Cow's milk allergens identification by two-dimensional immunoblotting and mass spectrometry

Cow's milk allergy (CMA) has become a common disease in early childhood, its prevalence ranging from 1.6% to 2.8% among children younger than 2 years of age. The role of different cow's milk protein (CMP) in the pathogenesis of CMA is still controversial. Even if the proteins most frequently and most intensively recognized by immunoglobulin E (IgE) seem to be the most abundant in milk (caseins and beta-lactoglobulin), with an although great variability all milk proteins appear to be potential allergens, even those that are present in trace amounts (i.e., lactoferrin, IgG, and BSA). In this work proteomics techniques have been applied for CMP allergens analysis. Allergens have been identified by immunoblotting following resolution of CMP components by two-dimensional electrophoresis. Sera from 20 milk-allergic subjects, as proven by oral provocation test, CAP-RAST and skin prick test, have been used for cow's milk major allergen identification. Cow's milk proteins and their isoforms were identified by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry. In our group of patients, the prevalence of CMP allergens, i.e., the total number of subjects sensitized to CMP divided by the total number of the subjects enrolled in the study, was: 55% alpha(s1)-casein, 90% alpha(s2)-casein, 15% beta-casein, 50% kappa-casein, 45% beta-lactoglobulin, 45% BSA, 95% IgG-heavy chain, 50% lactoferrin, and 0% alpha-lactalbumin.     

Influence of Edible Coating on the Drying and Quality of Papaya (Carica papaya)

The edible coating applied to food pieces prior to hot air drying is a technology that can improve the nutritional and sensory qualities of dehydrated products. The effects of the pectin coating technique on the drying efficiency and quality of papaya slices of the Formosa cultivar were investigated, determining the cell structure, color, and vitamin C contents of the fresh and dried fruits, with and without a pectin coating. The drying kinetics was evaluated based on Fick’s Law. The analytical solution for a plane sheet was used to estimate the water effective diffusion coefficients, and, in order to take into account shrinkage during drying, the average and variable thicknesses were considered in an approximate manner. Diffusion modeling presented a better fit when considering the thickness of the slices as variable. Regarding fruit quality, the coating applied to papaya slices before drying enhances vitamin C retention in comparison to papaya dried without coating, showing that pectin coating efficiently prevented oxidation of this bioactive compound. In addition, the moisture diffusivity of the coated samples was higher than that of the non-coated slices, due to the hydrophilic nature of the pectin. Light and transmission electron microscopy images revealed intense rupturing of the cell membranes in the dried tissues. The cell tissue arrangement in the coated papaya slices was similar to that found in the fresh papaya slices, before and after drying.     

Cheese whey fermented with kefir micro‐organisms: Antagonism against Salmonella and immunomodulatory capacity

The antagonistic effect against Salmonella spp. and the immunomodulatory capacity of whey fermented with kefir grains and with three strains isolated from them – Lactobacillus plantarum CIDCA 8327, Lactobacillus kefiri CIDCA 8348 and Kluyveromyces marxianus var. marxianus CIDCA 8154 – were evaluated. Both fermented products interfered with the capacity of Salmonella spp. to associate and invade Caco‐2/TC7 cells and reduced up to the basal level the expression of the CCL20 in response to a pro‐inflammatory stimulus on Caco‐2 CCL20:luc cells. The products with potential application as probiotics obtained by fermentation of whey with kefir micro‐organisms represent an alternative to increase whey economic value.     

Aquatic Training after Joint Immobilization in Rats Promotes Adaptations in Myotendinous Junctions

The myotendinous junction (MTJ) is the muscle-tendon interface and constitutes an integrated mechanical unit to force transmission. Joint immobilization promotes muscle atrophy via disuse, while physical exercise can be used as an adaptative stimulus. In this study, we aimed to investigate the components of the MTJ and their adaptations and the associated elements triggered with aquatic training after joint immobilization. Forty-four male Wistar rats were divided into sedentary (SD), aquatic training (AT), immobilization (IM), and immobilization/aquatic training (IMAT) groups. The samples were processed to measure fiber area, nuclear fractal dimension, MTJ nuclear density, identification of telocytes, sarcomeres, and MTJ perimeter length. In the AT group, the maintenance of ultrastructure and elements in the MTJ region were observed; the IM group presented muscle atrophy effects with reduced MTJ perimeter; the IMAT group demonstrated that aquatic training after joint immobilization promotes benefits in the muscle fiber area and fractal dimension, in the MTJ region shows longer sarcomeres and MTJ perimeter. We identified the presence of telocytes in the MTJ region in all experimental groups. We concluded that aquatic training is an effective rehabilitation method after joint immobilization due to reduced muscle atrophy and regeneration effects on MTJ in rats.     

