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•Cellulose nanofibers from banana peel were incorporated in banana starch-based films.•Cellulose nanofibers showed no cytotoxic effect on the Caco-2 until 2000 μg/mL.•CNFs improved ...the mechanical, optical and water barrier properties of the starch film.•The nanocomposites properties were strongly influenced by CNFs aspect ratio.•Banana peel CNFs are potentially applicable as reinforcement in polymeric matrices.
The potential use of cellulose nanofibers (CNFs) as a reinforcing agent in banana starch-based nanocomposite films was investigated. CNFs were isolated from banana peel (Musa paradisiaca) by enzymatic hydrolysis. Banana starch-based nanocomposite films were prepared with CNFs using the casting method. CNFs effect on cell viability and on nanocomposite films properties’ was investigated. The cytotoxicity of CNFs was assessed on Caco-2 cell line. CNFs were not cytotoxic at 50–2000 μg/mL. However, CNFs above 2000 μg/mL significantly decreased cell viability. Topography analysis showed that the incorporation of CNFs modified the film structure. The nanocomposites exhibited a complex structure due to strong interactions between CNFs and starch matrix, promoting a remarkable improvement on mechanical and water barrier properties, opacity and UV light barrier compared to the control film. CNFs can offer a great potential as reinforcing material for starch-based nanocomposite films, producing a value-added food packaging from a waste material.
Cellulose nanofibers (CNFs) were isolated from unripe banana peel by acid hydrolysis, with different acid concentrations (0.1%, 1.0% and 10% v/v), followed by mechanical treatment with high-pressure ...homogenizer. Banana starch-based films added with CNFs (0.2% w/w) as a reinforcing agent were produced by the casting method. The rheological behavior of aqueous dispersions of CNFs (1.0% w/w) and their effects on the properties of nanocomposite films were investigated. All aqueous dispersions of CNFs showed gel-like behavior and, when incorporated to the films, CNFs improved their water barrier properties and mechanical resistance as demonstrated by the increase in tensile strength and Young's modulus. Moreover, CNFs were well dispersed in the composite matrix. CNFs prepared at higher concentration, followed by mechanical treatment (FNM1 and FNM10), formed films with low moisture (13.66%) and solubility in water (24.1%). Whereas, CNFs prepared at the lowest acid concentration without mechanical treatment (FN0.1) led to films with high elongation at break (30.6%) and good tensile strength (12.3 MPa). Regardless of the used CNFs, all the nanocomposites displayed lower UV/light transmission than control film. The nanocomposite has potential use in food packaging, since the use of CNFs can promote improvements on barrier, optical and mechanical properties. Cellulose nanofibers isolated from agro-industrial residues offer the potential to reinforce composites of biodegradable polymers, producing a value-added material.
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•Cellulose nanofibers from banana peel were incorporated in banana starch-based films.•Suspension of cellulose nanofibers (CNFs) showed gel-like behavior with G′ > G″.•CNFs from milder process conditions led to films with higher elongation at break.•CNFs improved mechanical, optical and water barrier properties of the starch film.
Image analysis can serve as a fast and convenient approach for the analysis of particle size and shape. However, there is no consensus as to the minimum number of particles required for such analysis ...and the statistical methodology to be used in its evaluation. Four methodologies for determination of this minimum number for particle size distribution analysis and two for that of particle shape were tested using particles of guava juice powder and guava juice powder granulated in a fluidized bed. The Chi-Square test proved to be a robust and efficient mean for determination of particle size distribution and particle shape characterization. 550 particles was found to be the minimum number of particles necessary for the determination of the particle size distributions, with 100 particles required for determination of the shape descriptors for this specific material.
There is no consensus on the minimum number of particles that should be analyzed for determination of particle size distributions and particle shape characterization. Four methodologies for determination of this number for particle size distribution and two for particle shape were tested using particles of guava juice powder and guava juice powder granulated in a fluidized bed.
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► What’s the minimum number of particles (MNP) to be analyzed by image analysis. ► Comparison between different methodologies. ► 550 would be the MNP necessary for determination of the percentage distributions. ► 100 would be the MNP required for determination of the shape descriptors.
