Osmotic membrane distillation for retention of antioxidant potential in Nagpur mandarin (Citrus reticulata Blanco) fruit juice concentrate

Consumers desire for processed fruit juices which are of higher quality, nutritionally rich, and convenient to prepare and store. Membranes have found many applications throughout the food processing industry. The present study describes the potential use of osmotic distillation process for concentrating Nagpur mandarin (Citrus reticulata Blanco) juice for the first time and to study its impact on ascorbic acid content and antioxidant activity assessed by ABTS, DPPH, FRAP, and TPC assays. The flux and concentration factor was also determined to evaluate the performance of the OD process. The juice clarified by the ultrafiltration technique having a TSS of 9.0°Brix was concentrated up to 60.4°Brix. The ascorbic acid content (15.5 mg/100 mL) and antioxidant activity by ABTS (9.69 mmolL⁻¹ Trolox), DPPH (2.77 mmolL⁻¹ Trolox), FRAP (1.33 mmolL⁻¹ Trolox), and TPC content (13 mg GAE L⁻¹) was retained, thus suggesting the use of membrane technology for concentrating fruit juice providing an alternative to the traditionally employed thermal evaporation processes. PRACTICAL APPLICATIONS: This work offers an alternative to the thermal evaporation method for concentrating Nagpur mandarin juice with less energy consumption, low equipment cost, and less damage to the product and retention of antioxidant compounds, for example, ascorbic acid, which plays an important role in human health. The Nagpur mandarin juice was transformed to concentrate with the osmotic membrane distillation (OD) technique. The concentrate so produced is significantly potential to the food processing industry with retained nutritional qualities, and is suitable for many purposes due to its reduced weight and volume, less handling and storage costs and reduced in water activity with enhancement of product stability. Production of Nagpur mandarin juice concentrate also broadens its potential applications in food industry and its good quality renders it easily acceptable to consumers.