Martínez, M.L. Reyes-Vega, E. Morales-Sánchez Optimization Osmotic Dehydration by Vacuum Packaging of Fresh-cut Mango.…… M.L. Zambrano-Zaragoza, A. Álvarez-Cárdenas, M.E. Jiménez-Vieyra, E. Gutiérrez-Cortez, G.G. Ayala Scale-Up and Sustainability Evaluation in the Solvent Extraction of Peanut Skin Antioxidants ……………………………………………………………………………………………………………… S.A. Medina-González, H.F. Almeida-Trasviña, I. Salmerón-Ochoa, D. Morales-Corral, S.B. Pérez-Vega Shelf Life Estimation of Extruded Snacks Expanded by Frying and by Using Hot Air Stored in Polypropylene and Metallized Polypropylene Packaging ………...………… J.C.I. Barcenas Serrano, J.G. Pérez Flores, A. Castañeda Ovando, J. Jaimez Ordaz, E. Contreras López Rehydration of Cooked-Lyophilized longissimus dorsi Pork…………..……………… J. Coria-Hernández, R. Meléndez-Pérez, J.L. Arjona-Román, J. López-Pérez, A. Llorente-Bousquets Effect of Heat Treatment on the Degradation of β-Carotene Nanocapsules in a
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Scraped Surface Heat Exchanger (SSHE)……………………………………………… R.M. González-Reza, M.L. Zambrano-Zaragoza, J.J. Flores-Minutti, D. Quintanar-Guerrero Precooling by Nanocapsule Coating Application and Hydrofluidization on Fresh-Cut Fruit……………………………………………………………………..……………… A. Álvarez-Cárdenas, J. Hernández-Viveros, T.L. Vázquez-Avila, D. Quintanar-Guerrero, M.L. Zambrano-Zaragoza A Feasibility Study for the Production of Added Value Compounds from Apple Waste: A Simulation Case……………………………………………………………… H.F. Almeida-Trasviña, S.A. Medina-González, E. Ortega-Rivas, S.B. Pérez-Vega Elaboration of a Carboxymethylcellulose/Gelatin Based Edible Coating for Application in Minimally Processed Golden Delicious Apple and Cantaloupe Melon... A.L. Velázquez Mendoza, J. Castillón Jardón
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Part IV Food Safety and Food Microbiology Pycnoporus sanguineus Pigment Extracts Against Phytopathogenic Fungi (Colletotrichum fragariae, C. gloeosporioides and Botrytis cinerea) ……………….... R. Cruz-Muñoz,, Y. M. Gómez-Gómez, G. Valencia-del-Toro, F. Robles-Martínez, J. Yañez-Fernández, R. Villanueva-Arce, S. Bautista-Baños Production of Pectate Lyase by Colletotrichum spp. from Mango Ataulfo as a Mechanism of Pathogenicity…………………………………………………………… A. Berecochea-López, J.A. Ragazzo-Sánchez, R. Allende-Molar, G.D. Avila-Quezada, H. Cabanillas-Beltrán, M. Calderon-Santoyo Evaluation Effectiveness Evaluation Of Extracts Of Wild And Cultivated Axihuitl (Eupatorium Aschembornianum Sch) To Control Phytopathogens …………………. J. Canales-Enriquez, E. Nava-Reyna, G. Rincón-Enriquez, A. Iliná, J.L. Martínez-Hernández Plant Growth Promoting Bacteria in the Nutraceutical Quality of Mexican Strawberry Fruits……………………………………………………….…………………………... M.A. González-Urías, G. Vázquez-Gálvez, J. Molina-Torres, E. Ramírez-Chávez, L.F Soria-Martínez, R. Serrato-Flores, M.V. Angoa-Pérez, H.G Mena-Violante Analysis of Some Mechanisms of Inhibition by Chitosan in Cell Germination of Colletotrichum sp. Isolated from Banana Fruits (Musa sapientum).………………….... V.A. Ochoa-Jiménez, G. Berumen-Varela, M.A. Chacón-López, P. Gutiérrez-Martínez Isolation and Molecular Identification of Curvularia lunata/Cochliobolus lunatus Causal Agent of Leaf Spot Disease of Cocoa …………………………………..…...... J. A. Cuervo-Parra, T. Romero-Cortes, M. Ramírez-Lepe Antimicrobial Activity of Rosmarinus officinalis on Methicillin-Resistant Staphylococcus aureus, susceptible Staphylococcus aureus and Salmonella typhi. ………
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I. Piñón-Trinidad, O. Gaona-Quintanilla, J. A. Torres-Castillo, E. Sánchez-González, C. Bautista-Carrillo, C. Martínez-Caballero, A. Gutiérrez-Diez, C. Ojeda-Zacarías, V. E. Aguirre-Arzola
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Antimicrobial Activity Against Escherichia coli or Listeria monocytogenes of Extracts Obtained from Three Mexican Pepper (Capsicum) ………………………… T.G. Cerón-Carrillo, N.A. Santiesteban-López, A. López-Malo, E. Palou Viability of Lactobacillus paracasei Encapsulated by Spray Gun…………………… A.G. Peredo Lovillo, H.E. Romero Luna, C.I. Beristain Guevara, E. Azuara Nieto, G. Luna Solano, M. Jiménez Fernández Use of ICMSF sampling programs for the detection of Listeria spp in pork obtained from a TIF slaughterhouse……..……………………………………………………… S. García-Pedraza, J. López-Pérez, A. Llorente-Bousquets
