Effects of Processing on Starch Structure, Textural, and Digestive Property of “Horisenbada”, a Traditional Mongolian Food

Horisenbada, prepared by the soaking, steaming, and baking of millets, is a traditional Mongolian food and is characterized by its long shelf life, convenience, and nutrition. In this study, the effect of processing on the starch structure, textural, and digestive property of millets was investigated. Compared to the soaking treatment, steaming and baking significantly reduced the molecular size and crystallinity of the millet starch, while baking increased the proportion of long amylose chains, partially destroyed starch granules, and formed a closely packed granular structure. Soaking and steaming significantly reduced the hardness of the millets, while the hardness of baked millets is comparable to that of raw millet grains. By fitting digestive curves with a first-order model and logarithm of the slope (LOS) plot, it showed that the baking treatment significantly reduced the digestibility of millets, the steaming treatment increased the digestibility of millets, while the soaked millets displayed a similar digestive property with raw millets, in terms of both digestion rate and digestion degree. This study could improve the understanding of the effects of processing on the palatability and health benefits of Horisenbada.

Chlorosis seedling lethality 1 encoding a MAP3K protein is essential for chloroplast development in rice

Background Mitogen-activated protein kinase (MAPK) cascades are conserved signaling modules in eukaryotic organisms and play essential roles in immunity and stress responses. However, the role of MAPKs in chloroplast development remains to be evidently established. Results In this study, a rice chlorosis seedling lethality 1 (csl1) mutant with a Zhonghua11 (ZH11, japonica) background was isolated. Seedlings of the mutant were characterized by chlorotic leaves and death after the trefoil stage, and chloroplasts were observed to contain accumulated starch granules. Molecular cloning revealed that OsCSL1 encoded a MAPK kinase kinase22 (MKKK22) targeted to the endoplasmic reticulum (ER), and functional complementation of OsCSL1 was found to restore the normal phenotype in csl1 plants. The CRISPR/Cas9 technology was used for targeted disruption of OsCSL1, and the OsCSL1-Cas9 lines obtained therein exhibited yellow seedlings which phenocopied the csl1 mutant. CSL1/MKKK22 was observed to establish direct interaction with MKK4, and altered expression of MKK1 and MKK4 was detected in the csl1 mutant. Additionally, disruption of OsCSL1 led to reduced expression of chloroplast-associated genes, including chlorophyll biosynthetic genes, plastid-encoded RNA polymerases, nuclear-encoded RNA polymerase, and nuclear-encoded chloroplast genes. Conclusions The findings of this study revealed that OsCSL1 played roles in regulating the expression of multiple chloroplast synthesis-related genes, thereby affecting their functions, and leading to wide-ranging defects, including chlorotic seedlings and severely disrupted chloroplasts containing accumulated starch granules.

The Process of Pasting and Gelling Modified Potato Starch with LF-NMR

Currently, society expects convenience food, which is healthy, safe, and easy to prepare and eat in all conditions. On account of the increasing popularity of modified potato starch in food industry and its increasing scope of use, this study focused on improving the physical modification of native starch with temperature changes. As a result, it was found that the suggested method of starch modification with the use of microwave power of 150 W/h had an impact on the change in starch granules. The LF-NMR method determined the whole range of temperatures in which the creation of a starch polymer network occurs. Therefore, the applied LF-NMR technique is a highly promising, noninvasive physical method, which allows obtaining a better-quality structure of potato starch gels.

Effect of ethanol treatment on morphological and technical properties of corn starch

Solvent exchange is considered an effective method that changes the physicochemical properties of starch, especially the absorption. Ethanol concentration is one of the important influencing factors to form porous pores from the surface to inside starch granules. In this study, the effect of ethanol concentration on technical properties of starch treated by solvents were investigated. The ratio of ethanol/water was prepared at 1/9, 3/7, 5/5, 7/3 and 10/0 (w/w), respectively. Corn starch was treated by solvent at 8% concentration. Morphology, oil and water holding capacity, solubility, swelling power, viscosity, and transmittance were studied to elucidate the effect of the ethanol concentration on the morphological and technical properties of corn starch treated by solvent. As a result, starch treated by solvent with different concentrations tended to form wrinkles and pore from the surface to the inside of the starch granules during ethanol immersion. Therefore, the oil and water holding capacity, solubility, swelling and viscosity of the solvent-treated starch samples increase as the concentration of ethanol increases. Otherwise, the transmittance of starch glues tends to decrease when the ethanol concentration increases.

