Sprouting of oats: a new approach to quantify compositional changes

Background and objectives: The aim of this research was to gain a deeper insight into the effect caused by the addition of sprouted oat to food products. The effect of temperature and duration of the sprouting process was systematically studied by sprouting oat grains between 10 and 30°C for up to 3 days. Findings: Overall, it was found that temperatures between 20 and 25°C yield the most dramatic changes in the properties of sprouted oats. Based on the data, a simple system to characterize the sprouting progress by a visual inspection of the lengths of the coleoptile and radicles was developed. This degree of sprouting (DoS) was correlated with further grain properties. Conclusions: It was found that an exponential relationship between the DoS and grain properties existed. Furthermore, the observed increase in the reducing sugar content (up to 14.6 g/100 g) with increasing DoS was closely related to the increase in α‐amylase activity (up to 25 U/g). Significance and novelty: The good predictive power found indicates that the application of the concept degree of sprouting could develop into a reliable characterization method for sprouted grains usable for product development and specification.TU Berlin, Open-Access-Mittel - 201

Effect of sprouting temperature on selected properties of wheat flour and direct expanded extrudates

The effect of the sprouting temperature on wheat sprouting and on the properties of expanded extrudates produced from sprouted wheat flour was studied. Therefore, wheat was sprouted at five different temperatures and subsequently dried, milled, and the resulting flour was used to produce extrudates using a twin‐screw extruder. In order to understand the sprouting temperature effect, the degree of sprouting (DoS) of the differently sprouted samples and characteristic properties of flour and extrudates were studied and compared. During sprouting of wheat with increasing temperature and time an increase of the α‐amylase activity, the vitamin C and reducing sugar content, and a decrease of the peak viscosity was observed. The greatest effect was found at 20°C. Furthermore, the lowering of the viscosity of the flour suspension results in a reduction of the pressure and temperature in the extruder die. The extrudates of sprouted wheat flour were found to be easier to break, had a lower density, an increased longitudinal expansion index, and an improved cold‐water solubility. A good correlation between the DoS and other properties of flour and extrudates was found, indicating a good predictive power and applicability of the DoS concept for wheat samples and their product development and specification.TU Berlin, Open-Access-Mittel - 202

Influence of Levan on the Thermally Induced Gel Formation of β-Lactoglobulin

In this study, the influence of levan on the phase behavior and the thermally induced gelation of the mixed β-lactoglobulin—levan gels as a function of polymer content, molecular weight and ionic strength was characterized. For this purpose, rheology was used to study the mechanical properties of the gels and the water binding of the network structure was investigated by time domain nuclear magnetic resonance. Phase behavior and network type were analyzed by optical observation and electron microscopy. Levan enhanced the aggregation and gel formation of β-lg due to segregative forces between the polymer species. Segregation was caused by the excluded volume effect and was more pronounced at lower ionic strength, higher levan contents and higher levan molecular weights. The presence of levan increased the water binding of the gel networks. However, this effect decreased with increasing levan content. At high ionic strength and high levan content, phase separated gels were formed. While segregative forces enhanced network formation, and therefore, increased the gel strength of mixed gels at low ionic strength, levan had also antagonistic effects on the network formation at high ionic strength and high polymer contents