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Foreword When we talk about science, biotechnology and safety of food, we encompass critical areas, not only for the survival of the population, but also to provide ways to improve the wellbeing of society. Every region, country or consortium of countries, must work in these areas to improve or maintain the quality of food provided for their own people. Academia, government and industry also must work together to promote food security, safety, quality and innovation. Working together is the key, and this team has the tools to discover, develop or innovate in the science of food and apply these results to resolve challenges facing our society. The studies presented in this book reflect the effort of many institutions to provide better food. Many of them reflect the cooperation between national institutions, which is needed in most cases to generate more information. Others show international collaborative efforts most of them to resolve international or global challenges. The main objective of this book is to publish selected studies presented at the 5th Food Science and Food Biotechnology in Developing Countries. These studies provide an idea of what is being done in our societies. What needs to be clarified is that this kind of science is not “developing science” conducted in developing countries, but modern science conducted in developing countries to be applied globally. As seen in this book, traditions and behaviors are unique to specific regions or countries. Each of the latter, are able to provide much information and many resources to develop, innovate and offer an unlimited number of food products to the word. On the other hand, the unlimited possibilities for the mixing compounds and use of various technologies to grow, produce and process foods, are what make food science very attractive to me and to others.
Dr. Santos García President, Asociación Mexicana de Ciencias de los Alimentos
Preface The book constitutes a volume, part of a series, based on selected contributions presented at the 5th International Congress on Food Science and Food Biotechnology in Developing Countries. The congress took place at Nuevo Vallarta, Nayarit, Mexico, in October 2012. The event gathered experts and delegates, not only from developing countries but from nations all around the globe, and served the purpose of discussing and analysing the stateof-the-art on food science, food biotechnology and Food Safety. The main objective of the series of congresses organised by AMECA has been always to promote a harmonic development in research and technology transfer in the ample subject of food science and food biotechnology. The strategy has been aimed at placing into perspective the situation of research efforts of developing countries but with the intention to promote exchange, discussion, and analysis with the global academic community, in order to seek a more uniform development in the general area of food sciences. So far the series of congresses have provided a proper forum of interaction of all the sectors involved in food production, processing and distribution, including students, academics, and industrialists alike. The book comprises four sections or parts, dealing with relevant main themes of the subject of food science, i.e.: food chemistry and biochemistry, food biotechnology, food processing and engineering, and food safety and microbiology. Food chemistry and biochemistry section includes topics of food properties, nutrition, functional foods, sensory evaluation, etc. Food biotechnology focuses on topics like food fermentations, enzymes in foods, etc. Food processing and engineering includes conventional processing and preservation technologies, such as drying and pasteurisation, as well as non-predominant food methodologies including ohmic heating. Each part includes several research papers drawn from the voluntary contributions of the meeting. The purpose of the book is to give an insight on how food components and preservation technologies can be combined to provide healthy foods to the world population.
