The extent of maize starch crystal melting as a critical factor in the isolation of amylose via aqueous leaching

Critical examination of the characterization techniques, and the evidence, for the existence of extra-long amylopectin chains

It has been suggested that amylopectin can contain small but significant amounts of extra-long chains (ELCs), which could affect functional properties, and also would have implications for the mechanism of starch biosynthesis. However, current evidence for the existence of ELCs is ambiguous. The amylose/amylopectin separation and the characterization techniques used for the investigation of ELCs are reviewed, problems in those techniques are examined, and studies of ELCs of amylopectin are discussed. A model for the biosynthesis of amylopectin chains in terms of conventional biosynthesis enzymes, which provides an excellent fit to a large amount of experimental data, is used to provide a rigorous definition of ELCs. In addition, current investigations of ELCs, involving separation, is hindered by the lack of a method to quantitatively separate all the amylopectin from starch without any traces of residual amylose (which would have long chains). Unambiguous evidence for the existence of ELCs can be obtained using two-dimensional (2D) characterization, these dimensions being the degree of polymerization of a chain and the size of the whole molecule. Available 2D data indicate that there are no ELCs present in currently detectable quantities in native rice starches. However, concluding this more rigorously requires improvements in the resolution of current 2D methods.

Formation, Structural Characterization, and Functional Properties of Corn Starch/Zeaxanthin Composites

Zeaxanthin is a natural xanthophyll carotenoid and the main macular pigment that protects the macula from light-initiated oxidative damage, but it has poor stability and low bioavailability. Absorption of this active ingredient into starch granules as a carrier can be used to improve both zeaxanthin stability and controlled release. Optimization using three variables judged important for optimizing the system (reaction temperature of 65 °C, starch concentration of 6%, and reaction time of 2 h) was conducted for incorporation of zeaxanthin into corn starch granules, aiming for high zeaxanthin content (2.47 mg/g) and high encapsulation efficiency (74%). Polarized-light microscopy, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy showed that the process partially gelatinized corn starch; additionally, it showed the presence of corn starch/zeaxanthin composites, with the zeaxanthin successfully trapped in corn starch granules. The half-life time of zeaxanthin in corn starch/zeaxanthin composites increased to 43 days as compared with that of zeaxanthin alone (13 days). The composites show a rapid increase in zeaxanthin release with in vitro intestinal digestion, which is favorable for possible use in living systems. These findings could have application in designing effective starch-based carriers of this bioactive ingredient with enhanced storage stability and improved intestines-targeted controlled-release delivery.

Effect of inulin on the pasting and retrogradation characteristics of three different crystalline starches and their interaction mechanism

At present, there are hardly any studies about the effect of inulin (IN) on the physicochemical properties and structures of different crystalline starches. In this study, three different crystalline starches (wheat, potato, and pea starch) were compounded with natural IN, and its pasting, retrogradation, and structural characteristics were investigated. Then, the potential mechanism of interaction between IN and starch was studied. The results showed that there were some differences in the effects of IN on the three different crystalline starch. Pasting experiments showed that the addition of IN not only increased pasting viscosity but also decreased the values of setback and breakdown. For wheat starch and pea starch, IN reduced their peak viscosity from 2,515 cP, 3,035 cP to 2,131 cP and 2,793 cP, respectively. Retrogradation experiment dates demonstrated that IN delayed gelatinization of all three starches. IN could reduce the enthalpy of gelatinization and retrogradation to varying degrees and inhibit the retrogradation of starch. Among them, it had a better inhibitory effect on potato starch. The addition of IN reduced the retrogradation rate of potato starch from 38.45 to 30.14%. Fourier-transform infrared spectroscopy and interaction force experiments results showed that IN interacted with amylose through hydrogen bonding and observed the presence of electrostatic force in the complexed system. Based on the above, experimental results speculate that the mechanism of interaction between IN and three crystalline starches was the same, and the difference in physicochemical properties was mainly related to the ratio of amylose to amylopectin in different crystalline starches. These findings could enrich the theoretical system of the IN with starch compound system and provide a solid theoretical basis for further applications.

Characterization and application of a coating of starch extracted from avocado (Persea americana L. cv. Hass) seeds as an alternative to reduce acrylamide content in French fries

The starch extracted from avocado (Persea americana L. cv. Hass) seeds was characterized and used in the preparation of an edible coating to reduce the oil uptake and acrylamide content in French fries. Starch characterization was carried out using Differential Scanning Calorimetry, Fourier transform infrared spectrophotometry, gelatinization, and scanning electron microscopy. Uncoated (UFF) and coated (CFF) French fries were compared and evaluated for moisture, water activity (Aw), fat, color, firmness, acrylamide content, and sensorial analysis. The extracted starch presented a high crystalline structure and good stability to mechanical work and heat treatments. The CFF French fries showed significantly higher Aw, color parameter a*, but lower luminosity and acrylamide content than UFF samples. Similarly, the CFF samples tended to decrease the fat content, although without statistical differences. Avocado seed starch can be an economical and technically feasible alternative to the food industry as an effective coating to reduce acrylamide content in French fries.

Starch and Glycogen Analyses: Methods and Techniques

For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included.

Effect of germination duration on structural and physicochemical properties of mung bean starch

Mung bean seeds were germinated at 25 °C for 12, 24, 36, 48, 60 and 72 h. Changes in structural and physicochemical properties of mung bean starch during germination were investigated. Microscopy analysis showed germination did not change the shape of starch granules, but granules isolated from germinated mung bean starch exhibited dents surface structure compared with smooth surface of native starch. The molecular weight of starch isolated from germinated mung bean was found to be smaller than that of native ones. Although germinated mung bean showed greater crystallinity than that of native sample, the germination did not change the crystalline structure type of starch (C-type). Moreover, solubility and swelling power of starch varied depending on germination duration and testing temperature. Peak viscosity and trough viscosity slightly decreased as germination prolonged to 72 h. Furthermore, starch isolated from mung bean germinated for 12 h showed greater enthalpy (ΔH) than that of starch isolated from native sample; while, ΔH decrease as germination time prolonged from 36 to 72 h. The obtained results may help in understanding the influence of germination on functional properties of mung bean starch and choosing appropriate applications to promote utilization of mung bean starch in food industry.

Insight on the changes of cassava and potato starch granules during gelatinization

Gelatinization is an important property of starch for biomedical applications. However, studies on the changes in starch granules in terms of morphology, swelling, amylose leaching and so on during gelatinization, which are key to uncovering the starch gelatinization process, have rarely been reported. Herein, changes of cassava and potato starch granules during gelatinization were investigated. It was found that there is a substantial difference in the granule changes during gelatinization between cassava and potato starch. Cassava starch granules remain intact with slight swelling, with approximately 8.5% amylose leaching in water for 30 min at 60 °C. In sharp contrast, potato starch granules swell very well and rapidly, losing much integrity with 51.05% amylose leaching. The gelatinization time and temperature have much greater effects on the changes of potato starch granules than cassava starch granules.