Domande d'esame VERIFICATO
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- Post-Harvest Management & Preservation:
- Symptomatology in produce depends on environmental conditions.
- Ozone is advantageous for preservation due to its residue-free nature and its action on carbon double bonds.
- Low-dose UV rays can enhance the defenses of harvested produce.
- High CO2 levels decrease ethylene production, while chilling injury blocks electron transport systems.
- Refrigeration helps reduce respiration in produce.
- Low temperatures can either reduce or increase disease severity, depending on specific conditions.
- Preventing "water film" during harvest helps avoid counter-bacteriosis.
- Field conditions, healthy seeds, and avoiding wounds significantly influence post-harvest produce health.
- Penicillium digitatum is specifically associated with citrus.
- Disease and respiratory activity are linked to cellular metabolism and fungal growth rates.
- Mycotoxins & Fungi:
- Mycotoxins are low molecular weight toxins produced by fungi, not primary metabolism or bacteria.
- Common mycotoxins discussed include Aflatoxin (most dangerous, B1 and total are monitored), Ochratoxin (produced by Aspergillus and Penicillium), Zearalenone (Fusarium), Fumonisin, Patulin (apples, pears, red fruits), and Citrinin (Aspergillus and Penicillium).
- Ascomycetes are a primary cause of fungal damage post-harvest, while Glomeromycetes are older fungal groups.
- Fungi can have both haploid and diploid stages, and their classification includes imperfect fungi (no sexual form).
- Factors influencing mycotoxin production include seed density.
- Physical methods to lower ochratoxin A exist but may compromise chemical properties.
- Detection, Regulation & Contaminants:
- Analytical aspects of mycotoxins (CAS number, retention time, daughter ions) are crucial for identification.
- Official confirmation requires three parameters.
- EU legislation on mycotoxin levels dates back to 2006, regulating more than 5 toxins in cereals.
- LC-MS/MS is the reference method for mycotoxin determination, though immunoenzymatic measurements can yield false positives/negatives.
- Multi-toxin methods can quantify up to 40 mycotoxins.
- Sampling must be homogeneous and representative of the entire batch.
- Phytopharmaceuticals (e.g., glyphosate) are regulated by CE 2008, with residues mostly found in fruits and vegetables.
- Developing a new phytopharmaceutical takes about 10 years.
- Fusarium also produces natural gibberellins (phytoregulators).
- Bacteriology:
- Phytopathogenic bacteria thrive in subalkaline environments.
- "Candidatus" indicates a bacterium not yet classified as a species.
- Bacterial carbon requirements are higher than those of fungi.
- "Fastidious" bacteria are difficult to cultivate in vitro.
- Anchoring refers to the physical attachment phase to plant cells.