In this study, a natural fermentation starter formulation was developed for functional bread products by substituting baker's yeast with naturally fermented sourdough added with sea buckthorn leaf (SBL). The quality and antioxidant properties of morning bread (MB) with 0%, 10%, 20%, and 30% SBL added to sourdough were investigated. The pH of MB dough decreased when the mixing ratio (MR) of SBL was increased. The dough-raising power by incubation time (20-60 min) increased when the MR of SBL was increased. In the MB containing 30% SBL sourdough, the height was lowest, and the baking loss rate was highest. The specific volume of the control was the highest. The L value decreased, whereas the b values increased, when MR of SBL was increased. Hardness was the highest in MB containing 20% SBL sourdough. Total polyphenolic and total flavonoid contents tended to increase as SBL increased. DPPH and ABTS + radical scavenging activities and reducing power of MB were also elevated due to addition of MR of SBL. The sensory evaluation results revealed that MB containing 20% SBL sourdough the highest overall preference. Collectively, these results indicated that sourdough with 20% SBL was a very useful substitute for baker's yeast when making naturally fermented functional bread. Key words：sea buckthorn leaf, sourdough, morning bread, quality characteristics, antioxidant activity

This study investigated the quality characteristics and antioxidant activity of rye cookies prepared using sea buckthorn leaf powder (SBLP), which is known to contain various functional ingredients. Rye cookies were prepared by replacing 0%, 3%, 5%, 7%, and 9% flour with SBLP. The pH of cookie dough was significantly decreased with increasing amount of added SBLP. The loss and leavening rate of cookie also showed a similar decreasing tendency, whereas the moisture content and sweetness of cookie were significantly increased with increasing amount of SBLP. Analysis on the hunter color system showed significantly decreased L, a, and b values of cookie with increasing amount of SBLP. Hardness was also observed to proportionately increase with increasing SBLP content. Moreover, supplementation with SBLP resulted in higher levels of total polyphenol, flavonoid, chlorophyll, and carotenoid contents. The antioxidant activities measured by the DPPH and ABTS + radical scavenging activities, and reducing power were highest in rye cookies supplemented with 9% SBLP. The overall acceptability of rye cookies containing 7% SBLP received the highest score in the sensory evaluations. Thus, 7% SBLP was determined to be the appropriate supplement for making rye cookies. We suggest supplementation with SBLP for preparing a functional cookie with improved consumer acceptance.