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.

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.

Enhancement of Composition and Oxidative Stability of Chia (Salvia hispanica L.) Seed Oil by Blending with Specialty Oils.

Chia seed (Salvia hispanica L.) oil is mainly composed of ω-3 fatty acids (61% to 70%). Despite being nutritionally favorable, higher amounts of polyunsaturated fatty acids result in poorer oxidative stability. Thus, the aim of this work was to produce edible vegetable oil blends rich in ω-3 fatty acids and with greater oxidative stability than pure chia oil. Blending of chia with other specialty oils (walnut, almond, virgin, and roasted sesame oils) was assessed in the following respective proportions: 20:80, 30:70, and 40:60 (v/v). An accelerated storage test was conducted (40 ± 1 °C, 12 days). Primary and secondary oxidation products, free fatty acid content, antioxidant compounds, fatty acid composition, and induction time were determined. The blends presented higher oxidative stability indices than chia oil. Sensory analysis showed that, given a pure oil, judges did not identify statistically significant differences among the blends. The results suggest that blending of chia oil is an adequate alternative to obtain ω-3-enriched oils with higher oxidative stability indices. PRACTICAL APPLICATION: Vegetable oil blending is a widely used practice in the edible oil industry to produce blended oils with enhanced stability and nutritional and sensory properties at affordable prices. The blends developed in this study from chia, sesame, walnut, and almond oils take advantage of the properties of each parent oil to yield products with improved oxidative stability, essential fatty acid presence, and sensory characteristics. To achieve a daily intake of 2.22 g/day of ω-3 fatty acids as recommended by the Intl. Society for the Study of Fatty Acids and Lipids (ISSFAL), it is necessary to consume approximately one spoonful of the formulated mixtures.