In this master thesis we investigated the effect of hot water dipping (HWD) and/or blue LED light (LBL) irradiation on the physiochemical properties of "Idared" apples and the
growth of Penicillium expansum on inoculated fruit. The apples were first treated with hot water (52 °C, 2 min), after 24 hours, they were inoculated with mold and irradiated with LBL. The control group was not treated and stored in the dark. In total there were 8 treatments. The HWD reduced mass loss during initial storage phase, but had no significant effect on fruit firmness and soluble solids content. Regarding ethylene production, the HWD had an inhibitory effect at the beginning, but later ethylene release was higher compared to the control group and remained higher until the end of storage. The analysis of polyamines revealed that spermidine (SPD) was the most abundant in the fruits, followed by γ-aminobutyric acid (GABA) and spermine (SPR). Ethylene production was strongly negatively correlated with SPD (r = –0,75) and cadaverine (r = –0,68), moderately negatively correlated with phenethylamine (r = –0,53), and weakly negatively correlated with GABA (r = –0,26). A moderately positive correlation with ethylene was found with SPR (r = 0,38). Irradiation of the apples with LBL did not lead to statistically significant changes in the total phenolic compound content, but had a strong influence on the change in fruit colour, especially the parameter a*, while HWD significantly inhibited the increase in the parameter a*. None of the treatments had a statistically significant effect on the suppression of mold growth.
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