Investigating the postharvest performance of vitamin-C improved tomato fruit.

BSc-thesis abstract (submitted 7 June 2016): Tomato fruit is a common source of ascorbic acid (AsA), or vitamin C. It is of crucial importance for
human health. It could be of commercial interest to improve AsA concentrations in tomato fruit, this can be achieved by a high light intensity treatment.
The aim of the present research is to investigate if the postharvest performance of light treated fruit is at least equal to conventional fruit.

Elevated AsA concentrations were obtained by treating detached green mature tomato fruit cv. Vimoso with light intensity of 412µmol m-2 s-1 with white LEDs, for 8 days and a photoperiod of 24 hours. The control includes a dark treatment for 11 days and red mature tomato fruit without a light treatment.

After the treatment the fruit were stored under a constant abiotic environment (19°C ; 19µmol m-2 s-1) for two weeks. The post-harvest performance is determined by physiological quality traits (firmness, colour and water content), and quality traits that can be related to taste (soluble carbohydrate content and organic acid content).
In addition to this a taste panel was performed. Based on the firmness degradation, the LED light treated fruit showed indications of prolonged shelf-life, which could not be confirmed due to variations in significance during the last days of the measurements.
During the shelf-life, the upregulated AsA concentration maintained. Low carbohydrate concentrations and relatively high acid concentrations were found in LED light treated tomato fruit. In the best scored taste panel, the LED light treated fruit were preferred by only 11% of the participants.

It can be concluded that the postharvest performance of tomato fruit with upregulated vitamin C concentrations is lower compared to conventional fruit. Results of the present research can contribute to obtain more insight in fruit quality improvement and in metabolomics studies.

Keywords: AsA, Tomato, light, LED, shelf-life, post-harvest, product quality.