Electrochemical Sensor Detecting Free Sulfhydryl Groups: Evaluation of Milk Heat Treatment

We describe a new and rapid method for the evaluation of reactive sulfhydryl groups in whey proteins obtained after precipitation of casein by acetic acid at pH 4.6. The procedure is based on the use of a wire tungsten electrode operating at -0.2 V versus saturated calomel electrode in flow injection analysis. The method was applied to raw milks and to commercial pasteurized and UHT milks. Results showed that the tungsten electrode constituted a robust amperometric sensor that could be used to differentiate milks that underwent different heat treatments. The decrease of thiol content in the whey proteins from samples was in agreement with the whey protein content found by HPLC. The procedure is suitable for on-line quality control of heat-treated milks

Immobilisation of bifidobacteria in biodegradable food-grade microparticles

The present research features a natural polymer that can be used for immobilisation of bifidobacteria as well as a method of immobilisation. We described a modified method of microencapsulation of probiotics using sodi- um alginate. The experiment studied the effect of encapsulation on probiotic stability and involved an in vitro model of human digestive tract. The test sample of microencapsulated Bifi obacterium bifi um 791 showed a decrease in the activity from 3.0×107 to 2.2×105 CFU/ml in a mouse model with pH 1.2. By contrast, the control sample, unprotected by biodegradable polymer microcapsules, demonstrated a higher death rate of bifidobacteria: from 2.6×108 CFU/ml to 5.0×103 CFU/ml. The control sample demonstrated the same downward trend in in vitro gastrointestinal models with pH values of 4.5, 6.8, 7.2, and 5.8. Because the total plate count fell down to 4.0l g CFU/ml in acidity gradients, the titres of the initial microencapsulated biomass had to be increased up to > 109 CFU/ml. According to the results of scanning electron microscopy, the new type of microcapsules obtained by using a resistant starch had a closed sur- face. Prebiotics increased the resistance of bacteria to low pH and bile salts. Bifidobacteria encapsulated with natural biodegradable polymers proved to be well-tolerated and harmless for mice. The experiment revealed that biodegrad- able polymer microcapsules did not cause any chronic or acute toxicity when administered orally at 2×107 CFU per 1 gram of animal mass. The microcapsules demonstrated neither dermonecrotic properties nor any irritant effect on the ocular mucosa and, thus, can be used for food enforcement

Evaluation of the physicochemical and functional properties of Colombian bee pollen

ABSTRACT Objective. To establish current knowledge about Colombian bee-pollen from a point of view nutritional and functional, contributing towards creating national technical standards and the identification of chemical differentiation factors for further researches. Material and methods. One hundred ninety-six samples of dried bee pollen were collected in the center region of Colombia known as Cundi-boyacense high plateau, where nearly 90% of total bee pollen production is concentrated in this country. Performed physicochemical analyses in this study were: moisture, pH, acidity, ash, carbohydrates, lipids, proteins, dietary fiber, fatty acid profile and mineral elements. Results. Bee pollen from this region had 7.7±5.2 g/100 g moisture content, and a following centesimal composition based on dry matter: ashes 2.5±0.4 g; lipids 6.90±3.5 g; proteins 23.8±3.2 g and total dietary fiber 14.5±3.5 g. The most abundant fatty acids were α-linolenic, palmitic and linoleic. Carbohydrates were the main components and fructose and glucose the most concentrated sugars. The predominant minerals assessed here were potassium, calcium and magnesium. The results were also discussed in terms of the characteristics found in Colombian bee-pollen in comparison to international regulations and findings for other varieties of commercial bee-pollen from eight different countries. Conclusions. The results found in this study suggest that bee-pollen may be used as a dietary supplement and agree with bibliographical reports and international regulations. Such characterization will enable to be proposed technical standards in line with Colombian bee-pollen properties and it is expected to improve marketing and production chain conditions

Polymer Composites Containing Gated Mesoporous Materials for On-Command Controlled Release

Polyamidic nanofibrous membranes containing gated silica mesoporous particles, acting as carriers, are described as novel hybrid composite materials for encapsulation and on-command delivery of garlic extracts. The carrier system consists of MCM-41 solids functionalized in the outer surface, with linear polyamines (solid P1) and with hydrolyzed starch (solid P2), both acting as molecular gates. Those particles were adsorbed on electospun nylon-6 nanofibrous membranes yielding to composite materials M1 and M2. FE-SEM analysis confirmed the presence of particles incorporated on the nylon nanofibers. The release of the entrapped molecules (garlic extract) from the P1, P2, M1, and M2 materials was evaluated using cyclic voltammetry measurements. Electrochemical studies showed that at acidic pH P1 and M1 were unable to release their entrapped cargo (closed gate), whereas at neutral pH both materials release their loading (open gate). Dealing with P2 and M2 materials, in the absence of pancreatin a negligible release is observed (closed gate), whereas in the presence of enzyme the load is freely to diffuse to the solution. These newly developed composite nanomaterials, provide a homogeneous easy-to-handle system with controlled delivery and bioactive-protective features, having potential applications on pharmacology, medical and engineering fields.The authors wish to express their gratitude to the Generalitat Valenciana (Grisolia scholarship 2011/012, project PROM-ETEO/2009/016), Spanish Government (MINECO Projects AGL2012-39597-C02-01, AGL2012-39597-C02-02 and MAT2012-38429-C04-01) and the CIBER-BBN for their support. IILA thanks DISTAM and Universita degli di Milano for a specialization scholarship. We would also like to thank the Institut de Ciencia dels Materials (ICMUV) and to the Microscopy Service of the Universitat Politecnica de Valencia for technical support. We thank Roquette for the Glucidex samples.Acosta Romero, C.; Pérez Esteve, E.; Fuenmayor, CA.; Benedetti, S.; Cosio, MS.; Soto Camino, J.; Sancenón Galarza, F.... (2014). Polymer Composites Containing Gated Mesoporous Materials for On-Command Controlled Release. ACS Applied Materials and Interfaces. 6(9):6453-6460. https://doi.org/10.1021/am405939y645364606

Electronic nose and neural network use for the classification of honey

Seventy samples of honey of different geographical and botanical origin were analysed with an electronic nose. The instrument, equipped with 10 Metal Oxide Semiconductor Field Effect Transistors (MOSFET) and 12 Metal Oxide Semiconductor (MOS) sensors, was used to generate a pattern of the volatile compounds present in the honey samples. The sensor responses were evaluated by Principal Component Analysis (PCA) and Artificial Neural Network (ANN). Good results were obtained in the classification of honey samples by using a neural network model based on a multilayer perceptron that learned using a backpropagation algorithm. The methodology is simple, rapid and results suggest that the electronic nose could be a useful tool for the characterisation and control of honey