Santos García Hugo Sergio García Galindo Guadalupe Virginia Nevárez-Moorillón
Chapter 37
Precooling by Nanocapsule Coating Application and Hydrofluidization on Fresh-Cut Fruit A. Álvarez-Cárdenasa*, J. Hernández-Viverosa, T.L. Vázquez-Avilaa, D. Quintanar-Guerrerob, M.L. Zambrano-Zaragozaa. Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México. aLaboratorio de Procesos de Transformación y Tecnologías Emergentes en Alimentos. bLaboratorio de Posgrado en Tecnología Farmacéutica. Cuautitlán Izcalli, Edo de México, CP 54740. México.
Abstract
The hydrofludization is an operation for precooling and freezing of food. This technology has the advantage of generating a surface turbulence and an increase in the surface heat transfer. The nanotechnology applied to food preservation has been recently applied by our group to encapsulate active substances such as antioxidants (e.g. a-tocopherol) and incorporated in coatings for fresh-cut fruit. The results have showed an important effect to maintain the quality of different food products. The purpose of this study was to evaluate the effect of nanocapsule coatings combined with hydrofluidization and their influence on precooling process on fresh-cut fruit. The physical behavior of model system of nanocapsule coating (0.1% xanthan and 0.5% propylene glycol) and the size of hydrofluidization plate holes (2 and 4 mm) were evaluated in order to obtain the thermal parameters during the process as a new way to apply the coating and precooling (2ºC ± 0.5°C). The rheological characterization showed that the fluid at 2ºC had a power law behavior. After 30 s it act as Newtonian fluid with a viscosity of 0.008 Pa·s, which determined the pump selection for recirculation, thus there is not objection for coating application. The Biot values were between 8 and 13.5 in spheres of d’Anjou pears and Red Globe grapes did not show resistance to the convection heat transfer. The higher coefficient of heat transfer was obtained with plate holes of 2 mm and the grapes had the longest time of cooling. According to the results of color, the thickness of coating, the cooling time and the superficial characterization of fresh-cut fruits, hydrofluidization can be used for precooling the product and coating application. Keywords: nanocapsules, cooling, fruit, heat transfer, coating. Introduction The increase in consumption of fresh-cut fruit and vegetables has resulted in frequent foodborne outbreaks. It is well known that minimally processed fruits and vegetables are generally more perishable than the original raw materials, being prone to surface browning caused by oxidase enzymes (Rojas-Graü et al., 2006). The use nanocapsule dispersion in coatings has revealed effectiveness in the fresh-cut preservation particularly with apples (Zambrano-Zaragoza et al., 2014). Coating formulation is important because may release active sustances during the storage time, helping in this way in the increase of fresh-cut fuits shelf life (Embuscado and Huber, 2009). Due to the benefits of nano coatings and the need to integrate components on the application in fresh-cut fruit, it is necessary to *
Corresponding autor: Phone: +52(55)56232032, Email: alfac@unam.mx
Science, Biotechnology and Safety of Foods
develope techniques for practical application. One way to carry out the cooling is hydrofluidization. Hydrocooling is the most efficient method to cover the total area of the fruit reducing the cooling times compared to other methods (Teruel et al., 2003). This process consistists in a recirculation system wherein the product is immersed in a fluid at low temperature. The cooling medium is pumped through orifices or nozzles to a container, creating a fluid bed that agitates the liquid increasing the heat transfer and lowering the temperature of food (Brosnan and Sun, 2001). The hydrofluidization is a method that arose from the combination of fluid bed and immersion cooling, offering the advantages of both. This is an emerging technology and it has been applied for pre-cooling and freezing operation in horticulture products. Hydrofluidization has numerous potential advantages: 1) The turbulence and the velocity of the cooling medium guarantee to cover the entire surface of the product and can increase the heat transfer coefficient; 