Leszek Mościcki

Influence of Buckwheat Addition on Physical Properties, Texture and Sensory Characteristics of Extruded Corn Snacks

Abstract The influence of buckwheat addition on physical properties, texture, colour and sensory characteristics of extruded corn snacks are presented in this paper. Snacks were prepared with a single screw extrusion-cooker TS-45 with L:D=12:1, shaped on the circular open die 3 mm, screw speed during processing was set to 120 rpm. Buckwheat flour was added in the amount from 10 to 50% of corn grits mass. Selected physical properties, cutting force and texture with Kramer cell were evaluated. The sensory characteristics and acceptability of buckwheat enriched snacks were evaluated. The expansion ratio lowered, whilst bulk density and durability increased with a higher level of buckwheat addition. Fracturability and hardness lowered with higher buckwheat amount in the recipe. Colour measurements showed lower L* and higher b* values with higher buckwheat addition. Higher buckwheat amount influenced lower sensory notes of snacks.

Effect of wheat bran addition and screw speed on microstructure and textural characteristics of common wheat precooked pasta-like products.

Effect of Wheat Bran Addition and Screw Speed on Microstructure and Textural Characteristics of Common Wheat Precooked Pasta-Like Products. The present paper describes the wheat bran addition on microstructure, texture, colour and sensory characteristics of enriched precooked pasta-like products. Precooked pasta-like products were processed on a single screw extrusion-cooker TS-45 with L:D=16:1, shaped on the circular open die. Screw speed during the extrusion-cooking ranged from 60 to 120 rpm. Wheat bran were added in the amount from 5 to 25% of common wheat flour mass. The microstructure showed unmodified bran fractions at low screw speed, in turn higher rpm disrupted wheat bran cell walls. Hardness of dry pasta-like products, evaluated with the cutting test, was diminishing with a higher bran content in the recipe and was increasing with rpm applied. The firmness of hydrated products was decreasing with increasing bran addition (20 and 25% of bran in the recipe), whilst processing at low rpm caused poor quality of pasta-like products with great adhesiveness and stickiness. The higher bran content affected also the lower sensory notes. Colour measurement showed lower L* values for both raw and hydrated products with higher bran addition.

Radical Scavenging Activity of Instant Grits with Addition of Chamomile Flowers Determined by TLC–DPPH• Test and by Spectrophotometric Method

Phenolic compounds possess multiple biological effects, including antioxidant activity. They may act as scavenger of free radicals or prevent their formation. The antioxidant properties of extruded grits enriched with 5%, 10%, and 20% addition of chamomile were evaluated. In order to determine antioxidant activity of samples, TLC–DPPH• test and spectrophotometric method, using DPPH (2,2′-diphenyl-1-picrylhydrazyl radical), were performed. The results of TLC–DPPH• test and spectrophotometric analysis indicated that antioxidant potential of corn grit increased with the addition of Matricaria chamomilla. The study findings confirmed that high-temperature extrusion process has no negative influence on antioxidant activity of polyphenolic compounds, which are present both in the raw and enriched with the Matricaria chamomilla final product.

Influence of water addition on mechanical properties of thermoplastic starch foils

Abstract The aim of this paper is to study the influence of water on the mechanical properties of thermoplastic starch films. Experimental observations of Young modulus and the breaking force of thermoplastic starch foils with different percentages of polyvinyl alcohol and keratin additives and screw rotation speeds are reported. Thermoplastic starch foils are prepared by the extrusion method with the bowling from potato starch and glycerol as a plasticizer. Young modulus and the breaking force were determined by the random marker method. Measurements of Young modulus and the breaking force of the films were performed after their production and after dosing with water. It was observed that in all cases Young modulus decreases after dosing with water, but the breaking force lied in the same range. Thermoplastic starch foils produced at the screw rotation speed equal to 60 r.p.m. have the best mechanical properties. The highest value of Young modulus and the breaking force were obtained for samples with a 1% keratin additive.

