Nanoscience and nanotechnology are new frontiers of this century. Their application to the agriculture and food sectors is relatively recent compared with their use in drug delivery and pharmaceuticals. Smart delivery of nutrients, bioseparation of proteins, rapid sampling of biological and chemical contaminants, and nanoencapsulation of nutraceuticals are some of the emerging topics of nanotechnology for food and agriculture. In this review, some applications of nanotechnology in agro-food sector are discussed. Nanociências e nanotecnologia são fronteiras novas deste século. Suas aplicações à agricultura e ao setor alimentar são relativamente recentes quando comparadas com a sua utilização em entrega de fármacos. Entrega inteligente de nutrientes, biosseparação de proteínas, amostragem rápida de contaminantes químicos e biológicos e nanoencapsulamento de nutracêuticos são alguns dos tópicos emergentes relativamente à aplicação de nanotecnologia em agricultura e alimentação. Nesta revisão, abordam-se possíveis aplicações de nanotecnologia no sector agroalimentar

This study assessed the effect of molecular weight (MW) reduction by gamma irradiation on the antioxidant capacity of chitosan with potential application in the preservation of foodstuffs. Two batches of chitosan were obtained by heterogeneous chemical N-deacetylation of chitin from common lobster (Panulirus argus). Irradiation of chitosan was performed using a 60Co source and applying doses of 5, 10, 20 and 50 kGy with a dose rate of 10 kGy/h. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy was used to identify main chemical features of chitosan. The average viscosimetric MW was determined by the viscosimetric method while the deacetylation degree by a potentiometric method. Thermogravimetric analysis and differential scanning calorimetry were conducted to evaluate the thermal degradation behavior of the chitosan samples, both under nitrogen flow. The antioxidant activity of chitosan solutions at 1% (w/v) in lactic acid at 1% (v/v) and Tween 80 at 0.1% (v/v) was evaluated through the ABTS assay and scavenging of DPPH radical by chitosan. The increase of irradiation dose with 60Co until 50 kGy decreased significantly the MW of chitosan through the scission of glycosidic bonds without affecting its functional groups, while the DD (72–75 %) did not vary (p > 0.05). The AC of the chitosan solutions increased with the reduction of MW of chitosan by gamma irradiation

The objective of the study was to evaluate the effect of chitosan coatings combined with zeolite on tomato (Lycopersicon sculentum cv. FA-180 HAZERA) quality attributes during refrigerated storage. Coatings were applied by double immersion of fruits in the film-forming solutions for 5 min, depending on treatments: (i) chitosan at 1.5% (w/v) in lactic acid 1% (v/v); (ii) chitosan at 1.5% (w/v) in lactic acid 1% (v/v) and Tween 80 at 0.1% (w/v); and (iii) chitosan at 1.5% (w/v) in lactic acid 1% (v/v) and zeolite at 3% (w/w based on chitosan). Fruits were allowed to dry by forced convection for 2 h at 25ºC and were subsequently stored at 10ºC during 37 days. The effectiveness of the treatments in extending fruit shelf-life was evaluated by determining fungal decay, respiration rate, quality attributes and overall visual appearance. No sign of fungal decay was observed during the storage period. The addition of zeolite at 3% (w/w based on chitosan) and Tween 80 at 0.1% (v/v) in chitosan solution improved its coating properties delaying the ripening of tomatoes, although did not constitute an effective barriers against the weight losses.

Ozone is an effective alternative for the postharvest treatment of fruits and vegetables. The purpose of this study was to evaluate the ozone application in gaseous or aqueous phases for postharvest disinfection of tomatoes (Lycopersicon esculentum Mill) cultivar FA-180. Fruits harvested at the breaker stage were exposed to ozone concentrations of 25 and 45 mg m⁻³ for 2 h per day during 16 days, at non-controlled temperature and relative humidity. Exposure to ozone during storage extends the shelf-life of tomatoes, besides preserving its sensory attributes. Mature tomatoes, inoculated with Escherichia coli ATCC 25922, were washed with ozonated water containing 0.5 to 1.0 mg L⁻¹ during 15 to 30 min. To achieve an adequate disinfection, 1 mg L⁻¹ and 15 min are recommended. The disinfection with ozonated water was effective.