Paul B. Zamudio-Flores

Physicochemical, Antimicrobial and Antioxidant Properties of Chitosan Films Incorporated with Carvacrol

Chitosan films (CF) with carvacrol (CAR) [0.5%, 1.0% and 1.5% v/v] were prepared by the emulsion method. The retained CAR, water solubility, water vapor permeability (WVP), optical, mechanical properties, antibacterial and antioxidant capacity of films were analyzed. The results indicate that the retention of CAR in the CF was ≈50%. The incorporation of CAR to CF decreased the water solubility, the WVP, the yellowing and transparency and the tensile strength, but increased the stiffness. Microcapsules with diameters of 2 to 7 µm were found on the surface CF-CAR. The CF-CAR with highest CAR concentrations showed antibacterial activity against S. typhimurium and E. coli O157:H7. The CF-CAR had higher antioxidant capacity and an increased protective effect against oxidation of erythrocytes in different grades. These results suggest potential applications of CF-CAR as active packaging to preserve food products.

Development and characterization of edible films based on mucilage of Opuntia ficus-indica (L.).

Mucilage of Opuntia ficus-indica (OFI) was extracted and characterized by its composition and molecular weight distribution. Mucilage film-forming dispersions were prepared under different pHs (3, 4, 5.6, 7, and 8) and calcium concentration (0% and 30% of CaCl(2), with respect to mucilages weight), and their particle size determined. Mucilage films with and without calcium (MFCa and MF, respectively) were prepared. The effect of calcium and pH on mucilage films was evaluated determining thickness, color, water vapor permeability (WVP), tensile strength (TS), and percentage of elongation (%E). The average molecular weight of the different fractions of mucilage was: 3.4 x 10(6) (0.73%), 1 x 10(5) (1.46%), 1.1 x 10(3) (45.79%), and 2.4 x 10(2) Da (52.03%). Aqueous mucilage dispersions with no calcium presented particles with an average size d(0.5) of 15.4 microm, greater than the dispersions with calcium, 13.2 microm. MFCa films showed more thickness (0.13 mm) than the MF films (0.10 mm). The addition of calcium increased the WVP of the films from 109.94 to 130.45 gmm/m(2)dkPa. Calcium and pH affected the mechanical properties of the films; the largest TS was observed on MF films, whereas the highest %E was observed on MFCa films. The highest differences among MF and MFCa films were observed at pHs 5.6 and 7 for TS and at pHs 4 and 8 for %E. No effect of pH and calcium was observed on luminosity and hue angle. Chroma values were higher for MF when compared with MFCa, and increased as pH of the films increased. Practical Application: In this study mucilage from nopal was extracted and characterized by its ability to form edible films under different pHs, and with or without the addition of calcium. Opuntia ficus-indica mucilage had the ability to form edible films. In general, it can be considered that mucilage films without modification of pH and without the addition of calcium have the best water vapor barrier properties and tensile strength. Mucilage from nopal could represent a good option for the development of edible films in countries where nopal is highly produced at low cost, constituting a processing alternative for nopal.

Effect of ripening and heat processing on the physicochemical and rheological properties of pepper pectins.

Water-, chelator-, and alkali-soluble pectins were isolated from raw and heat-processed Jalapeño peppers (green and red) and their physiochemical and rheological properties were determined. The yield, tristimulus color, degree of methyl esterification, monosaccharide composition, molecular weights distribution, and protein content depended on ripening and heat processing. The viscosity properties of pectins were independent of ripening. The water-soluble pectin was the most abundant pectin. Pectins from grilled peppers showed the lowest L* values. The alkali-soluble pectin showed the highest protein content. The content of xylose, rhamnose, and mannose in pectins was highly altered by tested factors. The degree of methyl esterification of pectins ranged from 26.8 to 91.6%. The peak Mw of the main fraction of tested pectins was sequentially reduced by ripening and heat processing. Pectins from raw peppers showed the best viscosity properties.

Effect of storage time on physicochemical and textural properties of sausages covered with oxidized banana starch film with and without betalains

In this study, two types of oxidized banana starch films (betalains and no betalains) were prepared and used as covering for sausages, then were refrigerated for 20 days at 4°C and 5% relative humidity (RH). The sausages covered were analyzed (covered with films without betalains = F1 and covered with films with betalains = F2) and they were compared with a control (without covering). The sausages were evaluated every 5 days by physicochemical analysis of color, size, weight loss, pH and quantification of betalains in the films. Textural analysis was performed on the sausages. The results indicated that films did not significantly alter the color or moisture loss during storage (P > 0.05), while the F2 films maintained the amount of thiobarbituric acid reactive substances in the sausages during storage (P < 0.05). Sausages covered with both types of film maintained their texture characteristics for longer compared to the control.

Effect of ripening, heat processing, and fat type on the micellarization of pigments from jalapeño peppers.

