Effect of extrusion-cooking conditions on the physical properties of Jerusalem artichoke straw

The paper presents the effect of extrusion-cooking conditions (moisture content and screw speed) on the physical properties of extruded Jerusalem artichoke straw. A single screw extruder was used for straw processing. Shredded Jerusalem artichoke straw moistened to 30, 40, and 50% was subjected to an extrusion-cooking process at various screw speeds (70, 90, and 110 rpm). Selected physical properties and pasting profile were tested. Significant differences were observed depending on the moisture content of the samples and the various screw speed on their physical properties. Notably, increased moisture content lowered the specific mechanical energy, increased processing efficiency, water solubility, peak viscosity and breakdown. The maximum efficiency and the highest breakdown was observed for the sample with 50% moisture content processed at an extruder screw speed of 90 rpm. The sample obtained at 30% moisture and at 90 rpm was characterized by the lowest efficiency and hot paste viscosity, and the highest specific mechanical energy. The results showed that the extrusion-cooking process yielded desirable changes to the structure of the analysed lignocellulosic biomass

Energochłonność ekstruzji pszennych spienionych materiałów opakowaniowych

Extrusion-cooking technique, known from food processing, may be used in production of environmentally friendly foamed materials based on starch. The objective of the paper was to determine the specific mechanical energy consumption of the extrusion-cooking process of foamed materials made of wheat starch at a varied level of moisture of raw materials mixtures and varied participation of foaming components. Functional additives which support the foaming process were applied: PDE foaming agent and polyvinyl alcohol. Specific mechanical energy consumption (SME) was determined according to the moisture content of raw materials and additives used. Energy consumption of the extrusion-cooking process of foamed materials with addition of the foaming agent PDE was increasing along with the increase of moisture and decreased at higher participation of the additive. In case of mixtures with an addition of polyvinyl alcohol the values of SME were getting higher along with the increase of the additive content and moisture of raw materials mixture. The research proved possibility of obtaining starch foamed packaging materials, which may function as a filler in transport packages, at the high efficiency of the process and low energy consumption.Technika ekstruzji, znana z przetwórstwa spożywczego, może być stosowana w produkcji przyjaznych dla środowiska materiałów spienionych opartych na skrobi. Celem pracy było określenie energochłonności procesu ekstruzji materiałów spienionych, wytworzonych ze skrobi pszennej przy różnej wilgotności mieszanek surowcowych i różnym udziale komponentów spieniających. Stosowano dodatki funkcjonalne wspomagające proces spieniania: środek spieniający PDE oraz alkohol poliwinylowy. Energochłonność wyznaczano, wykorzystując wskaźnik jednostkowego zapotrzebowania energii mechanicznej (SME). Energochłonność procesu ekstruzji materiałów spienionych z dodatkiem środka spieniającego PDE zwiększała się wraz ze wzrostem wilgotności i obniżała przy większym udziale dodatku. W przypadku mieszanek z dodatkiem alkoholu poliwinylowego wartości SME były wyższe wraz ze wzrostem zawartości dodatku i wilgotności mieszanki surowcowej. Badania wykazały możliwość uzyskania skrobiowych spienionych materiałów opakowaniowych, które mogą pełnić rolę wypełniacza w opakowaniach transportowych, przy wysokiej wydajności procesu oraz niewielkiej energochłonności

Effect of starch type and screw speed on mechanical properties of extrusion-cooked starch-based foams

Potato starch and corn starch are popular basic raw materials in the processing of biopolymers. One of the processing methods employed in the manufacture of biopolymers is extrusion-cooking technique. With specific parameters and equipment configurations, it is possible to obtain a wide variety of starch-based biopolymers. Loose fill foams are usually produced with the use of polystyrene, but the adverse environmental effects of conventional plastics provide an incentive for the development of new, environmentally friendly raw materials. The aim of the study was to apply the extrusion-cooking technique to prepare starch-based foams from potato starch and corn starch under various extruder screw speeds applied during processing. Process efficiency and energy consumption were also tested during processing. The expanded foams were analysed by means of cutting and compression tests to evaluate selected mechanical properties. The type of starch used and the processing screw speed had an impact on the efficiency and specific energy requirements of the process. The results showed that the screw speed had a significant effect on the cutting forces in the tested foams as well as on its compression properties. Higher hardness of foams was observed when potato starch was used as the basic raw material. Moreover, corn starch foams proved to be more elastic in compression tests

