Browsing by Author "Sfakiotakis, E. M."
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- Changes in fatty acid composition and electrolyte leakage of 'Hayward' kiwifruit during storage at different temperaturesPublication . Antunes, Maria Dulce; Sfakiotakis, E. M.Exposure to low storage temperature induces changes in electrolyte leakage and fatty acids composition, in a way depending on the plant tissue. Those changes alter the response of the fruit to storage conditions. The influence of storage temperature on ripening, fatty acids composition and electrolyte leakage of 'Hayward' kiwifruit were investigated. Harvested fruit were stored at 0, 5, 10,15 and 20 degrees C for 5, 12 and 17 days. Measurements of SSC, firmness, flesh colour, fatty acid composition and electrolyte leakage were performed during the experiment. Kiwifruit did not fully ripen during the 17 days storage at any temperature. The major fatty acid component in 'Hayward' kiwifruit consisted of linolenic, followed by oleic, palmitic, linoleic and stearic acid. Membrane permeability and unsaturated/saturated fatty acid ratio increased during storage in all treatments. The highest increase was during the first 5 days and at the lowest temperatures. The increase in unsaturated/saturated fatty acid ratio was caused mainly by a decrease in palmitic and an increase in oleic acids. Stearic, linoleic and linolenic acids had insignificant changes during storage. The main increase in electrolyte leakage and unsaturated/saturated fatty acid ratio occurred during the first storage days and at lower temperatures, probably as a response of the tissue to an adaptation to the new stress storage conditions. (C) 2008 Elsevier Ltd. All rights reserved.
- Chilling induced ethylene biosynthesis in 'Hayward' kiwifruit following storagePublication . Antunes, Maria Dulce; Sfakiotakis, E. M.'Hayward' kiwifruit were stored at 0, 5, 10, 15 and 20degreesC for 5, 12 and 17 days before rewarming to 20degreesC for 10 more days. Ethylene and CO(2) production, ACC, ACC synthase (ACS) and ACC oxidase (ACO) activities, flesh and core firmness, soluble solids content (SSC) and fleshy colour were measured. Kiwifruit stored at 0, 5, 10 and 15degreesC did riot ripen, produce ethylene or show increases in ACS or ACO activity. Fruit stored for 5 days at the above temperatures, then rewarmed to 20degreesC, did not show any change during the following 10 days. Rewarmed fruit, pre-stored at 0-10degreesC for 12 days, started autocatalytic ethylene production within 24 h, followed by fruit ripening. Fruit stored at 15degreesC for 12 days needed 72 h to start ethylene autocatalyse and did not fully ripen during 10 days at 20degreesC. After 17 days storage at 0-15degreesC kiwifruit started autocatalytic ethylene production with no delay upon exposure to 20degreesC. Autocatalytic ethylene production correlated with increased ACC content, and increased activities of ACS and ACO. Fruit held continuously at 20degreesC started autocatalytic ethylene production after 19 days, with concomitant increases in ACC content, ACS and ACO activities and ripening. Respiration increased after rewarming, concomitantly with the increase in ethylene production. We concluded that exposing kiwifruit to chilling temperatures (0-10degreesC) for 12 days advanced ethylene biosynthesis and ripening when compared with fruit held continuously at: 20degreesC. The advanced ethylene biosynthesis was due to increase ACS and ACO activities immediately upon rewarming of the fruit. (C) 2002 Elsevier Science B.V. All rights reserved.
- Differential effects of low-temperature inhibition on the propylene induced autocatalysis of ethylene production, respiration and ripening of 'Hayward' kiwifruitPublication . Antunes, Maria Dulce; Pateraki, I.; Kanellis, A. K.; Sfakiotakis, E. M.Previous studies (Stavroulakis and Sfakiotakis, 1993) have shown an inhibition of propylene-induced ethylene production in kiwifruit below a critical temperature range of 11-14.8 degrees C. The aim of this research was to identify the biochemical basis of this inhibition in kiwifruit below 11-14.8 degrees C. 'Hayward' kiwifruit were treated with increasing propylene concentrations at 10 and 20 degrees C. Ethylene biosynthesis pathways and fruit ripening were investigated. Kiwifruit at 20 degrees C in air started autocatalysis of ethylene production and ripened after 19 d with a concomitant increase in respiration. Ethylene production and the respiration rise appeared earlier with increased propylene concentrations. Ripening proceeded immediately after propylene treatment, while ethylene autocatalysis needed a lag period of 24-72 h. The latter event was attributed to the delay found in the induction of 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) activity and consequently to the delayed increase of l-aminocyclopropane l-carboxylic acid (ACC) content. In contrast propylene treatment induced 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activity with no lag period. Moreover, transcription of ACC synthase and ACC oxidase genes was active only in ethylene-producing kiwifruit at 20 degrees C. In contrast, treatment at 10 degrees C with propylene strongly inhibited ethylene production, which was attributed to the low activities of both ACC synthase and ACC oxidase as well as the low initial ACC level. Interestingly, fruit treated with propylene at 10 degrees C appeared to be able to transcribe the ACC oxidase but not the ACC synthase gene. However, propylene induced ripening of that fruit almost as rapidly as in the propylene-treated fruit at 20 degrees C. Respiration rate was increased together with propylene concentration. It is concluded that kiwifruit stored at 20 degrees C behaves as a typical climacteric fruit, while at 10 degrees C behaves like a non-climacteric fruit. We propose that the main reasons for the inhibition of the propylene induced (autocatalytic) ethylene production in kiwifruit at low temperature (less than or equal to 10 degrees C), are primarily the suppression of the propylene-induced ACC synthase gene expression and the possible post-transcriptional modification of ACC oxidase.
