| 1. |
- Gomez, Federico, et al.
(författare)
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Changes in the carrot (Daucus carota L. cv. Nerac) cell wall during storage
- 2004
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Ingår i: Food Research International. - : Elsevier BV. - 0963-9969. ; 37:3, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine biochemical changes in cell wall carbohydrates and extensin proteins during long-term storage of carrots (Daucus carota L. cv. Nerac). During the storage period of 6 months, cell wall fractions were isolated from the carrot at various times for carbohydrate and protein analysis. Signs of extensin cross-linking and its concomitant insolubilisation in the cell wall were found after 7 and 12 weeks of storage. During the same period the concentration of galactose and arabinose decreased, while other carbohydrate components as well as the degree of methylesterification remained virtually unchanged. After the 12th week of storage no changes in the extensin or carbohydrates were detected. Oxidative cross-linking between extensin molecules in the cell wall has been implicated in cell wall strengthening and may be part of the mechanism behind the storage-induced firmness of carrots. (C) 2003 Elsevier Ltd. All rights reserved.
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| 2. |
- Gomez, Federico, et al.
(författare)
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Cold acclimation of carrots during storage mechanical properties and antifreezing protein.
- 2003
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Ingår i: Acta horticulturae : technical communications of ISHS. - 0567-7572. ; 599, s. 699-703
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Konferensbidrag (refereegranskat)abstract
- Changes in the composition of carrot cell wall proteins were investigated, associating metabolic changes during long-term storage with changes in mechanical properties. Harvested carrots accumulate an antifreezing protein in their cell walls reaching a maximum level after 12 weeks of storage at 0°C, followed by a gradual decrease. During the same period of time, there is a decrease in the slicing force during the first 7 weeks of storage followed by an increase until the 12th week. The appearance and accumulation of the antifreezing protein suggest that structural changes leading to changes in mechanical properties during the first 12 weeks of storage might be associated with a cold acclimation process.
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| 3. |
- Gomez, Federico, et al.
(författare)
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Factors affecting quality and postharvest properties of vegetables: Integration of water relations and metabolism
- 2004
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Ingår i: Critical Reviews in Food Science and Nutrition. - : Informa UK Limited. - 1040-8398 .- 1549-7852. ; 44:3, s. 139-154
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Tidskriftsartikel (refereegranskat)abstract
- Growing of vegetables in the field, harvesting, handling in the packing house and storage are events in the lifetime of vegetables that arc analysed from the point of view of the complex series of physiological transitions taking place in each of these events. Water is the major factor limiting plant metabolism and plants have developed fascinating mechanisms to cope with this limiting factor. Therefore, water relations (water, pressure and osmotic potential) are used as criteria for discussing plant stress physiology aspects such as osmotic, elastic adjustment and cold acclimation, as well as mechanical stress when the vegetable is harvested and during handling in the packing house. Consequences for the storage potential and quality of the vegetable arc discussed. After harvesting, the postharvest cell has the ability to complete a complex series of physiological transitions that will influence vegetable quality and further processing operations. Metabolic changes in the cytosol, cell membrane and cell wall are described.
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| 4. |
- Gomez, Federico, et al.
(författare)
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Influence of cold acclimation on the mechanical strength of carrot (Daucus carota L.) tissue
- 2004
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Ingår i: European Journal of Horticultural Science. - 1611-4434. ; 69:6, s. 229-234
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the influence of cold acclimation on the mechanical strength of carrot (Daucus carota L.) taproots. Changes in the mechanical strength were monitored when cold acclimation was induced in carrot plants cultivated in a growth chamber under strict climate control and in taproots harvested from field cultivation, where the plants had been exposed to the natural variations in climate. The appearance and accumulation of an antifreeze protein in the cell wall isolated from cold-stored taproots showed that a cold acclimation process is in progress in the harvested taproot derived from carrot plants grown in the field. The force needed to slice the taproots significantly increased during the first 12 weeks of storage, where the higher concentration of the antifreeze protein indicated the highest development of cold acclimation during that period of time. The increase in tissue rigidity during cold acclimation was also shown by the increase of the Young's modulus in taproot tissue from carrot plants acclimated 11 weeks under controlled temperature conditions. After 24 weeks of storage there was a significant increase in slicing force that was accompanied by signs of cell membrane deterioration, as measured by relative electrolyte leakage. Thus, the later increase in tissue strength might be related with a senescence process.
