National Nanotechnology Laboratory for Agribusiness

São Paulo, Brazil

National Nanotechnology Laboratory for Agribusiness

São Paulo, Brazil
SEARCH FILTERS
Time filter
Source Type

Manrich A.,National Nanotechnology Laboratory for Agribusiness | Moreira F.K.V.,Federal University of São Carlos | Otoni C.G.,National Nanotechnology Laboratory for Agribusiness | Otoni C.G.,Federal University of São Carlos | And 4 more authors.
Carbohydrate Polymers | Year: 2017

Cutin is the biopolyester that protects the extracellular layer of terrestrial plants against dehydration and environmental stresses. In this work, cutin was extracted from tomato processing waste and cast into edible films having pectin as a binding agent. The influences of cutin/pectin ratio (50/50 and 25/75), film-forming suspension pH, and casting method on phase dispersion, water resistance and affinity, and thermal and mechanical properties of films were investigated. Dynamic light scattering and scanning electron microscopy revealed that cutin phase aggregation was reduced by simply increasing pH. The 50/50 films obtained by casting neutral-pH suspensions presented uniform cutin dispersion within the pectin matrix. Consequently, these films exhibited lower water uptake and solubility than their acidic counterparts. The cutin/pectin films developed here were shown to mimic tomato peel itself with respect to mechanical strength and thermal stability. Such behavior was found to be virtually independent of pH and casting method. © 2017 Elsevier Ltd


Steffens C.,Federal University of São Carlos | Steffens C.,National Nanotechnology Laboratory for Agribusiness | Leite F.L.,Federal University of São Carlos | Manzoli A.,National Nanotechnology Laboratory for Agribusiness | And 5 more authors.
Scanning | Year: 2014

In the present work, PANI (polyaniline) emeraldine salt (doped) and base (dedoped) were used as the sensitive layer of a silicon microcantilever, and the mechanical response (deflection) of the bimaterial (coated microcantilever) was investigated under the influence of humidity. PANI in the emeraldine base oxidation state was obtained by interfacial synthesis and was deposited on the microcantilever surface by spin-coating (dedoped). Next, the conducting polymer was doped with 1 M HCl (hydrochloric acid). A four-quadrant AFM head with an integrated laser and a position-sensitive detector (AFM Veeco Dimension V) was used to measure the optical deflection of the coated microcantilever. The deflection of the coated (doped and undoped PANI) and uncoated microcantilever was measured under different humidities (in triplicate) at room pressure and temperature in a closed chamber to evaluate the sensor's sensitivity. The relative humidity (RH) in the chamber was varied from 20% to 70% using dry nitrogen as a carrier gas, which was passed through a bubbler containing water to generate humidity. The results showed that microcantilevers coated with sensitive layers of doped and undoped PANI films were sensitive (12,717 ± 6% and 6,939 ± 8%, respectively) and provided good repeatability (98.6 ± 0.015% and 99 ± 0.01%, respectively) after several cycles of exposure to RH. The microcantilever sensor without a PANI coating (uncoated) was not sensitive to humidity. The strong effect of doping on the sensitivity of the sensor was attributed to an increased adsorption of water molecules dissociated at imine nitrogen centers, which improves the performance of the coated microcantilever sensor. Moreover, microcantilever sensors coated with a sensitive layer provided good results in several cycles of exposure to RH (%). © 2013 Wiley Periodicals, Inc.


Dominguez-Martinez B.M.,National Polytechnic Institute of Mexico | Martinez-Flores H.E.,Universidad Michoacana de San Nicolás de Hidalgo | Berrios J.D.J.,Healthy Processed Foods Research Unit | Otoni C.G.,Federal University of São Carlos | And 3 more authors.
Journal of Polymers and the Environment | Year: 2016

This study aimed to develop and characterize biodegradable films containing mucilage, chitosan and polyvinyl alcohol (PVA) in different concentrations. The films were prepared by casting on glass plates using glycerol as plasticizer. Mechanical properties, water vapor and oxygen barrier, as well as the interaction with water, were measured. The compatibility of the film-forming components and the uniformity of the films were determined by zeta potential and SEM, respectively. The glycerol and mucilage allowed obtaining more hydrophilic films. The barrier properties of the films made from 100 % chitosan were similar to composed films containing PVA up to 40 %. The results of this study suggest that the interaction between chitosan and mucilage could increase water vapor permeability. The films prepared from either 100 % chitosan or PVA showed a more hydrophobic behavior as compared to the composed films. The films were homogenous since no boundary or separation of components was observed, indicating a good compatibility of the components in the films. © 2016 Springer Science+Business Media New York


Pola C.C.,Federal University of Viçosa | Medeiros E.A.A.,Federal University of Viçosa | Pereira O.L.,Federal University of Viçosa | Souza V.G.L.,Federal University of Viçosa | And 7 more authors.
Food Packaging and Shelf Life | Year: 2016

The aim of the present study was to produce active films based on cellulose acetate (CAc) incorporated with different concentrations of oregano essential oil (OEO) and organophilic montmorillonite clay (MMT30B) to control the growth of phytopathogenic fungi. The active films were characterized by ATR-FTIR, XRD, TEM, mechanical resistance, WVTR, OTR, thermal stability, and antifungal activity against the phytopatogens Alternaria alternata, Geotrichum candidum, and Rhizopus stolonifer. The CAc-based active films presented high antifungal activity against the tested phytopathogens, mainly in vapor phase. MMT30B exhibit good dispersion in CAc matrix, resulting in a partially exfoliated conformation. In this way, MMT30B significantly increased films’ rigidity and thermal resistance while reduced OTR. OEO acted as plasticizer, facilitating MMT30B dispersion. Also, OEO increased extensibility and decreased WVTR of CAc-based films. Both OEO and MMT30B slightly improved the thermal resistance of films. The active films developed here denote a potential packaging system for postharvest conservation purposes. © 2016 Elsevier Ltd


