Composition and structure of barley (Hordeum vulgare L.) grain in relation to end uses

Barley (Hordeum vulgare L.) is a globally important grain crop. The composition and structure of barley grain is under genotypic and environmental control during grain development, when storage compounds (mainly starch and protein), are accumulated. Grain structure plays a significant role in malting and feed- and food-processing quality of barley. Hordeins, the major storage proteins in barley grains, are centrally located in the endosperm forming a matrix surrounding starch granules, but their role in the structural properties of barley grain is not completely understood. Thus, the main aim of the current study was to demonstrate the role of hordeins in barley grain structure. The dependence of the grain structure on the growth environment, in particular with respect to day-length and sulphur application relevant to northern growing conditions, was studied. The effects of the grain structure on end use properties in milling as well as in hydration and modification during malting were characterized. The longer photoperiod typical to latitudes in Southern Finland resulted in a C hordein fraction, entrapped by aggregated B and D hordeins, being more deeply located in the endosperm of barley cultivar Barke. Thus the impact of the growing environment on hordein deposition during grain filling was observed both at the tissue and subcellular level. However, the mechanism behind the differential accumulation of C hordein remains unclear. The deeper localization of entrapped C hordein was linked to improved hydration of grains during malting in three barley cultivars. Thus, the role of the subaleurone region in barley grain was found to be significant with respect to end use quality. Moreover, the results suggest that the growing environment affects the end-use properties of barley and that especially the northern growing conditions have a positive impact on barley processing quality. The influence of sulphur application on hordein composition in the Northern European growing conditions was demonstrated for the first time. Asparagine and C hordein served as nitrogen storage pools when the S application rate was lower than 20 mg S / kg soil, whereas total hordein and B hordein contents increased with higher S application rates. The current study also showed that even when sulphur is sufficiently available in field conditions, the hordein composition may react to sulphur application. The observed sulphur responses were in accordance with those reported earlier for hordein composition. This indicates that the more intensive growth rhythm induced in northern growing conditions does not alter greatly the effect of sulphur on grain composition. The current study confirmed that the main grain components: starch, protein and β-glucan, influence grain processing properties including milling, hydration and endosperm modification. However, their influence on endosperm texture (hardness or steeliness), which also affects the performance of barley grains in these processes, cannot be directly derived or estimated on the basis of the grain composition. The results obtained suggest that hordeins should also be taken into account in the evaluation of the processing behaviour of barley grains.Ohra (Hordeum vulgare L.) on tärkeä viljelykasvi niin Suomessa kuin maailmanlaajuisestikin. Ohran jyvän koostumus ja rakenne muodostuvat jyvän kehityksen aikana perimän ja ympäristön ohjaamina, kun varastoaineet, pääasiassa tärkkelys ja proteiini, kertyvät jyvään. Jyvän rakenteella on tärkeä rooli ohran prosessoinnissa. Tällä hetkellä ohraa hyödynnetään pääasiassa rehu- ja mallastamoteollisuuden raaka-aineena, mutta ohran elintarvikekäyttö on lisääntynyt viime vuosina. FM Ulla Holopainen-Mantila on väitöstyössään selvittänyt ohran jyvän rakenteen muodostumista erityisesti Pohjois-Euroopalle tyypillisissä kasvuolosuhteissa sekä rakenteen merkitystä ohran prosessoinnissa. Väitöstyössä osoitettiin, että Etelä-Suomen leveyspiireille tyypillinen päivänpituus vaikuttaa hordeiinien sijoittumiseen jyvän täyttymisen aikana sekä solukkotasolla että solujen sisällä. Jyvät, joissa oli havaitun kaltainen hordeiinien sijainti, kostuivat nopeammin mallastuksen alussa. Tulosten perusteella kasvuympäristö siis vaikuttaa ohran loppukäyttöominaisuuksiin ja erityisesti pohjoisilla kasvuolosuhteilla on myönteinen vaikutus ohran prosessointilaatuun. Koska muutokset hordeiineissa havaittiin erityisesti jyvän tärkkelyspitoisen solukon uloimmissa osissa, tulokset korostavat tämän osan merkitystä jyvän loppukäyttölaadulle. Rikkilannoituksen vaikutus ohran jyvän hordeiinikoostumukseen Pohjois-Euroopan kasvuoloissa osoitettiin tässä väitöstyössä ensimmäistä kertaa. Typen varastointi jyvän täyttymisen aikana keskittyi vähän rikkiä sisältäviin yhdisteisiin, kun rikin saatavuus oli matalampi kuin 20 mg S / kg maata. Tutkimuksessa näytettiin lisäksi, että rikkilannoitus voi vaikuttaa hordeiinikoostumukseen pelto-olosuhteissa, vaikka rikkiä olisikin riittävästi saatavilla. Havaitut rikkivasteet olivat yhdenmukaisia aiemmin raportoitujen tulosten kanssa. Tämä osoitti, että pohjoisten kasvuolosuhteiden kiivaampi kasvurytmi ei muuta merkittävästi rikin vaikutusta jyvän koostumukseen. Tutkimus vahvisti, että jyvän pääkomponentit, tärkkelys, proteiini ja β-glukaani, vaikuttavat jyvän prosessointiominaisuuksiin jauhatuksessa sekä mallastuksen aikaisessa kostumisessa ja muokkautumisessa. Näiden komponenttien vaikutus jyvän rakenteeseen ei kuitenkaan ole pääteltävissä suoraan jyvän koostumuksesta. Saatujen tulosten perusteella hordeiinit tulisi huomioida ohran jyvien prosessikäyttäytymisen arvioinnissa

