Effect of different fermentation techniques on the properties of water kefir produced using aronia, pomegranate and red beet juice

Consumers' healthy eating habits have increased the demand for products produced using natural fruit juices that are sugar-free and preservative-free. This has led food companies to produce affordable and packaged healthy and ready to eat/drink sources. Water kefir, which is a plant-based prebiotic carbonated drink, is a healthy option for consumers with vegan diets or allergies to milk and dairy products. In this thesis, two different fermentation methods SK1 (water kefir grain) and SK2 (water kefir inoculum) were used in water kefir production with agricultural products rich in phenolic compounds aronia (A), pomegranate (N) and red beet (P). The total phenolic compound (TFM) content in samples was 29.16±1.09 and 37.61±1.91 mg GAE/100 mL when aronia was used, 21.29±0.36 and 26.14±1.28 mg GAE/100 mL when pomegranate was used, and 12.25±0.37 and 13.52±0.89 mg GAE/100 mL when red beet was used. When fermentation methods were compared, water kefir produced using inoculum was found to have higher values for total phenolic content (TFM), total flavonoids (TF), and antioxidants (AOK) compared to that produced using kefir grains. Throughout these agricultural products, aronia had the highest phenolic compounds and the bioaccessibility of water kefir samples A-SK1 and A-SK2 was varying between 54.29±3.35 and 52.54±2.21% for TFC, 31.02±0.86 and 36.00±0.57% for TF, 41.95±4.92 and 40.28±0.78 (CUPRAC), and 71.73±2.65 and 64.19±5.11% (DPPH) for AOK, respectively. Besides the highest bioactive compounds and bioaccessibility of water kefir samples, acceptability in sensory evaluation reveals the potential as alternative beverage.