Fabio Yamashita

Antimicrobial, mechanical, and barrier properties of cassava starch-chitosan films incorporated with oregano essential oil.

The physicochemical and antimicrobial properties of starch-chitosan films incorporated with oregano essential oil (OEO) have been investigated. The antimicrobial effects of starch-chitosan-OEO films against Bacillus cereus, Escherichia coli, Salmonella enteritidis, and Staphylococcus aureus were determined by the disk inhibition zone method. The film mechanical properties, water vapor permeability (WVP), Fourier transform infrared spectra (FTIR), and thermograms (TGA) were also determined. Films added with OEO effectively inhibited the four microorganisms tested and demonstrated improved barrier properties. The presence of OEO in starch-chitosan films led to the formation of more flexible films. Chitosan was not effective against the tested organisms, but it decreased film rigidity and WVP. TGA analysis demonstrated that the addition of chitosan and OEO did not affect the thermal stability of the films.

Thermophysical Properties of Brazilian Orange Juice as Affected by Temperature and Water Content

Abstract The specific heat, thermal conductivity, thermal diffusivity and density of Brazilian orange juice were determined between 0.34 and 0.73 (w/w) water content and with temperatures from 0.5 to 62 °C. The experimental data were fitted as functions of temperature and water content and all properties showed a linear dependency with these variables. In the tested range, the water content exhibited a greater influence on the analyzed properties than temperature.

Diffusion coefficients during osmotic dehydration of tomatoes in ternary solutions

Abstract The apparent diffusion coefficients for sucrose, NaCl and water during osmotic dehydration of tomatoes in ternary solutions were determined. Long time experiments (up to 60 h) were carried out in order to determine equilibrium concentrations inside tomatoes, whereas short time experiments (up to 4 h) were performed to provide detailed information on kinetics of water loss and solids gain at the beginning of osmotic treatment. The mass transfer rates for water and solutes showed to be dependent of NaCl and sucrose concentrations in osmotic solution and simple regression models as functions of solutes concentration were determined for diffusion coefficients. Salt and sucrose diffusivities showed to be interdependent, with increasing NaCl concentration causing the enhancement of water loss, at the same time that higher sucrose contents hindered the excessive salt penetration.

Development of biodegradable flexible films of starch and poly(lactic acid) plasticized with adipate or citrate esters

Biodegradable films were produced from blends contained a high amount of thermoplastic starch (TPS) and poly(lactic acid) (PLA) plasticized with different adipate or citrate esters. It was not possible to obtain pellets for the production of films using only glycerol as a plasticizer. The plasticization of the PLA with the esters and mixture stages added through extrusion was critical to achieve a blend capable of producing films by blow extrusion. Adipate esters were the most effective plasticizers because they interacted best with the PLA and yielded films with appropriate mechanical properties.

Friction factors and rheological properties of orange juice

Abstract The rheological behavior of Brazilian orange juice with different water content (0.34–0.73 w/w) was studied at a wide range of temperatures (0.5–62 o C) using a concentric cylinder viscometer. The results indicated that the juices behave as pseudoplastic fluids with yield stress, being represented by the Herschel–Bulkley model. The rheological parameters were fitted as functions of both temperature and water content in the tested range. Based on dimensional analysis it was proposed a modified Reynolds number (Re M ), which includes the Herschel–Bulkley parameters. Experimental data of friction factors during heating and cooling processes of orange juice in laminar flow through circular tubes could be well correlated as a function of Re M .

Effect of organic acids as additives on the performance of thermoplastic starch/polyester blown films.

The influence of citric acid (CA), malic acid (MA) and tartaric acid (TA) in starch/poly (butylene adipate co-terephthalate) blown films was evaluated by examining the barrier, structural and mechanical properties of the films. These properties were analysed in different relative humidities. Greater concentrations of TA and CA (1.5 wt%) produced films with improved tensile strength (6.8±0.3 and 6.7±0.3 MPa, respectively), reduced water vapour permeability and a more homogeneous structure. The compatibilising effect of MA was less efficient, as shown in the scanning electron microscopy (SEM) images. Changes in the relative humidity (RH) affected the elongation of the films, which reached values of 5.7±0.5 at 33% RH and increased to 312.4±89.5% at 53% RH. The FT-IR spectra showed no additional reactions caused by the incorporation of the additives, and the observed results are attributed to the esterification reactions and/or hydrolysis of the starch, producing films with interesting properties. This process represents an alternative to the use of non-biodegradable materials.

