Postharvest Unit

Chelmsford, United Kingdom

Postharvest Unit

Chelmsford, United Kingdom

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Tshwenyane S.O.,Postharvest Unit | Bishop C.F.H.,Postharvest Unit
Acta Horticulturae | Year: 2010

The production areas for cut flowers destined for the UK, such as in Kenya, are far from the consumption areas. This poses a challenge for growers to be able to harvest flowers at the correct stage to reach the consumer in a suitable condition. Harvest time is fundamental as it can have a major effect on final flower quality. In this study, the effect of harvesting time on the vase life and quality of cut flower stems of Rosa hybrida 'Duett', 'Golden Gate' and 'Cream Prophyta' was investigated. Flowers were dry stored at 2°C for 10 days; control flowers were placed in vases without storage. Flowers harvested in the afternoon had a lower rate of respiration - around 89 ml CO 2/kg/h compared to 96 ml CO2/kg/h for morning harvested flowers. Respiration rate affected vase life; morning harvested flowers lasted 5.5 days while afternoon harvested flowers lasted 7.83 days. These results indicate how important timing of harvest is to quality and vase life.


Altisent R.,Postharvest Unit | Graell J.,Postharvest Unit | Lara I.,Postharvest Unit | Lopez L.,Postharvest Unit | Echeverria G.,Postharvest Unit
Journal of Food Quality | Year: 2012

Over two subsequent seasons, emission of volatile compounds, consumer acceptability and quality parameters were analyzed in "Fuji" apples. In both seasons, apples were harvested at the same maturity stage and stored for 19 or 30 weeks at 1C and 92% relative humidity under an ultralow oxygen (ULO) atmosphere (1% O 2+1% CO 2) or under an ULO atmosphere followed by different periods (2 or 4 weeks) in cold air. The results revealed, for both seasons, that 4 weeks of cold air storage after ULO storage helped to increase the emission of some volatile compounds for both storage period, including characteristic volatile compounds for the variety, and did not have a negative effect on quality parameters. Additionally, the consumer acceptability was superior for those fruits. © 2011 Wiley Periodicals, Inc.


Bishop C.F.H.,Postharvest Unit | Ramma I.,Agriculture Research and Extension Unit
Acta Horticulturae | Year: 2012

Trials were carried out on 'MST 32/1' cooking tomatoes locally known as "Pomme d'Amour" to evaluate the level of postharvest losses that occurred with small farmers using traditional systems of weekly harvesting the crop green. Three trials were carried out at different times of the year. It was found that only around 25% of the fruit fully ripened for market within a week of harvest which was the desired period for the farmers. Improved handling methods, by replacing deep wooden boxes with smooth sided plastic crates and keeping the crop on a wooden pallet in the shade whenever possible, reduced losses. The use of Ethrel® resulted in 60% of the tomatoes being fully ripened and marketable by the end of the week.


Tshwenyane S.O.,Postharvest Unit | Cullum F.J.,Postharvest Unit | Bishop C.F.H.,Postharvest Unit | Gash A.F.J.,Postharvest Unit
Acta Horticulturae | Year: 2012

Grey mould caused by Botrytis cinerea on flower petals is a common disease of greenhouse roses (Rosa hybrida L.). Infections due to B. cinerea may not be visible at the time of harvest but the disease is able to develop rapidly causing significant reduction in flower vase life and value. Carbon dioxide (CO2) was examined for postharvest control of Botrytis in 'Duett' roses. Flowers were treated with 10% CO2, 20% CO2 or normal air. Flowers were either inoculated with known concentration of B. cinerea conidia, or sprayed with equal volumes of sterile water. Flowers were then dry stored for 11days at 5°C. Treatment with CO2 significantly reduced Botrytis rot compared with normal air stored flower. Treating 'Duett' roses with 20% CO2 gave the significant reduction Botrytis rot, however, it resulted in foliage damage manifested by dark discoloration. However, 10% CO2 also gave a good reduction in Botrytis with no leaf damage and better colour retention in the petals.


Penicillium digitatum is the most serious citrus pathogen and the disease is currently controlled using conventional fungicides. Risk of increased pathogen resistance, withdrawal of chemicals, residue levels of chemicals on fruit and the disposal of fungicide solutions are major problems. 'Generally Recognized as Safe' (GRAS) chemical alternatives are being researched for controlling P. digitatum, including the food additive potassium sorbate (KS). Initially a practical, laboratory method was developed to induce conidial germination. Combinations of various fruit sugars with citric acid did not induce conidial germination. Three orange juices were trialled at 0.625% concentration with Minute Maid® and fresh 'Navel' orange juice inducing conidia germination after 8 h. With the germination medium established this was then amended with KS concentrations of 0.003, 0.005 and 0.050% w/v, buffered at pH 4.5 and 5.5, and 1.18×106 conidia/ml. After 9 h at 25°C all three KS concentrations gave EC95 concentrations at pH 4.5. At pH 5.5, 0.005 and 0.050% KS gave EC95 concentrations. The effect of pH on KS dissociation was evident. Germ tube measurement was difficult compared to recording the percentage germination. The combination of 0.050% KS, buffered to pH 4.5 with 0.0625% Minute Maid® gave significant inhibition of conidia germination. The method developed combines the chosen components in solution, in reusable containers, to then give a visual indication of pathogen presence and germination inhibition results in approximately 9 h. This technique provides a test kit which may be of potential use in the citrus supply chain.


