Refine
Document Type
- Article (14)
- Conference Proceeding (2)
Is part of the Bibliography
- yes (16)
Keywords
- Dynamic controlled atmosphere (2)
- Storage (2)
- Allergenität (1)
- Apfel (1)
- Apple breeding (1)
- Chlorophyllfluoreszenz (1)
- Controlled Atmosphere (1)
- Destruktive Analyse (1)
- Fermentation (1)
- Isoforms (1)
Institute
- Fakultät AuL (16)
Many people across the world suffer from iodine (I) deficiency and related diseases. The I content in plant-based foods is particularly low, but can be enhanced by agronomic biofortification. Therefore, in this study two field experiments were conducted under orchard conditions to assess the potential of I biofortification of apples and pears by foliar fertilization. Fruit trees were sprayed at various times during the growing season with solutions containing I in different concentrations and forms. In addition, tests were carried out to establish whether the effect of I sprays can be improved by co-application of potassium nitrate (KNO3) and sodium selenate (Na2SeO4). Iodine accumulation in apple and pear fruits was dose-dependent, with a stronger response to potassium iodide (KI) than potassium iodate (KIO3). In freshly harvested apple and pear fruits, 51% and 75% of the biofortified iodine was localized in the fruit peel, respectively. The remaining I was translocated into the fruit flesh, with a maximum of 3% reaching the core. Washing apples and pears with running deionized water reduced their I content by 14%. To achieve the targeted accumulation level of 50–100 μg I per 100 g fresh mass in washed and unpeeled fruits, foliar fertilization of 1.5 kg I per hectare and meter canopy height was required when KIO3 was applied. The addition of KNO3 and Na2SeO4 to I-containing spray solutions did not affect the I content in fruits. However, the application of KNO3 increased the total soluble solids content of the fruits by up to 1.0 °Brix compared to the control, and Na2SeO4 in the spray solution increased the fruit selenium (Se) content. Iodine sprays caused leaf necrosis, but without affecting the development and marketing quality of the fruits. Even after three months of cold storage, no adverse effects of I fertilization on general fruit characteristics were observed, however, I content of apples decreased by 20%.
Recording of Low-Oxygen Stress Response Using Chlorophyll Fluorescence Kinetics in Apple Fruit
(2023)
Long-term storage of apples (Malus x domestica, Borkh.) is increasingly taking place under Dynamic Controlled Atmosphere (DCA). The oxygen level is lowered to ≤ 1 kPa O2 and the apples are stored just above the Lower Oxygen Limit (LOL). Low oxygen stress during controlled atmosphere storage can lead to fermentation in apples if oxygen levels are too low. Chlorophyll fluorescence can be used to detect low-oxygen stress at an early stage during storage. The currently available non-imaging fluorescence systems often use the minimal fluorescence (Fo) parameter. In contrast, the use of chlorophyll fluorescence kinetics is insufficiently described. Therefore, this study aimed to gain more knowledge about the response of chlorophyll fluorescence kinetics to low oxygen stress in apples using a fluorescence imaging system. The results show that the kinetic fluorescence curves differ under aerobic and fermentation conditions. The fermentative conditions initiated a decrease in fluorescence intensity upon application of the saturation pulses during exposure to actinic light. This result was made at 18 °C and 2 °C ambient temperatures. Interestingly, the kinetic curve changed at 2 °C before fermentation products accumulated in the apples. Non-photochemical quenching (NPQ) decreased under fermentation conditions in the dark phase after relaxation. Upon entering the dark relaxation phase after Kautsky induction, ɸPSII began to increase. Under atmospheric oxygen conditions, ɸPSII reached values of 0.81 to 0.76, while under fermentation, ɸPSII values ranged from 0.57 to 0.44.
