Reducing of bitterness in green walnuts by ultrasonication

In this study, some chemical properties of green walnuts harvested in 4 different periods from 3 different regions in the around the Van Lake were determined and it was investigated to reducing of bitterness of green walnuts by using ultrasonic and classical extraction methods for jam production. In green walnut samples, juglon, gallic acid, neochlorogenic acid and routine as phenol compounds were determined. While the highest total phenolic content and antioxidant activity in green walnut samples were determined on June 1, the highest amount of Juglon was determined on June 30. Total phenolic, juglon, gallic acid, chlorogenic acid and ellagic acid contents and antioxidant activities of green walnut jams with increasing extraction time in both ultrasonic and classical extractions reduced. In all time, phenolic substance content and antioxidant activities of the green walnut jam with ultrasonic extraction were higher than those of the conventional extraction method, except elajic acid. In the sensory evaluation, bitterness level of green walnut jam produced after 12-hour ultrasonic extraction was found to be similar to 6 days of classical extraction. In addition, green walnut jam produced after 12-hour ultrasonic extraction has the highest general approval score. In the study, it was observed that 6-10 days debittering process with classical extraction can be decreased to 12-14 hours by ultrasonic extraction. As a result, it has been determined that ultrasonic extraction method reduce the debittering process time and provide better quality, faster and more production. Keywords: Antioxidant activity, Walnut jam, Extraction, Phenolic content, Ultrasonication, Green walnut.