Produtos de acerola: estudo da estabilidade de vitamina C

o C apresentaram teores de 1.314±6 e 1.322±2 mg vit.C/ 100g, respectivamente, representando uma perda de, aproximadamente, 3% e o suco apresentou uma perda de 32%, correspondendo a um teor final de 673±17mg vit.C/100g. Palavras-chave: armazenagem; congelamento; suco; polpa; frutas; rotulagem; cinetica. SUMMARY WEST INDIAN CHERRY PRODUCTS: STUDY OF VITAMIN C STABILITY. West indian cherry is a very perishable fruit and its vitamin C content is its principal nutritional appeal. Brazilian legislation admits a 20% variation in the nutrient content from the one specified on the label. Due to this requirement the initial vitamin C content and losses during storage should be known in products. Vitamin C stability in pasteurized pulp and west indian cherry in natura, both frozen and stored at -12 o C e -18 o C and of the pasteurized juice stored at room temperature, were determined during four months. Frozen pulps had no significant vitamin C degradation during this period and fruits in natura showed first order kinetics degradation and zero order for the juice. After four months, west indian cherry fruits stored at -12 o C and -18 o C showed 869±12 and 1.223±148 mg vit.C/100g, representing losses of 43% and 19%, respectively. Pulps at -12 o C and -18 o C showed a 1.314±6 and 1.322±2 mg vit.C/100g, respectively, representing approx. 3% losses and the juice

Comparative study of processing methods for starch/gelatin films

In this work, the influence of processing methods on the properties of starch/gelatin films plasticized with glycerol and sorbitol is reported. Four different processing techniques: casting; pressing; pressing followed by blowing and extrusion followed by blowing were evaluated. Bioplastics prepared by casting were homogeneous and transparent with lower opacity and water vapor permeability (WVP) values when compared to films prepared by other techniques. Among the cast films studied, those with 3% lipophilic starch, in 1:1 proportions and plasticized with sorbitol, showed lower WVP values and higher tensile strength (TS). Films obtained by pressing and blowing showed little expansion during blow, had cracks in the surface, low TS and higher WVP. These films were the only samples to show crystallinity as determined by thermal analysis and X-ray diffraction. In conclusion, different processing techniques have significantly affected the properties of these films.

Composites of thermoplastic starch and nanoclays produced by extrusion and thermopressing.

The aim of this study was to produce thermoplastic starch (TPS) films and to enhance their properties by reinforcing them with hydrophilic and hydrophobic nanoclays. TPS films were prepared by extrusion and thermopressing, and their crystallinity, water vapor permeability (WVP), and mechanical properties were studied. The hydrophilic nanoclay lowered the material WVP due to the formation of an intercalated composite. The hydrophobic nanoclays increased the rigidity of the films but did not alter the tensile strength. The blending of nanoclays with thermoplastic starch modifies the mechanical properties and WVP, and these changes are strongly associated with the dispersion of nanoclay in the polymer matrix. The dispersion, in turn, depends on the compatibility of the matrix and the nanoclay in terms of the hygroscopicity and the concentration in which the nanoclay is used. The addition of nanoclays to starch-based films is a promising way to enhance them for industrial manufacture.

Mixture design applied for the study of the tartaric acid effect on starch/polyester films.

Tartaric acid (TA), a dicarboxylic acid, can act as a compatibiliser in starch/polyester blends. A mixture design was proposed to evaluate the effect of TA on the properties of starch/poly (butylene adipate co-terephthalate) (PBAT) blown films plasticised with glycerol. The interaction between the starch/PBAT and the TA has a positive effect on the tensile strength and puncture force. Additionally, greater proportions of TA increased Youngs modulus. The starch+PBAT/TA and Gly/TA interactions contributed to a reduction in the water vapour permeability of the films. The inclusion of TA did not change the crystallinity of the samples. Formulations with intermediate proportions of TA (0.8 g/100 g) were shown to produce the best compatibilising effect. This was observed by DMA analysis as a consequence of the perfect equilibrium between the contributions of TA as a compatibiliser and in the acidolysis of starch, resulting in films with a tensile strength of 5.93 MPa, a possible alternative to non-biodegradable packaging.