The objective of this paper was to study the effect of plasticizers and their concentrations on the thermal and functional properties of gelatin-based films. Four polyols (glycerol—GLY, propylene ...glycol—PPG, di- DTG and ethylene glycol—ETG) were tested in five concentrations: 10, 15, 20, 25, and 30
g plasticizer/100
g of gelatin. For thermal analysis, the films were conditioned in desiccators with silica gel and for functional properties (mechanical properties, water vapor permeability, color and opacity) characterizations, the films were conditioned at 25
°C and 58% relative humidity. The results were discussed in terms of ‘plasticizer efficiency’ meaning plasticizer content effect and also in terms of ‘plasticizer effect’ meaning the plasticizer type effect on the properties. In a general manner, the higher plasticizing effect on thermal properties was observed with the DTG, followed by PPG, GLY and ETG, principally with low plasticizer content. However, also in terms of thermal properties, the ETG presented the higher plasticizer efficiency followed by the GLY, DTG and PPG. Concerning the mechanical properties, the GLY showed the greater plasticizing effect and efficiency, but the plasticizing efficiency of DTG on the puncture deformation was also considerable. The mechanical resistance could be related with the glass transition temperature of films. It was not possible to observe the plasticizer effect on the water vapor permeability (WVP), but the DTG had shown greater plasticizer efficiency, followed by GLY and ETG, while a counter effect was observed with PPG. The effect of the type and concentration of plasticizer on the color and opacity of films could be considered as negligible. In conclusion, the more important plasticizer effect and efficiency were observed with DTG and ETG on the thermal properties, and with the GLY in terms of functional properties. The behavior of the mechanical properties of films could be explained by its glass transition temperature.
The objective of this research was to evaluate the effects of the steam agglomeration process variables on the characteristics of cocoa beverage powders. A pilot scale agglomerator was used in the ...tests. For the cocoa beverage powder formulated with granulated sugar, most common commercial product, the increase in solids feed rate (400–700
g/min) led to a decrease in the mean particle diameter (400
g/min – 564.70
μm, 700
g/min – 438.40
μm) and an increase in the dryer rotation (12–52
rpm) led to an increase in the product moisture (12
rpm – 1.52% w.b., 52
rpm – 1.88% w.b.). The changing from 1.0
×
10
2 to 1.8
×
10
2
kPa of the vapor pressure resulted in an increase in moisture of the cocoa beverage powder (1.0
×
10
2
kPa – 1.46% w.b., 1.8
×
10
2
kPa – 1.94% w.b.) and the intensification of the yellow color of the product (1.0
×
10
2
kPa – 14.51, 1.8
×
10
2
kPa – 15.17).
The objective of this study was to select the optimal operational conditions for the production of instant soy protein isolate (SPI) by pulsed fluid bed agglomeration. The spray-dried SPI was ...characterized as being a cohesive powder, presenting cracks and channeling formation during its fluidization (Geldart type A). The process was carried out in a pulsed fluid bed, and aqueous maltodextrin solution was used as liquid binder. Air pulsation, at a frequency of 600
rpm, was used to fluidize the cohesive SPI particles and to allow agglomeration to occur. Seventeen tests were performed according to a central composite design. Independent variables were (i) feed flow rate (0.5–3.5
g/min), (ii) atomizing air pressure (0.5–1.5
bar) and (iii) binder concentration (10–50%). Mean particle diameter, process yield and product moisture were analyzed as responses. Surface response analysis led to the selection of optimal operational parameters, following which larger granules with low moisture content and high process yield were produced. Product transformations were also evaluated by the analysis of size distribution, flowability, cohesiveness and wettability. When compared to raw material, agglomerated particles were more porous and had a more irregular shape, presenting a wetting time decrease, free-flow improvement and cohesiveness reduction.
The objective of this study was to select the optimal operational conditions for the production of instant soy protein isolate by pulsed fluid bed agglomeration. When compared to raw material, agglomerated particles were more porous and had a more irregular shape, presenting a wetting time decrease, free-flow improvement and cohesiveness reduction.
Edible films are thin materials based on a biopolymer. The objectives of this work were to determine the water vapor permeability and the mechanical and thermal properties of edible films based on ...bovine hide and pigskin gelatins. These films were prepared with 1
g of gelatin/100
ml of water; 15–65
g sorbitol/100
g gelatin; and at natural pH. The samples were conditioned at 58% relative humidity and 22°C for 4 days before testing. The mechanical properties were determined by the puncture test and the water vapor permeability by gravimetric method at 22°C. For DSC analysis, samples were conditioned over silica gel for 3 weeks. Samples (∽10
mg) were heated at 5°C/min, between −150 and 150°C in a DSC TA 2010. A second scan was run after cell cooling with liquid nitrogen. As expected, the puncture force decreased and the puncture deformation and water vapor permeability increased with the sorbitol content. The origin of gelatin was important only above 25
g sorbitol/100
g gelatin. The DSC traces obtained in the first scan of samples with 15–35
g sorbitol/100
g gelatin, showed a well visible glass transition followed by a sol–gel transition. However, with the increase of sorbitol concentration, the glass transition became broader, typical of the system presenting a phase separation. The model of Couchman and Karazs for ternary system, was used to predict the Tg values as a function of sorbitol concentration.
