Wheat germ stabilization by infrared radiation

Abstract

Wheat germ has an important enzymatic activity, being lipases the enzymes which cause the highest impact in the reduction of shelf life. The objective of this study was to evaluate the effects of infrared radiation on wheat germ stabilization in an attempt to extend the shelf life. The effects of treatment time, gap (sample distance to IR emitters) and infrared radiation intensity on wheat germ were analyzed through response surface methodology. Final moisture content, final temperature, color of germ and germ oil quality parameters: free fatty acid content changes and total tocopherol content were the responses evaluated using a Box-Behnken design. A combination of an infrared radiation intensity of 4800 W/m 2 , a 3 min treatment and 0.2 m emitter-sample distance were the best processing condition to stabilize the wheat germ without significantly reduction of the tocopherol content. A confirmatory experiment was conducted with these optimal conditions, and the heat-treated and raw germ samples were stored for 90 days at room temperature in three layer packages to protect them against light and oxygen. The oil quality parameters indicated that the raw germ had a shelflife of about 15 days, with the heat-treated wheat germ maintaining its quality for at least 90 days under these stored conditions.

Physical characterization and fluidization design parameters of wheat germ

“…Therefore, a process to stabilize the wheat germ has to be devised. Different techniques can be found: application of heat (thermal processes) (Ferrara et al, 1991;Gili et al, 2017), irradiation (Jha et al, 2013), dehydration processes (Rothe, 1963) or else by chemical preservation, as, for instance by adding some chemical compound as antioxidant (Barnes, 1948) or alkalis (Grandel, 1959). Thermal processes have demonstrated to be effective to stabilize wheat germ, one of these, fluidization, provides an intense heat and mass transfer between material and the hot air, which imply a uniform treatment to the bed being fluidized.…”

Effect of Loading on Wheat Germ Drying in a Batch Fluidized Bed for Industrial Production

“…The lines of the dehydration time and heating time were almost parallel lines. In the meantime, the water activity of the WG could be maintained within a target range of 0.3 ± 0.1, which was able to attain the condition of the WG stored at a water activity of 0.4-0.5, so as to avoid spoilage from the enzymatic activity and lipid quality losses [16]. From a cost perspective, it had an effective drying performance in a batch process when the WG loading increased.…”

“…Stabilization methods for preventing WG spoilage can be grouped into the following three types: physical, chemical, and biological approaches [2]. The most common physical stabilization methods can be categorized as a number of different treatments, including fermentation [6,7,10,11], microwave [12][13][14], gamma irradiation [15], infrared radiation [16,17], and fluidization [11,[18][19][20][21], which limit the WG enzymatic activity. Controlling the water activity (WA) or moisture content (MC) of WG within a desired range is an important factor when preventing WG spoilage [18].…”

Investigating release kinetics of phenolics from defatted wheat germ incorporated chewing gums

“…Wheat germ (WG) is an important by‐product of the wheat milling industry that makes up about 2–3% of the kernel and it is valuable for human nutrition . However, the shelf life of the germ is adversely affected by the high oil content due to oxidative and hydrolytic enzyme activities.…”

“…8 Wheat germ (WG) is an important by-product of the wheat milling industry that makes up about 2-3% of the kernel and it is valuable for human nutrition. 9 However, the shelf life of the germ is adversely affected by the high oil content due to oxidative and hydrolytic enzyme activities. In order to eliminate this negative situation and extend the shelf life of the raw germ, various processes are applied, such as defatting process, heat treatment applications or using some chemical substances.…”