Food oral processing is a key stage for safe swallowing, during which ingested foods are broken down through compression and shear by teeth and tongue and then mixed with saliva to form a cohesive bolus. In this study, we prepared three model bakery crackers: control that was made from wheat flour and water, a shortening-added sample, and a WPI-added sample. The three model crackers were fragmented into granules of ~1 mm for preparing artificial boluses by subsequently impregnating the granules with an amount of artificial saliva without amylase. The mechanical strength of the saliva-absorbed granules was evaluated by a penetration test, and the bolus rheology was characterized by strain-sweep and frequency-sweep measurements. The cracker samples with added fat exhibited a brittle and weak structure compared with the control, possibly due to the disruption of the gluten network by shortening. In contrast, the WPI-added samples showed greater mechanical strength than the control, which was attributed to the reinforcement of the protein network by WPI. As a result, the fat-added sample developed a sticky surface layer after absorbing 60% saliva, as the granule surface partially broke down. This sticky layer promoted strong inter-granular adhesion. However, the WPI-added samples showed weak adhesion due to lubrication by unabsorbed saliva, as their firm structure limited saliva penetration. With increasing saliva uptake, the mechanical strength of all samples decreased, while the overall strength remained in the order WPI-added > control > fat-added. The elastic modulus (G′) obtained from rheological measurements also decreased with saliva uptake in all samples. However, at 60% saliva, the fat-added samples showed a higher G′ than the control, despite their weaker individual granules, indicating that adhesive interactions between granules contributed to the bolus elasticity. In contrast, the WPI-added samples maintained higher elasticity than the other samples at all saliva levels, reflecting their inherently greater mechanical strength. In conclusion, our study clarified how the mechanical strength of the granules and the adhesion formed between them after saliva uptake influence bolus rheology. In addition, adjusting ingredient composition can modulate these rheological properties, providing useful insights for designing bakery products with improved texture and swallowability.