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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.
Banana is a starchy food that contains a high proportion of undigestible compounds such as resistant starch and nonstarch polysaccharides. Products with low glycemic response such as pasta are ...considered favorable to health. The objective of this study was to use unripe banana flour to make spaghetti with low‐carbohydrates digestibility and evaluate its physical and texture characteristics, as well as consumer preference. Formulations with 100% durum wheat semolina (control) and formulations with 3 semolina: banana flour ratios (85: 15, 70: 30, and 55: 45) were prepared for spaghetti processing. The use of banana flour decreased the lightness and diameter of cooked spaghetti, and increased the water absorption of the product. Hardness and elasticity of spaghetti were not affected by banana flour, but adhesiveness and chewiness increased as the banana flour level in the blend rose. Spaghettis prepared in the laboratory (control and those with banana flour) did not show differences in preference by consumers. In general, the preference of spaghettis with different banana flour level was similar. The addition of a source of undigestible carbohydrates (banana flour) to spaghetti is possible without affecting the consumer preference.
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.
Three composite cereal bars containing white maize, blue maize, or unripe banana flours were prepared. The glycemic response in rats feed with a dose available carbohydrates, and the bars effect on a ...glucose tolerance test were evaluated. A dose of 0.85 g/kg was used in the experiments with the three bars. The experiment with a glucose load showed that rats previously fed with blue maize and unripe banana bars showed reduced glycemic response, probably as consequence of glucose entrapment within the food matrix and produce a slow release. The effect was more pronounced for the unripe banana bar. The groups fed with equivalent load of available carbohydrates from the various bars exhibited lower and slower glycemic responses than a control group administered only with a glucose load. The white maize bar elicited a maximal blood glucose level at 30 min postprandial, blue maize at 45 min and unripe banana bar at 60 min. Bars inducing variable glycemic response may be prepared following the proper choice of functional ingredients.
The development of functional foods with low glycemic index and high levels of RS are of importance in the fight against the rapidly increasing rates of obesity and chronic diseases in modern ...societies. In this work, three cereal bars containing white maize, blue maize, or unripe banana flours were prepared. The proximal composition, in vitro starch digestibility and product acceptability were evaluated. The bar prepared with blue maize exhibited the highest level of protein and fat, and that containing white maize the highest dietary fiber and indigestible fraction contents. However, the product prepared with unripe banana flour showed the highest total and rapidly digestible starch levels, while that added with blue maize exhibited greater slowly digestible starch values. No difference in RS content was detected among the three bars. The starch hydrolysis indices and predicted glycemic indices of the three preparations were low (40-54% and 42-54%, respectively). Similar acceptation scores were recorded for the three experimental bars. Cereal bars with variable starch digestibility features and good acceptation by consumers may be prepared following the proper choice of functional ingredients.
In this study, some morphological, physicochemical, and the initial characterization of the starch granule enzymes of blue and white maizes of small and large granules are described. Starch was ...isolated from blue and white maizes, and the small and large granules were separated. The efficiency of separation was higher in large granules than small of the blue maize starch. The amylose content was slightly greater (1.3%) in large granules than smaller in both starches studied. No differences in the average gelatinization temperature were found between large and small granules, but the enthalpy of gelatinization value was higher in the small granules. The electrophoretic pattern showed that the granule-bound starch synthase (GBSSI) had higher expression in large than small granules and that explain the higher amylose content in the former granules. The differences showed in the starch biosynthesis enzymes in small and large granules might explain partially the physicochemical and functional properties of maize.
The evolution of acid hydrolysis (sulfuric acid 3.16 M) at the onset gelatinization temperature (57.73 ± 0.72°C) of native corn starch was monitored. A first‐order kinetics fitting was used to ...estimate the mean hydrolysis time (τH=29.26±3.86 min) and maximum conversion (X∞=96.62±2.70%). Amylose content presented a sharp decrement of about 90% in the first 30 min. XRD results indicated A‐type to B‐type crystallinity transition in the first 10 min, with maximum crystallinity increase of about 14% after 30 min. SEM micrographs showed that hydrolysis disrupted granule morphology from regular oval‐like shape to irregular geometries with aggregation of small‐size debris. Granule size distribution broadened as hydrolysis proceeded due to fragmentation‐adhesion phenomena of eroded starch granules. Fast changes in the thermal effects during the first minutes were caused by molecular rearrangements due to fast hydrolysis of amylose in the amorphous regions. Steady shear rate and oscillatory tests showed a sharp viscoelasticity decrease caused by amylose degradation.
Commonly, the interpretation of starch XRD patterns is hampered by the lack of sharp intensity peaks and the presence of a broad background band. This work proposes a fractal analysis approach for ...the analysis of XRD patterns obtained from starches. The idea behind the fractal analysis approach is that the broad background pattern contains information pertaining the complexity of the material structure that presumably is arranged within fractal geometries. Thus, the quest is to detect regularities reflected as auto‐correlations of the complex intensity signal. The fractal rescaled range (R/S) analysis is proposed in this work to obtain an index for the regularity of the complex intensity signal. In turn, such regularity index should reflect the regularity of the complex starch structure. The approach is illustrated with native starches from maize, banana, and potato, showing that the former is more regular (i.e. more ordered starch structure) than the latter two. Gelatinization is used to contrast the fractal analysis results. In turn, it is shown that gelatinized starches exhibit a nearly amorphous structure reflected as non‐correlated XRD sequences.
Resumen Los maíces pigmentados se usan tradicionalmente en la alimentación en diversos países, principalmente de América Latina. En México se usan en productos nixtamalizados como las tortillas, ...botanas, tostadas y tamales, entre otros. El principal componente del grano de maíz es el almidón, el cual imparte las propiedades funcionales y nutricionales a los productos elaborados con este cereal. Las antocianinas dan la coloración características a estos maíces y tienen propiedades benéficas para la salud de los humanos. Las antocianinas están asociadas con la prevención de padecimientos, como el cáncer, por sus propiedades antioxidantes, ya que secuestran radicales libres en el torrente sanguíneo, los cuales están asociados con el desarrollo de estas patologías. Las interacciones entre compuestos bioactivos y carbohidratos son importantes porque pudieran limitar o potenciar su bioaccesibilidad y disminuir la digestibilidad del almidón. El estudio de las interacciones entre carbohidratos y antocianinas en maíces pigmentados está poco desarrollado, pero las evidencias señalan la función nutracéutica de ambos compuestos, por lo cual es necesario realizar más investigación al respecto.
The use of pigmented maize varieties has increased due to their high anthocyanins content, but very few studies are reported about the starch properties of these grains. The aim of this work was to ...isolate the starch granules from pigmented blue maize and carry out the morphological, physicochemical, and biochemical characterization studies. The proximate composition of starch granules showed high protein contents, after purification, the blue maize starch presented lower protein amount than starch from white maize (control). Although the purity of starch granules was increased, the damaged starch (determined for the Maltase cross absence) was also increased. Scanning electron microscopy showed the presence of some pores and channels in the blue maize starch. The electrophoretic protein profiles showed differences in the bands that correspond to the enzymes involved in the starch biosynthesis; these differences could explain the variation in morphological characteristics of blue maize starches against starch from white maize.
