Costas Stathopoulos

Alternaria alternata and Alternaria citri are two major pathogens affecting sweet cherries and citrus respectively which can lead to significant postharvest losses. Alternaria sp. can be controlled with synthetic fungicides, but due to the development of resistance and the need to find sustainable disease control solutions, alternative control measures need to be developed. We have previously shown that extracts derived from lemon waste (pomace) contain bioactive compounds with high levels of antioxidant, antifungal, and antibacterial activities. The aim of this study was to investigate the in vitro antifungal activity of lemon waste aqueous extracts at different concentrations (14, 7, 3.5 and 1 mg mL(-1)) against both A. alternata and A. citri. The results showed that lemon aqueous extracts suppressed the mycelial growth and spore germination of both species in a concentration-dependent manner. The mycelial growth inhibition (MGI) for A. alternata varied between 31 to 68%, while for the A. citri the MGI varied between 14 to 49%. Scanning electron microscopy showed that lemon waste extracts affected the morphology of both species.These results indicate that the aqueous extracts of lemon by-products contain bioactive compounds which could be potentially useful as an alternative to synthetic fungicides for controlling Alternaria.

Freshly harvested cucumbers (Cucumis sativus L.) were stored under low pressure (4 kPa) at 10 degrees C for 7 and 11 days with 100% RH. Upon removal from low pressure storage and after being transferred to normal atmosphere (101 kPa) at 20 degrees C for 3 days, fruits were assessed for weight loss, flesh rots, color, firmness and overall acceptability. Fruit weight loss was significantly higher in fruit which stored at low pressure (4 kPa) for 11 days at 10 degrees C than fruits that were stored at regular atmospheres (101 kPa) at 10 degrees C. The effect of low pressure treatment on fruit weight loss was greater after the additional three days storage at normal atmospheric pressure at (101 kPa) at 20 degrees C. There was no difference in flesh rots, flesh firmness and color retention between fruits stored at low pressure and regular pressure at 10 degrees C for 7 and 11 days. Cucumbers were stored at regular pressure (101 kPa) 20 degrees C for 11 days had highest flesh rots and lowest acceptability compared to other treatments.

Ultraviolet irradiation (100-400 nm) has been reported to have beneficial effects on maintaining the postharvest quality of horticultural produce. Specially, a short-term pre-storage treatment with UV-C (180-280 nm) has been shown to extend the postharvest shelf-life of many horticulture crops. In this preliminary experiment, mature green 'Kensington Pride' mangoes (Mangifera indica Linn.) were exposed to UVC light at four different intensities 0, 4.0, 8.3 and 11.7 kJ m(-2), and stored for 7 days at 20 degrees C. After storage, fruit were assessed for skin color, flesh color, flesh firmness, soluble solids content (SSC) and titratable acidity (TA). The results showed that the rate of peel degreening following UV-C treatment and storage at 20 degrees C was significantly lower than untreated fruit. This response was dose dependent, where increasing levels of UV-C irradiation resulting in slower peel degreening. UV-C irradiated fruits also remained significantly firmer than untreated fruits. In addition, UV-C treatment also significantly affected the flesh color, SSC and TA levels. These results show that a pre-storage UV-C irradiation treatment could be a potential postharvest treatment that can delay the peel degreening and other associated ripening related events in 'Kensington Pride' mango fruit when handled and stored at 20 degrees C.

Pancreatic cancer is a devastating disease with a 5-year survival rate of less than 5%. Resistance to conventional treatment options and toxicity of current chemotherapy agents (gemcitabine) makes pancreatic cancer a target for the development of novel therapeutic agents. Oleuropein is the most abundant biophenol found in olive products; it has anti-atherogenic and anti-inflammatory properties as well as activity against cancers of the breast, colon and prostate. However, there has yet to be any investigation into the effects of oleuropein on pancreatic cancer cells. Consequently, this study aimed to assess the anti-pancreatic cancer activity of oleuropein in vitro. Two cell lines were investigated; a pancreatic cancer cell line (MiaPaCa-2) and a normal pancreas cell line (HPDE). The viability of cells after treatment with 0-200μM oleuropein was assessed using the Dojindo CCK-8 viability assay and compared to gemcitabine. The induction of apoptosis was measured by way of caspase 3/7 activation, using a MUSE flow cell analyser, and expression of Bcl-2, Bax and Bac using Western blot. Cell cycle analysis was conducted using the MUSE flow cell analyser. RNA expression was assessed using Affymetrix GeneChip® Whole Transcript (WT) expression arrays. The IC50 values for oleuropein against MiaPaCa-2 cells was148μM. However, importantly, oleuropein did not decrease the viability of HPDE cells within the treatment range. In comparision, 20nM of gemcitabine did not show selectivity; it reduced the viability of MiaPaCa-2 cells to 21% and of HPDE cells to 2%. An increase in the expression of caspase 3/7 was seen in MiaPaCa-2 cells when treated with oleuropein but it had no effect on the HPDE cells. Furthermore, when treated with oleuropein, an increase in the expression of genes involved in the NRF-2 (oxidative stress) pathway was observed in MiaPaCa-2 cells, an effect not observed in HPDE cells.

Conclusion Oleuropein selectively induced apoptosis in the pancreatic cancer cells (MiaPaCa-2), appearing non-toxic to normal pancreas cells (HPDE) within the treatment ranges; this is significant, since gemcitabine was comparatively more toxic to HPDE cells. Furthermore, the link between oleuropein and the NRF-2 pathway in MiaPaCa-2 cells justifies further study into the mechanisms of action of oleuropein and its potential as a novel therapeutic approach for pancreatic cancer.

Note: This abstract was not presented at the meeting.

The appearance of cherry stems greatly influences consumer perception of cherry quality, where green stems are often used as indicators of overall cherry fruit freshness. In a series of storage trials with a range of cherry cultivars ('Sweetheart', 'Stella', 'Sweet Georgia'), we examined the effect of different storage temperatures (5 or 20°C) and display relative humidities (70 and 100%RH) on stem browning and water loss. The results showed that water loss from the stems was strongly affected by all storage factors. As expected, according to the vapour pressures of the different treatments, water loss from the stems was greatest in the high temperature (20°C) and low humidity storage (70%). The treatments with the lowest water loss from the stems were the low temperature storage (5°C) with high relative humidity (100%). The overall 'freshness' of the stems was significantly affected by all storage factors and is a better indication of stem acceptability. A linear relationship between stem diameter and water loss was determined with each cultivar, with over 85% of the variance in the data accounted by each relationship. In conclusion, the results clearly demonstrate the importance of temperature and relative humidity during the retail display of cherries.