Microwave expansion

Corn starch was extruded with 4% stearic acid in Brabender single screw and twin screw laboratory extruders. The screws were cooled and removed and samples were collected from locations along the screws. In the single screw extruder, starch gelatinization as determined by DSC and polarized light microscopy started in the compression zone and was completed in the metering zone. Starch-stearic acid complex formation as determined by iodine binding capacity and X-ray diffraction started at the same point as gelatinization and increased to a maximum near the tip of the screw. In the twin screw extruder, starch gelatinization and starch-stearic acid complex formation started at a distance of seven screw diameters and continued from there to the die end.

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Extruded snacks are products which are easy to consume, tasty, crispy, with thousands of shapes, flavours, textures and are consumed worldwide. They can be expanded directly or indirectly. Directly expanded products are cooked, expanded, shaped and cut off the extruder, dried and packaged. It is a less complicated process than the indirect expansion, products have low bulk density, and are seasoned with different types of flavours and oils. Indirectly expanded products are stable during storage and have high bulk density, provide opportunity to produce a wide range of products. Different types of raw materials (corn, potato, wheat, oat, by-products of food industry, etc.) and combination of ingredients can be incorporated into the products. Non-starch ingredients such as protein, fibre, vitamins and minerals are more likely to be incorporated into indirectly expanded products than into directly expanded products. This makes them delicious, healthier and more interesting to customers. The most commonly used ways of expansion are deep fat frying, hot-air puffing and microwave heating.

A comparison was made of extrudes made from pure sorghum flour (Ll87), wheat flour (biscuit) and composites of the two flours containing various percentages of sorghum. The different parameters which were contrasted included expansion and density, mechanical strength (shear) and colour. Correlation of these properties to the extent to which starch was gelatinized at the extrusion temperature was made. Amount of gelatinized starch was monitored by Direct Scanning Calorimetry (D.S.C) in conjunction with Scanning Electron Microscopy (S.E.M). Results indicated that there is a direct relationship between extent of product expansion and extent of gelatinization, loss of shear with extent of gelatini1..ation; increase in expansion with increased moisture content for sorghum products and-decrease of colour (tannin content) with increased gelatinization. The ability of wheat and sorghum to gelatinize at different temperatures was identified as the main setback to production of good composite extrudes.

Orange-flashed sweet potato (OFSP) is considered of nutritional interest because it contains higher βcarotene content, which is a precursor of vitamin A. The use of food products with OFSP and sunflower oil are associated with health promotion, which helps increase the nutritional value and consumption of these products. Among these, cakes are consumed by people of any age group and can be considered an alternative for adding raw materials as a way to improve the nutritional value of these products. The combinations between 35.86 to 40.00g/100g OFSP and 3.00 to 11.00g/100g sunflower oil showed better physical characteristics and sensory acceptance by consumers. Thus, it is possible to make available to the groups in the population in general at risk of vitamin A deficiency cakes with good sensory acceptance and easy reproduction in domestic, school and commercial environments.

Rice is one of the most important staple foods in Asia, including Indonesia. Despite great efforts to increase rice production in Indonesia, imported rice is still needed due to high per capita consumption coupled with high population growth. One approach to overcoming these problems is to prepare extruded rice analogues by using yellow corn flour (maize flour or cornmeal) and corn starch as the base material. The dough moisture content and the extrusion temperature can influence the degree of gelatinization of rice analogues, which in turn affects the hardness of the rice analogue. This research studied the effects of dough moisture contents of 35%, 40%, and 45% and extrusion temperatures of 70°C, 80°C, and 90°C on the degree of gelatinization and the crystallinity of the resulting rice analogue. Raw materials used in this study were yellow corn flour, corn starch, glycerol monostearate and water. A twin screw extruder was utilized, operating at a screw speed of 75 rpm and a feed r...

The evolution of dielectric properties of starch-based food pellets with different moisture contents was measured during microwave expansion to determine the effect of water content on the expansion dynamics. Dynamic dielectric measurements were found to be an excellent procedure to in situ monitor and characterize the different stages in the material transformation of food pellets during microwave expansion. Although the maximum bulk expansion of pellets was achieved at a moisture content of approximately 8% (wet basis), comparative analysis showed that a moisture content 10-11% produced the best results considering the tradeoff between the foaming and expansion temperature. This was due to the high expansion index and an expansion temperature that was sufficiently lower than the onset temperature for pellet scorching, which provides an operating window to maximize expansion and minimize the likelihood of burning. Dielectric measurements during microwave heating in short on/off cycles prior to pellet expansion suggested that the water was not as dielectrically bound for high moisture content pellets