Variability of carbohydrate composition and pasting properties of oat flakes and oat flours produced by industrial oat milling process – Comparison to non-heat-treated oat flours

This study characterised the starch and dietary fibre properties and their significance to the pasting characteristics of oat flakes and flours produced from 30 Finnish pure cultivar oats with or without the industrial scale milling process. Large variation in carbohydrate characteristics was observed, the insoluble dietary fibre content of flours was 2.4–5.7 % and soluble dietary fibre was 4.9–8.0 %. The oat milling process induced a significant amount of starch damage (p < 0.05), a fourfold increase from 1 % to 4 % in average was observed. The pasting properties of both flakes and flours were interlinked (p < 0.05) with the chemical composition of oats, i.e., high starch content of flours was connected to higher paste viscosity values. The milling process increased the peak, trough, setback, final and time to peak viscosities of oat flours. These results show the significance of oat milling process, including kilning, to the carbohydrate quality of oats

Clustered Single Cellulosic Fiber Dissolution Kinetics and Mechanisms through Optical Microscopy under Limited Dissolving Conditions

Herein, we describe a new method of assessing the kinetics of dissolution of single fibers by dissolution under limited dissolving conditions. The dissolution is followed by optical microscopy under limited dissolving conditions. Videos of the dissolution were processed in Image) to yield kinetics for dissolution, based on the disappearance of pixels associated with intact fibers. Data processing was performed using the Python language, utilizing available scientific libraries. The methods of processing the data include clustering of the single fiber data, identifying clusters associated with different fiber types, producing average dissolution traces and also extraction of practical parameters, such as, time taken to dissolve 25, SO, 75, 95, and 99.5% of the clustered fibers. In addition to these simple parameters, exponential fitting was also performed yielding rate constants for fiber dissolution. Fits for sample and cluster averages were variable, although demonstrating first-order kinetics for dissolution overall. To illustrate this process, two reference pulps (a bleached softwood kraft pulp and a bleached hardwood pre hydrolysis kraft pulp) and their cellulase-treated versions were analyzed. As expected, differences in the kinetics and dissolution mechanisms between these samples were observed. Our initial interpretations are presented, based on the combined mechanistic observations and single fiber dissolution kinetics for these different samples. While the dissolution mechanisms observed were similar to those published previously, the more direct link of mechanistic information with the kinetics improve our understanding of cell wall structure and pre-treatments, toward improved processability.Peer reviewe

Impact of in situ produced exopolysaccharides on rheology and texture of fava bean protein concentrate

The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) on the rheological and textural properties of fava bean protein concentrate (FPC). EPS (dextrans) were produced from sucrose by two lactic acid bacteria (LAB). The acidification, rheology, and texture of FPC pastes fermented with Leuconostoc pseudomesenteroides DSM 20193 and Weissella confusa VTT E-143403 (E3403) were compared. A clear improvement in rheological and textural parameters was observed in sucrose-added pastes after fermentation, especially with W. confusa VTT E3403. Only moderate proteolysis of fava bean protein during fermentation was observed. The microstructure of the protein in FPC pastes, as observed by confocal laser scanning microscopy, revealed a less continuous and denser structure in EPS-abundant pastes. The beneficial structure formed during EPS-producing fermentation could not be mimicked by simply mixing FPC, isolated dextran, lactic acid, and acetic acid with water. These results emphasize the benefits of in situ produced EPS in connection with the LAB fermentation of legume protein-rich foods. Fermentation with EPS-producing LAB is a cost-effective and clean-labeled technology to obtain tailored textures, and it can further enhance the usability of legumes in novel foods.Peer reviewe

