Józef Fornal

Effect of microwave radiation on physico-chemical properties and structure of cereal starches

Abstract Wheat, corn and waxy corn starches of intermediate moisture content (30%) were subjected to microwave processing and the effect of microwave radiation on physico-chemical properties and structure of cereal starches was studied. The experimental starches were examined by the Brabender rheological method, light microscopy, X-ray diffractometry and differential scanning calorimetry. Microwave radiation was evidenced to cause a shift in the gelatinisation range to higher temperatures, and a drop in solubility and crystallinity. The extent and type of these changes depended on the variety of starch. Normal corn and wheat starches underwent pronounced changes, whereas under the same conditions waxy corn starch was almost unchanged. It was concluded that susceptibility of different starches to changes due to microwave irradiation depended not only on their crystal structure, but also on their amylose content.

Effect of microwave radiation on physico-chemical properties and structure of potato and tapioca starches

Abstract The time-temperature profiles of selected starch-water systems subjected to microwave processing were established and the effect of microwave radiation on the physico-chemical properties and structure of potato and tapioca starches was studied. The experimental starch samples were examined by the Brabender rheological method, light microscopy, scanning electron microscopy and X-ray diffractometry. Microwave radiation was evidenced to affect the temperature and moisture contents of the experimental starches, with a strong correlation between the moisture content and the rate of temperature rise. An isothermal transformation was revealed with the samples of moisture contents over 20%, causing a rise in the gelatinisation temperature of the starch and a drop in its solubility in water. The most pronounced change was observed in the case of potato starch: its crystal structure changed from type B to type A. The tapioca starch underwent similar but less marked changes.

Structure and thermodynamic melting parameters of wheat starches with different amylose content

The hierarchical granule structure of starches with different amylose content extracted from winter wheat was investigated using light microscopy (LM), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXS), high-sensitivity differential scanning calorimetry (HS DSC) and different thermodynamic approaches. Morphology (size, size distribution and shape), crystallinity of native granules with different amylose content (1.5-39.5%), as well as the cooperative melting unit, thickness of crystalline lamellae, heat capacity drop related to hydration during melting of native granules, and thermodynamic parameters related to the surface of crystalline lamellae were determined. The relationship between structure and thermodynamic properties of mutant wheat starches is discussed.

Starch esters obtained by microwave radiation — structure and functionality

Abstract The structure and functionality of starch esters obtained in rotating roasters and in microwave ovens were examined. Native potato starch was prepared for esterification according to the procedure applied in industrial processes. It was found that microwave heating is a convenient way to obtain a wide range of products of inorganic starch ester type usually produced in rotating roasters. Microwaves do not affect the kind of chemical groups substituted into the starch and the molecular mass distribution of inorganic starch esters as compared to traditional products. There are no changes in the chemical structure, microstructure and crystal structure between inorganic starch esters obtained in microwave and in conventional technology. In order to obtain a satisfactory degree of substitution by microwave radiation a significantly shorter time is required than in conventional technology.

Lentil Starch Content and its Microscopical Structure as Influenced by Natural Fermentation

Lentil seeds (Lens culinaris var. vulgaris, cultivar Magda-20) were allowed to ferment naturally at different lentil flour concentrations (79 g/L, 150 g/L and 221 g/L) and temperatures (28 °C, 35 °C and 42 °C). During fermentation, samples were taken at 24 h intervals. The changes in starch content in all samples were studied. Scanning electron microscopy (SEM) was used to investigate changes in samples fermented for 96 h at two different concentrations (79 g/L and 221 g/L) and two different temperatures (28 °C and 42 °C). A considerable decrease in starch content was observed at 0 h of fermentation, defined as the time when the lentil flour was completly suspended at the established temperature. Once fermentation began, flour concentration and temperature modified starch content. Fermentation brought about a general decrease in starch content and a 32—37 % dry matter content was found in the samples after 96 h. Microscopical studies showed that endocorrosion, i.e., breakdown starting from the center of starch granules, was the main pattern observed during lentil fermentation.

