Phenolic compounds, amino acid profiles, and antibacterial properties of kefir prepared using freeze-dried Arbutus unedo L. and Tamarindus indica L. fruits and sweetened with stevia, monk fruit sweetener, and aspartame

Abstract

This study attempts to investigate physicochemical and antibacterial properties of kefir enriched with freeze-dried Arbutus unedo L. and Tamarindus indica L. fruits and sweetened using stevia, monk fruit sweetener, aspartame, and sucrose (beet and cane sugar). Based on the findings of the study, the pH values of kefir decreased with the addition of fruits. The lowest syneresis and the highest dry matter values were found in the samples with sucrose. 15 phenolic compounds and 31 amino acids were detected using LC-MS/MS. The major phenolic components of the samples added with Arbutus unedo L. and Tamarindus indica L. fruits were gallic acid and syringic acid, respectively. Only gallic, protocatechuic, salicylic, and caffeic acids were detected in the control sample (C1). The primary amino acids were l-proline, l-glutamic acid, and l-valine, respectively. Kefir and fruit samples demonstrated antibacterial effect against Bacillus cereus, Staphylococcus aureus, and Escherichia coli. Novelty impact statement Freeze-dried Arbutus unedo L. and Tamarindus indica L. fruits were used in kefir sweetened with various sweeteners. The syneresis values of kefir samples decreased with the addition of freeze-dried fruits. 15 phenolic compounds and 31 amino acids were detected in kefir samples by using LC-MS/MS.