Raw and heat-processed (boiled and grilled) jalapeño peppers at three intermediate ripening stages (brown, 50% red, and 75% red) were digested in vitro without fat and in the presence of soybean oil (SO) or beef tallow (BT), and the micellarization of their lipid soluble pigments (LSP) was measured. The micelles from digestions with brown, 50% red, and 75% red peppers contained up to 27, 35, and 29 different LSP, respectively. Boiling and grilling decreased the micellarization of LSP from brown peppers, whereas the opposite was observed with 75% red peppers. Heat processing did not clearly affect the micellarization of LSP from 50% red fruits. The impact of fat on LSP micellarization was ripening-dependent, but the micellarization of the less polar carotenoids was always increased by SO or BT. This positive effect of fat was higher with SO than with BT.

Partial characterization of chayotextle starch-based films added with ascorbic acid encapsulated in resistant starch

Chayotextle starch was modified by subjecting it to a dual treatment with acid and heating-cooling cycles. This caused a decrease in the content of amylose, which showed values of 30.22%, 4.80%, 3.27% and 3.57% for native chayotextle starch (NCS), starch modified by acid hydrolysis (CMS), and CMS with one (CMS1AC) and three autoclave cycles (CMS3AC), respectively. The percentage of crystallinity showed an increase of 36.9%-62% for NCS and CMS3AC. The highest content of resistant starch (RS) was observed in CMS3AC (37.05%). The microcapsules were made with CMS3AC due to its higher RS content; the total content of ascorbic acid of the microcapsules was 82.3%. The addition of different concentrations of CMS3AC microcapsules (0%, 2.5%, 6.255% and 12.5%) to chayotextle starch-based films (CSF) increased their tensile strength and elastic modulus. The content of ascorbic acid and RS in CSF was ranged from 0% to 59.4% and from 4.84% to 37.05% in the control film and in the film mixed with CMS3AC microcapsules, respectively. Water vapor permeability (WVP) values decreased with increasing concentrations of microcapsules in the films. Microscopy observations showed that higher concentrations of microcapsules caused agglomerations due their poor distribution in the matrix of the films.

Use of High-Performance Size-Exclusion Chromatography for Characterization of Amylose Isolated from Diverse Botanical Sources

Amyloses were isolated from diverse botanical sources (apple, mango, maize, and potato), and they were studied in their molecular characteristics (amylose content, molar mass, and molecular weight) using high-performance size-exclusion chromatography as a repetitive and faster protocol. The amylose purity ranged between 85.6–92.6 %, in agreement with the λmax values (601–610 nm), showing that some impurities with molecules of higher molar mass (amylopectin) were present. The standard curve of pullulan showed a high regression coefficient (0.998) inside of the limits of molar mass of amylose. Chromatograms of amylose showed the presence of components of high molar mass with a principal peak that corresponds to amylose. Molar mass of amylose ranged between 1.2 and 8.5 × 105 g/mol with polydispersity values between 1.3–4.1, indicating a narrow range of molar mass distribution of the amyloses analyzed. The high-performance size-exclusion chromatography coupled with a refractive index methodology used in this study may be considered simple and rapid for molecular studies of amylose.

Prevalence, typing and phylogenetic analysis of Melissococcus plutonius strains from bee colonies of the State of Chihuahua, Mexico

European foulbrood (EFB) caused by Melissococcus plutonius is an important bee brood disease but, in Mexico, information about this bacterium is limited. We evaluated the prevalence of typical and atypical strains in beehives of seven apicultural regions of the state of Chihuahua, Mexico. We performed MLST and phylogenetic analysis to characterize the isolates. Prevalence was highest 59%, in the region of Chihuahua, and lowest, 14%, in the regions of Cuauhtémoc and Nuevo Casas Grandes. Typical and atypical strains were identified in hives from all regions; however, in the regions of Parral, Cuauhtémoc and Aldama, the atypical strains were only detected in combination with typical strains. We obtained 81 isolates of M. plutonius and identified seven sequence types, of which three were new types. Additionally, we observed a relation between sequence type and the region where the strain was isolated. Phylogenetic analysis and multilocus sequence typing using goeBURST analysis showed that 97.5% of the isolates correspond to the Clonal Complex (CC) 12 and 2.5% to the CC3. Our work is the first molecular characterization of M. plutonius in Mexico and contributes to global information about the epidemiology of this pathogen.

Predation Capability and Functional Response of Chrysoperla carnea1 to Choristoneura rosaceana2 under Laboratory Conditions

