A novel one-pot ‘green’ synthesis of stable silver nanoparticles using soluble starch

Rice starch is one of the major cereal starches with novel functional properties. Significant progress has been made in recent years on the characterization of rice starches separated from different rice cultivars. Studies have revealed that the molecular structure and functional properties are affected by rice germplasm, isolation procedure, climate, agronomic conditions, and grain development. Morphological studies (microscopy and particle size analysis) have reflected significant differences among rice starch granule shapes (polyhedral, irregular) and in granule size (2 to 7 μm). Nonwaxy and long-grain rice starches show greater variation in granular size than the waxy starches. Rice starch granules are smaller than other cereal starches with amylose contents varying from virtually amylose-free in waxy to about 35% in nonwaxy and long-grain rice starches. Amylose content appears to be the major factor controlling almost all physicochemical properties of rice starch due to its influence on pasting, gelatinization, retrogradation, syneresis, and other functional properties. Waxy rice starches have high swelling and solubility parameters, and larger relative crystallinity values than nonwaxy and long-grain starches. However, nonwaxy rice starches have a higher gelatinization temperature than the waxy and long-grain starches. The bland taste, nonallergenicity, and smooth, creamy, and spreadable characteristics of rice starch make it unique and valuable in food and pharmaceutical applications. This review provides recent information on the variation in the molecular structure and functional properties of different rice starches.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2012.00193.x

Rice Starch Diversity: Effects on Structural, Morphological, Thermal, and Physicochemical Properties—A Review

Progress in starch modification in the last decade

Starch is, after cellulose, the most abundant organic compound in nature. Modification of starch is carried out to enhance the positive attributes and to eliminate the shortcomings of the native starches. Various methods have been developed to produce a range of modified starches with a variety of characteristics and applications. Physically modified starches are simple and inexpensive because they can be produced without chemicals or even biological agents. In contrast, chemical modification is possible due to ubiquitous hydroxyl groups in starches that have been exploited for over a century, principally in the preparation of starch esters and ethers, but also in more subtle alterations, e.g., in order to tune the structure of starches for specific applications. All these techniques tend to alter the highly flexible starch polymer with changed physicochemical properties and modified structural attributes of high technological value for the food and non-food industries. Modification of starch is an ever evolving industry with numerous possibilities to generate novel starches which includes new functional and value added properties as demanded by the industry. This review aims to summarize the latest developments and recent knowledge regarding physically and chemically modified starches. This paper covers physical modification methods (pre-gelatinization, hydrothermal, and non-thermal processes), some chemical modifications and a combination of both.

Recent trend in the physical and chemical modification of starches from different botanical sources: A review

The importance of amylose and amylopectin fine structures for starch digestibility in cooked rice grains

Structural changes in corn starches during alkaline dissolution by vortexing

Structural changes of corn starches by heating and stirring in DMSO measured by SEC-MALLS-RI system

Waxy maize (native and hydroxypropylated [HP]) and potato starches were impregnated with ionic gums (sodium alginate, CMC, and xanthan, 1% based on starch solids) and heat-treated in a dry state for 0, 2, or 4 hr at 130°C. Effects of the dry heating on paste viscosity (RVA) and clarity (light transmittance) were examined. Heat treatment with sodium alginate and CMC raised the paste viscosities of native and HP waxy maize starches, but decreased that of potato starch. Xanthan provided the most substantial changes in paste viscosity among the tested gums. It appeared to heavily restrict granule swelling of the waxy maize starches, but it increased swelling of potato starch granules. Dry heating raised the paste viscosity of all the starch-gum mixtures tested, except the potato starchalginate mixture. The final viscosity at 50°C of a 7% paste was raised in all other starches by ≈500–1,000 cP by this treatment. The paste of waxy maize starch-gum products became opaque and shorter textured by the heat...

Modification of Starch by Dry Heating with Ionic Gums

Aqueous dispersions (2 mg/mL) of debranched corn starches of different amylose contents (waxy, normal, and high-amylose) were subjected to extensive autoclaving and boiling-stirring, and then the changes in starch chain profile were examined using medium-pressure, aqueous, size-exclusion column chromatography. As autoclaving time increased from 15 to 60 min, weight-average chain length (CLw) of waxy, normal, and high-amylose corn starches determined using pullulan standards decreased from 46 to 41.2, from 122.1 to 96.3, and from 207.3 to 151.8, respectively. Number-average chain length (CLn) measured by the Nelson-Somogyi method also decreased from 23.0 to 18.4, from 26.4 to 21.8, and from 66.5 to 41.5, respectively, indicating that thermal degradation of starch chains occurred. The CLw/CLn ratio for normal corn starch was higher than that for waxy corn starch, indicating an increase in polydispersity of the amylose fraction. Thermal degradation was also observed when the debranched starch was su...

Structural Changes of Debranched Corn Starch by Aqueous Heating and Stirring

A traditional waxy rice gel cake in Korea, Injulmi, was prepared with hydroxypropylated waxy rice and corn starches (molar substitutions 0.13 and 0.11, respectively), and the textural and retrogradation characteristics of the cake were compared with a conventional cake made of waxy rice flour. In the pasting viscogram, hydroxypropylated starches exhibited reduced pasting temperatures, but increased peak viscosities compared with the unmodified starches. Under differential scanning calorimetry, the Tg′ and ice melting enthalpy of the starch gel cakes were reduced by hydroxypropylation, which indicated that the modified starches had higher water-holding capacity than the unmodified starches. The degree of retrogradation, as measured by the hardness of the gel cake and the melting enthalpy, was significantly reduced by hydroxypropylation and hydroxypropylated waxy rice starch was more effective in retarding the retrogradation than hydroxypropylated waxy corn starch

Jung Ah Han

Papers

Structural changes in corn starches during alkaline dissolution by vortexing

Structural changes of corn starches by heating and stirring in DMSO measured by SEC-MALLS-RI system

Modification of Starch by Dry Heating with Ionic Gums

Structural Changes of Debranched Corn Starch by Aqueous Heating and Stirring

Utilization of Hydroxypropylated Waxy Rice and Corn Starches in Korean Waxy Rice Cake to Retard Retrogradation