Changes in phenolics and antioxidant activity at each step of processing from pomegranate into nectar

Not-from-concentrate pilot plant 'Wonderful' cultivar pomegranate juice changes: Quality

Colorful fruits conveying astringent beverages providing well documented health-benefits may present clarification, turbidity and sedimentation problems. Hydraulic pressing whole 'Wonderful' pomegranates and ultrafiltration followed by high temperature short-time pasteurization was used to mimic the dominant U.S. commercial juicing protocol, delivering not-from-concentrate juices, stored at 4 and 25 °C for 3 months. A goal was to avoid expensive and complicated clarification and fining steps. Data were subjected to an analysis of variance and principal components analysis. Changes in quality attributes, organic acids and anthocyanidins are presented. Hydraulic pressing, ultrafiltration and initial pasteurization had minor effects on color parameters, organic acids and anthocyanidins. There were no significant temperature, time or factorial effects for all color parameters during storage of the not-from-concentrate pasteurized juices. However, there were significant time- and temperature-effect decreases in organic acids and anthocyanidins. This is the first report on quality attributes in ultrafiltered, pasteurized and stored not-from-concentrate 'Wonderful' pomegranate juice.

Perspective of Membrane Technology in Pomegranate Juice Processing: A Review

Pomegranate (Punica granatum L.) juice is well recognized for its high content of phytochemicals with proven health-promoting effects. Conventional processing techniques including clarification with fining agents, pasteurization and thermal concentration have significant influences on bioactive compounds and antioxidant activity of the juice. The growing consumers demand for high-quality pomegranate juice as well as the industrial interest for the production of functional foods, nutraceuticals, and cosmetics from its bioactive compounds have promoted the interest for minimal processing technologies. In this context, membrane-based operations represent an innovative approach to improve the overall quality of pomegranate juice production. This review focuses on the recent advances and developments related to the application of membrane technology in pomegranate juice processing. Conventional pressure-driven membrane operations and innovative membrane operations, such as osmotic distillation and pervaporation, are discussed in relation to their potential in juice clarification, fractionation, concentration and aroma recovery. Their implementation in integrated systems offer new opportunities to improve the healthiness and quality of the juice as well as to recover, purify and concentrate bioactive compounds for the formulation of functional ingredients.

Comparison of Iron (III) Reducing Antioxidant Capacity (iRAC) and ABTS Radical Quenching Assays for Estimating Antioxidant Activity of Pomegranate

Pomegranate juice (PJ) has total antioxidant capacity which is reportedly higher compared to other common beverages. This short study aimed to assess the total antioxidant capacity of commercial PJ and pomegranate fruit using a newly described method for iron (III) reducing antioxidant capacity (iRAC) and to compare with the ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) and Folin–Ciocalteu assays. Commercial PJ, freeze-dried pomegranate, and oven-dried pomegranate were analyzed. The calibration results for iRAC were comparable to ABTS and Folin–Ciocalteu methods in terms of linearity (R2 > 0.99), sensitivity and precision. The total antioxidant capacity for PJ expressed as trolox equivalent antioxidant capacity (TEAC) was 33.4 ± 0.5 mM with the iRAC method and 36.3 ± 2.1 mM using the ABTS method. For dried pomegranates, total antioxidant capacity on a dry weight basis (DB) was 89–110 mmol/100 g DB or 76.0 ± 4.3 mmol/100 g DB using iRAC and ABTS methods, respectively. Freeze-dried pomegranate had 15% higher total antioxidant capacity compared with oven-dried pomegranate. In conclusion, pomegranate has high total antioxidant capacity as evaluated by the iRAC and ABTS methods, though variations occur due to the type of cultivar, geographic origin, processing and other factors. The study is relevant for attempts to refine food composition data for pomegranate and other functional foods.