Mario García

Potential applications of nanotechnology in the agro-food sector

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.Nanociencias e nanotecnologia sao fronteiras novas deste seculo. Suas aplicacoes a agricultura e ao setor alimentar sao relativamente recentes quando comparadas com a sua utilizacao em entrega de farmacos. Entrega inteligente de nutrientes, biosseparacao de proteinas, amostragem rapida de contaminantes quimicos e biologicos e nanoencapsulamento de nutraceuticos sao alguns dos topicos emergentes relativamente a aplicacao de nanotecnologia em agricultura e alimentacao. Nesta revisao, abordam-se possiveis aplicacoes de nanotecnologia no sector agroalimentar.

Effect of molecular weight reduction by gamma irradiation on the antioxidant capacity of chitosan from lobster shells

Abstract 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.

Influence of chitosan addition on quality properties of vacuum-packaged pork sausages

Resumo O objetivo do estudo foi avaliar a influencia da adicao de quitosana sobre a qualidade de salsichas embaladas a vacuo. Elaborou-se uma variante do produto com 1% (m/m) de quitosana adicionada em dissolucao de acido lactico a 1% (v/v) e manteve-se um lote controle sem adicao de quitosana. Formaram-se pecas mediante torcao manual e envasadas a vacuo. Determinaram-se, durante o armazenamento a 4 °C, varios parâmetros de qualidade: avaliacoes microbiologicas, pH, analise do perfil de textura e avaliacao sensorial mediante a analise descritiva quantitativa. A adicao de quitosana na formulacao das salsichas nao reduziu os conteudos microbiologicos e os valores de pH obtidos em todas as amostras foram similares, o que sugere que a adicao de quitosana nao influencia os valores de pH das salsichas. A adicao de quitosana nao afetou significativamente (p ≤ 0,05) os valores de textura nem as analises sensoriais estudadas mantendo, portanto, a qualidade do embutido. Palavras-chave: salsichas; produtos carneos; quitosana; qualidade microbiologica; qualidade sensorial; armazenamento.

Potencial risks of nanoparticles

Nanotoxicology is an emergent important subdiscipline of Nanosciences, which refers to the study of the interactions of nanostructures with biological systems giving emphasis to the elucidation of the relationship between the physical and chemical properties of nanostructures with induction of toxic biological responses. Although potential beneficial effects of nanotechnologies are generally well described, the potential (eco) toxicological effects and impacts of nanoparticles have so far received little attention. This is the reason why some routes of expousure, distribution, metabolism, and excretion, as well as toxicological effects of nanoparticles are discussed in this review.

Evaluation of Chitosan Acid Salts as Clarifying Agents of Orange Nectar

The use of chitosan acid salts was assessed in the clarification orange nectar. Clarification process was performed at laboratory scale by the classical methodology of jar test by adding chitosan acetate or chitosan lactate at concentrations between 0 g/L and 2 g/L of nectar. Numerical optimization method was used through an IV Optimal response surface for the best variant of coagulation-flocculation based on clarification yield. No significant effect of the salt type and concentration or clarification time on the physicochemical parameters of nectars were observed. Both chitosan acid salts could be used as clarifying agents, although chitosan lactate at 1 g/L was more effective, obtaining the highest yield (66.14%) to a time of 90 min. In general, there was no significant influence of the type and concentration of chitosan acid salt on the sensory attributes of the products and nectar clarified with chitosan lactate showed the higher overall quality.

Partial substitution of nitrite by chitosan and the effect on the quality properties of pork sausages

The aim of the study was to evaluate the influence of partial nitrite replacement by chitosan on the quality of Ham Visking (a type of pork sausages). Five Ham Visking formulations were elaborated modifying the sodium nitrite (0.011; 0.016 or 0.0212%) and chitosan concentrations (0.25 or 0.5%) in the products. Sausages were stored at 4 oC and physicochemical, microbiological, and sensorial evaluations were performed in order to estimate their shelf life. Chitosan can be used in pork sausages without affecting ensory attributes such as color although the panelists detected textural differences among the samples with chitosan, which suggests that there is some influence of deacetylation degree of chitosan on the textural behavior of sausages which still needed to be explained for a successful application of chitosan in meat products. The reduction of residual sodium nitrite did not affect the color and flavor of such products, but the use of chitosan increasedsignificantly the shelf life of sausages.

Effect of chitosan-olive oil emulsion coating on quality of tomatoes during storage at ambient conditions

BACKGROUND: Tomato, a berry with a high nutritional content, is one of the most important vegetables due to its commercial importance, easy manipulation and rapid production cycle. The application of biodegradable films and coatings as alternative preservation method, provides a protective layer and creates a modified atmosphere in the fruit. OBJECTIVE: The aim of the present study was to evaluate the influence of chitosan-olive oil coatings on the quality of tomatoes cv. Charleston during their storage at 27 ± 1◦C and 80% RH. METHODS: According with the treatments, chitosan at 1 and 2% (w/v) in 1% (v/v) of lactic acid was dissolved by stirring during 2 h at 40◦C and then was emulsified with olive oil at 2 and 4% (v/v). RESULTS: Tomatoes coated with chitosan at 2% (w/v) with 2 and 4% (v/v) of olive oil presented the higher weight losses. CONCLUSIONS: Coatings from chitosan-olive oil emulsion delayed the ripening and maintained the firmness of tomatoes cv. Charleston with respect to uncoated fruits during storage, although these coatings did not act as an effective barriers against the weight loss. These results can be helpful for horticulturists and agro-food products distributors, as well as for the postharvest technologists.