Renato Souza Cruz

Zinc Oxide Nanoparticles: Synthesis, Antimicrobial Activity and Food Packaging Applications

Zinc oxide (ZnO) is an inorganic compound widely used in everyday applications. ZnO is currently listed as a generally recognized as safe (GRAS) material by the Food and Drug Administration and is used as food additive. The advent of nanotechnology has led the development of materials with new properties for use as antimicrobial agents. Thus, ZnO in nanoscale has shown antimicrobial properties and potential applications in food preservation. ZnO nanoparticles have been incorporated in polymeric matrices in order to provide antimicrobial activity to the packaging material and improve packaging properties. This review presents the main synthesis methods of ZnO nanoparticles, principal characteristics and mechanisms of antimicrobial action as well as the effect of their incorporation in polymeric matrices. Safety issues such as exposure routes and migration studies are also discussed.

Bioactive Peptides: Synthesis, Properties, and Applications in the Packaging and Preservation of Food

Abstract:  Bioactive peptides are protein fragments which have a positive impact on the functions and conditions of living beings. Peptides have shown several useful properties for human health, including antimicrobial, antifungal, antiviral, and antitumor activities. These compounds are produced by almost all species of life. However, they are produced in limited quantities in nature. As a result, researchers have tried to synthesize bioactive peptides to study their properties and applications in various areas. Among their applications in food preservation, peptides have been incorporated into packaging materials. This review begins with a brief description of the methods used for the synthesis, purification, and characterization of peptides. Also, the main bioproperties and mechanisms of action of peptides are discussed. Finally, some applications of peptides are presented, especially their use in active packaging, their effects on the polymeric matrix, and peptide migration.

Oxygen Scavengers: An Approach on Food Preservation

Oxygen (O2) presence in food packages is mainly due to failures in the packaging process, such as mixture of gases containing oxygen residues, or inefficient vacuum. Vacuum packaging has been widely used to eliminate oxygen in the package prior to sealing. However, the oxygen that permeates from the outside environment into the package through the packaging material cannot be removed by this method (Byun et al., 2011).

Efficiency of oxygen: absorbing sachets in different relative humidities and temperatures

O objetivo principal deste trabalho foi avaliar a eficiencia de saches absorvedores de oxigenio a 75%, 80% e 85% de umidade relativa e diferentes temperaturas, 10±2 oC e 25±2 oC. O experimento consiste em determinar a absorcao de O2 sob essas condicoes. Um sache foi colocado dentro de um dessecador contendo um sistema de homogeneizacao do ar interno. Aliquotas de ar sao retiradas dos dessecadores em intervalos de tempos pre-estabelecido e seu conteudo de oxigenio analisado. Os resultados mostraram que a absorcao de oxigenio pelos saches aumentaram com o aumento da temperatura para ambas as temperaturas. No entanto, os saches mostraram uma maior eficiencia para 85% de umidade relativa e 25±2oC de temperatura. Na condicao ambiente (25±2oC/75%RH), a taxa de absorcao dos saches foi de 50 mL/dia e 18,5 mL/dia para 10±2oC. O experimento foi conduzido com delineamento experimental inteiramente casualizado, com tres repeticoes.

Evaluation of oxygen absorber on antimicrobial preservation of lasagna-type fresh pasta under vacuum packed

Foi avaliado o sistema de absorvedor de oxigenio para inibicao de microrganismos em massa fresca de lasagna durante estocagem a 10±2oC. A massa de lasagna foi produzida com e sem sorbato de potassio e acondicionada em embalagens com alta barreira a oxigenio contendo um sache absorvedor em seu interior. Foram avaliados tres tratamentos: massa com sorbato de potassio (1), massa sem sorbato de potassio e com sache absorvedor de oxigenio (2) e massa sem sorbato de potassio e sem sache absorvedor de oxigenio (3). Em todos os tratamentos, a massa foi envasada a vacuo e distribuida aleatoriamente sob temperatura de 10±2oC e avaliada microbiologicamente quanto o crescimento de bolores e leveduras, Staphylococcus spp, coliformes totais e Escherichia coli. Todos os tratamentos foram efetivos na inibicao do crescimento dos microrganismos avaliados durante o periodo de 30 dias de armazenamento. O tratamento 2 inibiu o crescimento de bolores e leveduras e Staphylococcus spp, em 1 e 1,5 ciclos logaritmicos, respectivamente. Nao houve diferenca significativa para coliformes em todos os tratamentos.

Antimicrobial and aromatic edible coating on fresh-cut pineapple preservation

The present research aimed to develop an edible coating incorporated with mint essential oil, evaluate its effectiveness in inhibiting in vitro microbial development, and improve both quality and shelf-life of fresh-cut pineapple. Mint essential oil-containing edible coatings showed in vitro antimicrobial efficiency against Escherichia coli and Salmonella Enteritidis. Titratable acidity, pH, and texture were not affected (P>0.05) by coating or storage time. Mass loss was not higher than 1.0% after the 6th day of storage. No effect of storage time and coating on total soluble solids was observed. Mint essential oil-containing coatings inhibited the growth of yeasts and molds in fresh-cut pineapple. Compared to uncoated and control-coated samples, mint essential oil-containing coatings lessened psychrotrophic bacteria counts throughout storage. Counts of thermotolerant coliforms were not higher than 3.0MPN·g-1 in all treatments, whereas no Salmonella sp. was detected during the 6-day storage. Mint essential oil provided a strong flavor to the fruit, as shown by sensory evaluations.

Avaliação do volume de oxigênio absorvido por sachê absorvedor de oxigênio em diferentes temperaturas e umidades relativas

Oxygen absorbers have been presenting a growing demand for application in food packaging. Thus, it is important to know the efficiency of those absorbers in different relative humidity and temperatures. Therefore, equations were developed to predict the volume of absorbed oxygen at 10±2 oC and 25±2 oC, according as the relative humidity ranging from 75% to 85% and the oxygen transmission rate through the package. At 25±2oC the equation was V = -32,770+10,440*RH-104,385*ln(O2 TR), with R2 = 0,9151. At 10±2oC, V=107,321+6,221*RH-105,166 ln(O2 TR) with R2 = 0,8729. As a consequence, activity time for the oxygen absorbers can be calculated with the following equation: T = (V-Vi) / (ln(O2 TR*A). Using these equations and considering a packaging area of 0,05m2 for each face, oxygen transmission rate of 8,63 cm3.m-2.dia-1, relative humidity of 80% and an initial oxygen volume inside the package of 2,5 mL, absorber activity times when stored at 10±2oC and 25±2oC were 435 and 666 days, respectively.