José Ángel Guerrero-Beltrán

High Hydrostatic Pressure Processing of Fruit and Vegetable Products

High hydrostatic pressure (HHP) as a minimal thermal technology is a valuable tool for microbiologically safe and shelf-stable fruit and vegetable production. Microorganisms and deteriorative enzymes can be inhibited or inactivated depending on the amount of pressure and time applied to the product. The resistance of microorganisms and enzymes to pressure in fruit and vegetable products also is dependent on both the type and the amount of enzymes or microorganisms as well as food composition. While on one hand, microorganisms (other than spores) can be inactivated at mild pressures (< 300 MPa), on the other, enzymes can be very resistant to pressure and their resistance may increase when isolated forms are pressurized. Nevertheless, microbiologically safe fruit and vegetable products can be obtained without change in flavor if temperature is not increased beyond pasteurization temperatures. The remaining enzyme activity in HHP processed fruit and vegetable products can be delayed if a combination of obstacles, such as refrigeration temperatures, low pH, and antibrowning agents, are used to increase the shelf life of these types of products. Therefore, HHP is a promising minimal thermal technology that can be used to deliver more variety of less processed fruit and vegetable products than consumers are demanding today.

Inactivation of Saccharomyces cerevisiae and polyphenoloxidase in mango nectar treated with UV light.

Fresh mango nectar was processed by UV light at five flow rates (0.073 to 0.451 liter/min) and five UV light doses (75 to 450 kJ/m2) to evaluate total microbial load, Saccharomyces cerevisiae survival, and polyphenoloxidase activity. UV systems containing an inner mercury lamp (254 nm) each with intensity of 25 mW/cm2 were used as germicidal sources. In addition, mango nectar was treated for 15 min at 0.073 and 0.451 liter/min, stored at 3°C, and evaluated periodically for total microbial count, yeast count, color, and polyphenoloxidase activity. The first-order kinetics modeling found that DUV-values in mango nectar ranged from 27.9 to 10.9 min (R2 > 0.950) and 26.0 to 11.8 min (R2 > 0.962) for total microbial count and yeast count, respectively. The maximum log reduction (CFU per milliliter) was 2.71 and 2.94 for total microbial count and yeast count, respectively, after 30 min of UV treatment at 0.451 liter/min. DUV-values ranging from 156 to 204 min were observed for polyphenoloxidase activity. The re...

High hydrostatic pressure processing of mango puree containing antibrowning agents

Natural mango puree and purees containing cysteine (Cys, 200 ppm) or ascorbic acid (AA, 500ppm) were treated at high hydrostatic pressure, HHP (379 to 586 MPa) for selected times (0, 0.033, 5, 10, 15 and 20min) to assess changes in polyphenoloxidase (PPO) activity. Mango purees were stored at 31°C. Colour parameters (L*, a* and b*) were analysed to evaluate colour stability. PPO activity was inhibited from 93.8 to 89.7 or 85.5 enzyme activity units (EAU) after adding AAor Cys, respectively. Such inhibition was improved after applying HHP, by an average of 69.5± 10.6, 4.2 ± 2.2 and 47.0 ± 35.2 EAU for natural purees, purees containing ascorbic acid or cysteine, respectively. No significant differences (p≥ 0.05) were observed in PPO activity at 448, 517 and 586 MPa after 10 or 20 min of treatment for natural mango puree and puree containing cysteine. The total colour difference (Δ E*) increased as storage time increased. However, this colour difference was barely noticeable (p≥ 0.05) after 27 days of storage for natural puree (9.1 ± 0.9), puree containing ascorbic acid (8.8 ± 1.2), and cysteine (16.4 ± 3.5).

