Shelf life of pomegranate juice concentrate as influenced by packaging materials and storage conditions

The influence of packaging materials and storage conditions on colour, physicochemical, microbial, sensory attributes and shelf life of pomegranate juice concentrate was evaluated. The pomegranate juice concentrate was prepared from clarified ‘Bhagwa’ juice by the atmospheric heating method (open pan heating at 85±3°C). The pomegranate juice concentrate was packaged in six different packaging containers, viz., wide mouth PET bottle (transparent and amber-coloured), glass bottle (amber-coloured and transparent), polystyrene cup, and stand-in pouches, and was stored at ambient (25±3°C) and cold storage (5±1°C) conditions. The freshly prepared juice concentrate recorded 16.48 L*, 13.52 a* and 1.82 b* values, 65 °Brix, 0.841% acidity, 53.37% sugars, 321.97 mg 100 mL^‑1 anthocyanins, 833.92 mg 100 g^‑1 polyphenols with 7.41% antioxidant activity initially. Best colourimetric properties (13.71 L*, 12.17 a* and 1.95 b* value) and a higher concentration of anthocyanins (280.12 mg 100 mL^‑1) were maintained in the wide-mouthed amber-coloured glass bottle kept in cold storage. A significant decrease in colour intensity in respect of L* and a* values while an increase in b* value of juice concentrate was noted in all treatments under study leading to dark brownish yellow coloured concentrate at the end of 180 days of storage. Compared to cold storage, a significant change in concentrate colour at ambient storage was observed. A slight increase in soluble solids, sugars and pH, and a relative decrease in titratable acidity compared to the initial values were noted in all samples, irrespective of packaging materials or storage conditions. A slower change in the polyphenols (743.69 mg 100 g^‑1), anthocyanins (254.28 mg 100 mL^‑1) and antioxidant activity (61.87%) was recorded in concentrate stored at 5±1°C compared to ambient storage. No microbial growth was observed till 90 days of storage in both storage conditions and all packaging used. However, the total aerobic count increased with storage duration after 90 days, irrespective of the treatments under study. Slow changes in the levels of physicochemical parameters and minimum changes in colour and microbial growth were recorded in juice concentrate packed in wide-mouthed amber-coloured glass bottles stored at 5±1°C. Pomegranate juice concentrate stored for up to 180 days at both storage conditions retained sensorial properties, physicochemical parameters, and acceptable microbial limits. The pomegranate juice concentrate packed in amber-coloured glass bottles and stored in cold storage (5±1°C) performed the best as it recorded minimum changes in physicochemical parameters, microbial and sensorial attributes after 180 days.