Andean tubers and tuberous roots have nutritional and medicinal properties transferred through ancestral generations. In this study, we aim to promote cultivation and consumption by developing a snack based on these crops. Corn grits were thoroughly mixed with sweet potato, mashua, and three varieties of oca flour (white, yellow, and red) in an 80:20 ratio, and a single-screw laboratory extruder was utilized to produce third-generation (3G) dried pellets. Microwave expansion was studied, and the dried 3G pellets and expanded snacks were characterized. The microwave expansion curves of the dried 3G pellets were adjusted to the Page, logarithmic, and Midilli–Kucuk models. During the characterization, the influence of the raw material composition was observed in sectional expansion, water content, water activity, water absorption, water solubility, swelling, optical and textural properties, and bioactive compounds. According to global color variation (mixture vs. expanded and dried vs....

The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions Effect of extrusion conditions on physicochemical characteristics and anthocyanin content of blue corn third-generation snacks Efecto de las condiciones de extrusión sobre características fisicoquímicas y contenido de antocianinas de alimentos botana de tercera generación de maíz azul

The objective of this study was to evaluate the effects of starch source and amylose content on the expansion ratio, density, and texture of expanded extrudates, as well as to investigate the structural and molecular changes that occur in starch granules as a function of extrusion. The starches employed were rice starches (8%, 20%, and 32% amylose), carioca bean starch (35% amylose), and Hylon V(®) corn starch (55% amylose). The extrudates from rice starches containing 20% and 32% amylose exhibited the highest expansion ratio, while, extrudates from Hylon V(®) corn starch containing 55% amylose exhibited the lowest expansion ratio. The hardness values of the extrudates with 55% amylose were twice those of the extrudates with 20%, 32%, and 35% amylose. An additional finding was that although the amylopectin promoted the expansion of the gelatinized starch matrix, it failed to strengthen and sustain the walls of the extrudate bubbles during expansion.

The alkaline cooking process produces important changes in the components of the maize kernel during the production of corn tortillas. A relevant role in these changes has been ascribed to the structural characteristics of the corn starch, mainly in the amylopectin polymer. The objective of the present study was to use an optical system to measure light transmission and scattered light in suspensions of: (1) amylopectin and (2) amylopectin added with calcium hydroxide. Heated suspensions of amylopectin (0.5 %), calcium hydroxide (0.025 and 0.25 %), and a solution combining 0.5 % of amylopectin with 0.025 % of calcium hydroxide were tested. The partial integrated scattering and variance (measure of spreading of scattered light) were calculated. A clear relationship was found between the optical signals as a function of amylopectin structural changes. Laser light Scattering optical system was validated to be used as an instrument to follow real-time changes in solutions during their heating like amylopectin-calcium hydroxide solution.

The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions Effect of extrusion conditions on physicochemical characteristics and anthocyanin content of blue corn third-generation snacks Efecto de las condiciones de extrusión sobre características fisicoquímicas y contenido de antocianinas de alimentos botana de tercera generación de maíz azul

As with any variety of rice, red rice characteristics are subject to varietal differences, growing conditions, types of processing, and nutritional and rheological properties. This study determined the nutritional characteristics (centesimal composition and minerals) and paste viscosity properties of raw grains of four red rice genotypes (Tradicional MNAPB0405, MNACE0501 and MNACH0501) and the paste viscosity properties of pre-gelatinized flours obtained at different cooking times (20, 30 and 40 min). The main nutritional properties were correlated with the pasting properties of the pre-gelatinized flours. The samples showed differences in nutritional properties and paste viscosity. MNAPB0405 and MNACE0501 showed higher levels of fiber and fat and provided higher caloric energy than Tradicional and MNACH0501, which, in turn, showed higher levels of amylose. MNACH0501 showed higher peak viscosity (2402 cP), higher breakdown viscosity (696 cP) and a greater tendency to retrogradation ...

A blend containing almond and wheat flours (about 1:2.5, dry basis) was extruded through a co-rotating twin-screw extruder with a screw diameter of 25 mm. The effects of barrel temperature (61.72-118.28°C) and feed moisture (21.17-26.83%) on starch-lipid complex formation (X-ray diffraction, melting enthalpy, and complexing index) as well as on fat loss (which occurs during extrusion processing), break strength, deformability and expansion index of extrudates were investigated using response surface methodology (RSM). The only variable that had a significant influence on the formation of starch-lipid complexes was feed moisture (the high values of melting enthalpy and complexing index, i.e. 3.67 J/g and 94.34%, respectively, were obtained with the smallest value of feed moisture, i.e. 21.17%). The highest fat loss and the hardest texture of extrudates were obtained at the highest values of barrel temperature and feed moisture (118.28°C and 26.83%, respectively).