Elicitor-induced production of bioactive metabolites in aronia and grapevine in vitro cultures and their application in functional yogurt fortification

This study investigated the effects of elicitor applications on bioactive metabolite accumulation in aronia (Aronia melanocarpa L.) and grapevine (Vitis vinifera L.) in vitro cultures and evaluated the potential of the obtained extracts for functional yogurt fortification. In vitro cultures of aronia (‘Nero’) and grapevine (‘Yalova İncisi’) were established on Murashige and Skoog (MS) medium and treated with salicylic acid (100-200 µM), methyl jasmonate (50-100 µM), polyethylene glycol (5% w/v), and UV-B (10 min/day) for 14 days. Total phenolic, flavonoid, and antioxidant capacities (DPPH, ABTS, FRAP) were determined spectrophotometrically. The most effective extracts (100 µM MeJA for aronia and 200 µM SA for grapevine) were incorporated into set-type yogurts at 1% (w/v) following pasteurization (90 °C, 10 min), inoculation with starter culture at 43 °C, and fermentation to pH 4.6. Control and fortified yogurts were stored at 4 °C and analyzed on days 0, 7, and 14. MeJA and UV-B treatments yielded the highest phenolic (75.8 mg GAE g-1 DW) and flavonoid (37.5 mg QE g-1 DW) levels in aronia, while SA increased phenolics in grapevine to 57.4 mg GAE g-1 DW. Fortified yogurts showed higher antioxidant activity (ABTS: 1.92; FRAP: 1.48 mmol g-1 DW), lower syneresis (12.9%), greater firmness (0.41 N), and reduced yeast-mold growth (1.10 log CFU g-1). These findings confirm that elicitor-enhanced cultures provide sustainable bioactive sources for functional dairy applications.