Relating microstructure, sensory and instrumental texture of processed oat

Abstract

This study is a part of a larger project aiming to produce new, healthy, and tasty food ingredients from oat. Germination and different heating processes can be used to improve the texture and flavour of cereals. In this study effects of germination and wet and dry heating on the microstructure, instrumental structure and sensory properties of two oat varieties were assessed. The microstructure of native, germinated, autoclaved and extruded grains of the hulled cv. Veli and hull-less cv. Lisbeth was examined by light microscopy, the texture was measured by determining the milling energy and hardness of the grains and sensory characteristics were evaluated with descriptive sensory profile analysis. In cv. Veli the cells of the starchy endosperm were smaller than in cv. Lisbeth and β-glucan was concentrated in the subaleurone layer. In cv. Lisbeth β-glucan was evenly distributed in the starchy endosperm. The grains of cv. Lisbeth were more extensively modified in the germination process than the grains of cv. Veli, otherwise the effects of processing on the grains of the two cultivars were similar. Germination caused cell wall degradation, autoclaving and extrusion cooking caused starch gelatinization. Autoclaving resulted in the hardest perceived texture in oat. Gelatinization of starch appeared to contribute more to the hardness of oat groats than the cell wall structure. Of the instrumental methods used in this study the milling energy measurement appeared to be the most useful method for the analysis of the effects of processing on grain structure.

Processing of oat: the impact on oat's cholesterol lowering effect

“…Germination/malting stimulates the expression of cell wall degrading enzymes, 143 such as xylanases and glucanases, to break down the endosperm cell walls and allow access to the starch as an energy source to support germination and growth. The enzyme action will solubilise β-glucan from the cell walls and make it more available, but also the molecular weight may well be reduced.…”

Germination: a means to improve the functionality of oat

“…However, release of small granules from the compound starch granules was observed. Salmenkallio-Marttila et al (2004) found in their detailed microstructure studies that after 3 days of germination the starch granules remained intact but the protein network surrounding the…”

Effect of Heat Treatments on Starch Pasting, Particle Size, and Color of Whole‐Grain Barley

“…Heat treatments can alter kernel hardness (Salmenkallio-Marttila et al 2004;Murthy et al 2008), which in turn may change how the barley kernel fractures during milling and may affect the nutrient composition of fractions created during air classification. Heat treatments can alter kernel hardness (Salmenkallio-Marttila et al 2004;Murthy et al 2008), which in turn may change how the barley kernel fractures during milling and may affect the nutrient composition of fractions created during air classification.…”

“…Little research has been done to examine the impact of heat treatment on particle size and fractionation of barley. Heat treatments can alter kernel hardness (Salmenkallio-Marttila et al 2004;Murthy et al 2008), which in turn may change how the barley kernel fractures during milling and may affect the nutrient composition of fractions created during air classification. Particle size can also influence other attributes, including water absorption (Al-Rabadi et al 2012), BG viscosity (Izydorczyk et al 2014), dough rheology (Ahmed et al 2015), and starch pasting (Becker et al 2001).…”