Abstract. Functional response of third-instar larvae of green lacewing, Chrysoperla carnea (Stephen) (Neuroptera: Chrysopidae), to four densities of single-instar larvae of the five instars of obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), was evaluated at 25 ± 1°C in a laboratory. The aims were to determine the type and other characteristics of functional response including predatory capacity of green lacewing for possible use in augmentative biological control in apple (Malus × domestica Borkh; Rosales: Rosaceae) orchards where obliquebanded leafroller was recently introduced in Mexico. Abundance of the pest increased rapidly, causing significant foliar damage and some fruit blemish. Third-instar green lacewing larvae based on logistic regression analysis showed Type II functional response to four densities of single-instar larvae of obliquebanded leafroller. Among the five instars of prey, the largest average number consumed per green lacewing predator was a relative density of four second-instar larvae at a rate of 1.93 in 24 hours. Also, substantial average consumption was by two third-instar prey larvae per predator whereby an average of 1.5 third-instar obliquebanded leafrollers were consumed per third-instar green lacewing in 24 hours. The third-instar predator captured and consumed third-instar prey larvae in the shortest handling time (h), i.e., only 6.46 minutes, whereas the handling times for the other instars ranged from 23.48 minutes for the fifth instar to 31.56 minutes for the fourth instar. However, attack coefficients (a) of green lacewings were slightly greater for third- and fourth-instar prey larvae, with 0.19 hour (11.4 minutes) and 0.15 hour (9.0 minutes) until the first attack, respectively, compared to 0.09–0.11 hour (5.4–6.6 minutes) until the first attack for the other instars. Results indicated that the green lacewing could be considered a prospective candidate for use as a biological control agent against lepidopteran leafrollers.

Detection of viruses in colonies of honey bees (Apis mellifera L.) in the state of Chihuahua, Mexico

The honey bee Apis mellifera L. is the most studied insect due to its ecological and economic importance as a plant pollinator and producer of honey, beeswax, royal jelly and propolis. In recent years, there have been significant colony losses, due to multiple factors that include pests and pathogens such as mites, bacteria, fungi, protozoa and viruses. Of these, viruses are of great interest because of their adverse effects on bee populations, because of the limited information that we possess on these pathogens (Bailey & Ball, 1991), also because most of them persist simultaneously as sublethal infections (Allen & Ball, 1996). The mite Varroa destructor plays an important role as a mortality factor, and acts as an activator or virus vector (Bowen-Walker, Martin, & Gunn, 1999). Asymptomatic viral infections in A. mellifera, hinder visual diagnosis, so one of the most accurate methods for rapid, sensitive and specific diagnosis is the reverse transcription-polymerase chain reaction (RT-PCR) (Tentcheva et al., 2004). In Mexico a decrease in the number of honey bee colonies has been observed in recent years. The information available indicates that in 2008 there were about 1.8 million colonies, a significant reduction from the nearly two million hives that were available in 2000, although in the southeastern part of the country the loss has been attributed to weather issues (Ministry of Agriculture and Livestock, SAGARPA Mexico, 2010). In the Northern region this loss is probably due to the incidence of diseases such as Nosemosis, American foulbrood and European foulbrood (Casavantes, 2011; Gonzalez, 2014; Mancinas, 2013). Despite this, however, there is little information on the presence and distribution of viral diseases in honey bee colonies in the country. Ellis and Munn (2005) reported the presence of chronic bee paralysis virus (CBPV) and sacbrood virus (SBV) in their report about the worldwide health status of honey bees. Recently Guzman-Novoa et al. (2012) and Guzman-Novoa, Hamiduzzaman, Correa-Benı́tez, Espinosa-Montaño, and Uribe-Rubio (2013), also reported the presence of these two viruses and others including acute bee paralysis virus (ABPV), deformed wing virus (DWV) and black queen cell virus (BQCV) in A. mellifera in the region of the Mexican high plateau. However, this virus complex still retains the status of an exotic disease to Mexico, and these viruses have not been reported from the northern region. In this study we studied the incidence of these viruses in 56 apiaries in the state of Chihuahua, México using the RT-PCR technique. Larvae, adult bees and mite samples were selected randomly from eight hives from each of eight apiaries in seven major beekeeping regions of the state of Chihuahua, Mexico (Figure 1), from August to October 2013 and from March to May 2014. The sample collection and sample homogenization were as previously described by De Miranda et al. (2013) with some modifications. Firstly the samples were macerated separately in lysis buffer (0.8 M Guanidine thiocyanate, 0.4 M Ammonium thiocyanate, 0.1 M Sodium acetate, and 5% glycerol (v/v), 2% (v/v) Triton-X 100) and homogenized in TRI Reagent (Sigma–Aldrich, St. Louis, EU). RNA was isolated with the protocol according to the manufacturer. The RevertAid H Minus Reverse Transcriptase kit (Thermo Scientific, Lithuania, USA) was used for cDNA synthesis, subsequently carried out PCR amplification of cDNA. The sequence primers for ABPV, CBPV, BQCV, DWV, Kashmir bee virus (KBV), SBV and Apis-β-actin as previously described by Chen, Pettis, Collins, and Feldlaufer (2006) were used. The final volume was 25 μl including 2.5 μl 10× buffer, 1 μl of 0.4 mM dNTP mix, 1 μl of a stock 0.4 μM of each primer, 2 μl of the enzyme Taq polymerase solution and 2 μl of cDNA. Reactions were processed using two designs PCR under the following conditions: the first design for SBV, KBV and DWV was 2 min at 95 ̊C, followed by 35 cycles (30 s at 95 ̊C, 30 s at 57 ̊C and 1 min at 72 ̊C) and a