Influence of thermoplastic extrusion on the nutritive value of bovine rumen protein

This study investigated the impact of thermoplastic extrusion on the nutritive quality of bovine rumen protein. Proximal composition, amino acid profile and in vivo true protein digestibility among rats were determined in raw (RBR) and extruded (EBR) rumen. Raw and extruded bovine rumen presented high percentages of protein (more than 95% on dry basis). Neither raw nor extruded proteins had any limiting amino acid, and the RBR and EBR amino acid scores were, respectively, 1.28 (leucine) and 1.25 (methionine plus cystine). Extrusion reduced significantly true protein digestibility from 97.7% to 93.1% (p < 0.001), but protein digestibility-corrected amino acid scores for both proteins (RBR and EBR) were 100%. Animal growth presented comparable profiles using raw and extruded rumen. In conclusion, thermoplastic extrusion did not affect the protein quality of bovine rumen, and this does not hinder the use of this material as a food ingredient.     

Effect of acid‐ethanol treatment followed by ball milling on structural and physicochemical characteristics of cassava starch

Structural and physicochemical characteristics of cassava starch treated with 0.36% HCl in anhydrous ethanol during 1 and 12 h at 30, 40, and 50°C followed by ball milling for 1 h were analyzed. Average yield of acid‐ethanol starches reached 98% independent of the treatment conditions. Solubility of acid‐ethanol starches increased with reaction temperature and time, but it did not change after ball milling. Granule average size reduced with chemical treatment from 25.2 to 20.0 µm after 12 h at 50°C. Ball milling decreased the granule average diameter of the native starch and those chemically treated at 30°C/1 h or 40°C/1 h, but it did not alter the starches treated for 12 h, independent of temperature. From scanning electron microscopy (SEM), starch granules presented round shape and after modification at 50°C/12 h, before and after ball milling, showed a rough and exfoliated surface. Some granules were deformed, suggesting partial gelatinization that was more intense after milling. Starch crystallinity increased as temperature and time of chemical treatment were increased, while amylose content, intrinsic, and pasting viscosities decreased. Gelatinization temperatures increased for all chemical starches. The findings can be related to the preferential destruction of amorphous areas in the granules, which are composed of amylose and amylopectin. After ball milling, the starch crystallinity decreased, amylose content, intrinsic, and pasting viscosities kept unchanged and gelatinization temperatures and enthalpy reduced. Ball milling on native and chemical starches caused the increase of amorphous areas with consequent weakening and decreasing of crystalline areas by breaking of hydrogen bonds within the granules.     

Silicates characterization as potential bacteriocin-carriers

Two different silicates, zeosil and expanded perlite, were characterized as potential carriers of a bacteriocin with anti-Listeria monocytogenes activity, produced by Enterococcus faecium CRL1385. Specific surface areas showed a value significantly higher for zeosil (146 m² g^? 1) than for perlite (0.65 m² g^? 1). Potential zeta measurements revealed that both silicates had negatively charged surfaces between pH 2 and 11, but zeosil presented zero charge near pH 2. Fourier Transform Infrared (FTIR) spectra proved that zeosil presented more silanol groups available for bacteriocin interaction than perlite. Bacteriocins present in the cell-free supernatant (CFS) were adsorbed by both silicates. Adsorption was highest from pH 4 to 8 and, regardless of exposure time (0.5 or 4 h) and silicate concentration (1 or 4% w/v) at 25 °C. Bacteriocin adsorption onto zeosil (ca. 99%) was higher than onto expanded perlite (ca 80%). However, antimicrobial activity of bacteriocins adsorbed onto perlite was higher than onto zeosil. After 2 h contact between L. monocytogenes 01/155 cells and each silicate plus the bacteriocin sample, the number of Listeria viable cells decreased close to 2 and 6 log orders for zeosil and expanded perlite, respectively.Industrial relevance: One of the crucial problems in the use of bacteriocins as food biopreservatives is obtaining and purifying these antimicrobials. The process generally has a poor yield and is industrially expensive. Hence, alternative techniques to deliver bacteriocins may be a likely option to encourage their use as bioprotectors. Silicates, inert compounds of large surface area, are suggested in this work as peptide immobilizers so that they may later be used in food. These inorganic compounds have already been authorized as food-grade anticaking, clarifying or filtering agents. The results achieved so far with adsorption and anti-Listeria activity preservation of bacteriocin, once they have been immobilized onto silicates, offer a promising and simple alternative to incorporate this compound into food.