Effect of long-term retrogradation on the crystallinity, vibrational and rheological properties of potato, corn, and rice starches

Starch retrogradation remains as an area of interest due to its technological implications. The long-term structural changes taking place during the retrogradation process of gels from rice, potato, and corn starches were investigated using X-ray diffraction (XRD), rheology, and Fourier transform infrared spectroscopy (FTIR). Rietveld refinement of XRD showed that initial crystalline arrangement of starches transitioned to a combination of hexagonal and monoclinic structure in varying proportions, also the distribution of crystalline and amorphous phases had a preferential growth depending on the starch source. Final crystallinity values after 28 days in gels were potato (12.38 %) > corn (7.26 %) > rice (1.92 %). All starch gels showed a viscoelastic behavior with a mesh size of the gel network decreasing over time. FTIR showed a close relationship with crystallinity growing. These results enhance the understanding of structural changes in starch gels during retrogradation and help predict their behavior.

Effect of endogenous protein on starch before and after post-harvest ripening of corn: Structure, pasting, rheological and digestive properties

This work revealed the effects of endogenous proteins on the structural, physicochemical, and digestive properties of starch in corn before and after ripening and explored the binding mechanism of proteins with starch. The microstructure showed that the postharvest ripening process resulted in a thinning of the protein layer on the surface of starch particle. After the removal of protein, the uniformity of the sample surface increased, with tiny pores. The proportion of double helix structure of starch were significantly reduced, while the proportion of amorphous structure and the thickness (da) of the amorphous region were significantly increased. The gelatinization enthalpy, gelatinization viscosity value, consistency coefficient, elasticity, and rapid digestibility of starch (RDS) were all significantly increased. Due to the weakening of the interaction between starch (including amylose and amylopectin) and protein in post-ripened corn, the effect of protein removal on the structure and properties of unripened samples was more significant.

Effect of ultrasonically stimulated potato germination during soaking on the physicochemical properties of starch and its use in edible films

The aim of this work was to investigate the effects of ultrasonic treatment during soaking of potatoes on the physicochemical properties of starches obtained after 16 weeks of germination. The ultrasonic treatment showed a direct correlation between sprout length and ultrasonic time. The protein content decreased from 0.63 to 0.38 % and the fat content decreased significantly from 0.31 to 0.01 % after germination. The amylose content changed depending on the ultrasonic treatment, and increased from 36.27 to 40.92 % after 16 weeks of germination, which was related to the amylopectin debranching and the duration of the ultrasonic treatment. X-ray diffraction showed that the nanocrystals with hexagonal structure were not affected by the germination and the duration of ultrasonic treatment. Scanning electron microscopy showed that the surface of the starch granules was not affected by the enzymatic treatment. The sprouted potato starch resulted in films with better tensile strength and lower water vapor permeability (WVP) compared to the native potato starch films. In addition, the films produced with ultrasound stimulated potato starch exhibited better properties (high strength and low permeability), which is desirable when it comes to controlling moisture exchange between a food product and the surrounding atmosphere.

Characterization of starches isolated from Mexican pulse crops: Structural, physicochemical, and rheological properties

This work aimed to characterize and compare the physicochemical properties of four pulse starches: bean, chickpea, lentil, and pea. Chemical proximate analysis, elemental composition, morphological grain characterization, crystalline structure, thermal analysis, FTIR analysis, and pasting properties were conducted. The proximate analysis shows that these starches have low fat, mineral, and protein content but high amylose values ranging from 29 to 36 % determined by colorimetry. Despite the high amylose content, the starches did not exhibit the typical behavior of an amylose-rich starch, with high peak viscosity and low breakdown and setback. It was found that this behavior was likely due to the large granule size of the ellipsoidal, spherical, and kidney-shaped granules and the high content of some minerals such as Na, Mg, K, Fe, Mn, P, and Si. The study also found that all pulse starches simultaneously contain monoclinic and hexagonal crystals, making them C-type starches. The findings were verified through the Rietveld analyses of X-ray diffraction patterns and differential scanning calorimetry, in which bimodal endothermic peaks evidenced both types of crystals being gelatinized.

