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.

Techno-Functional and Gelling Properties of Acha (Fonio) (Digitaria exilis stapf) Flour: A Study of Its Potential as a New Gluten-Free Starch Source in Industrial Applications

Fonio (Digitaria exilis Stapf) is an ancient African cereal that represents a rich source of carbohydrate, fat, fiber, vitamins, minerals, and sulfur-containing amino acids. Processing and utilization of fonio require adequate knowledge of its structural, chemical, and nutritional characteristics. The present work evaluates the structural, techno-functional, and gelling properties of fonio and compares them to other major gluten-free cereals (rice, maize, sorghum, and millet). Fonio flour presented significantly higher water absorption index and swelling power, while it scored a lower water solubility index than the reference flours. The pasting viscosity profile of fonio was similar to that of rice, with equivalent peak viscosity but a breakdown viscosity 24% lower than rice, indicative of higher stability and resistance to shearing and heating. Rheological properties demonstrated that fonio generates gels with remarkably strong structures. At 15% concentration, fonio gel withstood stress 579% higher than those observed in the reference flours without breaking its structure. Fonio flour presented the highest gelatinization enthalpy (11.45 J/g) and a narrow gelatinization temperature range (9.96 °C), indicative of a better-packed starch structure than the other analyzed flours. The texture of the gels made with fonio showed higher firmness over the evaluated period. These combined results suggest that fonio is a suitable ingredient for gel-like food formulations.

Genetic Control and High Temperature Effects on Starch Biosynthesis and Grain Quality in Rice

Grain quality is one of the key targets to be improved for rice breeders and covers cooking, eating, nutritional, appearance, milling, and sensory properties. Cooking and eating quality are mostly of concern to consumers and mainly determined by starch structure and composition. Although many starch synthesis enzymes have been identified and starch synthesis system has been established for a long time, novel functions of some starch synthesis genes have continually been found, and many important regulatory factors for seed development and grain quality control have recently been identified. Here, we summarize the progress in this field as comprehensively as possible and hopefully reveal some underlying molecular mechanisms controlling eating quality in rice. The regulatory network of amylose content (AC) determination is emphasized, as AC is the most important index for rice eating quality (REQ). Moreover, the regulatory mechanism of REQ, especially AC influenced by high temperature which is concerned as a most harmful environmental factor during grain filling is highlighted in this review.

Effect of Heat-Moisture Treatments on Digestibility and Physicochemical Property of Whole Quinoa Flour

The starch digestion processing of whole grain foods is associated with its health benefits in improving insulin resistance. This study modified the digestibility of whole quinoa flour (WQ) via heat-moisture treatment (HMT), HMT combined with pullulanase (HMT+P), HMT combined with microwave (HMT+M), and HMT combined with citric acids (HMT+A), respectively. Results showed that all the treatments significantly increased (p < 0.05) the total dietary fiber (TDF) content, amylose content, and resistant starch (RS) content, however, significantly decreased (p < 0.05) the amylopectin content and rapidly digestible starch (RDS) content of WQ. HMT+P brought the highest TDF content (15.3%), amylose content (31.24%), and RS content (15.71%), and the lowest amylopecyin content (30.02%) and RDS content (23.65%). HMT+M brought the highest slowly digestible starch (SDS) content (25.09%). The estimated glycemic index (eGI) was respectively reduced from 74.36 to 70.59, 65.87, 69.79, and 69.12 by HMT, HMT+P, HMT+M, and HMT+A. Moreover, a significant and consistent reduction in the heat enthalpy (ΔH) of WQ was observed (p < 0.05), after four treatments. All these effects were caused by changes in the starch structure, as evidenced by the observed conjunction of protein and starch by a confocal laser scanning microscope (CLSM), the decrease in relative crystallinity, and transformation of starch crystal.

Soluble Starch Synthase Enzymes in Cereals: An Updated Review

Cereal crops have starch in their endosperm, which has provided calories to humans and livestock since the dawn of civilization to the present day. Starch is one of the important biological factors which is contributing to the yield of cereal crops. Starch is synthesized by different enzymes, but starch structure and amount are mainly determined by the activities of starch synthase enzymes (SS) with the involvement of starch branching enzymes (SBEs) and debranching enzymes (DBEs). Six classes of SSs are found in Arabidopsis and are designated as soluble SSI-V, and non-soluble granule bound starch synthase (GBSS). Soluble SSs are important for starch yield considering their role in starch biosynthesis in cereal crops, and the activities of these enzymes determine the structure of starch and the physical properties of starch granules. One of the unique characteristics of starch structure is elongated glucan chains within amylopectin, which is by SSs through interactions with other starch biosynthetic enzymes (SBEs and DBEs). Additionally, soluble SSs also have conserved domains with phosphorylation sites that may be involved in regulating starch metabolism and formation of heteromeric SS complexes. This review presents an overview of soluble SSs in cereal crops and includes their functional and structural characteristics in relation to starch synthesis.