Steffens C.,Federal University of São Carlos | Steffens C.,National Nanotechnology Laboratory for Agribusiness | Leite F.L.,Federal University of São Carlos | Manzoli A.,National Nanotechnology Laboratory for Agribusiness | And 6 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2014

This paper describes a silicon cantilever sensor coated with a conducting polymer layer. The mechanical response (deflection) of the bimaterial (the coated microcantilever) was investigated under the influence of several volatile compounds-methanol, ethanol, acetone, propanol, dichloroethane, toluene and benzene. The variations in the deflection of the coated and uncoated microcantilevers when exposed to volatile organic compounds were evaluated, and the results indicated that the highest sensitivity was obtained with the coated microcantilever and methanol. The uncoated microcantilever was not sensitive to the volatile organic compounds. An increase in the concentration of the volatile organic compound resulted in higher deflections of the microcantilever sensor. The sensor responses were reversible, sensible, rapid and proportional to the volatile concentration. Copyright © 2014 American Scientific Publishers.


Otoni C.G.,Federal University of São Carlos | Otoni C.G.,National Nanotechnology Laboratory for Agribusiness | Espitia P.J.P.,Observatorio del Caribe Colombiano Research Institute | Espitia P.J.P.,Sinú University | And 2 more authors.
Food Research International | Year: 2016

Active antimicrobial packaging interacts with packaged food and headspace to reduce, retard, or even inhibit the growth of spoilage and pathogenic microorganisms. Sachets and pads are one of the most successful applications of active food packaging. This review discusses recent developments of antimicrobial active packaging focused exclusively on emitting sachets and absorbent pads, including elaboration techniques, characterization methods, and applications for food preservation purposes. Advantages, drawbacks, and future trends are also discussed, as well as the antimicrobial compounds incorporated in emitting sachets and absorbent pads, including ethanol, chlorine dioxide, a variety of plant essential oils and their main active compounds, and nanoparticles. © 2016 Elsevier Ltd.


Steffens C.,Federal University of São Carlos | Steffens C.,National Nanotechnology Laboratory for Agribusiness | Manzoli A.,National Nanotechnology Laboratory for Agribusiness | Leite F.L.,Federal University of São Carlos | And 3 more authors.
Microelectronic Engineering | Year: 2014

A microcantilever sensor is presented. Functionalization of the cantilever with a polyaniline (PANI) sensitive layer and its use as a humidity sensor were investigated. Polyaniline was produced by interfacial synthesis and the sensitive layer was deposited on the microcantilever surface by the spin-coating method. The microcantilever deflection at various levels of relative humidity (RH) was read by means of the optical lever of an atomic force microscope (AFM Veeco Dimension V). A range of RH from 20% to 70% was introduced into the AFM chamber by mixing streams of dry and wet nitrogen. The sensitivity and reversibility of the sensors were assessed at various RH and temperatures (10, 20 and 30 C). A large deflection was observed in the coated microcantilever sensors, with faster response time at 10 C and better sensitivity and reversibility at 30 C. These results demonstrate that the spin-coated microcantilever can be used as a sensor to detect relative humidity at various different temperatures. © 2013 Elsevier B.V. All rights reserved.


Espitia P.J.P.,University of the Atlantic | Batista R.A.,Federal University of Sergipe | Azeredo H.M.C.,Embrapa Tropical Agroindustry Rua Dra Sara Mesquita | Otoni C.G.,Federal University of São Carlos | Otoni C.G.,National Nanotechnology Laboratory for Agribusiness
Food Research International | Year: 2016

The global market for probiotics has been increasingly growing in recent years guided by the rising consumers’ demand for healthy diets and wellness. This has caused food industries to develop new probiotic-containing food products as well as researchers to study specific characteristics of probiotics as well as their effects on human health. Probiotics are defined as live microorganisms that confer a health benefit to the host when administered in adequate quantities. Probiotics have been added to several food products as well as incorporated into biopolymeric matrices to develop active food packaging as an alternative method for controlling foodborne microorganisms, improving food safety, and providing health benefits. This review includes definition of probiotics, description of their effects on human health, discussion on their applications in edible biopolymeric matrices to develop active edible films and coatings, as well as the probiotics-related legislation. © 2016 Elsevier Ltd


De Paula Herrmann Jr. P.S.,National Nanotechnology Laboratory for Agribusiness
International Journal of Nuclear Desalination | Year: 2011

A low-cost optical sensor built-in strip has been developed from a composite obtained with application of in-situ chemical polymerisation, using polyaniline in the emeraldine oxidation state, doped with HCl onto poly(ethylene terephthalate) (PET) film, used to measured the pH of water. The absorption of UV-Vis spectra was used to evaluate the optical response to pH change of natural water. The strip showed a reversible colour change upon variation of the pH. The pH range used to calibrate the optical sensor was from 2.0 to 12.0. These kinds of sensors show the potential to investigate the pH of natural waters, with application to limnological studies, as well as to investigate the influence of the ionic strength. This paper describes new techniques that can be used to conduct research with pesticides in water using electrochemistry and biosensors, and an electronic tongue with conductive polymers for global quality evaluation. © 2011 Inderscience Enterprises Ltd.

Loading National Nanotechnology Laboratory for Agribusiness collaborators
Loading National Nanotechnology Laboratory for Agribusiness collaborators