Changes in the physicochemical properties of isolated starch and plantain (Musa AAB Simmonds) flours for early maturity stage

This work focuses on the study of the physicochemical changes that take place during the first stage of ripening of plantain, with particular attention to the changes in the orthorhombic and hexagonal nanocrystals present in this starch, and its relation shift with resistance starch. Significant changes were observed in the proximal analysis of plantain flour. A gradual increase in moisture content was attributed to the high content of crystalline structures and molecules that can be removed by drying. Water activity increased with ripening, which was attributed to the hygroscopic nature of the flours. The protein content increased, and the carbohydrate content decreased, indicating the progress of biochemical reactions. The changes in the fat content are consistent with the hydrolysis and resynthesis of lipids during the ripening process. The obtained results indicate a significant influence of the ripening stage on the physicochemical properties of flour and starch of plantain, which is associated with the occurrence of a climacteric peak on the 4th day of ripening. The hydration properties of plantain flour decreased significantly during the ripening days, consistent with the occurrence of a climacteric peak. Water holding capacity (WHC) and water binding capacity (WBC) were affected by the degree of digestion of native starch granules and protein denaturation during fruit ripening. Scanning electron microscopes (SEM) showed that during ripening the surface of the isolated starches do not suffer any significative damage. X-ray diffraction patterns were used to identify crystalline structures and to study the changes in the crystalline structures. These results showed that the starch contains orthorhombic and hexagonal nanocrystals, which play and important role and which show small structural damage during ripening reflected in a decrease in their relative crystallinity. This is the first time that these nanocrystals have been studied and considered in the ripening process. Differential scanning calorimetry was used to study the thermal transition in isolated starch. The results indicated that the gelatinization of starch corresponds to the solvation of orthorhombic and hexagonal nanocrystals, and that during ripening there is a decrease in the enthalpy reflecting some crystal structural damage. Pasting properties were studied using a Starch cell for flours and isolated starches, indicating that the pasting profile is governed by intrinsic and extrinsic factors. The resistant starch does not show significant changes at this stage of maturation. This starch is the one with the highest resistant starch content reported in the literature (38%). It was hypothesized that the resistant starch is directly related to the amount of whole starch granules, and more importantly, directly related to the number concentration of orthorhombic and hexagonal nanocrystals. Therefore, knowledge of the physicochemical and nutritional properties of plantain and flour at each stage of ripening allows better selection according to industrial applications.

Microstructured lipid microparticles containing anthocyanins: Production, characterization, storage, and resistance to the gastrointestinal tract

Anthocyanins from grape peel extract have several biological properties and can act as a natural colorant and antioxidant agent. However, these compounds are susceptible to degradation by light, oxygen, temperature, and the gastrointestinal tract. Thus, this study produced microstructured lipid microparticles (MLMs) containing anthocyanins by the spray chilling technique and evaluated the particle stability. trans-free fully hydrogenated palm oil (FHPO) and palm oil (PO) were used as encapsulating materials in the ratios 90:10, 80:20, 70:30, 60:40, and 50:50, respectively. The concentration of grape peel extract was 40 % (w/w) in relation to the encapsulating materials. The microparticles were evaluated for thermal behavior by DSC, polymorphism, FTIR, size distribution and particle diameter, bulk density, tapped density, flow properties, morphology, phenolic compounds content, antioxidant capacity, and retention of anthocyanins. Furthermore, the storage stability of the microparticles was investigated at different temperatures (-18, 4, and 25 °C), and the anthocyanins retention capacity, kinetic parameters (half-life time and degradation constant rate), total color difference, and visual aspects were evaluated during 90 days of storage. The resistance of MLMs to the gastrointestinal tract was also evaluated. In general, higher FHPO concentrations increased the thermal resistance of the MLMs and both showed defined peaks of β' and β forms. The FTIR analysis showed that the MLMs preserved the original forms of their constituent materials even after atomization, with interactions between them. The increase in the PO concentration directly affected the increased mean particle diameter, agglomeration, and cohesiveness, as well as lower bulk density, tapped density, and flowability. The retention of anthocyanins in MLMs ranged from 81.5 to 61.3 % and was influenced by the particle size, with a better result observed for the treatment MLM_90:10. The same behavior was observed for the phenolic compounds content (1443.1-1247.2 mg GAE/100 g) and antioxidant capacity (1739.8-1660.6 mg TEAC/100 g). During the storage, MLMs made with FHPO to PO ratios of 80:20, 70:30, and 60:40 showed the highest stability for anthocyanin retention and color changes at the three temperatures (- 18 °C, 4 °C, and 25 °C). The gastrointestinal simulation in vitro revealed that all treatments were resistant to gastric phase and maintained a maximum and controlled release in the intestinal phase, demonstrating that FHPO together with PO are effective to protect anthocyanins during gastric digestion, and can improve the bioavailability of this compound in the human organism. Thus, the spray chilling technique may be a promising alternative for the production of anthocyanins-loaded microstructured lipid microparticles with functional properties for various technological applications.

