Process optimization of vacuum concentration of Karonda fruit juice using response surface methodology: effects on antioxidant activity, iron content and GCMS profile

Abstract In the realm of fruit processing, karonda juice stands out for its elevated moisture levels, posing challenges in storage and transportation. This study presents a pioneer effort for concentration of karonda juice through optimizing the process parameters viz., temperature and time using central composite design (CCD) of response surface methodology (RSM) within rotary evaporator setup. Through ten experimental runs, variations were introduced, adjusting temperatures from 45 to 55 °C and duration from 90 to 210 min. The results showcased the efficacy of vacuum concentration, reducing moisture content to 16.43% and significantly elevating total soluble solids (TSS) from 9.02 to 89˚B. Moreover, key nutrients experienced substantial increase: ascorbic acid surged from 3.79 to 14.66 mg per 100 g, total phenolic content (TPC) soared from 100.74 to 386.97 mg GAE per 100 g, total antioxidant activity (mg AAE/100 g) escalated from 76.74 to 328.10 mg AAE per 100 g, anthocyanin content (mg/100 g) increased from 10.9 to 129.34 mg per 100 g, and iron content rose from 39 to 150.54 mg per 100 g. GC–MS profile elucidated compounds like Tetrahydrofuran, 3-Hydroxy-3-methylvaleric acid, 3-Hexen-2-one, Hydroperoxide and Octane. The optimization process, guided by RSM revealed the ideal parameters: 55 °C for 150 min, marking a significant advancement in karonda concentration techniques.