Effect of microwave and hot air treatment on enzyme activity, oil fraction quality and antioxidant activity of wheat germ.

The aim of this work was to study the effects of microwaves (MW) and hot air (HA) treatments on enzyme activities and quality parameters in wheat germ (WG). Both MW and HA were effective at inactivating lipases. MW treatment inactivated lipases more at lower temperatures (60 and 70 °C) than HA (150-200 °C). Peroxide values, acidity, and fatty acid profiles of WG oil remained unaltered after HA and MW treatments. Loss of α-tocopherol contents was observed following HA treatment, but total tocopherol content remained above 77% baselines values in all treated samples. The main antioxidant mechanism of WG extracts was associated with inactivation of radicals, rather than reducing capacity. MW treatment at 60 and 70 °C enhanced radical scavenging activity, while total polyphenol contents and reducing capacities were negatively affected. Therefore, MW treatment is a promising technology to stabilise WG, retaining quality and antioxidant activity.

Sorghum Pasta and Noodles: Technological and Nutritional Aspects.

Sorghum is a major cereal crop with various agronomic advantages, contains health-promoting compounds and is gluten-free. There is a growing tendency to use sorghum in pasta and noodle formulations, which are among the most widely consumed products in the world, but its potential benefits in human diet are not being fully exploited. Here we review research carried out during the past few years on the use of sorghum as the main ingredient or as an additive in pasta and noodles, highlighting its properties and production technology. Pasta and noodles can be produced with 5 to 100% of sorghum at laboratory, pilot or industrial scale with suitable cooking and textural quality coupled with distinctive sensory attributes. Cooking loss shows minimum values of 0.85 and 1.9 g/100 g for pasta and noodles, respectively, and high water absorption (up to 345 g/100 g). The interesting nutritional profile of the products generally includes up to 45% resistant starch (RS) and phenolic compound content with high antioxidant activity. In addition, tannins decrease starch digestibility 15-20%, producing low glycemic index (GI) products (below 65). This is especially important for celiac people, offering them the alternative of gluten-free sorghum pasta and noodles.

Physico-chemical characterization of protein fraction from stabilized wheat germ.

Wheat germ shows the highest nutritional value of the kernel. It is highly susceptible to rancidity due to high content of unsaturated fat and presence of oxidative and hydrolytic enzymes. In order to improve its shelf life, it is necessary to inactivate these enzymes by a thermal process. In this work the functional properties and some characteristics of the protein fraction of treated wheat germ were evaluated. Sequential extraction of proteins showed loss of protein solubility and formation of aggregates after heating. DSC thermograms showed that wheat germ treated for 20 min at 175 °C reached a protein denaturation degree of ~ 77%. The stabilization process of wheat germ affected significantly some functional properties, such as foaming stability and protein solubility at pH 2 and pH 8. Nevertheless, heating did not affect the water holding, oil holding and foaming capacity of protein isolates.

Impact of chemical modifications in pilot-scale isolated sorghum starch and commercial cassava starch.

The aim of this work was to evaluate the impact of different chemical modification methods on starch from different botanical sources. Brown and white sorghum starch was isolated throughout a time saving process and avoiding the use of dangerous compounds. Brown and white sorghum and commercial cassava starch were treated using acetic acid, acetic anhydride and octanoyl chloride. Its chemical, morphological and thermal characterization was afterwards carried out. The modifications reduced amylose content and increased damaged starch. Both acetylation and acid treatment produced no significant changes in the size and shape of granules; yet, they increased superficial pores. SEM observations supported the results, indicating that octanoyl modification causes a partial destruction of the granule structure. Thus, particle size distribution changes significantly. Crystallinity degree decreased with all the modifications. However, the effect was more pronounced in octanoyl esterification. In general, modifications increase the water absorption of the native starch but no considerable effect was found over oil absorption, and gelatinization parameters were significantly altered as a result of modifications. Starch from these subtilized sources was successfully modified, which could arouse interest in its industrial production.

Effect of Ingredients on the Quality of Gluten-Free Sorghum Pasta.

Sorghum is an underutilized cereal in human food production, despite its flour being a potential gluten-free (GF) source in the development of several foods. Thus, the aim of the present investigation was to evaluate the effects and interactions of different ingredients on cooking quality and texture of GF pasta. Egg albumen (A), egg powder (E), xanthan gum (X), and pregelatinized corn starch (P) were used as ingredients, and Box-Behnken experimental design was applied to study the effects of these ingredients on pasta cooking behavior, color, and texture attributes. Responses were fitted to a second order polynomial equation, and multivariable optimization was performed using maximization of general desirability. Next, optimal formulations were validated, compared with two commercial gluten-free pastas by sensory evaluation, and finally, an industrial assay was carried out. Regression coefficients indicated that A and P improved cooking properties while A and E contributed the most to improving the pasta textural properties. As, X and P effects varied depending on the kind of sorghum flour used, the optimal formulations levels were different, but in both cases these models were satisfactory and capable of predicting responses. The industrial assay was carried out with white sorghum flour because it showed a higher acceptability in the sensory evaluation than brown sorghum flour pasta. This industrially made pasta resulted in slightly better cooking properties than the laboratory produced one, with the formulation adapting well to the conventional wheat pasta industrial process. Gluten-free sorghum pasta was produced, showing good cooking and textural properties and being a suitable option for gluten-sensitive individuals.