Antioxidant properties and color of Hibiscus sabdariffa extracts

Se obtuvieron extractos liquidos de calices secos de flor de Jamaica (Hibiscus sabdariffa) usando etanol:agua (en proporciones de 50:50 y 70:30%, v/v), agua, etanol:HCl 1.5 N (85:25%, v/v), y etanol (96%), para evaluar algunas caracteristicas antioxidantes (compuestos fenolicos y capacidad antioxidante), parametros de color (L, a, and b), antocianinas (delfinidin-3-O-sambubiosido, delfinidin-3-O-glucosido (mirtillin) y cianidin-3-O-sambubiosido), por cromatografia liquida de alta resolucion (HPLC), y antocianinas monomericas totales, por el metodo de pH diferencial. Los compuestos fenoli-cos se encontraron en un intervalo de 1.067±22 (en etanol) a 2.649±96 (en etanol:agua 70:30%, v/v) mg of acido galico 100 g-1 de calices secos de flor de Jamaica. La capacidad antioxidante se encontro en un rango de 3,11±0,50 (en etanol) a 8,04±0,22 mmoles de trolox 100 g-1 de calices secos de flor de Jamaica. El contenido de antocianinas monomericas totales (209±21 mg 100-1 g), evaluado por el metodo de pH diferencial, resulto similar al obtenido por el metodo de HPLC (215±31 mg 100 g-1) al usar la solucion de etanol:agua al 50:50% (v/v) como agente de extraccion. La solucion de color rojo mas intenso (Tono = 62,50±0,34) fue la obtenida con etanol. Las propiedades antioxidantes y de color de flor de Jamaica hacen que los extractos de esta flor sean de importancia primordial para ser usados en alimentos como extractos naturales, en forma concentrada o en polvo.

Ultraviolet-C light effect on physicochemical, bioactive, microbiological, and sensorial characteristics of carrot (Daucus carota) beverages

The aim of this research was to evaluate the effect of ultraviolet-C light on physicochemical, bioactive, microbial, and sensory characteristics of carrot beverages. Beverages were formulated with different concentrations of carrot juice (60, 80, and 100% [v/v]) and treated with ultraviolet-C light at different flow rates (0, 0.5, 3.9, and 7.9 mL s−1) and times (5, 10, 15, 20, and 30 min), equivalent to ultraviolet-C dosages of 13.2, 26.4, 39.6, 52.8, and 79.2 J cm−2. Total soluble solids, pH, and titratable acidity were not affected by the ultraviolet-C light treatment. Ultraviolet-C light significantly affected (p < 0.05) color parameters of pure juice; however, at low concentration of juice, total color change was slightly affected (ΔE = 2.0 ± 0.7). Phenolic compounds (4.1 ± 0.1, 5.2 ± 0.2, and 8.6 ± 0.3 mg of GAE 100 mL−1 of beverage with 60, 80, and 100% of juice, respectively) and antioxidant capacity (6.1 ± 0.4, 8.5 ± 0.4, and 9.4 ± 0.3 mg of Trolox 100 mL−1 of beverage with 60, 80, and 100% of juice, respectively) of carrot beverages were not affected by ultraviolet-C light treatment. Microbial kinetics showed that mesophiles were mostly reduced at high flow rates in carrot beverages with 60% of juice. Maximum logarithmic reductions for mesophiles and total coliforms were 3.2 ± 0.1 and 2.6 ± 0.1, respectively, after 30 min of ultraviolet-C light processing. Beverages were well accepted (6–7) by judges who did not perceive the difference between untreated and Ultraviolet-C light treated beverages.

Physicochemical and antioxidant characterization of Justicia spicigera

Extracts with water:ethanol (100:0, 70:30, 50:50, 30:70, 0:100) solutions from fresh (F), just dried (JD), dried and stored for one year (DS) Justicia spicigera leaves were obtained using the stirring and ultrasound techniques. Extracts were analyzed in physicochemical and antioxidant characteristics. Identification of chemical compounds by gas chromatography-mass spectroscopy (GC-MS) was also performed. 2.14±0.91, 5.67±1.70, and 8.52±4.97g Gallic acid equivalents/100g dry weight (d.w.) of phenolic compounds were found, in average, for F, JD, and DS J. spicigera, respectively. 2.22±1.31, 2.58±2.11, and 8.48±3.78g Trolox equivalents/100g d.w. were detected with the ABTS method and 0.49±0.33, 1.23±0.87, and 0.88±0.94g with the DPPH method for F, JD and DS J. spicigera, respectively. Eucalyptol, phytol, and azulene were identified as the main compounds. J. spicigera showed colors (green-iridescent, green-yellow, or pink of different intensities) and antioxidant characteristics depending on the solvent concentration. Extracts could be used in the food and pharmaceutical industries.

