This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/JFPP.15174 This article is protected by copyright. All rights reserved DR. CEM BALTACIOGLU (Orcid ID : 0000-0001-8782-3568) Article type : Original Article INVESTIGATION OF THE EFFECT OF OYSTER MUSHROOM (Pleurotus ostreatus) POWDER ON BISCUIT PRODUCTION AND EFFECT ON QUALITY CRITERIA BY FOURIER-TRANSFORM INFRARED SPECTROSCOPY Cem BALTACIOĞLU a* , Hande BALTACIOĞLU a , Rabia SEYHAN a , Özlem UĞUR a , Oğuzhan AVCU a a Department of Food Engineering, Faculty of Engineering, Nigde Ömer Halisdemir University, Nigde, 51240, Turkey * Corresponding Author: cembaltacioglu@ohu.edu.tr Abstract The purpose of this study was to determine the effects of oyster mushroom powder addition (10, 20, and 30% levels by the replacement method with wheat flour) on the chemical and physical characteristics of biscuits. With the addition of oyster mushroom powder, an increase was observed in volume, spread ratio and protein content of control biscuit group 5.36%, 6.87%, 40.96%, respectively. As a result of addition of mushroom powder, 26.97% decrease was observed on hardness values of the biscuit, while 5.94% increase in fracturability value was observed. According to sensorial analysis results, the 10% oyster mushroom powder in biscuit products showed the best sensory properties in terms of general acceptibility and average values. Accepted Article