# Study of the Effects of Plasma Pretreatment on the Microstructure of Peanuts
## 3 Results and Discussion
### Effects of Plasma Treatment on the Internal Structure of Peanuts  
The results are presented in Figure 7. Figure 7a,b represent the control group observed under SEM at 200\(\times\) and 500\(\times\) magnification, respectively. The images reveal that the internal fiber morphology of peanuts remains intact, resembling irregular leaf shapes. Protein particles, starch granules, and macromolecule polymer structures inside the peanuts are tightly and orderly arranged, uniformly congregating around the fiber structures, with some covered by lipid bodies. Figure 7c,d are SEM images at 200\(\times\) and 500\(\times\) magnification, corresponding to plasma treatments with helium (He) for 150 s. The images reveal that the internal fiber morphology of peanuts nearly disappears. Starch granules, protein particles, and polymers undergo depolymerization, while lipid particles increase and stack, resulting in larger gaps. The surface exhibits a concave and piled-up appearance. Figure 7e is an SEM image at 200\(\times\) magnification, corresponding to plasma treatment with helium (He) at 500 w. It shows similar structural changes to Figure 7c, with more escaping protein particles, starch granules, and micromolecule polymers. This may be attributed to the rise in temperature within the plasma chamber as treatment duration extends and power increases. At 500 W, the vacuum chamber temperature measures approximately 45-50 \({}^{\circ}\)C. Under these conditions, protein cell walls are disrupted, causing proteins and lipids to flow out during plasma treatment and interact [40], resulting in the observed phenomenon.  
Figure 7h is an SEM image at 500\(\times\) magnification, corresponding to plasma treatment with O\({}_{2}\) at 200 w for 60 s. This image reveals increased internal pores. Lipid particles become smaller and denser, and the fiber structure breaks into plate-like protrusions. No protein particles or polymers escape, but lipid bodies are distributed around the small pores. Figure 7j is an SEM image at 500\(\times\) magnification, corresponding to plasma treatment with argon (Ar) at 200 w for 60 s. This image reveals that the structural changes resemble those in Figure 7h, but with slightly lighter etching. The internal structure of peanuts remains mostly intact, although the fiber structure breaks. Fewer lipid particles escape, while starch granules evade more. The reason lies in Ar being an inert gas, relatively stable, with its ionization producing only excitation effects; in contrast, O\({}_{2}\) ionization, even at a lower voltage, generates abundant reactive oxygen species, exhibiting strong oxidative properties. This leads to lipid cell wall rupture, promoting the fusion of large and small lipid particles and exposing protein particles previously enveloped by lipid bodies [41]. [PERSON] et al. [37] found that after high-temperature frying of peanuts, the cell wall undergoes significant rupture, and the loss of water leads to the  
Figure 6: Appearance of peanut embryos subjected to different treatment gases observed under a scanning electron microscope. Note: The left column shows SEM images at 500\(\times\) magnification. (**a**) Corresponds to the control group peanuts. (**c**,**e**,**g**) Correspond to peanuts treated with cold plasma of He, Ar, and O\({}_{2}\), respectively, at 200 w for 60 s. The right column shows SEM images at 2000\(\times\) magnification. (**b**) Corresponds to the control group peanuts. (**d**,**f**,**h**) Correspond to peanuts treated with cold plasma of He, Ar, and O\({}_{2}\), respectively, at 200 w for 60 s.  
emergence of more porous structures inside the peanut, which provides a channel for the oil body to enter the cell. Additionally, the etching phenomenon resulting from plasma treatment increases the number of internal pore-like structures, accelerating oil leakage and water loss within peanuts. It also provides suitable plasma treatment conditions for seed screening for high oil content [41] and oil extraction.  
Figure 7: _Cont._