Zeaxanthin biofortification of sweet-corn and factors affecting zeaxanthin accumulation and colour change

Zeaxanthin, along with its isomer lutein, are the major carotenoids contributing to the characteristic colour of yellow sweet-corn. From a human health perspective, these two carotenoids are also specifically accumulated in the human macula, and are thought to protect the photoreceptor cells of the eye from blue light oxidative damage and to improve visual acuity. As humans cannot synthesise these compounds, they must be accumulated from dietary components containing zeaxanthin and lutein. In comparison to most dietary sources, yellow sweet-corn (Zea mays var. rugosa) is a particularly good source of zeaxanthin, although the concentration of zeaxanthin is still fairly low in comparison to what is considered a supplementary dose to improve macular pigment concentration (2 mg/person/day). In our present project, we have increased zeaxanthin concentration in sweet-corn kernels from 0.2 to 0.3 mg/100 g FW to greater than 2.0 mg/100 g FW at sweet-corn eating-stage, substantially reducing the amount of corn required to provide the same dosage of zeaxanthin. This was achieved by altering the carotenoid synthesis pathway to more than double total carotenoid synthesis and to redirect carotenoid synthesis towards the beta-arm of the pathway where zeaxanthin is synthesised. This resulted in a proportional increase of zeaxanthin from 22% to 70% of the total carotenoid present. As kernels increase in physiological maturity, carotenoid concentration also significantly increases, mainly due to increased synthesis but also due to a decline in moisture content of the kernels. When fully mature, dried kernels can reach zeaxanthin and carotene concentrations of 8.7 mg/100 g and 2.6 mg/100 g, respectively. Although kernels continue to increase in zeaxanthin when harvested past their normal harvest maturity stage, the texture of these 'over-mature' kernels is tough, making them less appealing for fresh consumption. Increase in zeaxanthin concentration and other orange carotenoids such as p-carotene also results in a decline in kernel hue angle of fresh sweet-corn from approximately 90 (yellow) to as low as 75 (orange-yellow). This enables high-zeaxanthin sweet-corn to be visually-distinguishable from standard yellow sweet-corn, which is predominantly pigmented by lutein

Differences in the anthocyanin profile of different tissues of the strawberry fruit

Strawberries are most commonly red in colour, which is largely due to the anthocyanin, pelargonidin-3-glucoside, a bioactive flavonoid with potential health benefits. Variation in the intensity of red colour across strawberry varieties, from a light pink to a deep cherry colour, is solely associated with a change in concentration of this single anthocyanin, rather than the synthesis of an anthocyanin with a different colour. In this study, the anthocyanin profiles of the two constituent edible tissues of strawberry fruit were determined. The main tissue of the strawberry consists of a swollen fleshy receptacle. The second tissue consists of the achenes, visible on the surface of the strawberry, with each achene consisting of a dry single-seeded fruit formed from a fertilised ovule. The current study showed that the anthocyanin profile of a strawberry achene is totally different from that of the receptacle. While red-coloured pelargonidin-3-glucoside is the main anthocyanin component (about 94%) in the receptacle, purple-coloured cyanidin-3-glucoside accounts for approximately 90% of the anthocyanin content in the achene. This would indicate that flavonoid 3’-hydroxylase (F3’H), the enzyme responsible for shifting anthocyanin biosynthesis towards cyanidin and away from pelargonidin, is functional in strawberry achene tissue, but not in the receptacle tissue. This may indicate that other factors, such as transcription factors, can modulate the anthocyanin profile of different strawberry tissues, rather than strawberries having a non-functional F3’H gene. However, the relevance of these findings for potential strawberry breeding programs and subsequently the nutritional quality of strawberry fruit needs to be investigated further

Σύστημα επεξεργασίας θαλάσσιου έρματος & προμελέτη εγκατάστης σε υπάρχον δεξαμενόπλοιο

102 σ.Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Ναυτική και Θαλάσσια Τεχνολογία και Επιστήμη”Νικάολας Γ. Τσούμα

Field evaluation of transgenic pineapple (Ananas comosus (L.) Merr.) cv. ‘Smooth Cayenne’ for resistance to blackheart under subtropical conditions

A comparative analysis of transgenic pineapple lines transformed with a polyphenol oxidase (PPO) gene (ppo) and the untransformed cultivar ‘Smooth Cayenne’ was made from plants grown in a series of field trials under cool subtropical conditions in southeast Queensland. In the four field trials where blackheart was recorded, all of the control lines expressed blackheart on each occasion and exhibited the greatest incidence (50%) and severity (34%) of symptoms. Irrespective of the gene transfer method or the gene construct used, 38% of the lines produced were regarded as blackheart resistant, having no blackheart symptoms in two or more trials. Five blackheart resistant transgenic lines consistently performed as well as or better than control plants in terms of fruit characteristics and quality

The effect of post-harvest storage on the physicochemical properties and phytochemical content of Queen Garnet plum

The Queen Garnet Plum (QGP), a cultivar of Japanese plum (Prunus salicina Lindl.), was developed as a high anthocyanin plum in a Queensland Government breeding programme. Anthocyanins have been associated with various health attributes, including diabetes control, cardiovascular disease prevention and anti-inflammatory activity. This study was aimed at identifying the changes in physiochemical properties and important phytochemicals of QGP when stored under two storage temperatures. QGP from two growers were stored at 4 and 23 oC for 0, 4, 7, 10 and 14 days. At the end of each storage period the peel, outer flesh (up to 7 mm from the peel) and inner flesh were separated and analysed for chroma, total soluble solids (TSS) and titratable acidity (TA). The grower source had a significant effect on the measured parameters when considered as a covariate. Chroma values of the peel, inner and outer flesh were significantly (P < 0.05) different at 4 and 23 oC, after 14 days. There was no significant difference in the inner flesh TSS (IF-TSS) and outer flesh TSS (OF-TSS) between the different storage temperatures, but compared to day 0, after 14 days IF-TSS and OF-TSS were significantly (P < 0.05) lower. TA of the inner and outer flesh were significantly (P < 0.05) different at the two storage temperatures, but only the inner flesh TA was significantly (P < 0.05) different after 14 days. Further analysis is in progress for anthocyanins, total phenolics, carotenoids, folates and vitamin C. The current study indicates that QGP is climacteric and grower source, storage temperature and time as well as tissue can significantly affect the studied physicochemical parameters