Andreas Klieber

Quality maintenance of minimally processed Chinese cabbage with low temperature and citric acid dip

Chinese cabbage (Brassica campestris L pekinensis group) was minimally processed using best preparation techniques and stored at 0 and at 5°C with and without dips in either citric acid, calcium chloride or ascorbic acid, all at 10 g litre−1. The visual quality, degree of chilling injury, pH and taste were evaluated. The most deleterious effects on quality were produced by black speck (gomasho) and browning. Citric acid inhibited the development of black speck and extended storage life from 10 days of the control to 14 days at 5°C. At 0°C the storage life was not extended by any dip, but citric acid improved quality by reducing black speck. Minimally processed Chinese cabbage treated with citric acid showed only a slight reduction of pH from 6·3 of the control to 6·1 (P⩽0·05) and taste was not significantly affected (P>0·05). Microbial spoilage was not apparent during storage at 0°C for 35 days and 5°C for 21 days under any treatment.

Effect of post-ripening nitrogen atmosphere storage on banana shelf life, visual appearance and aroma

Abstract Bananas ( Musa acuminata Colla, Cavendish cv. ‘Williams’) were stored in nitrogen at 22 °C for 6, 12 and 24 h at a more green than yellow (stage 3) or more yellow than green (stage 4) ripening stage. Shelf life in nitrogen at 22 °C, that is the time taken from a more yellow than green colour stage 4 to yellow with slight brown flecking stage 7, was not extended when compared to air-stored bananas. However, areas of brown discolouration appeared on bananas placed in nitrogen-storage. The aroma of ripe bananas was assessed with a mass spectrometry-based chemical nose. Bananas stored in nitrogen generally had a riper aroma profile compared with air-storage. An ion with a mass to charge ratio of 61 was strongly associated with nitrogen-treated bananas; this ion is a decomposition product of a known banana aroma compound, ethyl acetate that produces an over-ripe banana note. An ion with a mass to charge ratio of 55 was associated with air-stored bananas; this ion is a decomposition product of ripe bananas (3-methylbutyl ester and 1-butanol). Post-climacteric nitrogen storage is not a suitable method for increasing shelf life, as it causes skin browning.

Colour at harvest and post-harvest behaviour influence paprika and chilli spice quality.

Abstract Capsicum annuum L. paprika and cayenne chilli pepper fruit were grown for red spice production and harvested at various colour stages on the same day. Fruit of each stage were allowed to change colour at room temperature with or without the addition of 100 μl l−1 ethylene. Fruit appearance and colour development, and respiration and ethylene production were measured during the colouring period. Ethylene treatment had no effect on colour development or pungency for both cultivars, even though it easily crossed the cuticle, epidermis and flesh tissues into the fruit cavity. Green or deep green harvested fruit failed to fully colour red, while fruit that were harvested at or after the colour break stage visually completed their red colour development within 7–9 days. However, the colour intensity of spice powder was low for all fruit that had not developed a deep red colour prior to harvest. For paprika no difference between deep red fruit that were succulent or that had partially dried on the plant was found, but chilli fruit that had partially dried before harvest produced the most intense colour. American Spice Trade Association (ASTA) extractable red colour was the best measure of spice colour quality, compared to reflected lightness (L*), chroma (C*) and hue angle (h°) colour measurements. Pungency did not change between ripeness stages for chilli and was absent in paprika. Paprika and chilli fruit showed climacteric behaviour as long as they were attached to the plant, but when detached were non-climacteric.

Effects of low oxygen and high carbon dioxide on tomato cultivar 'Bermuda' fruit physiology and composition

Abstract Breaker stage tomatoes (Lycopersicon esculentum Mill., cultivar ‘Bermuda’) were treated in air, 0.5% or 1.0% oxygen (O2) in nitrogen (N2) or 80% carbon dioxide (CO2) in air for 1, 3, 5 or 7 days at 22 °C. A 1 day low O2 treatment delayed ripening after treatment by 1–2 days compared to a ripening period of 4 days for the control; elevated CO2 for 1 day had no effect on ripening after treatment. Low O2 increased production of ethanol and acetaldehyde compared to the control and high CO2. Fruit treated for 3 or more days in low O2 or high CO2 showed skin injury and blotchy ripening. Disease incidence increased with treatment time, but could be controlled in 1 day treatments by reducing relative humidity to about 70%. Firmness, total soluble solids, titratable acidity and pH of pericarp and gel of 1 day treated fruit were not different from the control.

Postharvest vase life of two flowering Eucalyptus species

Abstract Continuous application of 0.5–5.0% sucrose in the vase solution reduced vase life of Eucalyptus tetragona flowers, from >13 days for the reverse osmosis (RO) water control to

Preference of banana flavour and aroma are not affected by time of the year or 'winter' chilling

Banana (Musa acuminata Coll. Cavendish cv. Williams) eating quality was assessed through winter, spring and summer, and for mildly chilled bananas with symptoms mimicking that of ‘winter-chilled’ fruit using sensory testing and principal component analysis of mass-spectrometric data obtained from a ‘chemical nose’. Sensory testing of bananas harvested at different times of the year showed no differences in flavour preference, even though soluble solids were higher in spring at 23.6%, compared with winter at 22.6% and summer at 21.9%. Principal component analysis of mass-spectrometric data did not reveal aroma differences between times of the year. Results of difference tests for mildly chilled and non-chilled bananas indicated no differences in aroma intensity or sweetness. Mild chilling did not alter soluble solids and principal component analysis of mass-spectrometric data did not discriminate between chilled and non-chilled bananas.

Effect of sucrose at different concentrations and cold dry storage on vase-life of three ornamental Eucalyptus species

Summary Cut stems from the genus Eucalyptus are widely sold on World floriculture markets; however, there has been limited research into the optimal post-harvest requirements of most commercially significant species. Previous research has shown a range of responses to varying combinations of sucrose concentrations and time periods. In this study, we investigated the effects of a 2 h pulse of 20% sucrose, a 24 h pulse of 5% sucrose, 2% sucrose supplied continuously or 24 h dry storage at 3°C on vase-life of bud and flowering stems of E. lesouefii and E. yalatensis, and woody fruit stems of E. tetragona syn. E. pleurocarpa. Data indicated that 2% sucrose applied continuously was detrimental to the vase-life of all three species, significantly shortening the vase-life of E. tetragona syn. E. pleurocarpa and E. lesouefii compared to other treatments. The most successful treatment for E. tetragona syn. E. pleurocarpa was a 2 h pulse of 20% sucrose that resulted in a mean vase-life of 29 d, significantly longer than the control treatments (27 d). For E. lesouefii, a 24 h pulse of 5% sucrose resulted in a vase-life of 17 d, significantly longer than the control (15 d). The vase-life of E. yalatensis was 12– 15 d across all treatments, with none significantly better than the control. Symptoms of damage and senescence observed during the trials included “leaf blueing”, bud and leaf softening, bud splitting, new growth desiccation and blackening. These symptoms could not be correlated to treatment. Differences in vase-life and leaf damage symptoms were found between plants within a species (grown from open-pollinated seed) indicating a genotype effect. This study indicates that for these three Eucalyptus species, post-harvest damage to leaves, buds, fruits and stems varies with treatment, genotype and species. The overall implications of this trial are that each species requires specific testing to determine its optimal post-harvest requirements.