2) it allows individual cooling and 3) the addition of substances to the cooling medium such as antioxidants, flavors and stabilizers help to maintain the sensory and quality properties of foods (Peralta et al., 2009). However, to our knowledge there is not studies reporting hydrofluidization as method for coating application. Nanotechnology applied to food preservation has been currently focused to develop nutraceutical and functional coatings, encapsulation of actives and other preservation applications (Weiss et al., 2006). One very important aspect is that the film forming system and their application needs to provide a uniform distribution and homogenous nanocapsule allocation. The immersion, aspersion and brushes are the more common forms of application of coatings in fruits. In general, the application by immersion and by aspersion has not an adequate uniformity. Therefore, the hydrofluidization may be used to develop an alternative method for cooling and coating application, thereby achieving a decrease in the reactions rate of product for the pre-cooling, and increasing the maintenance of quality and sensorial characteristic of fresh-cut fruit during refrigeration. The aim this study was to evaluate the effectiveness of coating application by hydrofluidization at low temperature on fresh-cut fruit. The model system was a coating based on nanocapsules and xanthan gum; interrelating the superficial characteristics and color coating with the heat transfer parameters. This process is evaluated as an alternative approach to handle fresh-cut fruits.
Materials and Methods Red Globe grapes and d’Anjou pears in their commercial maturity were purchased in a local market. The fruit selection was made based on color, shape and dimensions. The fruits were minimally processed, skin was removed and the pears were cut in spheres with dimensions similar to the grapes. Three homogeneous lots of fruits were selected, weighed and measured with a digital caliper. The factors to study were type of fruit (grape or pear) and diameter of holes in the fluidization plate (2 and 4 mm). All experiments were done in triplicate. The output values were flow rate at the exit of the holes, cooling time, surface structure of coating (optical microscope IROSCOPE brand with PHF SI-20X magnification), color (Minolta CR-300, USA) and thermal history. Responses variables 270
Food Processing and Engineering
were: cooling rate, cooling parameters (Dinçer, 1997), thermal diffusivity, heat transfer coefficient (Correlation with Re, and Nu) and color. Nanocapsules dispersion used as coating and cooling system was prepared with 1 g/L xanthan gum, 5 g/L propylene glycol, 0.1 g/L antifoam and 0.1 g/L methylene blue as coating tracer. Figure 1 shows the hidrofluidizatior adaptation that was done based on the initial operation with water. Two plates with holes of 2 and 4 mm of diameter were used by modified the flow rate of fluidizing streams, generating change of fluid turbulence around of fruit that affect the heat transfers coefficients and the superfitial characteristics or fruit by application of coating. Adaptation and characterization of the equipment (Figure 1) was done based on the operation with water and subsequently with the fluid model with nanocapsules. Two plates were used with holes of 4 and 2 mm of diameter. The effect of diameter of the holes over the velocity of the fluidizing streams and the turbulence generated around the food were evaluated in relation to the effect on heat transfer coefficients and the characteristic of coating formed for each fruit. In order to do a comparison between condition of hydrofluidization and application of coating, the color surface were evaluated in the following treatments: (1) covering by hydrofluidization, with initial temperature at 20 ± 1.5°C and cooling medium at 2 ± 0.5°C and pre-cooling time of 5 to 6 min, (2) covering by hydrofluidization for 1 min, initial temperature of product at 20 ± 1.5°C and cooling medium at 2 ± 0.5°C; (3) hydrofluidization for 1 min , cooling medium at 2 ± 0.5°C with pre-cooled product in the cooling chamber 4 ± 0.5°C; and (4) conventional dip coating 1min at room temperature 20 ± 1.5°C. After doing the above treatments, samples were stabilized and dried in contact with air at 16 ± 0.5°C.
