Investigation of the effect of using wheatgrass powder on quality parameters in biscuit production

The aim of this study is to determine the effects of adding wheatgrass powder (WGP) at different levels (2%, 5%, and 7%) to biscuit dough on the physical, chemical, rheological, textural, and sensory quality characteristics of the biscuits. In the study, control samples (white flour) and WGP-enriched biscuits at different levels were produced, and various analyses were performed on the samples obtained. Physicochemical analyses revealed that the addition of WGP increased the moisture, ash, protein, cellulose, and dietary fiber contents of the biscuits, while the fat content decreased (p<0.05). In terms of color properties, a general decrease in L* values was observed, resulting in darker biscuits. In addition, increases in a* and b* values, particularly at 7% supplementation, were detected, which can be attributed to the natural pigment composition of wheatgrass powder. Based on diameter and thickness measurements, biscuit thickness increased with higher levels of WGP, while the spread ratio decreased. Rheological analyses demonstrated that, according to farinograph results, the addition of WGP enhanced water absorption capacity, dough stability, and farinograph quality number, while reducing the dough development time. Extensograph results showed that maximum resistance (Rmax) and energy values increased up to 5% supplementation, whereas extensibility values decreased as the supplementation level increased. Textural analyses indicated no statistically significant difference in hardness values (p>0.05). However, elasticity and cohesiveness values increased with the addition of WGP. Sensory evaluation results revealed that the highest acceptance scores were obtained for the control group, while overall acceptability decreased as the level of WGP increased. In particular, higher supplementation (7%) had a negative effect on sensory quality. In conclusion, limited supplementation of WGP (2–5%) improved the nutritional, rheological, and textural properties of biscuits, whereas higher supplementation levels weakened the gluten network and negatively affected quality parameters. This study demonstrates that biscuits enriched with an optimum level of WGP can be produced with enhanced functional properties and may contribute to the development of functional foods.