Um zusätzlich zu bestehenden Qualitätsmanagementsystemen im Handel auch den Aspekt der Verbraucherpräferenzen besser berücksichtigen zu können, hat die vorliegende Studie zum Ziel, innerhalb der Laufzeit von zwei Jahren einen Qualitätsindex zu entwickeln, der sensorische Merkmale impliziert. Dazu wurden in der ersten Versuchsphase etwa 4000 Früchte der Sorten ‘Fuji, Yataka’, ‘Elstar, Elshof’, ‘Golden Delicious, Reinders’ und ‘Jonagold, Rubinstar’ in drei Schritten untersucht (etwa 1000 Früchte pro Sorte). Zunächst wurden verschiedene Fruchteigenschaften nicht destruktiv gemessen. Anschließend fand eine sensorische Beurteilung der Äpfel durch Konsumenten an vier verschiedenen Einzelhandelsstandorten statt. Für die geschmackliche Bewertung wurde jeweils ein Achtel jedes Apfels verwendet. Die übrig gebliebenen sieben Achtel des Apfels wurden auf unterschiedliche qualitätsrelevante Parameter mittels destruktiver Methoden untersucht. Zur Überprüfung von Zusammenhängen zwischen nicht destruktiv und destruktiv gemessenen Werten auf der einen Seite und sensorisch ermittelten Werten auf der anderen Seite wurden Korrelationskoeffizienten berechnet. Ein Teilziel besteht darin, die Eignung nicht destruktiver Analyseverfahren nachzuweisen, um sie als Vorhersage für den Konsumentengeschmack anwenden zu können. Nicht erwartungsgemäß sind die Zusammenhänge zwischen physikalischen bzw. chemischen und sensorischen Messwerten gering und bedingt aussagekräftig. Um einen Qualitätsindex dennoch entwickeln zu können, werden in einer weiteren empirischen Projektphase erneut Daten erhoben.
Dynamic Controlled Atmosphere-Chlorophyll Fluorescence storage (DCA-CF) uses a fluorescence-based measurement method to detect fermentation in apples (Malus × domestica BORKH.) caused by low-oxygen levels at an early stage. In recent years, it has been observed that individual apples of the same variety and origin can exhibit different fermentation behavior when stored under completely identical conditions. The causes of the different fermentation behavior must be found in order to be able to use DCA storage optimally. This study aimed to find the causes of the different fermentation behaviors of individual apples. Our results show that fruit ripeness can affect the lower oxygen limit (LOL), especially immediately after harvest, when the starch degradation in the fruit is not yet complete. A significant increase in the LOL was observed in ‘Elstar’ (2020: 0.3 kPa, 0.6 kPa, 0.9 kPa; 2021: 0.3 kPa, 0.4 kPa, 0.6 kPa). ‘Braeburn’ also exhibited this behavior regarding the LOL at a lower level. The LOL could not be identified for some of the fruit (varying from 12.5% to 41.7% of the examined apples) previously stored in Ultra Low Oxygen (ULO) storage for 4 months. Also, the chlorophyll content in the apple skin influences the fluorescence measurement method. Within 2 weeks, the chlorophyll content in the apple skin was halved. If the chlorophyll content drops, the reliability of the fluorescence measurement also decreases. It turned out that apples with an Fv/Fm < 0.7 were unsuitable for valid LOL identification.
Derzeit wird nur die nicht-bildgebende Chlorophyllfluoreszenz in der DCA-Lagerung eingesetzt, um den LOL zu identifizieren. Das Ziel dieser Untersuchung war es, die Chlorophyllfluoreszenz von einzelnen Apfelfrüchten mit einem Fluoreszenz-Bildgebungssystems (FluorCAM 701 MF, Photon Systems Instruments, Brno, Tschechische Republik) unter aeroben und fermentativen Bedingung zu messen. Der Grad der Heterogenität der Fluoreszenz am Apfel wurde ermittelt und der Fluoreszenzanstieg visualisiert. Mit der Methode der Histogramm Division konnten alle Fluoreszenzinformationen gebündelt werden.