Comparison of Whole and Gutted Baltic Herring as a Raw Material for Restructured Fish Product Produced by High-Moisture Extrusion Cooking

Interest in using undervalued forage fish for human consumption has recently increased due to its environmental benefits. However, feasible strategies to process the undervalued fish species to food use are limited. Therefore, this study investigated the possibility to utilise whole (ungutted) Baltic herring as a raw material for hybrid plant-fish meat analogues produced by high-moisture extrusion cooking. The sample properties were compared with ungutted Baltic herring. Produced meat analogues showed sufficiently high microbial quality, with spoilage microbes showing growth levels of under 1.4 log CFU/g. Whole fish and gutted fish extrudates showed uniform flavour- and odour-related sensory profiles. Colour values of the whole fish (L* 57.8) extrudates were similar to the values of gutted fish extrudates (L* 62.0). The whole and gutted fish extrudates had tensile strength in a cross-cut direction of 25.5 and 46.3 kPa, respectively. This correlated with the tearing force of the extrudates analysed by a trained sensory panel. Furthermore, a more explicit protein network was microscopically observed in gutted fish than in whole fish extrudates. The present study showed that high-moisture extrusion cooking enables the use of whole small-sized fish for human consumption

Variation in the physical properties of oat groats, flakes and oat flake flour - Processability of thirty pure cultivar oat batches from Finland

The aim of this study was to understand the processability of thirty pure cultivar oat batches and how the physical properties of oat groats and flakes affect the characteristics of oat flake flour. This was conducted by investigating the relationship between the chemical composition of oats and the physical characteristics of oat groats, flakes and flours produced by industrial scale milling process. It was clearly shown that the oat batches behaved differently in the milling process and that the physical characteristics of oat groats, flakes and flours were interrelated. For example, separation of bran and endosperm particles of oat flours by dry fractionation was connected to the chemical composition as well as particle size distribution of the flours. Furthermore, it was shown that flowability properties of oat flours affect the bran-endosperm separation of oat flour by dry fractionation. This study demonstrated the role of the oat raw material in the milling process as well as the relationship between the different mill products, which deepens the understanding of oat milling process and is important when aiming at producing oat products with high quality.Peer reviewe

Predicting the Properties of Industrially Produced Oat Flours by the Characteristics of Native Oat Grains or Non-Heat-Treated Groats

The aim of this study was to determine whether the properties of the native oat grain or non-heat-treated groats (laboratory-scale dehulling) can be used to predict the quality of the industrially produced oat flour produced from heat-treated groats. Quality properties such as the color, hectoliter weight, thousand seed weight and hull content of Finnish native grains (n = 30) were determined. Furthermore, the relationship between the properties of the native grains and the chemical composition of the raw oat materials before and after the milling process were studied. A significant relationship (p < 0.01) was observed between the thousand seed weight of the native oat groats and the chemical composition of the industrially produced oat flour. Furthermore, the protein content of the native grains measured by NIT correlated with the chemical composition of the oat flours. These results suggest that the properties of oat flour produced on an industrial scale, including heat treatment, could be predicted based on the properties of native oat grains

Predicting the Properties of Industrially Produced Oat Flours by the Characteristics of Native Oat Grains or Non-Heat-Treated Groats

The aim of this study was to determine whether the properties of the native oat grain or non-heat-treated groats (laboratory-scale dehulling) can be used to predict the quality of the industrially produced oat flour produced from heat-treated groats. Quality properties such as the color, hectoliter weight, thousand seed weight and hull content of Finnish native grains (n = 30) were determined. Furthermore, the relationship between the properties of the native grains and the chemical composition of the raw oat materials before and after the milling process were studied. A significant relationship (p < 0.01) was observed between the thousand seed weight of the native oat groats and the chemical composition of the industrially produced oat flour. Furthermore, the protein content of the native grains measured by NIT correlated with the chemical composition of the oat flours. These results suggest that the properties of oat flour produced on an industrial scale, including heat treatment, could be predicted based on the properties of native oat grains

Predicting the properties of industrially produced oat flours by the characteristics of native oat grains or non-heat-treated groats

The aim of this study was to determine whether the properties of the native oat grain or non-heat-treated groats (laboratory-scale dehulling) can be used to predict the quality of the industrially produced oat flour produced from heat-treated groats. Quality properties such as the color, hectoliter weight, thousand seed weight and hull content of Finnish native grains (n = 30) were determined. Furthermore, the relationship between the properties of the native grains and the chemical composition of the raw oat materials before and after the milling process were studied. A significant relationship (p View Full-TextKeywords: oats; quality; processing; color; composition; NIT</p