Altisent R.,Postharvest Unit | Graell J.,Postharvest Unit | Lara I.,Postharvest Unit | Lopez L.,Postharvest Unit | Echeverria G.,Postharvest Unit
European Food Research and Technology | Year: 2011

'Golden' is the most cultivated apple group in Europe. In recent years, new mutants have emerged which improve both aspects of production and sensory attributes. In this work, emission of volatile compounds and the activity of lipoxygenase system-related enzymes in 'Golden Reinders®' apples were analysed after 19 and 30 weeks under ultra low oxygen atmosphere (ULO) or under ULO plus different periods in cold air atmosphere and after remaining 1 and 7 days at 20 °C. This study examined modifications in the capacity for volatile ester production, specifically focusing on modification in lipoxygenase and hydroperoxide lyase activity. Volatile compound emission reached a maximum after 30 weeks of cold storage plus 7 days at 20 °C. Straight-chain esters were closely related to lipoxygenase activity in the flesh tissue, leading, suggesting that lipoxygenase enzyme plays an important role in the emission of straight-chain esters: the most characteristic volatile type associated with this apple variety. © 2010 Springer-Verlag.


Bishop C.F.H.,Postharvest Unit | Bingley E.,Postharvest Unit | Matthews H.,Postharvest Unit
Acta Horticulturae | Year: 2011

Knowledge Transfer Partnerships are an established method of developing academic-commercial relationships to further competitiveness and productivity through the better use of knowledge, technology and skills. Building on the UK model, the British Council is currently piloting AKTP (Africa Knowledge Transfer Partnerships) in Uganda, Ghana, Nigeria and Kenya. AKTP facilitates a partnership between an African commercial organisation and African higher education institution; supported by UK academic partner institutions. The commercial organisation employs a recent graduate ("associate") who works in the company to implement the project by transferring knowledge between the higher education institutions and the company. The programme is designed to help businesses improve their productivity and competitiveness using the scientific knowledge, technology and skills available from the higher education Institutions. Five AKTP pilot projects have a horticultural focus [three in Kenya, one in Nigeria, and one in Ghana]; Writtle College has participated as UK academic partner for the Kenyan projects. The first case study examines the AKTP between the University of Nairobi and MEA, a fertiliser production company, in order to commercialise a legume inoculant. The product was developed by the University of Nairobi in the late 1970's but the University was able to achieve only minimal market penetration. The projected outcomes for the AKTP are reviewed against the actual achievements for the company, the associate and the academic partner. The second case study reviews the progress to date of a two-year AKTP launched in January 2010 to measure the carbon footprint of key horticultural exports from Kenya. This partnership between Sunripe Ltd, producers and exporters of fruit and vegetables to Europe, Asia and South Africa, and Jomo Kenyatta University of Agriculture and Technology seeks to build capacity in both academic and commercial sectors through knowledge transfer from the UK. The third project which is only recently started is on postharvest aspects between East Africa Growers and Egerton University.


Altisent R.,Postharvest Unit | Graell J.,Postharvest Unit | Lara I.,Postharvest Unit | Lopez L.,Postharvest Unit | Echeverria G.,Postharvest Unit
Journal of Agricultural and Food Chemistry | Year: 2011

All efforts to improve fruit quality are rewarded when consumers are satisfied after tasting the fruit. Apples are often stored under controlled atmosphere conditions to preserve them over time, but this frequently results in a loss of flavor. The aim of this work, which was based on two seasons, was to evaluate the influence of a period of short-term air storage (periods of 2 and 4 weeks) after removal from ultralow oxygen (ULO) storage (1 kPa of O 2/1 kPa of CO2) with respect to increases in volatile compound emissions and the effect on standard and sensory quality in 'Golden Reinders' apples. The results showed that emissions of 26 volatile compounds increased as a result of ULO + 2 weeks or ULO + 4 weeks of storage. However, the results of tastings involving a panel of consumers and trained experts revealed that this increase was not matched by corresponding increases in either the degree of consumer preference or flavor attributes. © 2011 American Chemical Society.

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