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Because of chilling injury (CI), the benefit of low temperature storage to maintain freshness and quality along the chain cannot be maximized. Reducing CI will not only assure good performance of fruit and vegetable in the chain but also reduce postharvest loss and preserve nutritional sources for individuals, especially in developing countries. Therefore, efforts and studies are devoted to tackle CI in numerous fresh produce. Tackling CI problems needs synergistic approach that encompasses preharvest and postharvest factors. This thesis emphasis preharvest factors determining chilling sensitivity and postharvest factors that induce or alleviate CI. The state of the art with respect to the possible role of preharvest factors such as lighting and temperature in chilling sensitivity in tomato is described in Chapter 1. The possible interaction between the above mentioned preharvest factors and some postharvest factors on the development of CI in tomato were also elaborated. We reported that preharvest FR light induced cold tolerance in both MG and R tomatoes (Chapter 1). In MG tomatoes, additional FR light resulted in reduced weight loss, less pitting and faster red colour development during shelf life, and less softening after cold stored. Preharvest FR is likely protects the membrane integrity of MG tomatoes allowing uninterrupted lycopene synthesis. In R tomatoes, preharvest FR lead to firmer fruit at harvest lead to reduced weight loss and less decay during shelf life. The study showed that induced cold tolerance by FR light applied during cultivation, might be related to FR induced cuticle wax biosynthesis and the action of lycopene as an antioxidant during cold storage. Next to FR light we also showed that to some extent, preharvest blue LED lighting (BL) induces postharvest cold tolerance in ‘Foundation’ tomatoes. In this study CI indices and important quality properties such as colour, firmness, hydrogen peroxide, malondialdehyde, ascorbic acid and catalase activity were characterised during cold storage at 4 °C for different durations followed by shelf life of twenty days. Acquired cold tolerance of R fruits harvested from the 12B lighting conditions was related to its ability to loose red colour, presumably in favour of the scavenging of ROS. MG-tomatoes showed no CI symptoms, regardless of the preharvest lighting. No effects of light treatments were found on several antioxidant capacity indicators of both tomatoes. Because improved cold tolerance for R fruit was not due to differences in redox statues indicators (CAT activity, total ascorbic acid, H2O2 and MDA levels), the idea that lycopene in 12B tomatoes is a more efficient antioxidant compared to that of the other BL treatments is put forward (Chapter 3). Varying growth temperature (16, 22, 26 °C) effect quality properties and CI development in dwarf cultivars (Ponchi Re and Tarzan) tomatoes grown in climate chambers. The lowest growth temperature (16 °C ) performed better during shelf life and the effect of low growth temperature has a genetic component (Chapter 4). Low growth temperature delays the onset of red colour development during shelf life and the delay was more pronounced when fruit were first stored at low temperature. Cultivation at 16 °C resulted in fruit firmness retention during cold storage and shelf life which corroborated with lower weight loss. ‘Ponchi Re’ tomatoes showed less CI symptoms during after storage shelf life with higher growth temperatures, whereas the opposite was observed for ‘Tarzan’. We hypothesised that the delay in the start of the red colouration for ‘Ponchi Re‘ grown at 16 °C exposed the tomatoes to ROS without proper scavenging capacity provided by lycopene during cold storage. For ‘Tarzan’ tomatoes higher CI tolerance of tomatoes cultivated at 16 °C might be induced by higher firmness at harvest and lower weight loss during storage. The role of low oxygen storage in limiting CI development in tomatoes was also elucidated (Chapter 5). The effect of low oxygen on cold tolerance were consistent in different tomato types. Low oxygen (down to 0.5 kPa) during cold storage was beneficial for cold tolerance of MG stage of cherry type tomatoes. 5 kPa O2 showed the best results for both MG and R tomatoes in terms of delayed softening, less decay and full colouration (MG) during the after storage shelf life. Following this result, the combination of FR and low oxygen was tested. We investigated the role of low oxygen (0.5, 2.5 and 5 kPa O2) in limiting CI in round tomato cultivar for MG and R stage. Next we applied low oxygen (1 and 5 kPa O2) storage on tomato cultivated under additional FR. Low oxygen induced cold tolerance in MG and R tomatoes. We showed that decay, firmness loss and weight loss during were reduced under influence of low oxygen. Red colour degradation of R tomatoes (a CI symptom) was suppressed under low oxygen. The effect of low oxygen was greater on FR cultivated MG tomatoes due to a lower respiration rate that might resulted in low singlet oxygen formation. No clear relation was found between H2O2 level and the extent of CI. Therefore, we propose the idea that oxidative stress initiated by singlet oxygen and not superoxide anion plays a more pronounced role in inducing CI in tomato. Furthermore, we hypothesised that the formation of singlet oxygen was suppressed by low oxygen. The new understanding of the effect of pre- and postharvest conditions on tomato fruit postharvest CI development described in chapter 2-5 is discussed (Chapter 6). The possible role of the fruit’s physical properties in establishment of cold tolerance is explored. We proposed that the role of singlet oxygen as oxidative stress initiator and the ability of lycopene to scavenge singlet oxygen is important for cold tolerance in lycopene rich fruit like tomatoes. Furthermore, the limitation of the studies presented in this thesis as well as consequences of the main findings and further research recommendations are discussed.
|Qualification||Doctor of Philosophy|
|Award date||8 Dec 2021|
|Place of Publication||Wageningen|
|Publication status||Published - 2021|
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Minimizing chilling sensitivity and chilling injury in tomato.
Affandi, F., Marcelis, L., Schouten, R., Verdonk, J., Woltering, E., Affandi, F., Woltering, E., Schouten, R. & Verdonk, J.
15/02/16 → 8/12/21