ﺳﺎزﻣﺎن ﭘﮋوهشهای ﻋﻠﻤﯽ و ﺻﻨﻌﺘﯽ اﯾﺮان فناوری‌های جدید در صنعت غذا 2783-350X 13 3 2026 04 21 Kinetic Modeling of Physicochemical Changes in Protein Bars Enriched with Aqueous and Ethanolic Rice Bran Extracts During Storage Kinetic Modeling of Physicochemical Changes in Protein Bars Enriched with Aqueous and Ethanolic Rice Bran Extracts During Storage 307 324 1612 10.22104/ift.2025.7910.2242 FA Zahra Ashrafpour Ardakani M.Sc. Graduate, Department of Food Science and Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran. Amir Pourfarzad Department of Food Technologies, Institute of Chemical Technologies, Iranian Research Organization for Science & Technology (IROST), Azadegan Highway-South, Ahmadabad Mostoufi, Parsa Sq., Enghelab St., Tehran, Iran Journal Article 2025 10 04 Protein bars are among the popular, healthy, and safe products; however, they may undergo physicochemical changes during storage, leading to reduced attractiveness and consumer acceptance. The use of natural compounds with antioxidant activity, particularly plant extracts, is considered an effective approach to control and mitigate undesirable changes. In this study, aqueous and ethanolic extracts of rice bran were employed as functional ingredients due to their antioxidant properties and the presence of phenolic and flavonoid compounds, aiming to improve the quality of protein bars. The stability of the rice bran extract–enriched products was evaluated in comparison with the control sample over a 28-day storage period at ambient temperature, with assessments conducted at 7-day intervals. Moisture, water activity, acidity, peroxide value, and color changes were measured, and suitable kinetic models were determined using the coefficient of determination and other error indices. The findings indicated that the addition of rice bran extracts, particularly the ethanolic form, effectively reduced undesirable changes, enhanced stability, and preserved higher product quality during storage. These results suggest that the incorporation of safe and natural compounds can improve the functional properties of food products and facilitate the development of healthier and more sustainable products. Protein bars are among the popular, healthy, and safe products; however, they may undergo physicochemical changes during storage, leading to reduced attractiveness and consumer acceptance. The use of natural compounds with antioxidant activity, particularly plant extracts, is considered an effective approach to control and mitigate undesirable changes. In this study, aqueous and ethanolic extracts of rice bran were employed as functional ingredients due to their antioxidant properties and the presence of phenolic and flavonoid compounds, aiming to improve the quality of protein bars. The stability of the rice bran extract–enriched products was evaluated in comparison with the control sample over a 28-day storage period at ambient temperature, with assessments conducted at 7-day intervals. Moisture, water activity, acidity, peroxide value, and color changes were measured, and suitable kinetic models were determined using the coefficient of determination and other error indices. The findings indicated that the addition of rice bran extracts, particularly the ethanolic form, effectively reduced undesirable changes, enhanced stability, and preserved higher product quality during storage. These results suggest that the incorporation of safe and natural compounds can improve the functional properties of food products and facilitate the development of healthier and more sustainable products. https://jift.irost.ir/article_1612_baa3aeffc52cdffb4943826ea8fb9628.pdf