*Article* **Effects of** γ**-Irradiation on Structure and Functional Properties of Pea Fiber**

**Tianfu Cheng, Caihua Liu, Zhaodong Hu, Zhongjiang Wang and Zengwang Guo \***

College of Food Science, Northeast Agricultural University, Harbin 150030, China; ctf2303@163.com (T.C.); 17686963949@163.com (C.L.); 2021nodanger@163.com (Z.H.); wzjname@126.com (Z.W.)

**\*** Correspondence: gzwname@163.com; Tel.: +86-182-4955-4700

**Abstract:** In this study, pea residue reserve insoluble diet fiber (hereinafter referred to as pea fiber) was used as a raw material. The effects of γ-irradiation doses (0, 0.5, 1, 2, 3, and 5 kGy) on the structural properties (main composition, particle size and specific surface area, scanning electron microscope (SEM) microstructure, Fourier transform infrared spectroscopy, and X-ray diffraction) and functional properties (oil-holding capacity, swelling and water-holding capacity, and adsorption properties) of pea fiber were explored. The results show that, when the γ-irradiation dose was 2 kGy, compared with the untreated sample, the contents of cellulose, hemicellulose and lignin in pea fiber decreased by 1.34 ± 0.42%, 2.56 ± 0.03% and 2.02 ± 0.05%, respectively, and the volume particle size of pea fiber decreased by 17.43 <sup>±</sup> 2.35 <sup>μ</sup>m. The specific surface area increased by 23.70 <sup>±</sup> 2.24 m2/kg and the crystallinity decreased by 7.65%. Pore and irregular particles appeared on the microstructure surface of the pea fiber treated with γ-irradiation. The results of the infrared spectrum showed that the hemicellulose and lignin in pea fiber were destroyed by γ-irradiation. These results indicate that γ-irradiation can significantly affect the structural properties of pea fiber. When the γ-irradiation dose was 2 kGy, the highest oil-holding capacity, swelling capacity and water-holding capacity of pea fiber were 8.12 ± 0.12 g/g, 19.75 ± 0.37 mL/g and 8.35 ± 0.18 g/g, respectively, and the adsorption capacities of sodium nitre, cholesterol and glucose were also the strongest. These results indicate that the functional properties of pea fiber are improved by γ-irradiation. In this study, γ-irradiation technology was used as pretreatment to provide a theoretical basis for the application of pea fiber in food processing.

**Keywords:** γ-irradiation; pea fiber; structural properties; functional properties
