Improving the in vitro digestibility of rice starch by thermomechanically assisted complexation with guar gum

The effects of thermomechanical treatment and guar gum (GG) addition on the in vitro digestibility of rice starch have been investigated. Rice starch added with GG at concentrations of 0, 0.025, 0.05, 0.075, or 0.10 g/100 g (wet basis) was subject to a micro-extrusion process. The in vitro digestibility, predicted glycemic index (pGI), and multi-scale structures (granule, lamellar, crystalline, and molecular structures) were examined. Micro-extruded rice starch (MERS) with GG presented reduced digestion rate and pGI, a higher degree of structural ordering, and altered crystalline, single-helical and double-helical structures. Using Pearson correlation analysis, the relationships among extrusion, the molecular interaction and multi-scale structure, and the digestibility were established. The content of resistant components (RC) was positively correlated with crystallinity (r = 0.836, p < 0.05), fractal dimension (r = 0.966, p < 0.05), A-type crystallinity (r = 0.954, p < 0.01), V-type crystallinity (r = 0.987, p < 0.05), R 1045 / 1022 (r = 0.987, p < 0.05), single-helix content (r = 0.897, p < 0.05), and double-helix content (r = 0.991, p < 0.01); and was negatively correlated with pGI (r = −0.947, p < 0.05). Overall, this study showed that thermomechanical treatment assisted the complexation of GG with starch, which could be an effective means to improve the resistant properties of rice starch

Basic principles in starch multi-scale structuration to mitigate digestibility: A review

peer-reviewedBackgroundIn the human diet, starch makes a significant contribution to the maintenance of human nutrition and health due to its controlled digestibility. Starch digestion is controlled by its microstructure. Increasing developments in the modification of starch multi-scale structures that modulate digestibility have taken place due to increasing attention to health-promoting starchy foods. The process of starch structuration is a challenging concern in food science since the basic principles for designing starch structures with a specific digestibility are unknown. Scope and approachStarch multi-scale structures significantly affect digestibility. However, starch digestibility cannot be precisely modulated without a solid theory of starch structuration to inform the tailoring of the digestibility of starchy foods. In this review, the effects of starch multi-scale structures (fine structures of amylose and amylopectin; short-range ordered structures; helical, crystalline, lamellar, aggregate structures; and structures formed after food processing) on the digestibility and the molecular mechanisms of the regulation of starch digestion are comprehensively discussed. The key structures that can be manipulated for target-modulation of starch digestibility are summarized. Key findings and conclusionsBasic principles for mitigating starch digestibility, such as increasing the thickness of semi-crystalline lamellae and crystalline lamellae, nanoscale aggregates, V-, A-, or B-type crystals, double helices, long amylopectin helices, short-range ordered structures, the content of amylose fractions and high-branched amylopectin are established. Ordered starch structures, including short-range and long-range ordered structures, play critical roles in mitigating starch digestibility while faulty- and perfectly arranged helical, crystalline, lamellar structures, and nano aggregates are proposed to be slowly digestible and resistant starches, respectively

A novel method for obtaining high amylose starch fractions from debranched starch

High amylose starch shows wide applications in food and non-food-based industries. Traditional complex-precipitation approach for the amylose fractionation required a large volume of organic reagents and was possibly risky for food safety. The object of this work was to establish a novel method to obtain starch fractions rich in amylose from debranch starch through repeated short-term retrogradation and centrifugation. Four starch fractions were obtained with the amylose content of 52.08% (C1), 62.28% (C2), 63.58% (C3), and 64.74% (C4). The thermograms of samples displayed that multiple endothermic peaks were detected in C1 and C2 and only one endothermic peak with melting temperature over 120 °C were observed in C3 and C4, indicating their differences in retrogradation behavior. The chain length distribution results of sample exhibited that C1 and C2 contained more short chains (DP ≤ 24), while C3 and C4 consisted of mainly long chains (DP ≥ 25). Accordingly, the differences in fine structures could provide more choices for these fractionated high amylose starch to utilize in practical applications

Football on mobile phones : algorithms, architectures and quality of experience in streaming video

In this thesis we study algorithms and architectures that can provide a better Quality of Experience (QoE) for streaming video systems and services. With cases and examples taken from the application scenarios of football on mobile phones, we address the fundamental problems behind streaming video services. Thus, our research results can be applied and extended to other networks, to other sports and to other cultural activities. In algorithm development, we propose five different schemes. We suggest a blind motion estimation and a trellis based motion estimation with dynamic programming algorithms for Wyner-Ziv coding. We develop a trans-media technology, vibrotactile coding of visual signals for mobile phones. We propose a new bandwidth prediction scheme for real-time video conference. We also provide an effective method based on dynamic programming to select optimal services and maximize QoE. In architecture design, we offer three architectures for real-time interactive video and two for streaming live football information. The former three are: a structure of motion estimation in Wyner-Ziv coding for real-time video; a variable bit rate Wyner-Ziv video coding structure based on multi-view camera array; and a dynamic resource allocation structure based on 3-D object motion. The latter two are: a vibrotactile signal rendering system for live information; and a Universal Multimedia Access architecture for streaming live football video. In QoE exploration, we give a detailed and deep discussion of QoE and the enabling techniques. We also develop a conceptual model for QoE. Moreover we place streaming video services in a framework of QoE. The new general framework of streaming video services allows for the interaction between the user, content and technology. We demonstrate that it is possible to develop algorithms and architectures that take into account the user's perspective. Quality of Experience in video mobile services is within our reach