Dielectric barrier atmospheric cold plasma applied to the modification of Ariá (Goeppertia allouia) starch: Effect of plasma generation voltage

The goal of this paper was to evaluate the influence of a range of plasma generation voltages on the physicochemical, structural, and technological properties of Aria (Goeppertia allouia) starch. Untreated (0 kV) and high voltages of cold plasma generation (7, 10, 14, and 20 kV) treated samples were evaluated according to their amylose content, pH, groups carbonyl/carboxyl, molecular size distribution, structure and technological properties (empirical viscosity, hydration properties, thermal analysis and gel strength). The applied voltage of 14 kV resulted in the greatest depolymerization of the starch chains, while 20 kV allowed the formation of oxidized complexes, promoting crosslinking of the starches chain. The cold plasma technique did not affect the levels of resistant starches, but increased the starch digestibility. The increased carbonyl and carboxyl groups also influenced the paste viscosity, improved hydration properties. This study suggests that the cold plasma technique can be useful in the controlled modification of starches, producing starches with different technological properties.

Effect of Extrusion on the Crystalline Structure of Starch during RS5 Formation

Amylose is well known to be organized helically with six glucose per turn, allowing it to form complexes with various ligands. This interaction can be affected by the type of crystalline structure present in the starch sources. This study evaluated the effect of extrusion on the crystalline structure of starch during RS5 formation. Rice and potato starches were extruded at 100 °C and 15 rpm with 5% and 10% oleic acid (OA), then the physical, thermal, paste properties, and resistant starch content (RS) were evaluated. Potato starch extruded with 10% OA showed granules embedded in a gelatinized starch matrix. The X-ray revealed that rice (orthorhombic) and potato (hexagonal) structures remain unchanged even after extrusion. Differential scanning calorimetry (DSC) evidenced the formation of type IIa amylose-lipid complexes in OA treatments, where potato extruded with 10% OA had the highest enthalpy (0.9 J/g). Moreover, the extruded potato showed the highest pasting temperature (87.19 °C), supporting the complex formation. The RS was reduced from 15.8 (isolated) to 4.14 mg/100 mg (extruded 10% OA) in rice. For potato, RS decreased from 17 to 13 mg/100 mg (isolated and extruded 10% OA). Overall, these findings suggest a tendency in potato starch (ortho-rhombic) to interact with OA during the extrusion process, promoting a crystalline lamellae growth when extruded with 10% OA; therefore, changing their properties.

Ariá (Goeppertia allouia) Brazilian Amazon tuber as a non-conventional starch source for foods

Ariá (Goeppertia allouia) is a tuber from the arrowroot's family widely found in the Brazilian Amazon. The tuber has a flavor similar to corn, besides high retrogradation when cooked, differing from other commercial starches. To enhance its added value, the Ariá starch was extracted to evaluate its potential as a food ingredient. The Ariá starch was compared to the commercially available corn and potato starches regarding their physicochemical, thermal, structural, and rheological properties based on the Duncan's test (p-value <0.05). The Ariá starch presented high amylose content (~38% w/w). Furthermore, the X-ray diffraction pattern confirmed its Type-C crystalline structure. The rheological properties showed that the starch gels presented high hardness and retrogradation as other studied starches. Ariá has great potential as a source of starch with low digestibility, increasing the satiety of food products.