Investigating the effect of extracts from the germs of different wheat cultivars (usual and under the ultrasonic process) in oxidative stability of soybean oil

In the present study, the effect of ultrasonic waves on the antioxidant activity of aqueous-ethanolic extract (50:50) of wheat germ of Tajan, N8019 and Morvarid cultivars was investigated. The results showed that ultrasonic waves increased the amount of, although their effect on the extraction of polyphenol compounds was much better. The amount of polyphenolic compounds of Tajan, N8019 and Morvarid wheat germ extracts were 679, 783 and 545 mg / kg, respectively. After applying ultrasonic waves, these compounds were 777, 891 and 593 mg/kg increased. Also, antioxidant activity (DPPH radical-scavenging assay, β-carotene bleaching assay and Rancimat test) of different treatments showed that the extracted extracts from wheat germ of N8019 under ultrasonic process was the best sample and then were 100 ppm TBHQ, extract of Tajan wheat germ under ultrasonic process, extract of Morvarid wheat germ under ultrasonic process, extracts of common wheat germ of N8019  and Tajan and extract of common Morvarid  wheat germ, respectively. The results showed that there is a strong correlation between the amount of antioxidant compounds of different extracts extracted from wheat germ, especially phenolic compounds and their antioxidant power. Also, the results of oven test (at 60 ºC during 24 day) indicated TBHQ was the best treatment and followed by extracted extracts from wheat germ of N8019 under ultrasonic process, Tajan under ultrasonic and Morvarid under ultrasonic and extracts of common wheat germ of N8019, Tajan and Morvarid, respectively.