Oil-absorbing paper doesn't actually "absorb" oil; rather, it utilizes the microporous structure of natural plant fibers and the synergistic effect of a hydrophobic and oleophobic coating to form a selective barrier layer.
Food-grade kraft paper, after being processed using the sulfate method, has high cellulose purity and strong crystallinity. Further treatment with light siliconization or mineral oil increases its surface tension, making it difficult for oils to spread and penetrate, while still allowing trace amounts of moisture to escape, preventing food from becoming soggy. This property is widely used in packaging high-fat, freshly prepared foods such as sandwiches, hamburgers, and pastries.
