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•Mechanical milling affects thermal properties at long milling times.•Milling increases amylose content and promotes the formation of elastic gels (Ǵ).•Modified starches show a ...non-Newtonian flow behavior as reofluidizers.•Tan δ shows the modification of starch-generated elastic gels.
This work evaluates the effect of high-energy mechanical milling time (7 levels, 20–80 min) on amylose content, crystallinity pattern, temperature and gelatinization enthalpy, morphology, and rheological properties of chayotextle (Sechium edule Sw.) starch. After 30 min of milling, granular structure was affected, and amylose values were the highest while crystallinity and gelatinization enthalpy decreased significantly. These changes allowed to obtain gels with viscoelastic properties where the elastic character (Ǵ) prevailed upon the viscous modulus (Ǵ́). Native starch showed Tan δ values of 0.6, increased significantly (0.9) after 30 min of milling due to the surge in linear chains (amylose) and loss of granular structure. Native and modified starches showed high dependence on cutting or shear speed, presenting a non-Newtonian behavior (reofluidizers). These results indicate that mechanical grinding is an alternative to obtain modified starches with applications in the food industry.
The objective of this work was to modify banana starch with pineapple leaf fibers (PALF) and its production of biodegradable films. The reaction conditions of the starch modification were a ...Starch/PALF mass ratio of 50, a time of 1 h and a temperature of 140 °C, to obtain a yield of 41.18 %. Characterization by FTIR and NMR confirmed that the chemical reaction was carried out. XRD and TGA analysis showed that the crystalline zones of the starch were affected during the modification and the product obtained is thermally less stable compared to unmodified starch. The modified starch showed a lower pasting profile compared to the native starch; however, the modified starch showed the ability to form a film. The starch-PALF films were obtained by the casting method and partially characterized. These films presented better mechanical properties compared to the unmodified films. Also, these films could compete with conventional non-biodegradable plastics.
The objective of this paper was to perform a copolymerization between polyethylene and starch in order to obtain new environmentally friendly materials. The copolymer obtained was characterized ...thermally, morphologically and structurally, including its pasting profile. The starch-g-PE copolymer showed lower thermal stability compared to the control materials. FTIR analysis determined that the chemical bond signal between the starch and polyethylene in the copolymer overlaps with the native starch signals. The signal from this chemical bond was assigned by proton NMR spectroscopy at δ 4.45 ppm. X-ray studies of the copolymer showed a material with more amorphous characteristics compared to native starch. SEM analysis demonstrated the presence of cracks in the starch granules which favored the chemical interaction between the polymers. The pasting behavior of the copolymer was less pronounced compared to native starch. Therefore, the copolymerization of both polymers could be an alternative to recycle polyethylene and make biodegradable materials.
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•The copolymerization of the starch and polyethylene was achieved by the bulk method.•The incorporation of polyethylene decreased the crystallinity in the starch.•The copolymer obtained had a lower thermal stability than the homopolymers.•Interaction of the starch with the polyethylene generated a low viscosity copolymer.
The objective of this work was to analyze the morphological and physicochemical properties of bean starch and its use in nanoencapsulation by spray drying. Starch purity was 81.21 ± 1.43% db with a ...resistant starch content higher than a commercial corn starch, but with a high protein content and a low amylose content. Starch granules presented smooth surfaces, polyhedral shape and sizes from ~ 1 to 6.3 µm. Black bean starch exhibited an A-type X-ray diffraction pattern with a crystallinity highest than corn starch. Black bean starch showed higher thermal stability than a commercial corn starch. At 90 °C, solubility was 31.0% and swelling power was 31.2 g g
−1
. The black bean starch gel showed a high stability under refrigeration and freeze–thaw. Small particles and viscosity profile suggested the potential application of black bean starch as wall material during nano spray drying. Black bean starch tends to form spherical aggregates during nano spray drying due to the protein content. Capsules size was in the range of 1.0–2.5 µm, however were observed agglomerated particles by SEM. The encapsulation efficiency of
l
-ascorbic acid was 36.88 ± 0.55%. The results indicate that black bean starch possesses properties with potential applications in food industries.