Figure 1. Hydrofludization system. (a) experimental tank; (b) perforated plate; (c) overflow; (d) fluid return (Jácome, 2011).
Experimental design In order to stablish the effectivity of hydrofluidization coating and pre-cooling a factorial desing 22 was used. The treatment of results were analyzer using Minitab Release 14®. Preparation of nanocapsules Nanocapsules were prepared by emulsification-diffusion method proposed by QuintanarGuerrero et al. (1998), considering the optimization approach proposed by Zambrano271
Science, Biotechnology and Safety of Foods
Zaragoza et al. (2011). An aqueous phase saturated with ethyl acetate (20 mL) containing pluronic-127 (50 g/L) and an oily phase saturated with water (40 mL) containing PCL (~250 mg) and α-tocopherol acetate (2 g/L) were used. The nanocapsules were characterized in relation to particle size, polydispersion index and zeta potential through an equipment of dispersion laser at 90° (Malvern Zetasizer, Nano Serie, Ltd Francia). Rheological characterization The rheological characterization of the model fluid was done on a Haake Rheometer 323 RehoWin using a concentric cylinder (Z-40 DIN). The test was conducted at flow conditions used in the pump of hydrofluidization equipment (1 - 400 s-1). The flow curves (rheograms) were evaluated using power law linear models. Determination of cooling parameters The temperature measurement in two opposing areas was monitored to obtain thermal histories using a digital thermocouple (K-type thermocouple, Check Temp digital Hanna HI 98509). The cooling coefficient was obtained for the equation: TP - Tm Ti - Tm
= je
- ( CC )( t )
and the convective coefficient was calculated in function to the Reynolds and Nusselt.
Results and Discussion The nanocapsules prepared had a particle size of 247 nm and polydispersion index of 0.18 which indicates that are submicronic particles with monomodal and narrow distribution. These results are similar to those obtained by Relkin et al. (2008), who reported a monomodal behavior for α-tocopherol nanoemulsions prepared by the homogenization method with particle sizes below 200 nm. Narrow PDI values (< 0.3) are indicative of a homogeneous particle distribution. Furthermore, zeta potential was of -37 mV meaning little likelihood of dispersion aggregation, since an absolute value less than or greater than 25 mV is indicative of flocculated and deflocculated emulsions, respectively (Mirhosseini et al., 2008). Rheological Characterization Figure 2 shows the rheograms for the shear stress and the viscosity change. The model had a thixotropic behavior with a fluidizer rise curve that fits with the power model and then decrease with a Newtonian behavior. This difference is attributed to changes in fluid viscosity as a function of time, probably due to the action of propylene glycol and xanthan gum structure causing a reduction in the cohesion of the polymer chain structure opening sheared so that the viscosity decreases dramatically. The centrifugal pump driving hidrofluidization at 3 560 rpm (372.8 s-1) carries the fluid to the bottom chamber to 4.2 s, so during this time the fluid shear caused by the pump is sufficient to change its apparent viscosity (10 – 8 cP).
