Juan Arturo Ragazzo-Sánchez

Covalently Cross-Linked Arabinoxylans Films for Debaryomyces hansenii Entrapment.

In the present study, wheat water extractable arabinoxylans (WEAX) were isolated and characterized, and their capability to form covalently cross-linked films in presence of Debaryomyces hansenii was evaluated. WEAX presented an arabinose to xylose ratio of 0.60, a ferulic acid and diferulic acid content of 2.1 and 0.04 µg∙mg−1 WEAX, respectively and a Fourier Transform Infra-Red (FT-IR) spectrum typical of WEAX. The intrinsic viscosity and viscosimetric molecular weight values for WEAX were 3.6 dL∙g−1 and 440 kDa, respectively. The gelation of WEAX (1% w/v) with and without D. hansenii (1 × 107 CFU∙cm−2) was rheologically investigated by small amplitude oscillatory shear. The entrapment of D. hansenii decreased gel elasticity from 1.4 to 0.3 Pa, probably by affecting the physical interactions between WEAX chains. Covalently cross-linked WEAX films containing D. hansenii were prepared by casting. Scanning electron microscopy images show that WEAX films containing D. hansenii were porous and consisted of granular-like and fibre microstructures. Average tensile strength, elongation at break and Young’s modulus values dropped when D. hansenii was present in the film. Covalently cross-lined WEAX containing D. hansenii could be a suitable as a functional entrapping film.

Use of Electrosprayed Agave Fructans as Nanoencapsulating Hydrocolloids for Bioactives

High degree of polymerization Agave fructans (HDPAF) are presented as a novel encapsulating material. Electrospraying coating (EC) was selected as the encapsulation technique and β-carotene as the model bioactive compound. For direct electrospraying, two encapsulation methodologies (solution and emulsion) were proposed to find the formulation which provided a suitable particle morphology and an adequate concentration of β-carotene encapsulated in the particles to provide a protective effect of β-carotene by the nanocapsules. Scanning electron microscopy (SEM) images showed spherical particles with sizes ranging from 440 nm to 880 nm depending on the concentration of HDPAF and processing parameters. FTIR analysis confirmed the interaction and encapsulation of β-carotene with HDPAF. The thermal stability of β-carotene encapsulated in HDPAF was evidenced by thermogravimetric analysis (TGA). The study showed that β-carotene encapsulated in HDPAF by the EC method remained stable for up to 50 h of exposure to ultraviolet (UV) light. Therefore, HDPAF is a viable option to formulate nanocapsules as a new encapsulating material. In addition, EC allowed for increases in the ratio of β-carotene:polymer, as well as its photostability.

Antimicrobial soy protein isolate-based films: physical characterisation, active agent retention and antifungal properties against Penicillium italicum

Summary Soy protein isolates (SPI) films were evaluated as carriers of citral and limonene, and their physical and antifungal properties were evaluated. The presence of antimicrobials in SPI films resulted in changes on colour without affecting the transparency. Films with citral added were more extensible; however, a reduction in tensile strength and elastic modulus was observed in films with limonene added. Aroma compounds addition in films induced a slight increase in water vapour properties in relation to discontinuity of network proteins evidenced by SEM. Besides, FTIR spectra evidenced a partial alteration of SPI secondary structure. Citral was less retained than limonene. The increase in limonene release with high relative humidity was explained by increase in protein chain mobility. SPI films enriched with limonene exhibited strong antifungal activity against the postharvest decay pathogen Penicillium italicum under storage conditions.

Application of high hydrostatic pressure on Pacific white shrimp (Litopenaeus vannamei) pâté: Microbiological, physicochemical and consumer acceptance

The locally elaborated shrimp pâté is highly susceptible to microbial spoilage and deterioration during storage due to its content in nutrients. These conditions limit its commercialization in a larger scale. High hydrostatic pressure is an alternative to heat treatments technology used to inactivate microorganisms. The aim of this project was to evaluate the effect of high hydrostatic pressure on quality parameters and microbiological stability of Pacific white shrimp (Litopenaeus vannamei) pâté during storage. Shrimp pâté was pressurized to 400, 500 and 600 MPa for 90 and 180 s. Samples were analysed for physicochemical, microbiological and flavour profile up to 21 days of storage at 4 ℃. A hedonic test was made to evaluate the acceptance of pâté. No microorganisms were detected at 600 MPa for 180 s and a shelf life of 14 days was reached. No relevant changes in pH or colour of pressurized samples were detected; flavour profile did not show any changes after being pressurized or during storage. Shrimp pâté treated with 600 MPa for 180 s presented good sensory acceptance. High hydrostatic pressure treatments could improve microbiological quality of shrimp pâté without a sensible modification of the physicochemical and sensorial qualities of this product.

Effect of maltodextrin reduction and native agave fructans addition on the physicochemical properties of spray-dried mango and pineapple juices:

The effects of the partial replacement of maltodextrin by native agave fructans on the characteristics of spray-dried pineapple and mango powder were evaluated in this study. An experimental 33 design, three concentrations of maltodextrin (5, 7, and 10%), three concentrations of native agave fructans (0, 2, and 4%), and three feed temperatures (110, 115, and 120  ℃) were used. The results using the treatment in which only maltodextrin was used as a reference indicated that an increment in the inlet temperature decreases the moisture content, aw, and solubility. Likewise, an increase (more than 2%) in fructans concentration generates products with increased aw, moisture, hygroscopicity, wettability, and greater solubility. Additionally, no modification of storage stability was observed. Mango and pineapple powder color were affected mainly by the inlet temperature, causing an increase in luminosity (L*) and a decrease in parameter (a*). A scanning electron microscopy showed spherical powder particles with certain contractions; powder stability in treatments with native agave fructans was not modified in the treatment at 2%. Finally, the addition of 2% agave fructans as carrier material was able to reduce the maltodextrin concentration of the spray drying process.

Optimisation of the spray drying process of formulating the post-harvest biocontrol agent Meyerozyma caribbica

ABSTRACT In this study, conditions of the spray-drying process of Meyerozyma caribbica were optimised using response surface methodology (RSM). The effect of three parameters (protective agent, inlet air temperature and protective agent concentration) on the cell viability of Meyerozyma caribbica was evaluated. Each parameter was evaluated at three levels. All of the evaluated factors presented an effect on the viability of the control agent. According to RSM, optimal conditions include the use of trehalose with a concentration of 7.75% (w/v) and inlet air temperature of 112.5°C. The validation of the optimal spray-drying conditions allows obtaining a formulation of M. caribbica with 95.41 ± 0.93% viability, 5 ± 0.37% humidity and aw of 0.33 ± 0.11. Storage for six months at 4°C presented a 5% loss in cell viability.

Data on enterobacteria activity on biofilm formation at surface mango fruit (Mangifera indica L.) cv Ataulfo

Abiotic factors influenced the capacity of the strains to form biofilms. Classification of the adhesion type is related with the optical density measured on the biofilm formation of tested strains. The relationship between the biofilm formation in real values with theoretical values of the strains was used to determine the mechanism involved during mixed cultures.