A Valdez-Fragoso

Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, Nuevo León, Mexico

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Publications (23)30.61 Total impact

  • Food Engineering Reviews 01/2014; In Review. · 2.81 Impact Factor
  • Food and Bioprocess Technology 01/2014; In Review. · 4.12 Impact Factor
  • Drying Technology 01/2014; Submitted. · 1.81 Impact Factor
  • 01/2014;
  • Drying Technology 01/2013; In preparation. · 1.81 Impact Factor
  • Journal of Functional Foods. 01/2013; 6:470-481.
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    ABSTRACT: Orange contains phytochemicals effective in the prevention/treatment of chronic diseases. Although many orange peel phytochemicals have been identified, information on their distribution in flavedo and albedo is incomplete limiting the development of applications for orange byproducts including comminuted orange obtained by grinding peel/juice and used in beverage formulations. Phytochemical concentration, antioxidant activity (AOA) and their relationship were determined for comminuted orange, juice and peel fractions. The highest vitamin C (74.7–98.2 mg ascorbic acid/100 g), flavones (235.9–265.0 mg hesperidin/100 g) and carotenoid (1.04–6.21 mg β-carotene/100 g) contents were found in flavedo. Albedo was the main source of phenolics (553.1–730.0 mg gallic acid/100 g), flavanones (1450.0–2084.5 mg hesperidin/100 g), and AOA (11953.2–15484.0 μmol trolox/100 g). AOA linearly correlated with phenolic, hesperidin, and flavonoid concentrations. Orange peel increased the phenolics, flavonoids and AOA of comminuted orange by 111%, 783% and 304%, respectively, when compared with juice, showing its potential to formulate functional foods.
    Journal of Functional Foods. 01/2013;
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    ABSTRACT: The food-processing industry has made large investments in processing facilities relying mostly on conventional thermal processing technologies with well-established reliability and efficacy. Replacing them with one of the novel alternatives recently developed is a decision that must be carefully approached. Among them, high-pressure processing (HPP), at room or refrigerated temperature, is now a well-established option experiencing worldwide commercial growth. Surveys have shown an excellent consumer acceptance of HPP technology. For financial feasibility reasons, HPP treatments must be kept short, a challenge that can be met by some of the alternatives here reviewed such as the use of the hurdle technology concept. Although HPP technology is limited to pasteurization treatments, the combination of high pressure and high temperature used in pressure-assisted thermal processing (PATP) can be used to sterilize foods. An analysis of alternatives to achieve the inactivation of bacterial spores at the lowest temperature possible highlights the need for additional research on the use of germinants. Because of incomplete research, PATP presents several implementation challenges, including the modeling of food temperature, the determination of inactivation kinetics particularly for bacterial spores, and the prediction of chemical changes including the potential formation of toxic compounds. KeywordsHigh-pressure processing (HPP)–Pressure-assisted thermal processing (PATP)–Pressure-induced pH sh
    Food and Bioprocess Technology 01/2011; 4(6):969-985. · 4.12 Impact Factor
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    ABSTRACT: Consumers demand, in addition to excellent eating quality, high standards of safety and nutrition in ready-to-eat food. This requires a continuous improvement in conventional processing technologies and the development of new alternatives. Prevailing technologies such as thermal processing can cause extensive and undesirable chemical changes in food composition while minimal processing strategies cannot eliminate all microbial pathogens. This review focuses on pressure-assisted thermal processing, a new alternative for shelf-stable foods. Its implementation requires an analysis of reaction kinetics at high pressure and elevated temperature. Acceleration of the inactivation of bacterial spores by the synergistic effect of pressure and temperature is expected to allow processing at lower temperature, shorter process time, or a combination of both. Therefore, thermal degradation of quality is expected to be lower than that of conventional thermal processes. However, few studies have focused on the effect of the conditions required for the inactivation of bacterial spores on the kinetics of chemical reactions degrading food quality, particularly at the high temperatures required for the processing of low-acid foods. KeywordsPressure-assisted thermal processing (PATP)–Reaction kinetics–Novel foods laws–Activation energy–Activation volume
