Understanding the influences of amylose and protein contents on rice sensory properties is key to maintaining quality and providing consumers with rice with desired flavour and textural attributes. This research focused on delineating the effects of nitrogen nutrition on cooked rice texture and flavour. The sensory properties of cultivars grown in adjoining fields with differing rates of nitrogen fertilizer (to yield grains with a large spread in protein contents) were measured by a panel trained in descriptive analysis. Second. rice sensory properties were modelled using apparent amylose and protein data. Fertilizer level affected protein and apparent amylose contents and, in turn, cooked rice texture. Protein contents were significantly higher (P < 0.0007) and apparent amylose contents were significantly lower (P < 0.0001) at the higher fertilizer level. Models revealed a negative correlation of protein content with initial starchy coating, slickness, and stickiness between grains—three attributes that are perceived when cooked rice is first introduced into the mouth. Models for roughness, hardness, and moisture absorption—attributes representing three phases of evaluation in the mouth—showed a positive correlation with protein content. The models provide insight into the magnitude of change in protein content that is likely required to observe textural changes in cooked rice.Read More
This IREC Farmers Newsletter report gives and overview of the 2006/07 season project of improving techniques for assessing rice grain quality. The project continued to evaluate the quality parameters of rice breeding lines and to improve screening techniques for more accuracy and efficiency under the Rice Grain Quality Project. A greater emphasis is being placed on the use of molecular markers to assist selection. The project has also focused on understanding the genetic characteristics that are linked to the cooking quality of different types of rice. This article focuses on grain quality, measurements of amylose types, validation and implementation of new methods, effect of starch components on cooking starch branching enzymes in Australian rice.Read More
This IREC Farmers Newsletter reports on the perfect moleculare markers for fragrance and geliatinisation temperature. It has been identified that there are difficult to measure certain traits such as fragrance and gelatinization temperature and it molecular markers for these will assist the Australian rice breeding program. With the use of molecular markers a quick DNA analysis methods on tissue from young rice plants can replace labour intensive, time consuming analysis on harvested rice grain.Read More
This IREC Farmers Newsletter presents an overview of a RIRDC funded project on genetics adn rice quality. Genetic make up of the variety can dictates its specific cooking properties and therefore identification of precise traits will allows for gene specific markers to be developed. Therefore understanding of the precise role of various starch synthesis genes and establishing detection tools for these genes enables the use of valuable genetic information which can allow for faster development of rice fasters. It also permits the breeders to predict the accurate quality traits while also giving the ability to identify different rice varieties by DNA finger printing.Read More
This RIRDC reports assesses the current conduct, implementation, grower use, and environmental and economic consequences of the NIR Rice Tissue Test. The objective outlined was to continue to research and improve NIR spectroscopy technology relevant to the NIR Tissue Testing Service, operated for rice growers by SunRice. 4 new initiatives were proposed including to implement a growth stage calibration, based on findings from the previous project, to check the growth stages indicated by growers when they submit samples. To increase the through-put of samples analysed per hour whilst reducing dust pollution. To further automating data handling to reduce the chance of errors and provide more reliable advice to growers. Determining the ability of the NIR to report the Mg : K ratios in plant tissue as an indicator of potential grain quality. The results included NIR calibrations for total nitrogen, starch, moisture, potassium, phosphorus and zinc in whole shoot samples were improved, and Calibrations for magnesium and for the Mg/K ratio were developed.Read More
This RIRDC report present the results of the Production of noval rice flour fractions project. The project objectives included investigation the flour and flour milling properties of individual rice varieties. It also focused on produce of new types of fine rice flour and assess the physical and functional properties of these flours. The method for the project was to test project varieties such Amaroo, Doongara, Illabong and Langi. Each were milled on the BRI Australia Pilot Mill to flour with a particle size of less than 100 μm. The results included Doongara producing the greatest amount of flour with an average flour yield of 80.9% compared with Illabong at 55.8%, Amaroo at 53.3% and Langi at 47.1% flour yield. Starch, protein, oil and amylose contents were investigated with all results presented within the report. varieties increased with increasing number of grinding passages. It was concluded that all these properties make the break flours very attractive as high value rice flours with potentially improved nutritional and functional properties for specific food applications. The outcome included these new flour types will potentially increase the value of the rice industry by expanding the rice value adding chain. Currently, rice flour production is approximately 40,000 tonnes per year. If sales or value of rice flour could be doubled, just by supplying new types of flour for new products the added value could be equivalent to $30 million.
Starch accounts for at least 92% (dry weight) of a milled rice grain. Starch is comprised of two fractions, amylose and amylopectin. Amylose content can range from 0% (in waxy rice) to about 30%. Amylose is essentially a linear molecule ranging from about 800 degrees of polymerization (DP) to about 10 000 DP. It carries a few widely spaced chains. Amylose plays a significant role in almost all of the cooking qualities of rice. The process of cooking
of rice begins with the softening of the starch granules, which is primarily a function of amylopectin. The next process, swelling, is greatly affected by amylose. As the starch granules swell, amylose leaches from the granules into the solution phase. Behaviour observed in the field of synthetic polymer science suggests that the linear amylose molecules surround the swelling granules and inhibit the swelling. After amylose leaches from granules,
it joins the continuous phase and van der Waal forces inside the helices of chains cause double helices to form.
This IREC Farmers Newsletter presents information and an update on the RIRDC project DAN 147A. The project states that high chalk content appears to be largely the result of high temperatures. It also states a better understanding of what causes chalk will lead to better understanding of the cooking characteristic of rice.Read More
This IREC Farmer Newsletter article presents information on the RIRDC funded project DAN 147A that was investigating chalk in medium grain. The article presents information on starch accumulation during grain filling in rice, the implication of chalkiness in under fertilized rice crops, early drainage. The article also presents information of the future of the project and further studies into chalk in rice.Read More
This IREC Farmers Newsletter article presents a summary of the data accumulated for medium grain and long grain crops grown in 1992/93. The aim was to show growers the range levels of nitrogen, starch, phosphorus and sulphur to enable growers to have a better understanding of the idea of ‘normal’ their crops were compared to other growers.Read More