- Effect of high temperature stress on ethylene biosynthesis, respiration and ripening of 'Hayward' kiwifruitPublication . Antunes, Maria Dulce; Sfakiotakis, E. M.Temperatures up to 35 degreesC have been shown to increase ethylene production and ripening of propylene-treated kiwifruit (Stavroulakis, G., Sfakiotakis, E.M., 1993. We attempted to study the regulation by high stress temperature of the propylene induced ethylene biosynthesis and ripening in 'Hayward' kiwifruit. 'Hayward' kiwifruit were treated with 130 mul/l propylene at temperatures from 30 to 45 degreesC up to 120 h. Ethylene biosynthesis pathway and fruit ripening were investigated. Propylene induced normal ripening of kiwifruit at 30-34 degreesC. Fruit failed to ripe normally at 38 degreesC and above 40 degreesC ripening was inhibited. Propylene induced autocatalytic ethylene production after a lag period of 24 h at 30-34 degreesC. Ethylene production was drastically reduced at 38 degreesC and almost nil at 40 degreesC. The 1-aminocyclopropane-1-carboxylic acid (ACC) content was similar at 30-38 degreesC and was very low at 40 degreesC. The 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) and 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activities decreased with a temperature increase above 30 degreesC, but ACC oxidase decreased at a faster rate than ACC synthase. Fruit not treated with propylene showed no ripening response or ethylene production. However, kiwifruit respiration rate increased with temperature up to 45 degreesC, reaching the respiration peak in 10 h. At temperatures up to 38 degreesC, propylene treatment enhanced the respiration rate. After 48 h at 45 degreesC, fruit showed injury symptoms and a larger decrease in CO(2). The results suggest that high temperature stress inhibits ripening by inhibiting ethylene production and sensitivity while respiration proceeds until the breakdown of tissues. (C) 2000 Elsevier Science B.V. All rights reserved.
- Ethylene biosynthesis and ripening behaviour of 'Hayward' kiwifruit subjected to some controlled atmospheresPublication . Antunes, Maria Dulce; Sfakiotakis, E. M.The effects of storage in air (AS), controlled atmosphere (CA) or ultra low oxygen (ULO) on ethylene biosynthesis and ripening of 'Hayward' kiwifruit during storage at 0 degreesC and post-storage at 20 degreesC, were investigated. Fruit were stored for 60, 120 and 180 days at 0 degreesC in AS, CA (2%O(2) + 5%CO(2)) and ULO (0.7%O(2) + 0.7%CO(2) and 1%O(2) + 1%CO(2)). Freshly harvested fruit and fruit removed from storage were treated with 130 mul/l propylene or propylene-free air for 9 days at 20 degreesC. Fruit treated with propylene at 20 degreesC at harvest produced ethylene with a tag period of 3 days, had concomitant 1-aminocyclopropane-1-carboxylic acid (ACC) production, 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) and 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activities, and were ripe after 3-5 days while fruit not treated with propylene were not able to produce ethylene and ripen during the 9 days experiment. AS fruit softened faster during the first 60 days of storage. This effect was reduced in CA and ULO treatments. The soluble solids content (SSC) increased markedly during the first 60 days of storage and remained almost constant thereafter in all treatments. After 9 days shelf life, only AS and CA stored fruit were ripe. Fruit from ULO storage required propylene treatment to ripen fully. When kiwifruit were placed at 20 degreesC, after 60, 120 or 180 days storage at 0 degreesC, there was an induction of ethylene production with no tag period in fruit from AS or CA, with or without propylene. There was some ACC content and ACC synthase activity after 60 days storage for all treatments, while ACC oxidase activity increased only upon rewarming of the fruit in AS or CA. Kiwifruit removed from ULO-storage showed drastically reduced capacity to produce ethylene mainly due to low ACC oxidase activity rather than reduced ACC production or ACC synthase activity. Respiration increased upon rewarming of the fruit in all treatments. With storage time, there was a decrease in the capacity of the warmed fruit to produce ethylene and CO(2) as well as in the activities of ACC synthase and ACC oxidase, mostly after 60 days storage. (C) 2002 Elsevier Science B.V. All rights reserved.