    Food and Bioprocess Technology 01/2010; 4(6):986-995. · 4.12 Impact Factor
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    ABSTRACT: The firmness of green prickly pear fruits (Opuntia ficus indica) impregnated with a sucrose isotonic solution (IS) was evaluated. Whole fresh-peeled prickly pears were processed under different combinations of vacuum pressure (pv), vacuum application time (tv) and relaxation time (tr). Puncture test was applied to impregnated and fresh whole prickly pears. The maximum force (Fmax), average force (Fav) and the work (Wp) required to puncture 3 cm in the fruits were measured. Second order models provided good fits to the experimental data of Fmax (R2 = 0.754), Fav (R2 = 0.788) and Wp (R2 = 0.792). Impregnation factors pv, tr, tv–tr significantly affected firmness parameters (P ≤ 0.05). Firmness parameters of fresh-peeled prickly pear were Fmax = 10.934 ± 1.571 N, Fav = 2.152 ± 0.270 N and Wp = 5.930 × 10−2 ± 0.0054 Nm. Firmness reduction of impregnated fruits was linked to the IS impregnation levels and deformation-relaxation phenomena.PRACTICAL APPLICATIONSThe aim of this study was to assess the influence of impregnation conditions on firmness of whole peeled prickly pear, as excessive softening is the main factor limiting consumer acceptability. This study helps to identify the better impregnation conditions for maintaining firmness. This information could be useful for the application of vacuum impregnation in the development of fruits and vegetables products, in which the impregnating solution is used as a carrier of active agents. To date, very limited studies have been conducted in whole fruits involving only peeling and impregnation operations.
    Journal of Texture Studies 09/2009; 40(5):571 - 583. · 1.05 Impact Factor
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    ABSTRACT: Mass transfer between whole red cherry pepper and pickling solution, as well as firmness and stability indicators of the pickled product, were studied. Experiments were conducted at atmospheric pressure with an initial vacuum pulse (50 cm Hg for 3 min) (PV) or without a vacuum pulse (PA), in sodium chloride (10–15 g/100 g) and acetic acid (2.3–3.5 g/100 g) solutions, during 0.3–30 days. Statistically significant equations were obtained (p ⩽ 0.05) to describe the pickling and firmness parameters of cherry pepper, and stability indicators. PA treatments mainly caused pepper dehydration, but PV promoted water and solutes gain. Firmness values were slightly lower in PV than in PA treatments. Vacuum pulse pickling allowed achieving lower pH and aw values (pH = 2.97, aw = 0.964) than pickling without the initial vacuum pulse (pH = 3.33, aw = 0.972). PV treatments resulted in weight gain of cherry peppers and succeeded in reducing pH and aw to levels that would enhance pepper stability.
    Journal of Food Engineering. 01/2009; 95(4):648-655.
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    ABSTRACT: Confectionery products constitute a very important branch in the food industry. There are several confectionery products: chewing gum, candy, and chocolate among others. Beside chocolate, chewing gum is one of the most consumed products in the world. Chewing gum is a product made with natural or man-made gums, polymers, and copolymers, added with other ingredients and food additives. Traditionally, chewing gum was made of natural gums, although for reasons of economy and quality, many modern chewing gums use synthetic gums. These have proven beneficial in providing high consistency of chewing quality. To obtain acceptable products, gum properties must be maintained during manufacture of chewing gum. Most chewing gums are manufactured according to the following steps: The gum base is melted; other ingredients are added and mixed. The blended gum passes onto cooling belts and is bathed in currents of cool air to reduce its temperature; after this, the gum is extruded and flattened into thinner and thinner sheets. The gum passes into the scoring machine. The scored sheets are conditioned (“set” in an air-conditioned room) and then, candy-coated. Finally, the chewing gum is wrapped.
