The objective this study was to study the antioxidant activity efficiency of extracts from irradiated defatted guava (Psidium guajava L.) seeds at dose levels of 0, 2, 4 and 6 kGy. The non-irradiated and irradiated defatted guava seeds samples were extracted with acetone: water: acetic acid (90:9.5:0.5). Immediately after irradiation, the antioxidant activity was studied. Gas chromatographic-Mass spectrum was applied to identify and quantify the constituents (%) of extracts and the amino acids composition was determined in all samples under investigation of defatted guava seeds powder. The measurements of the antioxidant activity, using a ?-carotene-linoleate model system and radical scavenging capacity effect on 2, 2-diphenyl-1- picrylhydrazyl (DPPH) radical, was determined in the extracts of non-irradiated and irradiated defatted guava seeds powder. Meanwhile, noodles (homemade strips macaroni) were prepared from blends of 72% wheat flour containing 0, 2.5, 5 and 7.5% levels of non-irradiated defatted guava seeds powder. The results showed that samples of extracts from non-irradiated and irradiated defatted guava seeds had contained a considerable total polyphenolic compounds and marked scavenging activity on DPHH radical. On the other hand , the gas chromatography (GC) and mass spectroscopy (MS) separation technique led to identification of 26 components the of extract non-irradiated and irradiated samples. Also, the data revealed that guava seeds powder samples under investigation passes the most important essential amino acids and for human health such as trace elements iron, zinc and manganese. Noodles prepared from 2.5% level of guava seeds powder-wheat flour blend had high acceptable quality. Thus, guava seeds, a waste from guava industry can be utilized improved nutritional properties of noodles or used its extracts as natural antioxidant in food industry field. Key words: Guava Seeds/ Antioxidant/ Extract/ Gamma irradiation