Effect of γ-radiation and microwave heating on endosperm microstructure in relation to some technological properties of wheat grain

Grains of the Polish winter wheat variety Begra were subject to gamma-radiation (60Co) within the dose range of 0.05-10 kGy and microwave treatment from 15 to 180 s, the latter resulting in a bulk grain temperature ranging from 28 to 98 degrees C. Both processes were responsible for marked structural changes of wheat kernel endosperm and were pronounced with increasing dose of ionizing radiation or with prolonged time of microwave treatment. Endosperm microstructures of wheat kernels treated with gamma-radiation ranging from 0.05 to 0.5 kGy did not differ from that of untreated ones. Only some changes in the structure of starch granules and proteins were observed at doses of 1, 5 and 10 kGy. Simultaneously at the doses of 5 and 10 kGy a statistically significant decrease of falling number, sodium dodecyl sulfate (SDS) sedimentation values, dough stability and energy were observed, while dough weakening progressed. Microwave treatment longer than 90 s caused marked changes in kernel endosperm structure. Some changes of proteins caused by denaturation created visible fibrils as well as high swelling and deformation of starch granules. This was followed by an increase in the falling number value, decrease in the estimated results of SDS sedimentation test, lowering of the percent of gluten washed out and of the dough energy, respectively. Also a significant decrease in bread quality expressed by volume and score was observed with increasing time of exposure to microwave.

Natural fermentation of lentils. Functional properties and potential in breadmaking of fermented lentil flour

The effects of fermentation on functional properties of lentil flour and rheological properties of doughs and breads produced from blends of wheat and fermented lentil flour were studied. Lentil protein solubility was higher at neutral pH than acid pH; the lowest and highest protein solubility values were observed at pH 4.0 and pH 7.0, respectively. Water hydration capacity and fat binding capacity of fermented lentil flour (FLF) were always higher than those of non-fermented lentil flour (NFLF), irrespective of fermentation temperature (28-42 °C) and flour concentration (79-221 g/l). Emulsifying properties of NFLF were similar to the properties of other legume flours in the range used in experiment. In contrast, the emulsion capacity and stability of FLF were very low and flours fermented at 42°C did not even form emulsion. Rheological properties of doughs made from wheat-fermented lentil blends were similar to those from wheat flour with the addition of other legume flours such as pea and bean. Good quality breads were produced at 2.5 to 10% NFLF and FLF supplementation (except for bread with 10% FLF addition which was middle quality).

Drying Conditions and Processability of Dried Rapeseed

The possibility of using the oil-point and compression tests for evaluation of dried rapeseeds processability was examined. Seeds of initial moisture 10, 14, 18 and 22% (w/w) were dried at 60, 80, 100 and 120°C to a final moisture of 6.5% (w/w). The values of pressure (P 0 ), work (L 0 ) and strain (e 0 ) determined by the oil-point test, and pressure at strain e = 0.45 mm mm -1 (P e ) and degree of elasticity (D) determined by the compression test for bulk dried seeds differed markedly from those found for non-dried seeds. The P 0 , L 0 and P e values were strongly correlated with the initial moisture of rapeseeds and drying temperature. All the strain values (e 0 ) were lower than those for non-dried seeds, and their changes depended solely on the initial moisture of seeds. Changes in the degree of elasticity were irregular and did not reach the value characteristic for over-dried seeds, ie 100%. High correlation of the agglomeration test data (Δ 1-3 values) with those of the P 0 , L 0 and P e made it possible to develop appropriate equations that proved the usefulness of the variables for determining the dried rapeseed processability.

13C and 1H NMR Study of Lysophosphatidylcholine (LPC) Isolated from the Surface of Wheat Starch Granules

Lysophosphatidylcholine (LPC) has been isolated from the surface of starch granules by extraction and subsequent chromatographic purification. The purified extract was examined by mono and bidimensional 1H and 13C NMR and identified as LPC. The NMR information also allowed the assignment of the length and nature of the acyl chains (18—20 carbon atoms, saturated). Se ha aislado lisofosfatidilcolina (LPC) de la superficie de gránulos de almidón mediante extracción y posterior purificación cromatográfica. El extracto purificado se analizó por espectroscopía de RMN de 1H y 13C mono y bidimensional, lo que permitió identificarlo como LPC. Las cadenas acilo se identificaron como cadenas pertenecientes a ácidos saturados de 18—20 átomos de carbono.

Digital Image Analysis — Essence and Application in Cereal Science

Sight is the most important sense of a human allowing him to perceive the surrounding world. Size, shape, structure and colour of examined objects are easily recognised by human eye and brain and simultaneously verify whether they correspond to the standard. Interpretation of images registered solely by the sight is somehow limited by the observer’s perception. Increased number of objects and their mobility resulted in difficulties of proper interpretation of human observations. Moreover, the eyes become tired quite fast, thus their ability to differentiate selected features of the object decreases.