    02/2008: pages 139-153;
  • Agro Food Industry Hi Tech 02/2008; 19(1):35-36. · 0.23 Impact Factor
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    ABSTRACT: Puffed wheat, traditionally consumed as a ready-to-eat breakfast cereal, is normally covered with sweet coatings. To make it more appealing to different tastes and consumers, the coating may also have colored ingredients added. Due to the rugged surface of puffed wheat, colored coats do not totally cover the particulate, causing problems of appearance that may affect overall quality. There is a need to develop uniform coats in order to improve physical properties, such as color and texture. Puffed wheat was coated with sweetened chocolate syrups by tumbling and a fluidized bed. Different proportions of sugar, cocoa, and starch were used to develop the cover and obtain an optimum formulation. The coated wheat was characterized by instrumental techniques. The developed product using the fluidized bed technique presented a firmer consistency and a more uniform color than the tumbling-coated and the commercial wheat.
    Particulate Science And Technology 11/2007; 25(6):549-554. · 0.44 Impact Factor
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    ABSTRACT: Pickling is a preservation method of vegetables by brine immersion. Residual pickling solutions cannot be reused owing to high yeast content and the presence of polygalacturonase, which may produce vegetable softening. It has been reported that high-pressure homogenization can reduce enzyme activity and microbial population in liquid foods. An investigation was aimed at studying the effect of high-pressure homogenization cycles on polygalacturonase activity and yeast survival of residual pickling solutions, from processing of six vegetables. Each pickling solution was pumped through a homogenizing valve at 69 MPa pressure and was recirculated up to 15 times. Yeast counts and polygalacturonase activity were determined in treated solutions after being subjected to 1, 2, 5, 10, and 15 pressure cycles. Untreated and thermally treated solutions were used for comparison. Up to 4 log reductions in yeast inactivation was observed after five high-pressure cycles treatments, contrasted with only 2 log reductions in thermal treatment. No clear relationship between enzyme inactivation and the number of high pressure cycles, or a thermal parallel effect, were observed. Copyright © 2007 Society of Chemical Industry
    Journal of the Science of Food and Agriculture 03/2007; 87(6):1157 - 1163. · 1.76 Impact Factor
  • A. VALDEZ-FRAGOSO, H. MUJICA-PAZ, F. GIROUX, J. WELTI-CHANES
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    ABSTRACT: Osmotic dehydration (OD) treatments of apple cubes were carried out in a pilot plant, which consisted of an OD vessel, a filter, a vacuum evaporator, and recirculating pumps. The osmotic solution (OS) was maintained at 59.5 ± 1.5 °Brix and 50C by reconcentration in the evaporator, and suspended particles were eliminated by filtration. OS was reused to process 20 batches of apple cubes, maintaining a constant OS/fruit ratio of 5/1 (w/w) by addition of new OS. Evolution of pH, titratable acidity, soluble solids, water activity, color, reducing sugars, and microbial load in the OS was evaluated along the OD process. The OD parameters and the apple color were determined. Values of the physicochemical properties of the OS stabilized after 10 treated batches. A microbial load of 2590 ± 330 CFU/mL was observed in the OS at the end of 20 OD treatments. Water loss, solids gain and color of dehydrated apple cubesobtained in OD process with reuse of the OS were similar to those found in an OD process carried out with a nonrewed OS.
