Hanne Lindhard Pedersen

Bioactivity and chemical composition of blackcurrant (Ribes nigrum) cultivars with and without pesticide treatment

Eleven blackcurrant cultivars grown with pesticide (PT) and without pesticide treatment (PF) were evaluated to compare the differences in plant growth and physical condition, total anthocyanin content, ascorbic acid content, total antioxidant capacity, effect on prostaglandin E2 (PGE2) production and anticancer cell proliferation activities. Results showed that the yield and growth of PT blackcurrants were higher. However, PF blackcurrants contained a higher amount of ascorbic acid, and displayed an increased inhibition against cancer cells compared to PT blackcurrants, indicating that PF blackcurrants have an increased potential to deliver health-promoting benefit for consumers. Significant differences were observed between blackcurrant cultivars in relation to plant growth and physical condition, total anthocyanin content and PGE2 assay, highlighting the importance of cultivar selection.

Modelling of the optimum harvest time for long-term storage of ‘Elstar’ and ‘Aroma’ (Malus domestica) apples at low oxygen concentration

Abstract Research evaluated modelling of optimum harvest time for long-term storage of ‘Aroma’ and ‘Elstar’ apples at 1 °C in three low-oxygen air compositions: (1) 1.5/1.5% O2/CO2 throughout the storage period; (2) 0.25/0.25% O2/CO2 for seven days, and then at 1.5/1.5% O2/CO2 for the remaining storage period; and (3) 1.5/1.5% O2/CO2 until the final three weeks of the storage period where it changed to 2.0/2.0% O2/CO2. The differences between measured and predicted fruit weight of ‘Aroma’ apples varied by 0–4 g during the six harvesting dates in 2005, whereas the differences for ‘Elstar’ apples were 1–10 g. Measured and predicted Streif index for ‘Aroma’ and ‘Elstar’ apples varied between 0.01 and 0.07 g/w/w%*index and from 0.04 to 0.10 kg/w/w%*index, respectively. For ‘Aroma’ the Streif index was 0.16 kg/w/w%*index at the beginning of the storage period and 0.04 kg/w/w*index at the end; whereas the Streif indexes were 0.16 and 0.05 kg/w/w*index for ‘Elstar’. The highest and the lowest levels of the gas compositions resulted in the least and most mature apples, respectively. Apple colour was unaffected by air composition. Improved prediction of fruit weight and Streif index for ‘Aroma’ and ‘Elstar’ may be obtained using four linear equations and degree days without a reference temperature and improvement in prediction of apple fruit diameter may be obtained using degree days and two exponential equations. The quality characteristics of both cultivars were extremely high after storage in controlled atmosphere for 204 days and the analytical data including the low weight losses indicate that the storage time for ‘Aroma’ and ‘Elstar’ may be extended by at least two and three more months, respectively. The highest level of the gas compositions resulted in the least mature apples and may therefore be recommended for storage of ‘Aroma’ and ‘Elstar’.

Effects Of Potassium, Phosphorus And Nitrogen Fertilization On Endogenous Ethylene And Quality Characteristics Of Apples (Malus Domestica L.)

Factor analysis of the data from experiment one with fertilization of ‘Spartan’ apples using various levels of nitrogen, phosphorus, and potassium and their interactions showed significances between ethylene and potassium, soluble solids and potassium, acidity and phosphorus, ethylene and phosphorus, and between ethylene and nitrogen. Factor analysis of data from experiment two with twenty apple cultivars showed that maturation time and ethylene were positively associated, whereas ethylene was inversely related to acidity that is reduced during the apple fruit maturation, and soluble solids are produced during apple fruit maturation. The effects of potassium on ethylene could be through promotion of enzyme activation, promotion of protein synthesis and increased solute transport in the xylem and phloem. Production of ethylene through soluble solids could be due to increased synthesis of the amino acid cysteine that is precursor of ethylene that may be extended to synthesis of other amino acids. The decreasing concentration of malic acid during fruit maturation may be due to increasing rates of several enzymes involved in the citric acid and glyoxylate cycles that are delivering precursors to synthesis of amino acids and porphyrins. The significant relationships between soluble solids and potassium and between acidity and phosphorus may increase the synthesis of nucleic acids and improve energy supply through adenosine phosphates. The significance between ethylene and nitrogen may also increase synthesis of amino acids, proteins and enzymes. On this basis it may be concluded that the three major minerals nitrogen, phosphorus and potassium are very important for apple fruit maturation because they may be involved in several biochemical processes.