Investigating carotenoid loss after drying and storage of
Investigating carotenoid loss after drying and storage of
Investigating carotenoid loss after drying and storage of
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Oxygen<br />
49<br />
1. Literature review<br />
Oxygen had a greater impact on β-carotene breakdown compared to light (clear or<br />
opaque packaging) (Vasquez-Caicedo et al. 2007). This was confirmed by Valdez et al.<br />
(2001). A significant decrease <strong>of</strong> β-carotene content was observed in sweet potatoes<br />
flakes stored at room temperature for 4 months in different packaging. Losses in β-<br />
carotene in foil packaging, laminate paper <strong>and</strong> in plastic (LDPE or HDPE) were 43%,<br />
46% <strong>and</strong> 54% respectively. Packaging had a minor impact compared to the effect <strong>of</strong> air<br />
oxidation. Emenhiser et al. (1999) stored sweet potato flakes at room temperature in a<br />
propylene film (high oxygen permeability) with air headspace, a nylon laminate film<br />
(low oxygen permeability) with air headspace under vacuum or an Ageless oxygen<br />
absorber sachet enclosed had their β-carotene determined at intervals from 0 to 210<br />
days. Results very clearly demonstrated that β-carotene retention was related to apparent<br />
availability <strong>of</strong> oxygen (i.e. nylon> polypropylene <strong>and</strong> oxygen absorber>vacuum>air<br />
headspace). Highest <strong>loss</strong>es were obtained with polypropylene headspace (calculated at<br />
66.8%) <strong>and</strong> lowest with nylon oxygen absorber (calculated from data at 1.0%). The<br />
impermeable packaging to oxygen (i.e. laminate) with an oxygen absorber was found the<br />
best system to protect provitamin A from the main factor <strong>of</strong> degradation which is air<br />
oxidation (Emenhiser et al. 1999). However because <strong>of</strong> its cost this type <strong>of</strong> system is not<br />
affordable to small-scale farmers in East <strong>and</strong> Southern Africa. Locally available<br />
packaging (i.e. LDPE, paper, traditional bags in jute) is permeable to oxygen therefore<br />
alternative ways need to be investigated.<br />
The main factors that contribute to the degradation <strong>of</strong> provitamin A in <strong>storage</strong> under<br />
ambient conditions described in literature were temperature, water activity (moisture),<br />
light <strong>and</strong> oxygen in air. Storage is a critical stage <strong>and</strong> oxygen was a very significant<br />
factor in studies at ambient temperature as demonstrated by study on packaging oxygen<br />
permeability (Emenhiser et al. 1999; Vasquez-Caicedo et al. 2007). More investigations,<br />
however, are needed to investigate the relative influence <strong>of</strong> these factors on the <strong>storage</strong><br />
<strong>of</strong> OFSP.<br />
1.4.5 Carotenoid <strong>loss</strong>es during food preparation<br />
Evaluation <strong>of</strong> finished food products from OFSP to meet nutritional requirements in<br />
provitamin A is an important matter. Few published works have been reported on the
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