Abstract
This study aimed to examine the effects of the substitution of wheat flour with rambutan seed flour (RSF) on the physical, textural, and nutritional properties of cookies. In the experiments, 0% (control), 10%, 15%, 20%, 25%, and 30% of the wheat flour was substituted with RSF. The findings indicated that the lightness (L*) and yellowness/blueness (b*) values reduced (from 64.50±1.64 to 53.28±2.35 and from 42.31±0.44 to 37.70±0.90, respectively) as the percentage of RSF increased. The redness/greenness (a*) value increased slightly from 15.08±0.91 to 16.50±0.89. The moisture content rose from 4.94% in the control sample to 7.99% in the sample where 30% of the wheat flour had been substituted with RSF, and the spread ratio decreased significantly, reaching its lowest (4.28±0.74) in the 30% substitution condition. The textural analysis revealed that the fracturability and hardness increased by 15% to 25%, while at 10% substitution with RSF, they were not different from control formula cookies. At 30% substitution, both the fracturability value and hardness decreased to 19.48±2.30 and 28.67±1.57 N, respectively, due to fiber-induced disruptions in the dough matrix. Nutritionally, the protein content increased significantly from 7.59% in the control to 14.73% at 30% substitution with RSF, while the fat content also increased with increasing RSF proportion, although the fat content did not vary (P<0.05) between the 20% and 30% RSF substitutions. The recommended substitution quantity of RSF is therefore 15% to 25%, which optimally balances the nutritional value with acceptable physical and textural properties. This work highlights the potential of using RSF, an upcycled agricultural by-product, in the development of sustainable food alternatives. This research adds to the existing understanding of biophysical interactions in the development of functional foods.