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Thermal parameters of cooling The thermal conductivity of the grapes and pears were 0.50 and 0.43 kJ/kg°C respectively and thermal diffusivity values were 1.81 x 10-7 and 1.25 x 10-7 m2/s. Table 1 shows the main parameters obtained during the hydrofluidization process. The use of the plate with holes of 4 mm increases cooling time due to the turbulence generated in the chamber which decreases with respect to the plate with 2 mm holes. The retardation factor (j) shows that the cooling hydrofluidization does not follow Newton's law. Therefore, this process should be treated differently, being necessary to consider the properties of the product (Dinçer, 1995). The retardation factor (j) obtained was significantly higher that the reported. This behavior is due to the turbulence generated by the hydrofluidization, because of the speed in the chamber is 0.028 m/s, which is greater than the minimum fluidization velocity that was of 0.019 m/s, this behavior facilitates the fluidization and cooling of the fruit. Table 1. Cooling parameters by hydrofluidization with nanocapsules. Fruit
Holes diameter
Time 1/2 of cooling (min)
Time 7/8 of cooling (min)
J
Bi
hm (W/m2°C)
2 mm
2.08
5.42
1.2153
13.4
805.08
4 mm
2.53
6.00
1.2494
8.1
485.32
2 mm
1.78
4.74
1.2135
17.5
602.33
4 mm
1.93
4.98
1.2025
10.5
363.10
Grape
Pear
Figure 3 shows the dependence of heat transfer coefficients on the surface respect to the diameter of the holes and the nature of the fruit. It is observed that highest speed was achieved with the 2 mm-holes plate for grapes; this velocity depends on the difference of temperatures between the cooling medium, the product temperature and the fruit structure.
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The hydrofluidization is a process that has been reported with transfer superficial coefficients of 154 to 1.54 W/m2 °C (Laurindo et al., 2010); in this study results were within this range, independently of the type and structure of fruit, but related to the diameter of the holes in the plate.
Evaluation of color of coating
The values of chroma (color intensity), Hue angle and total color difference (DE) were evaluated in the different treatments. The results demonstrated that the movement of the spheres during hydrofluidization fruit not allowed that the coating was deposited on the fruit and will form a non-homogeneous and thick film. The previously pre-cooling fruit at 4 °C by forced convection and subsequent hydrofluidization (1 min) in cooling medium at 2 ± 0.5 °C showed the lowest color intensity in grape. The adhesion of fluid to the wall of the fruit at 4 °C was lower compared with those treated from ambient temperature. This indicates that the time required for pre-cooling decrease the capacity to coat by the hydrofluidizator device.
Superficial structure of the coating Microscopic evaluation allowed the observation of the coating formed during the hydrofluidization process and compared with the dip coating application. Figure 4 shows the micrograph of untreated fruit and the Figure 5 shows the coating samples, these 274
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micrographs showed a uniform and continuous coating. The coating formed represents a resistance to heat loss. The cooling 7/8 was of 5.4 min in grape and of 4.7 min in pear with a hydrofluidization plate of 2 mm. The low viscosity of the fluid, porosity and turbulence in the chamber does not limit the coating layer formed around of the fruits. Another of most significant differences between the dip coating and hydrofluidization coating was that the fruit is in constant motion due to the turbulent movement in the system and constant transport of the fruits. The turbulence causes a boundary layer formed around the fruits which helps to control the thickness coating, as shown in the micrograph of the Figure 5. A
B
Figure 4. Micrographs with samples without treatment a) pear; b) grape (20 X).
A
B
Figure 5. Micrographs after hydrofluidization process a) pear coating; b) grape coating all at 20 X
Conclusions The dispersion of nanocapsules used as cooling medium and as coating in fresh-cut fruit applied by hydrofluidization had beneficial results, considering that values of heat transfer surface were between 363 and 805 W/m2 째C; high convective coefficients were obtained with plate of holes of 2 mm, with shorter cooling time. The coating formation during cooling was dependent on time, viscosity, cooling medium, porosity of fruit and the turbulence created during operation. The microscopy evidenced that the formation of the coating depends on the rheological properties of the fluid and the physical characteristics of the fruit. The main advantage was that precooling by hydrofluidization permits application of a coating on the fresh-cut fruit with nanocapsules, establishing this operation as an alternative effective of fruit postharvest handling that can be used on an industrial scale. Acknowledgement The authors acknowledge the financial support for this work from PAPIME PE206664 and PAPIIT IT-200814 of DGAPA-UNAM. 275
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Digital edition was done during January 2015, by the Asociación Mexicana de Ciencia de los Alimentos. San Nicolás de los Garza, Nuevo Léon, México. 250 CD units were produced.