This study investigated the impact of Parinari curatellifolia peel flour on the nutritional, physical and antioxidant properties of formulated biscuits. Biscuits enriched with 5%, 10%, 15% and 20% of Parinari (P). curatellifolia peel flour were formulated and characterised. Thermal, physicochemical, polyphenolic compounds and antioxidant properties of flour and biscuits were determined. The incorporation of P. curatellifolia peel flour significantly increased (p < 0.05) thermal properties (onset, peak and conclusion temperatures) of flour. However, enthalpy of gelatinisation, viscosity and pH of flour samples decreased. Nutritional analysis revealed an increase in ash (0.74% to 2.23%) and crude fibre contents (0.39% to 2.95%) along with an increase of P. curatellifolia peel flour levels. Protein content and carbohydrates decreased while moisture content was insignificantly affected by the addition of P. curatellifolia peel flour. The L*, b* values and whiteness index of formulated biscuits decreased while parameter a* value (10.76 to 21.89) and yellowness index (69.84 to 102.71) decreased. Physical properties such as diameter (3.57 mm to 3.97 mm), spread ratio (2.67 to 3.45) and hardness (1188.13 g to 2432.60 g) increased with the inclusion levels of peel flour while weight and thickness decreased. The inclusion of P. curatellifolia improved the polyphenolic compounds and antioxidant activity of biscuits with values of total flavonoids content ranging from 0.028 to 0.104 mg CE/g, total phenolic content increasing from 20.01 mg to 48.51 mg GAE/g, ferric reducing antioxidant power (FRAP) increasing from 108.33 mg to 162.67 mg GAE/g and DPPH (2,2-diphenyl-1-picrylhydrazyl) from 48.70% to 94.72%. These results lead to the recommendation of the utilisation of P. curatellifolia peel flour to enhance the nutritional value, polyphenolic compounds and antioxidant activity of bakery products such as biscuits.

中文翻译：

---

Parinari curatellifolia Peel Flour 对饼干营养、物理和抗氧化特性的影响

本研究调查了Parinari curatellifolia果皮粉对配方饼干的营养、物理和抗氧化特性的影响。饼干富含 5%、10%、15% 和 20% 的Parinari (P)。配制和表征了curatellifolia果皮粉。测定了面粉和饼干的热、物理化学、多酚化合物和抗氧化特性。掺入P. curatellifolia剥离面粉显著增加（p< 0.05) 面粉的热特性（起始温度、峰值温度和结束温度）。然而，面粉样品的糊化焓、粘度和pH值降低。营养分析显示灰分（0.74% 至 2.23%）和粗纤维含量（0.39% 至 2.95%）随着P. curatellifolia果皮面粉含量的增加而增加。添加P. curatellifolia后，蛋白质含量和碳水化合物减少，而水分含量不显着剥面粉。配方饼干的 L*、b* 值和白度指数下降，而参数 a* 值（10.76 至 21.89）和黄度指数（69.84 至 102.71）下降。物理性质，如直径（3.57 毫米至 3.97 毫米）、铺展率（2.67 至 3.45）和硬度（1188.13 克至 2432.60 克）随着果皮粉的加入水平而增加，而重量和厚度则下降。包含P. curatellifolia提高饼干的多酚类化合物和抗氧化活性，总黄酮含量从0.028到0.104 mg CE/g，总酚含量从20.01 mg增加到48.51 mg GAE/g，铁还原抗氧化能力（FRAP）从108.33 mg增加至 162.67 mg GAE/g 和 DPPH（2,2-二苯基-1-苦基肼）从 48.70% 至 94.72%。这些结果导致建议使用P. curatellifolia果皮粉来提高饼干等烘焙产品的营养价值、多酚化合物和抗氧化活性。