A STUDY OF THE SOLUBILITY OF BIODEGRADABLE FOAMS OF THERMOPLASTIC STARCH

The paper presents the results of a study on the water absorption capacity and solubility of biodegradable starch foams produced with single-screw extruder TS-45 with L/D=12. Two different moulding dies were used: one with a circular hole with the diameter of 3 mm and one with a ring hole with the inner diameter of 5 mm. During the extrusion process, the temperature of the cylinder ranged from 80 to 130°C and the screw speeds applied were: 100 and 130 rpm. For the application of the ring die, it was observed that regardless of the speed of the screw, the use of the raw material of higher moisture content led to the production of materials with higher solubility. As a result, the obtained materials revealed solubility at a level of 40%. The results demonstrate good solubility of the starchy fillers of the packaging, which may indicate their susceptibility to decomposition in the conditions of high ambient humidity. A statistical analysis showed a significant impact of moisture of the raw material on the WSI of starch foams used irrespective of the other parameters of the extrusion-cooking process. The raw material moisture had a significant effect on the water absorption capacity of only TPS foams produced in the ring die at the screw speed of 100 rpm.

Effect of PVA and PDE on selected structural characteristics of extrusion-cooked starch foams

The aim of this work was to determine selected physical properties of biodegradable thermoplastic starch (TPS) filling foams manufactured by extrusion-cooking technique from different combinations of potato starch and two additives: poly(vinyl alcohol) PVA and Plastronfoam PDE. Foams were processed with seven starch/additives combinations at two different extruder-cooker’s screw rotational speeds. The densities of starch foams depended significantly on the additive type and content. The linear relationship between the Young modulus and the ultimate compression force and apparent density was found. The foams processed with the addition of PVA had low density, porosity and lower values of the Young modulus than the foams prepared with PDE.

Effect of Processing Conditions on Microstructure and Pasting Properties of Extrusion-Cooked Starches

Abstract The aim of the work was to investigate the effect of extrusion-cooking process conditions on the structure and pasting properties of starch extrudates. In addition, the extrudates structure was observed using scanning electron microscopy (SEM) and confocal laser microscopy (CSLM). Wheat, corn and potato starch were extrusion-cooked with different process parameters (moisture content, screw speed, process temperature) in a single screw extruder. Results showed influence of the process parameters on extruded starches pasting properties. Viscosity measurements indicated that water content during starch extrusion is more important than process temperature. The extrudates structure observed with scanning electron and confocal laser microscopes showed that the main effect of extrusion-cooking was loss of the crystalline structure of the starch and the formation of a cellular structure of the extrudates. In extrudates processed at higher starch moisture content reduced the quantity and diameters of created cells was observed.

Moisture sorption characteristics of extrusion-cooked starch protective loose-fill cushioning foams

Abstract The aim of this work was to determine the water vapour sorption properties of thermoplastic starch filling foams processed by extrusion-cooking technique from various combinations of potato starch and two foaming agents: poly(vinyl) alcohol and Plastronfoam, in amount of 1, 2 and 3% each. Foams were processed with the single screw extruder-cooker at two different screw rotational speeds 100 and 130 r.p.m. The sorption isotherms of samples were determined and described using the Guggenheim-Anderson-de Boer model. Also, the kinetics of water vapour adsorption by foams, as a function of time, was measured and fitted with Peleg model. On the basis of the analysis the influence of the applied foaming agents, as well as the technological parameters of extrusion-cooking process in relation to water vapour adsorption by thermoplastic starch foams was demonstrated. There was no difference between the shapes of the isotherms for poly(vinyl) alcohol foams while for Plastronfoam foams a notable difference among foams extruded at 100 r.p.m. was observed in the regions of low and high humidity content. The analysis of the Guggenheim-Anderson-de Boer model parameters showed that the water molecules were less strongly bound with the foam surface when extruded at a lower screw speed.