Physicochemical Properties of Starches from Sri Lankan Rice Varieties

Abstract

Physico-chemical properties; amylose content, swelling power, pasting properties by Rapid Visco Analyzer (RVA), thermal properties by Differential Scanning Calorimeter (DSC), and enzymatic digestibility of starches isolated from 19 different Sri Lankan rice varieties were analyzed. Significant variation was shown in all the tested properties among tested varieties in which the amylose content varied from 16.0% to 34.7%. Amylose content appears to be the major factor controlling almost all physico-chemical properties of rice starch, as it showed significant correlations to all other properties tested. It correlated negatively to the peak and breakdown viscosities by RVA and enzyme digestibility but positively to all other tested properties. The peak and onset gelatinization temperatures and enzyme digestibility correlated to all properties except enthalpy for starch gelatinization. The peak and onset gelatinization temperatures, as well as the blue value, showed negative correlations to the peak and breakdown viscosities, indicating the importance of low amylose for easy starch pasting. According to our results, low amylose starches started to gelatinize at lower temperatures. During heating and cooling, such starch slurry showed higher peak and breakdown viscosities, but resulted in a softer gel. Low amylose starch was also easily digestible by enzymes. These properties are probably associated with the reduced compactness in the amorphous area of starch granules. Due to lower amylose in the amorphous area, loosely packed starch granules result in higher swelling power and disorganization with heating.

Morphological variation in selected rice (Oryza sativa L.) germplasm of Sri Lanka

“…At present the national average rice yield is 4.2 t ha -1 , which is 50-60% of the genetic potential (6-7.5 t ha -1 ) of NIVs recommended for cultivation in Sri Lanka (Dhanapala, 2000;Central Bank of Sri Lanka, 2008). Although NIVs produce comparatively higher yields, local and export market demand for traditional rice varieties is still higher because of their grain qualities, such as high fibre content, despite the lower production (Wickramasinghe and Noda, 2008). Furthermore, farmer's perceptions (Efisue et al, 2008), improvement of system sustainability (Abeyratne, 1956) and the higher adaptability to problem soils (Mandal et al, 1999) further increased interest towards traditional rice varieties.…”

Nutritional and antioxidant properties of selected traditional rice (Oryza sativa L.) varieties of Sri Lanka

“…Some of these varieties were claimed to have medicinal properties according to the Sri Lankan ethno medicine and folklore (Dharmasena, 2010;Abeysekera & Premakumara, 2016). These health claims including some nutritional and antioxidant properties were scientifically proven in recent studies (Premakumara et al, 2013;Abeysekera et al, 2015a;Abeysekera et al, 2015b;Abeysekera & Premakumara, 2016) and thus such traditional rice varieties currently have a good market value (Wickramasinghe & Noda, 2008;Suriyagoda et al, 2011). However, there are numerous varieties yet to be studied.…”

Diversity of physical and cooking quality characters of selected traditional and improved rice varieties in Sri Lanka

“…Only few studies have been carried out on the physical and cooking quality characteristics of traditional rice varieties in Sri Lanka (Abesekara et al, 2008;Wickramasinghe and Noda, 2008). Nevertheless, local germplasm has not yet been fully evaluated for their physical, engineering and cooking qualities.…”