Macromolecular modifications of manioc starch components by extrusion-cooking with and without lipids

Emulsifiers and thickeners on extrusion-cooked instant rice product

Extrusion-cooked instant rice was prepared by optimizing the formulation with emulsifiers, glycerol monostearate (GMS), soybean lecithin (LC), and sodiumstearoyl lactylate (SSL), and thickeners, gum Arabic (GA), sodium alginate (SA), and sticky rice (SR). The emulsifiers addition caused increase of degree of gelatinization (DG), and decrease of water soluble carbohydrate (WSC), α-amylase sensitivity, water soluble index (WAI) and adhesive for extrudates, while the thickeners addition increased extrudates DG, bulk density (BD), WSC, α-amylase sensitivity, WAI, hydration rate (HR) and adhesiveness. Based on the data generated by a single additive at various levels, optimum formulation was obtained employing orthogonal matrix system with combination of the selected additives for extrusion cooking. Extrudates were evaluated for optimum hydration time followed by drying to prepare the finished product. Texture profile analysis and sensory evaluation indicate that quality of the finished product is equivalent to that of the round shaped rice and superior to a commercial instant rice product. This study also demonstrates possibility of value-added and versatile instant rice product development using broken rice.

Influence of the process parameters on the characteristics of starch based hot stage extrudates

The influence of the process parameters on the characteristics of matrix formulations produced by means of hot stage extrusion was investigated using three experimental designs. The first one was designed to evaluate the importance of the screw speed (150-450 rpm) and the feed rate (2-12 kg/h), while the second and the third were designed to study the importance of the temperature profile (60-120 degrees C). The extrudates were produced with a laboratory twin screw extruder equipped with a 3-mm cylindrical die. The formulations consisted of 53% corn starch, 15% sorbitol, 2% glyceryl monostearate and 30% theophylline monohydrate as the model drug. The extrudates were characterized by Karl-Fischer titration, Hg-porosimetry, four-point bending and dissolution testing. From the first design it was concluded that the screw speed and feed rate hardly affected the water content of the extrudates, but that there was a clear influence on the extrudate radius, porosity, mechanical strength and dissolution behaviour. High screw speed-high feed rate processes in comparison with low screw speed-low feed rate processes caused an increase in extrudate radius and porosity and a decrease in mechanical strength and drug release rate from the matrix. It was clear that the contribution of the feed rate was higher than that of the screw speed. Expansion, promoted under certain extrusion conditions, could explain the obtained results. The second and third design revealed that only the maximum barrel temperature and not the whole temperature profile was responsible for the temperature effects on the extrudate characteristics. It was concluded that the maximum barrel temperature was the most critical parameter of the hot stage extrusion process.

Influence of the formulation composition on the in vitro characteristics of hot stage extrudates

The aim of this study was to evaluate the influence of the formulation composition on the characteristics of starch based hot stage extrudates in order to obtain high quality and high efficacy matrices for controlled drug delivery. Their characteristics were compared to those of a reference formulation, for which in vivo data were available. The influence of the starch type, the plasticizer and the lubricant were investigated. The extrudates were produced with a twin screw co-rotating extruder equipped with a twin screw powder feeder and a 3 mm cylindrical die. The extrudates were manually cut and dried for 48 h at 60 degrees C prior to analysis. They were characterized by Karl Fischer titration, Hg-porosimetry, 4-point bending and dissolution testing. Changing the formulation composition did not affect the water content or the porosity of the extrudates but had an influence on their mechanical strength and dissolution profiles. These characteristics were particularly dependent on the plasticizer and lubricant concentration used and on the nature of the starch component and the lubricant. Expansion, depending on starch conversion and amylose-lipid complex formation, played a major role in the explanation of the results obtained. All the formulations tested showed a slow drug release profile in vitro. However, the differences with the reference formulation--which was tested in vivo in earlier work--were probably too small to give a distinct improvement of its in vivo behaviour.

Functional suitability of commercially milled rice bran in India for use in different food products

The effect of blending of commercially available full fat and defatted rice brans in India from modern multistage rice mills with parboiling/stabilizing facilities in different food products in comparison to those obtained from laboratory milling of rice is reported. Bread volume and cookie spread decreased but muffin volume increased with the addition of different types of bran to wheat flour, however, the cookie spread factor was not affected by addition of full fat rice bran. The yields of the extrudate were increased by the blending of full fat rice bran but were decreased by the addition of defatted rice bran. Rice brans could be added to different food products to the extent of 5-10%. However, the full fat rice bran could not be used for production of extruded snack food.