Elsevier

Scientia Horticulturae

Volume 169, 16 April 2014, Pages 125-129
Scientia Horticulturae

Short communication
Effects of postharvest storage conditions on phytochemical and radical-scavenging activity of pomegranate fruit (cv. Wonderful)

https://doi.org/10.1016/j.scienta.2014.02.012Get rights and content

Highlights

  • Fruit total phenolic concentration increased during storage up till 3 month.

  • Ascorbic acid concentration was affected at by storage duration.

  • This study highlights the effects of storage regimes and duration on health promoting compounds in pomegranate fruit.

Abstract

This study was conducted to investigate the effects of storage temperature and duration on phytochemical and antioxidant properties of pomegranate fruit (cv. Wonderful). Commercially ripe fruit were stored at 5 ± 0.7 °C, 7.5 ± 0.3 °C, 10 ± 0.5 °C with 92 ± 2% relative humidity (RH) and 21 ± 3 °C with 65 ± 6% RH for 5 months. Fresh pomegranate juice was assessed for concentrations of total phenolic compounds (TP), total anthocyanin (Acy) ascorbic acid. The radical-scavenging activity of fruit juice was tested against 2, 2-diphenyl-1-picryl hydrazyl (DPPH). The investigated parameters differed significantly (p < 0.05) at different temperatures and duration. Results showed that TP increased with storage temperatures and duration with the maximum levels measured at 10 °C (364.47 mg/100 ml) for 3 months storage period. However, the concentration declined thereafter at all storage regimes, the lowest concentration was 196 mg/100 ml in fruit stored at 7.5 °C for 5 months. Similarly, Acy concentration increased with storage temperatures in the first month, and gradually declined thereafter. Furthermore, ascorbic acid concentration gradually declined with storage period, with the lowest concentration (12.69 mg/100 ml) measured at 7.5 °C after 5 month storage. For antioxidant activity, storage of fruit at 5 °C, 7.5 °C, and 10 °C significantly (p < 0.05) reduced the radical scavenging activity of juice by more than 56% when stored beyond 2 months. This study highlights the need to consider the effects of different temperatures and duration on health promoting compounds in pomegranate fruit, especially where fruit are stored for long term and primarily used for health-promoting purposes.

Introduction

Fresh fruit and vegetables play an essential role in human nutrition and health because they contain high concentration of beneficial phytonutrients, dietary fiber and other micro-nutrients (Kader, 2002, Opara and Al-Ani, 2010). Pomegranate fruit (Punica granatum L.) is known as a highly nutritional fruit, consisting of considerable amount of sugars, vitamins, polysaccharides and important minerals (Al-Said et al., 2009, Opara et al., 2009, Miguel et al., 2010). In addition, the fruit contain several important medicinal ingredients that are beneficial to human health. Such ingredients include several groups of phytochemical compounds, in particular, phenolic compounds which have high correlation with juice antioxidant capacity (Fawole et al., 2012a). Several studies suggest that polyphenolic compounds in pomegranate fruit and derived products may exhibit anti-mutagenic, anti-hypertension, and anti-inflammatory properties (Gil et al., 2000, Lansky and Newman, 2007, Elfalleh et al., 2009, Viuda-Martos et al., 2010, Fawole et al., 2012b).

As a result of the multi-functionality and great nutritional benefit of pomegranate in human diet, global commercial production and consumption of pomegranate fruit have increased remarkably (Fawole and Opara, 2013a). At present, ninety percent of the world's pomegranate productions are in the Northern Hemisphere, India, Iran, USA, Turkey, Spain and Israel being the main producers (Citrogold, 2011, Pomegranate Association of South Africa (POMASA), 2012). This has consequently spurred a growing export opportunity for countries in the Southern Hemisphere to provide fruit to international markets during the counter season (Fawole and Opara, 2013b). South Africa is one of the major producers of pomegranates in the Southern Hemisphere, competing with countries such as Chile, Argentina and Australia (Brodie, 2009). However, consumption and the availability of pomegranate fruit in the market are largely restricted to the harvesting season due to a high demand and lack of appropriate postharvest handling practices to extend the storage life and maintain fruit quality.

Postharvest handling conditions and practices like storage temperature, relative humidity and packaging could be used to maintain fruit quality for prolong storage (Nanda et al., 2001). Scientific assessment effects of storage condition on health beneficial phytochemicals and antioxidant attributes are lacking for South African commercially grown ‘Wonderful’ cultivar. The objective of this study was to investigate the effects of storage conditions phytochemical and antioxidant properties of pomegranate (cv. Wonderful) grown in South Africa. Such information would be useful in determining the postharvest handling of pomegranate with regards to health benefiting phytochemicals and antioxidant capacity of the fruit.

Section snippets

Plant material and storage conditions

Pomegranate fruit (cv. Wonderful) were obtained during commercial harvest from Sonlia Pack-house (33°34′851″S, 19°00′360″E) in Western Cape, South Africa. Fruit were transported in an air-conditioned vehicle to the Postharvest Technology and Research Laboratory, Stellenbosch University. Fruit were equilibrated at ambient temperature (21 ± 3 °C) before randomly divided into 4 lots. For the determination of phytochemical and antioxidant properties a sample of 60 fruit of the same size without any

Statistical analysis

Experimental trials were completely. Results of all studied variables are presented as mean (±S.E.) in replicates. Analysis of variance (ANOVA) was performed using SPSS software (version 10, SPSS Inc. Chicago, USA).

Results and discussion

Fruit stored at 21 °C and 10 °C were discarded after 1 and 4 months of storage, respectively due to complete fruit loss to decay.

Conclusions

Significant differences in total phenolic, total anthocyanin, free radical scavenging activity and ascorbic acid concentrations were found in ‘Wonderful’ pomegranate at different storage temperatures. Fruit total phenolic concentration increased with storage temperature and duration, resulting in the highest phenolic concentration of 364 mg/100 ml at 10 °C for 3 months. Reduction in phenolic concentration was observed after the third month with the lowest concentration measured at 7.5 °C of 196 

Acknowledgement

This work is based upon research supported by South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation.

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