2021/10/04 by Özge Duygu Okur
Biochemistry, Genetics and Molecular Biology · Medicine · #Consumer Attitudes and Food Labeling #Protein Hydrolysis and Bioactive Peptides #Tea Polyphenols and Effects
paper · doi:10.1108/bfj-07-2021-0721
openalex publication_date 2021/10/04 · crossref created 2021/10/04 · crossref issued 2021/10/05 · crossref published 2021/10/05 · crossref published-online 2021/10/05 · crossref published-print 2022/03/21 · crossref deposited 2025/07/24 · openalex created_date 2025/10/10 · crossref indexed 2026/07/31 · openalex updated_date 2026/07/31
Purpose This study aims to produce a new type of healthy functional kefir by adding olive ( Olea europaea ) leaf extract and to determine its potential effect on the quality (physicochemical, sensory, phenolic contents and antioxidant properties) of kefir samples during storage at 4°C for 21 days. Design/methodology/approach For this purpose, four kefir samples were produced by using olive leaf extract in different amounts (A: 0% (control), B: 0.1%, C: 0.15% and D: 0.35%). The physicochemical, sensory, phenolic contents and antioxidant properties of kefir samples were investigated during Days 1, 7, 14 and 21 of storage. The study was conducted to optimize the olive leaf extract addition level to obtain better-quality kefir functional food. Findings From the results, it was determined that the addition of olive leaf extract affected the entire chemical components of the kefir samples ( p < 0.05). It was found that the pH value decreased during storage. By contrast, it was observed that titration acidity values increased. The kefir sample with 0.35% olive leaf extract (D) had the highest total phenolic and antioxidant activity content (1,292.75 mg GAE/L and 10.20 mM TE, respectively) among the samples ( p < 0.05). In the sensory analyses, the kefir sample with the highest score – in terms of sensory attributes – was the kefir sample containing 0.15% olive leaf extract (C). Originality/value Thus, it was concluded that kefir with added olive leaf extract could serve as a functional kefir of benefit to human health. When we looked at the enrichment studies on kefir as a functional product, no study has been found on the use of olive ( Olea europaea ) leaf extract, especially with kefir. In this sense, it is thought that the study will contribute to published literature.