H. Mújica-Paz

IMPREGNATION AND OSMOTIC DEHYDRATION OF SOME FRUITS: EFFECT OF THE VACUUM PRESSURE AND SYRUP CONCENTRATION

Apple, mango and melon were subjected to impregnation and osmotic dehydration at vacuum pressure (VI-VOD). The effect of the vacuum pressure (135–674 mbar) and concentration of the sucrose solutions (41–60°Brix) on the mass transfer parameters were evaluated. The lowest final aw levels in apple and mango were achieved with 50°Brix syrup and vacuum pressure of 674 mbar and in melon with 57°Brix and 593 mbar. Water loss of similar magnitude was observed in melon and mango, and there was water gain in the case of apple. The solids gain (SG) in apple was higher than in melon and mango. Minimal values of SG were detected in mango, and a maximum SG value was observed in apple. Melon and mango presented weight losses of up to 8.9% while the weight of apple increased. Results indicated that the impregnation phenomena predominated in the combined VI-VOD process of apple and osmotic dehydration phenomena in melon and mango.

Impregnation properties of some fruits at vacuum pressure

Abstract The effects of vacuum pressure and its application time on the volume of isotonic solution (IS) impregnated in slices of mango, apple, papaya, banana, peach, melon, and mamey were studied using response surface methodology. Fruits were subjected to vacuum impregnation (VI) treatments using sucrose IS. VI times between 3 and 45 min and vacuum pressures (VP) between 135 and 674 mbar were applied. Second order polynomials were developed to estimate the volume of IS impregnated in each fruit (R2⩾0.870). VP had a significant effect (p⩽0.10) on the volume of IS impregnated in fruit slices of all the studied fruits. The impregnation also depended significantly (p⩽0.10) on the VI time, except for apple. Under the studied conditions, the effective porosity values of the fruits varied from 0.016 for mamey to 0.330 for apple.

Phytochemical Characterization of Prickly Pear (Opuntia spp.) and of its Nutritional and Functional Properties: A Review

Prickly pear is the fruit of the nopal cactus; native from Mexico, where approximately 80 species and 150 cultivars are harvested. Production of prickly pear has been expanded to more than 30 countries. In Latin America, almost 511,035 Ton per year of prickly pear are harvested, which represents more than 50% of the worldwide production of this fruit. There are studies that have demonstrated its importance as a source of nutritional and functional compounds that provide antioxidant, antiatherogenic, antiulcerogenic, immunomodulatory and anticarcinogenic properties. Prickly pear is commonly consumed fresh, since the pulp is the edible portion; while peel and seeds are discarded as waste, these residuals contain minerals, dietary fiber, phenolics, and flavonoids in higher levels than the pulp, which could be used as a source of functional ingredients. There are findings related to the phytochemical composition of the prickly pear with functional effects, and further clinical studies are still needed in order to determine the mechanisms of action of these compounds, which could provide a greater added value to this fruit in the health area.

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.

Coating of Puffed Wheat by a Tumbling Method a Fluidized Bed Technique

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.

Controlled Atmosphere Storage: Effect on Fruit and Vegetables

Controlled atmosphere storage is a useful technology for maintaining the quality of fresh fruits and extending their postharvest life. It is accomplished by lowering the metabolic activity of the commodities through rigorous control of the temperature, relative humidity, and concentrations of oxygen, carbon dioxide, and ethylene in the storage room.