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| 5. |
- Gomez, Federico, et al.
(författare)
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Isothermal calorimetry approach to evaluate tissue damage in carrot slices upon thermal processing
- 2004
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 65:2, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this investigation was to test calorimetry as a means of quantifying cell damage occurring at various stages of mild blanching treatments. Calorimetric measurements were carried out on cores taken from carrot slices blanched at 100 degreesC for 5-45 s. The calorimetric data were corrected for the influence of wounding stress due to slicing and coring. The validity of calorimetry to measure cell damage was assessed by simulating inactivation of cell metabolism based on bibliographic data on thermal inactivation kinetics of plasma membrane H+-ATPase, used as a marker of overall cell membrane damage. Calorimetric data paralleled the simulated decrease of actively metabolizing cells only in the first 20 s of blanching but diverged at higher blanching times. Our results suggest that inactivation of enzymes responsible for quality-related changes during frozen storage (e.g. blanching at 100 degreesC for 20 s) may be accompanied by cell damage in about 70% of the tissue. (C) 2004 Elsevier Ltd. All rights reserved.
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| 6. |
- Gonzalez-M, Gerardo, et al.
(författare)
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Analysis of temperature distribution in potato tissue during blanching and its effect on the absolute residual pectin methylesterase activity
- 2004
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 65:3, s. 433-441
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic changes in absolute residual PME activity in potato tubers undergoing blanching were analysed with regard to the temperature distribution in the tissue after the treatment. The finite-element technique was used to predict the temperature distribution within the tissue during blanching. The temperature-related behaviour of the enzyme indicated that blanching between 60 and 70 degreesC induced thermal activation of PME in blanched potatoes. The temperature distribution in the tissue during blanching showed that activation takes place as soon as the tissue reaches an average temperature above 50 degreesC. However, the temperature dependence of the absolute residual PME activity in the tissue, when blanching at temperatures between 50 and 70 degreesC, did not follow Arrehenius' law. The degree of PME activity in the blanched tissue was found to depend on the "effective exposure time" to the temperature at which the activation/deactivation of the enzyme takes places. Thermal activation of PME in potato tissue occurred during the first two minutes of blanching. Longer heating times induced rapid deactivation of the enzyme in the tissue. (C) 2004 Elsevier Ltd. All rights reserved.
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| 7. |
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| 8. |
- Görman, Ulf, et al.
(författare)
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Introductory remarks
- 2003
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Ingår i: 1. International conference: Christian Anthropology and biotechnological Progress, Orthodox Academy of Crete, Colymbari, chania, 26th–29th September 2002. ; , s. 9-12
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Boken är en rapport från en konferens på Kreta september 2002. I inledningsanförandet introducerar jag några i den moderna västliga diskussionen vanliga uppfattningar av betydelse för relationen mellan naturvetenskap och religion, bland andra panenteism och kritisk realism. Två exempel illustrerar frågor som berör relationen mellan bioteknologi och kristen antropologi: Möjligheten att med hjälp av genetisk modifiering förlänga det individuella mänskliga livet utmanar såväl kristendomens som medicinens värdering av ett gott mänskligt liv. Motsättningen mellan ambitionen att bevara eller förhoppningen att förändra ekologiska system relateras till kristna föreställningar om människan som förvaltare respektive medskapare. Avslutningsvis frågas: Vad betyder skillnaden mellan den ortodoxa och den västerländska kristna tolkningen av människan som guds avbild för att hantera frågor som dessa?
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