Rapid Ultrasound-Assisted Starch Extraction from Sago Pith Waste (SPW) for the Fabrication of Sustainable Bioplastic Film

The present study was conducted to optimize the extraction yield of starch from sago (Metroxylon sagu) pith waste (SPW) with the assistance of ultrasound ensued by the transformation of extracted starch into a higher value-added bioplastic film. Sago starch with extraction yield of 71.4% was successfully obtained using the ultrasound-assisted extraction, with the following conditions: particle size <250 µm, solid loading of 10 wt.%, ultrasonic amplitude 70% and duty cycle of 83% in 5 min. The rapid ultrasound approach was proven to be more effective than the conventional extraction with 60.9% extraction yield in 30 min. Ultrasound-extracted starch was found to exhibit higher starch purity than the control starch as indicated by the presence of lower protein and ash contents. The starch granules were found to have irregular and disrupted surfaces after ultrasonication. The disrupted starch granules reduced the particle size and increased the swelling power of starch which was beneficial in producing a film-forming solution. The ultrasound-extracted sago starch was subsequently used to prepare a bioplastic film via solution casting method. A brownish bioplastic film with tensile strength of 0.9 ± 0.1 MPa, Young’s modulus of 22 ± 0.8 MPa, elongation at break of 13.6 ± 2.0% and water vapour permeability (WVP) of 1.11 ± 0.1 × 10−8 g m−1 s−1 Pa−1 was obtained, suggesting its feasibility as bioplastic material. These findings provide a means of utilization for SPW which is in line with the contemporary trend towards greener and sustainable products and processes.

Starch Morphology and Metabolomic Analyses Reveal That the Effect of High Temperature on Cooked Rice Elongation and Expansion Varied in Indica and Japonica Rice Cultivars

Rice (Oryza sativa L.) is mainly grouped into indica and japonica varieties. The aim of this study was to investigate the effect of temperature on cooked rice elongation, cooked rice expansion, and rice fragrance. This study was conducted in three growth temperature chambers with indica cultivar Basmati 385 (B385) and japonica cultivar Yunjingyou (YJY). Grains of B385 grown in low-temperature regimes had the highest cooked rice elongation and expansion, whereas the grains of YJY grown in high-temperature regimes had the highest cooked rice elongation and expansion. Starch granules of B385 grown in low-temperature regimes were more compact and bigger, compared to grains grown in medium- and high-temperature regimes. Conversely, the starch granules of YJY grown in high-temperature regimes were more compact and bigger, compared to those grown in medium- and low-temperature regimes. Metabolomic analyses showed that temperature affected the rice metabolome and revealed that cyclohexanol could be responsible for the differences observed in cooked rice elongation and expansion percentage. However, in both B385 and YJY, grains from low-temperature regimes had the highest 2-AP content and the lowest expression levels of the badh2 gene. The findings of this study will be useful to rice breeders and producers.

Coalescence and directed anisotropic growth of starch granule initials in subdomains of Arabidopsis thaliana chloroplasts

Living cells orchestrate enzyme activities to produce myriads of biopolymers but cell-biological understanding of such processes is scarce. Starch, a plant biopolymer forming discrete, semi-crystalline granules within plastids, plays a central role in glucose storage, which is fundamental to life. Combining complementary imaging techniques and Arabidopsis genetics we reveal that, in chloroplasts, multiple starch granules initiate in stromal pockets between thylakoid membranes. These initials coalesce, then grow anisotropically to form lenticular granules. The major starch polymer, amylopectin, is synthesized at the granule surface, while the minor amylose component is deposited internally. The non-enzymatic domain of STARCH SYNTHASE 4, which controls the protein’s localization, is required for anisotropic growth. These results present us with a conceptual framework for understanding the biosynthesis of this key nutrient.

Protein Targeting to Starch Synthase 1, a Functional Protein of Starch Biosynthesis in Wheat (Triticum Aestivum L.)

In cereal endosperm, native starch comprising amylose and amylopectin is synthesized by the coordinated activities of several pathway enzymes. Amylose in starch influences its physio-chemical properties resulting in several human health benefits. The Granule-Bound Starch Synthase I (GBSSI) is the most abundant starch-associated protein. GBSSI lacks dedicated Carbohydrate-binding module (CBM). Previously, Protein Targeting Starch Synthase 1 (PTST1) was identified as a crucial protein for the localization of GBSSI to the starch granules in Arabidopsis. The function of its homologous protein in the wheat endosperm is not known. In this study, TaPTST1, an AtPTST1 homolog, containing a CBM and a coiled-coil domain was identified in wheat. Protein-coding nucleotide sequence of TaPTST1 from Indian wheat variety ‘C 306’ was cloned and characterized. Homology modelling and molecular docking suggested the potential interaction of TaPTST1 with glucans and GBSSI. The TaPTST1 expression was higher in wheat grain than the other tissues, suggesting a grain-specific function. In vitro binding assays demonstrated different binding affinities of TaPTST1 for native starch, amylose, and amylopectin. Furthermore, the immunoaffinity pull-down assay revealed that TaPTST1 directly interacts with GBSSI, and the interaction is mediated by a coiled-coil domain. The direct protein-protein interaction was further confirmed by bimolecular fluorescence complementation assay (BiFC) in planta. Based on our findings we postulate a functional role for TaPTST1 in starch metabolism by targeting GBSSI to starch granules in wheat endosperm.