    Journal of Food Process Engineering 01/2007; 25(2):125 - 139. · 0.56 Impact Factor
  • A. VALDEZ-FRAGOSO, H. MUJICA-PAZ, F. GIROUX, J. WELTI-CHANES
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    ABSTRACT: This work proposes a pilot scale equipment for osmotic dehydration (OD) of apple cubes that consists of a novel agitation-immersion device, a bag filter and a vacuum evaporator to conduct simultaneously the OD process, filtration and reconcentration of the osmotic solution (OS). The functional method analysis was used to design the pilot plant. Apple cubes (∼1 cm3) were dehydrated using a 60 ° Brix sucrose syrup OS at 50C and a syrup/fruit ratio of 5. OD was conducted either with or without reconcentration of the OS. During the OD process particles of fruit were eliminated from the OS by filtration and the OS concentration was kept at 60 ° Brix by reconcentration in the evaporator. A comparison of the dehydration parameters of apple cubes obtained at pilot scale to those obtained at laboratory scale was done to evaluate the performance of the pilot equipment. The results show that the proposed set-up can be suitable for commercial production of osmodehydrated fruits.
    Journal of Food Process Engineering 01/2007; 25(3):189 - 199. · 0.56 Impact Factor
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    ABSTRACT: Response surface methodology (RSM) was used for the optimization of the pickling process of whole jalapeño pepper, using a vacuum pulse. The pickling variables were the brine to pepper mass ratio (R = 1–10, w/w), sodium chloride concentration in the pickling brine ([NaCl]brine = 10–15%), and processing time (t2 = 10–30 d). The main response variables were solutes gain to water loss ratio (SG/WL), weight reduction (WR), concentration of sodium chloride ([NaCl]pepper), acetic acid ([CH3COOH]pepper) in the pepper tissue, and water activity of treated pepper and pickling solution. The polynomial models developed by RSM were highly significant to describe the relationships between the studied factors and the responses (p < 0.0001). Analytical optimization gave water activity values near equilibrium, the highest SG/WL ratio (2.1), and up to 6% of [NaCl]pepper and 2% of [CH3COOH]pepper, when using a [NaCl]brine = 12%, R = 4.6 and t2 = 22 d.
    Journal of Food Engineering. 01/2007; 79(4):1261-1268.
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    ABSTRACT: The kinetics incorporation of an isotonic solution (IS) into the whole jalapeño pepper, as a function of the vacuum pressure (p1, vacuum application time (t1), and relaxation time (t2), is necessary to determining the conditions leading to the highest incorporation of IS. This study was aimed at determining the operation conditions to achieve maximum impregnation (Min) of whole jalapeño pepper tissue, and a complete infiltration (Min) of its inner void with an IS, using a vacuum pulse. Impregnation of whole jalapeño peppers was conducted using an IS (aw= 0.993 ± 0.001), a vacuum pulse, and 5 levels for each process variable (t1, t2, p1), according to a central composite design. The amounts of impregnated and infiltrated IS were measured by following changes in pepper weight. The p1, t2 had a significant effect (P < 0.01) on the rate of Mim and Min (g IS/g pepper). It was found that the structure of whole jalapeño plays an important role in the deformation-relaxation process, which also affects the impregnation and infiltration kinetics. A high level of p1 (666 mbar) and t2 (840 min) allowed to achieve the maximum values of Mim and Min (0.07 and 0.29 g IS/g pepper, respectively). These results suggest that different driving force acts in promoting the Mim and Min, during the t1 and t2. This information will be of great value in the analysis of the pickling process of whole jalapeño pepper with a hypertonic solution and a vacuum pulse.
    Journal of Food Science 06/2006; 71(3):E125 - E131. · 1.78 Impact Factor
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    ABSTRACT: The combined effect of pickling time and pickling solutes concentration was studied on pickling whole jalapeño pepper by applying a vacuum pulse (VP) of 666 mbar for 5 min. Sodium chloride and acetic acid concentrations ranged from 10–15.1% to 2.3–3.2% (w/w), respectively, and the pickling or processing time varied from 0.3 to 30 days. The response surface methodology was used to evaluate the influence of the process variables on water loss (WL), solutes gain (SG) and weight reduction (WR) of jalapeño pepper. Processing time showed a linear effect on most of the pickling rate parameters (p
    Innovative Food Science & Emerging Technologies - INNOV FOOD SCI EMERG TECHNOL. 01/2006; 7(3):195-202.