Selected properties of snacks extruded at various screw speeds supplemented with Moldavian dragonhead seed addition

The main aim of the study was to determine selected characteristics of extruded snacks supplemented with Dracocephalum moldavica L. seeds added to the recipe in amounts ranging from 5 to 20% of the basic raw material composition. The effect of the screw speed on the selected corn-based snacks characteristics has also been been studied. A single-screw extruder was employed to obtain the snacks in the form of readyto- eat extrudates. Several properties were evaluated, among them: the expansion ratio, the water absorption and solubility indices as well as pasting properties, depending on the level of the additive and the screw speeds applied. Extruded snacks supplemented with Dracocephalum moldavica L. seeds exhibited an enhanced nutritional value compared with corn snacks due to the high content of fibre, protein and ash. The addition of the seeds decreased the expansion ratio significantly. The water absorption index of the snacks decreased as the level of seed addition in the processed blends was raised, while the water solubility index was significantly affected by the variable screw speed during the processing of the supplemented snacks. The recommended level of Dracocephalum moldavica seeds in corn-based snacks should not exceed 15% due to the high nutritional value as well as the high expansion and efficient treatment intensity of the components resulting in the ready-to-eat characteristic of the supplemented snacks

Effect of extrusion-cooking conditions on the pasting properties of extruded white and red bean seeds

The extrusion-cooking technique may be used to convert the common bean into functional food products. There is still insufficient information on the properties of extruded beans. The aim of this work was to investigate the effect of extrusioncooking conditions on the pasting properties of two cultivars of the common bean (Aura and Toska) available on the Polish market. The bean was extruded using a twin-screw extruder at variable screws speeds and different amounts of water were added directly to the barrel. The pasting properties of the obtained extrudates were measured using a Micro Visco-Amylo-Graph. The extruded beans revealed more stable viscosity characteristics than the unprocessed ones. The addition of increased amounts of water to the processed material raised the peak viscosity of both extruded bean varieties. A higher screws speed during bean processing resulted in a higher peak viscosity only in the case of the Aura cultivar. However, the decreasing value of the cold paste viscosity was observed at higher speeds. This may indicate the negative effect of the extruder’s screws speed on the gel formation ability of the extruded bean. The results showed that the extrusion-cooking process reduced the retrogradation tendency of bean paste due to starch degradation occurring during processing

Physical properties and texture of gluten-free snacks supplemented with selected fruit additions

Extrusion-cooking is used to produce directly expanded gluten-free snacks, especially for consumers with celiac disease. The aim of the study was to evaluate the effect of various fruits type supplementation as well as the processing screw speed on the physical properties and texture of ready-toeat corn-based gluten-free snacks. Black elderberry, chokeberry and strawberry were dried and used in the amount of 5 to 20% as a corn grit replacement. The directly expanded snacks were processed with a single-screw extruder at various screw speeds (80 and 120 rpm) and tested to measure their expansion ratio, bulk density, colour profile as well as their texture profile. The results showed the various effects of adding different types and amounts of fruit on the physical properties and texture of supplemented gluten-free snacks. A higher amount of fruit resulted in a significant decrease in the expansion ratio and an increase in the bulk density of the snacks. Reduced lightness and a more pronounced red tint were observed when red fruits were added. The desired hardness of the snacks suggested that the addition of fruit should be retained below 15% of the recipe content. The screw speeds applied showed a significant effect on the expansion, bulk density and texture of the tested snacks