Browsing by Author "O'Grady, Lizanne"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- ItemEffects of postharvest handling on nutritional quality of pomegranate (Punica granatum) Arils(Stellenbosch : Stellenbosch University, 2012-12) O'Grady, Lizanne; Opara, U. L.; Sigge, G. O.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.ENGLISH ABSTRACT: The aim of this study was to investigate the effects of storage temperature and duration on the proximate composition, physico-chemical properties and selected bioactive components (vitamin C, anthocyanins and β-carotene) of arils from three pomegranate cultivars (‘Arakta’, ‘Bahgwa’ and ‘Ruby’). Pomegranates were hand-peeled and stored at three different temperatures (1°, 4° and 8°C) at 95% relative humidity (RH) for 14 days, with an additional day at ambient conditions (~21°C). Physico-chemical attributes, anthocyanins, ascorbic acid and proximate composition was measured on day 0, 7, 14 and 15. O2 consumption and CO2 production increased at elevated temperatures. No visual mould growth was detected in ‘Arakta’ and ‘Bahgwa’ arils after 14 days at 1°C 95% RH and after 7 days at 4°C 95% RH. Higher storage temperature negatively affected the proximate composition, physico-chemical attributes and bioactive components. The physico-chemical properties and selected bioactive components (anthocyanins, ascorbic acid, β-carotene) of pomegranate arils (‘Arakta’, ‘Bahgwa’ and ‘Ruby’) packed in three punnets made of polyethylene terephthalate (PET1 - clampshell; PET2 - tub and lid) or polypropylene (PP - tub and lid) material were studied for a period of 14 days at 5°C 95% RH. Packaging did not have a major effect on the physico-chemical and bioactive components of pomegranate arils, although PET2 had relatively stable headspace gas composition within the punnets. Storage duration caused a rise in pH and a decline in titratable acidity irrespective of packaging type. No visual mould growth was detected in ‘Arakta’ arils after 7 days irrespective of the type of packaging, while mould growth was detected in all ‘Ruby’ in all types of packaging. The earlier onset of visual microbial growth lead to a baseline microbiological study evaluating the effect of pre-storage water dipping of whole fruit on the microbiological quality of pomegranate arils stored for 8 days at 5°C 95% RH. Freshly harvested pomegranate fruit (‘Bahgwa’) were dipped in distilled water and air-dried (dipped fruit) or stored without postharvest dipping (dry fruit) at 7°C 95% RH for 15 weeks. Arils were extracted, packaged and stored at 5°C 95±8.34% RH for 8 days. Total viable aerobic mesophillic bacteria, yeasts and moulds, Escherichia coli and Staphylococcus aureus were enumerated. After 8 days at 5°C 95% RH no microbial growth was detected on arils from ‘dry fruit’, while ‘dipped fruit’ showed increased yeast and mould counts (4.74 log cfu.g-1) and total viable aerobic mesophillic bacteria count (3.73 log cfu.g-1). In conclusion storage temperature affects the nutritional quality of pomegranate arils and is best maintained at 1°C for 14 days or 4°C for 7 days at 95% RH. Current South African packaging used to market pomegranate arils don’t have a major effect on the nutritional quality of pomegranate arils, although the headspace gas composition was most stable in PET2 packaging. Pre-storage water dipping of whole pomegranates should be avoided as this could reduce the shelf life of extracted pomegranate arils.