Effect of high hydrostatic pressure on mycelial development, spore viability and enzyme activity of Penicillium Roqueforti.

This study investigated the effect of high hydrostatic pressure treatments on mycelial development, spore viability, and total proteolytic and lipolytic activity of Penicillium roqueforti PV-LYO 10 D. Fungus growing in liquid medium was pressure-treated at 300, 400, and 500 MPa for 10 min at 20°C following seven days of incubation at 25°C and analyzed periodically up to day 9 after treatments to evaluate the effect on fungal growth. Mycelial mass of P. roqueforti was significantly affected at all pressure treatments evaluated, being 15.48%, 22.28%, 30.03%, and 12.53% lower than controls on day 1, 3, 6, and 9 after 300 MPa treatment, respectively. In a similar way, at 400 and 500 MPa, mycelial mass was 31.08% and 60.34% lower than controls one day after treatments and 49.74% and 80.85% lower on day 9, respectively. The viability of P. roqueforti spores decreased by 36.53% at 300 MPa, and complete inactivation took place at ≥400 MPa from an initial count of 7 log cfu/mL. Total proteolytic activity was not significantly affected at 300 MPa but was reduced by 18.22% at 400 MPa and by 43.18% at 500 MPa. Total lipolytic activity also decreased as the intensity of the pressure treatments increased. 21.69%, 39.12%, and 56.26% activity reductions were observed when treatments of 300, 400 and 500 MPa were applied, respectively. The results from this study show that pressure treatments are able to control growth, inactivate spores, and alter enzyme activity of P. roqueforti, which could be of interest in extending the shelf-life of blue-veined cheeses and other food products.

Moisture Sorption Isotherms of Foods: Experimental Methodology, Mathematical Analysis, and Practical Applications

Knowing the moisture content of a product is insufficient to predict its stability, making it necessary to also know its water activity (aw), a thermodynamic property describing the interactions between water molecules and the food matrix. Moisture sorption isotherms, i.e., the relationship between moisture content and aw at constant pressure and temperature describing the sorption process of water molecules into a specific material, are useful when identifying optimal food dehydration and storage conditions. Moisture sorption properties affect physicochemical and biological phenomena such as enzymatic degradation, microbial activity, food microstructure, sensory quality deterioration, nutrient losses, and other changes limiting the shelf life of food products. Some of these phenomena are associated with water mobility, which is also related with the phase transitions from a “glass” or amorphous to a “rubbery” state. Glass transition is a second order phase transition associated with time, temperature, and moisture content. When fresh foods are dried, water removal leaves behind an amorphous material. A desirable final product moisture level is one that corresponds to a glass transition temperature (Tg) higher than the product storage temperature. Therefore, knowing Tg helps in setting the food storage and/or process conditions required to retain textural properties and to predict the shelf life of low and intermediate moisture content foods.

Figo da india— Opuntia spp.

Abstract Prickly pear, cactus pear or “tuna” is the fruit of the cactus pads tree (Opuntia spp.) or “nopal” member of the Cactaceae family. There are a number of prickly pears with a wide range of flavors and colors. Prickly pears are known with different scientific names (Opuntia spp.) and common names, depending on the interior and exterior colors, size, and region of production. Pale-green, yellow, orange, magenta, red, and red–purple are the color of prickly pear pulp. Prickly pear is produced in Summer over a very short period of time. Fresh fruits do not last too long, even stored at refrigeration conditions. Today, the fruit is eaten fresh or as juice, chilled or at room temperature; however, there are some locally manufactured products such as preserves, prickly pear fudge, crystallized prickly pear, and prickly pear wine in some villages or towns where the fruit is grown. However, there are a number of Opuntia spp. prickly pears that grows in nature that are not consumed.