Two banana starches were studied to analyze the effect of the acid hydrolysis on their molecular structure, and the impact in their physicochemical features. The native banana starches exhibit ...differences in the amylose content, molar mass, gelatinization parameters, X-ray diffraction pattern, and pasting profile. These results suggested that different acid hydrolysis mechanisms may be operative in these two starches. The kinetic hydrolysis is different in both banana starches that are related to the crystalline packing of the starch molecules. This was confirmed by the amylose content, the X-ray diffraction pattern, and the thermal study in the acid hydrolyzed starches at different times. The acid-treated Roatan starch showed higher retrogradation than Macho starch, a phenomenon that increases in the sample hydrolyzed for the longer time. This pattern is related to the amylose/amylopectin ratio, the reduction in the molar mass and the gyration radius. The acid hydrolysis of banana starches, although they have some similarities, they are different.
•Hydrolysis rate depends on the internal structure of banana starches.•Structural characteristics indicate acid attacks the crystalline packing.•Enthalpy of acid-treated banana starches decreases when hydrolysis time increases.•The acid treatment results in a reduction in the amylose content.•Roatan starch shows higher retrogradation than Macho starch.
The effect of lintnerization on the banana starch of the Roatán cultivar from acid hydrolysis at 3, 5, and 7 days on the starch digestibility and morphological and thermal features was evaluated. ...Acid treatment produced an increase in the rapidly digestible starch (RDS) (20.2%) and slowly digestible starch (29.7%), but a decrease in the resistant starch (36.3%) content, as compared with its native counterpart. However, over the longest acid-treatment time, a decrease in the RDS over 5 days was observed. The lintnerized banana starch can be used in food products without additional cooking. The temperature (77-80°C) and enthalpy (11.6-14.1 J/g) of gelatinization increased significantly when the acid-treatment time increased, indicating an arrangement of the crystalline lamella by the double helices of the amylopectin chains. The acid treatment increased the retrogradation rate of the lintnerized banana starch gels. The lintnerization of banana starch for different lengths of time modified its morphology, starch digestibility, and thermal features, indicating changes in the crystalline lamella due to the arrangement of the double helices of amylopectin.
The banana starch reaction with polyethylene using ethylene carbonate was carried out by varying the starch/ethylene carbonate mass ratio (50–1000%). The starch-g-PE mass yield reached 89% mass ...conversion and a grafting yield of 0.52 when a starch/EC = 0.5 ratio was used, while the mass yield decreased until reaching a value of 26% when the starch/EC mass ratio increased. The final product was characterized by different instrumentals techniques to demonstrate copolymerization. The vibration signal of the carbonyl group (C=O) increased as that the starch/EC mass ratio decreased, indicating that the starch polymer chains are chemically interacting with the PE. The chemical bond signal between starch with carbonate group was assigned at
δ
4.8 ppm. This modified starch is a material with less thermal stability than banana starch and polyethylene, and its degradation temperature decreases by 20 °C and 50 °C, respectively. The micrographs shown that the starch granules randomly agglomerate due to the presence of PE. Modified starch has a lower crystallinity than native starch. The viscosity of the starch-g-PE granules reached a value of 0.1 Pa s at temperature of 33 °C, while native starch reached a value of 5.0 Pa s at this same temperature. This product obtained is a moisture-resistant material due to the presence of PE chains and that could be used as a compatibilizer for post-consumer polymers such as polyalkanes.
Graphical abstract
El almidón de plátano (AP) y proteínas del suero (PS) de leche (α-LA, β-LGA y β-LGB) fueron mezcladas para elaborar biopelículas por el método de vaciado en placa. La solubilidad en las biopelículas ...AP/PS (32.42%) fue mayor que las control, elaboradas con AP (7.2%). La adición de las PS en la biopelícula, mejoró las propiedades mecánicas, ya que aumentaron los valores del módulo de Young y esfuerzo máximo a la ruptura, patrón inverso fue observado en la elongación al rompimiento. La película AP/α-LA mostró mayor incremento en la temperatura de fusión que las mezclas AP/β-LGA y AP/β-LGB. La estabilidad a la temperatura (ΔH) en las biopelículas fue mejorado por la adición de PS. Los estudios de espectrofotometría mostraron una mayor longitud de banda en 3500 cm–1 en películas de AP/PS indicando un incremento en los grupos –OH, lo que tiene relación con la mayor solubilidad que presentaron estas biopelículas.
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