Abstract:
The determination of storage conditions leading to optimum quality attributes
and extended postharvest life of sweetcorn is essential. The increased consumption and
consequently the need for greater consumer satisfaction have resulted in the
introduction of supersweet sweetcorn. The present study, aimed to report on the effects
of various postharvest factors on biochemical and texture-related characteristics of
supersweet sweetcorn cultivars as current knowledge is still incomplete.
Validation and optimisation of commonly used methods for the analysis of
target compounds in sweetcorn was also an objective of the current work. The methods
developed for the analysis of the target analytes (viz. ferulic acid, individual
carotenoids, non-structural carbohydrates and vitamin C) were considered suitable.
However, the Folin-Ciocalteu assay and the ferric ion reducing power assay, as methods
for the determination of total phenolic content and total antioxidant capacity of
sweetcorn, respectively, were shown as not appropriate for sweetcorn analysis.
Documentation on firmness and biochemical compounds as affected by cooking
and the interaction with various storage conditions is still limited. The current project
was the first to extensively monitor quality changes in firmness, and other quality
attributes under cooking conditions. Results revealed that increased cooking time
resulted in greater ferulic acid content and a significant decline in firmness and qualityrelated
target analytes such as L-ascorbic acid and carotenoids, yet no change in sugars
was observed. The firmest kernels were reported to be those located in the central part
of the cobs, which is also the preferred edible portion for consumers. Surprisingly,
spatial sugar profiles indicated higher total sugar content in non-edible tissues (viz. core
and shank), rather than kernels and the implications of this are discussed.
Predictably, higher storage temperature and the longer storage period resulted in
lower quality, yet genotype, controlled atmosphere and origin of the cobs were
significant sources of variation for sugar content and firmness of kernels. The presence
of husks (i.e. non-removal) on sweetcorn cobs promoted the retention of sugar content
and colour over storage. Recommendations for improved methods for the measurement of target analytes leading to valid conclusions about optimum storage conditions are
also included.