Cellulose nanoparticles from a vegetable source (cellulose fiber) have been evaluated for future use as reinforcement of polymeric matrixes (e.g., biodegradable films). Cellulose nanoparticles have ...numerous advantages: they are inexpensive and biodegradable, and they originate from renewable sources. Here, cellulose nanofibers (CNFs) were isolated from banana peel by chemical (alkaline treatment and bleaching followed by acid hydrolysis with 0.1, 1, or 10% (v/v) H2SO4) and mechanical (high pressure homogenizer) treatments. Atomic Force Microscopy (AFM) analysis showed all treatments effectively isolated banana fibers at the nanometer scale (average diameter of 3.72 nm). CNFs displayed ζ-potential values ranging from −37.60 to −67.37 mV, which prevented their aggregation. CNFs had high crystallinity values, from 63.1 to 66.4%, which indicated they could be good reinforcing agents. FTIR results confirmed that the chemical and mechanical treatments removed the amorphous fractions. Regarding cytotoxicity, low CNF concentrations (50–500 μg/mL) did not cause cell death, but CNFs at concentrations above 1000 μg/mL significantly decreased cell viability. The use of different sulfuric acid concentrations provided more detailed knowledge of the treatment methods and CNF features, which could help to improve the CNF production process. The combination of chemical and mechanical treatments proved to be an efficient strategy to prepare CNFs from banana peels as a potential reinforcing agent of polymeric matrixes (e.g., food packaging).
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•CNFs were isolated from banana peel using acid and mechanical treatments.•CNFs showed no cytotoxic effect against Caco-2 at concentrations lower than 500 μg/mL.•Banana peel CNFs have potential application as reinforcing agent in polymeric matrices.
Microencapsulation by production of polymer beads from ionic gelation is a useful method to improve the stability of nutritional compounds. Wheat germ oil is a nutritional source of unsaturated fatty ...acids and phytonutrients, such as tocopherols (α and β), phytosterols, carotenoids, and phenolic compounds. This work studied the development of alginate‐starch beads over the stability of encapsulated wheat germ oil. The beads contained sodium alginate and gelatinized corn starch in proportions of 2:0, 1:1, 1:2, and 1:4. The addition of small amounts (1:1) of gelatinized starch in the alginate emulsions improved the physicochemical properties and stability during storage. The emulsions had oil droplets with mean sizes ranging from 4.5 to 12.2 µm. The 1:1 samples showed more disperse oil droplets, explained by the molecular interaction between the starch chains and oil. The encapsulation efficiency was higher than 91%, and the beads’ mean diameters were between 383.22 and 797.45 µm. The proportion of 1:1 alginate‐starch also enhanced the beads’ microstructures, avoiding oil oxidation. Six days accelerated stability (65 °C) evidenced higher tocopherols amounts (0.66 mg/g oil) and a lower oxidation (2.52 meq.O2/kg oil) for the 1:1 samples compared to the remained samples.
Practical Application
Alginate‐gelatinized corn starch beads loaded with wheat germ oil can be used as an ingredient in functional food products for the enrichment of nutrients. The use of starch decreased the oil oxidation and the loss of tocopherols during storage, indicating that the quality of the wheat germ oil will be desirable for longer durations of food storage.
Amaranth protein-lipid (PL) and protein (P) films were elaborated and compared with amaranth flour films in order to determine the contribution of the interactions between the biopolymer (starch and ...protein) and the lipids to the film properties. The films were made by the casting method, using the same glycerol concentration (0.9 g glycerol/100 g solution). A separation of the lipid fraction in the PL films and a polymorphic transformation of the corresponding fatty acids were observed by differential scanning calorimetry (DSC) and verified by an analysis of the microstructure by scanning electron microscopy (SEM). The flour films showed no separation of the lipid fraction, evidence that the lipids were strongly associated with the proteins and homogenously distributed throughout the starch network, contributing to the good mechanical properties when compared to the PL films and to the excellent barrier properties when compared to both the PL and P films. The protein-protein interactions also contributed to the mechanical properties of the flour films. The presence of proteins and lipids in the flour films had an important effect on film solubility, and also on the color and opacity of the films. This study showed that the flour film properties depended on the interactions formed by their polymers (starches and proteins) and by the lipid, on the distribution of these interactions within the film matrix and on the concentrations of each component in the film.
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