Development of cellulose-based bactericidal nanocomposites containing silver nanoparticles and their use as active food packaging

The use of nanomaterials, including metallic as active fillers in polymeric nanocomposites for food packaging has been extensively investigated. Silver nanoparticles (AgNPs), in particular, have been exploited for technological applications as bactericidal agents. In this paper, AgNPs were incorporated into a hydroxypropyl methylcellulose (HPMC) matrix for applications as food packaging materials. The average sizes of the silver nanoparticles were 41 nm and 100 nm, respectively. Mechanical analyses and water vapor barrier properties of the HPMC/AgNPs nanocomposites were analysed. The best results were observed for films containing smaller (41 nm) AgNPs. The antibacterial properties of HPMC/AgNPs thin films were evaluated based on the diameter of inhibition zone in a disk diffusion test against Escherichia coli (E. coil) and Staphylococcus aureus (S. aureus). The disk diffusion studies revealed a greater bactericidal effectiveness for nanocomposites films containing 41 nm Ag nanoparticles. (C) 2011 Elsevier Ltd. All rights reserved.

Probiotic yogurts manufactured with increased glucose oxidase levels: Postacidification, proteolytic patterns, survival of probiotic microorganisms, production of organic acid and aroma compounds

We investigated the effect of increased glucose oxidase concentration as a technological option to decrease oxidative stress during the processing of probiotic yogurts. Probiotic yogurts were produced with increased concentrations of glucose oxidase (0, 250, 500, 750, or 1,000 mg/kg) and submitted to physicochemical and microbiological analysis at 1, 15, and 30 d of refrigerated storage. Higher concentrations of glucose oxidase (750 and 1,000 mg/kg) and a longer storage time were found to have an influence on the characteristics of the probiotic yogurt, contributing to more extensive post-acidification, an increase in the dissolved oxygen level, and higher proteolysis. In addition, increased production of aroma compounds (diacetyl and acetaldehyde) and organic acids (mainly lactic acid) and a decrease in the probiotic bacteria count were reported. The use of glucose oxidase was a feasible option to minimize oxidative stress in probiotic yogurts. However, supplementation with excessive amounts of the enzyme may be ineffective, because insufficient substrate (glucose) is present for its action. Consumer tests should be performed to evaluate changes in the sensory attributes of the probiotic yogurts with increased supplementation of glucose oxidase. In addition, packaging systems with different permeability to oxygen should be evaluated.

Approach to Food and Nutrition issues in Teaching Materials in Elementary School: interface with food and nutritional security and national curriculum parameters

Food and Nutrition Security (FNS) must be ensured to everybody. The school environment is favorable to the formation of healthy habits and citizenship. The National Curriculum Parameters (PCNs) guide the promotion of health concepts in a transversal way in the school curriculum. This study aimed to identify and analyze the approach used for food and nutrition themes in Fundamental Education's teaching material and its interface with the concept of FNS and the PCNs. Documental research was conducted on the teaching material from 5th to 8th grades of Fundamental Education in Public School of the state of Sao Paulo. The diffuse presence of food and nutrition themes was found in most disciplines in all bimesters in the four series, which shows the interdisciplinarity in health. It was found that the PCNs are related to the concept of SAN in its various aspects and that most subjects include topics that approach this relationship. In the correlation between themes, there is emphasis to health promotion and food production. The methodology used in the teaching material presents the theme, but not the correspondent content, what made the analysis of its suitability impossible. We conclude that there is the approach of the issues related to food and nutrition in the teaching material, some of them in an inconsistent way; it is the educators' task to select the contents and the appropriate strategy, doing an effort of constant update. This isbeing proposed by the State, however it is not accessible to all professionals and therefore still depends on the initiative of each teacher.

Inactivation of Neosartorya fischeri and Paecilomyces variotii on paperboard packaging material by hydrogen peroxide and heat

This study reports on the influence of heat and hydrogen peroxide combination on the inactivation kinetics of two heat resistant molds: Neosartorya fischeri and Paecilomyces variotii. Spores of different ages (1 and 4 months) of these molds were prepared and D-values (the time required at certain temperature/hydrogen peroxide combination to inactivate 90% of the mold ascospores) were determined using thermal death tubes. D-values found for P. variotii ranged from 1.2 to 25.1 s after exposure to different combinations of heat (40 or 60 degrees C) and hydrogen peroxide (35 or 40% w/w) while for N. fischeri they varied from 2.7 to 14.3 s after exposure to the same hydrogen peroxide concentrations and higher temperatures (60 or 70 degrees C). The influence of temperature and hydrogen peroxide concentration on the d-values varied with the genus of mold and their ages. A synergistic effect of heat and hydrogen peroxide in reducing D-values of Paecilomyces variotti and N. fischeri has been observed. In addition to strict control of temperature, time and hydrogen concentration, hygienic storage and handling of laminated paperboard material must be considered to reduce the probability of package's contamination. All these measures together will ensure package's sterility that is imperative for the effectiveness of aseptic processing and consequently to ensure the microbiological stability of processed foods during shelf-life. (C) 2011 Elsevier Ltd. All rights reserved.

Periodic sterility assessment of materials stored for up to 6 months at continuous microbial contamination risk: Laboratory study

An investigation was conducted to test the hypothesis that the storage time of packaging sterility has no effect on contamination susceptibility even under deliberate bacterial exposure (Serratia marcescens). No growth of the test microorganisms was identified in the experimental group in any of the storage intervals (7, 14, 28, 90, and 180 days). Current recommendations/guidelines suggest that contamination of packaging occurs only because of events. This study, done in vitro, supports these recommendations. Copyright (c) 2012 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Rapid sample preparation procedure for As speciation in food samples by LC-ICP-MS

This paper describes a rapid method for arsenic (As) speciation by LC-ICP-MS in several types of food samples. Prior to analysis, samples were milled and the As species extracted from biological tissues by sonication in only 2 min with a solution containing MeOH (10%, v/v) plus HNO3 (2%, v/v). As species were separated by LC using an anion exchange column. Method detection limits for AsB, As3+,DMA, MMA and As5+ were 1.3, 0.9, 0.6, 0.7 and 0.8 ng g(-1), respectively. Method accuracy and precision were traceable to Certified Reference Materials SRM1577 bovine liver from the National Institute of Standards and Technology, CE278 mussel tissue from the Institute of Reference Materials and Measurements and DOLT-3 dogfish liver tissue and DORM-3 fish protein from the National Research Council of Canada. Finally, the method was applied to speciate As in food samples (egg, fish muscle, beef and chicken) purchased in Brazilian markets.