Using survival analysis to investigate the effect of UV-C and heat treatment on storage rot of strawberry and sweet cherry (original) (raw)
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Combined use of UV-C irradiation and heat treatment to improve postharvest life of strawberry fruit
Journal of The Science of Food and Agriculture, 2004
The effects of UV-C (4.1 kJ m−2) and heat treatment (45 °C, 3 h in air) either separately or combined on the quality of strawberries (Fragaria × ananassa cv Seascape) at the 75 or 50% surface red ripening stage were assessed, the latter stage being used only in the firmness test. In addition, the development of surface fungal infections was followed and in vitro germination assays on conidia of Botrytis cinerea and Rhizopus stolonifer performed. Both heat and combined treatments, decreased hue and delayed changes of the L* parameter. All treatments reduced the accumulation of anthocyanins. Control fruit softened most while fruit treated by the combined method were the firmest. The combined treatment reduced fungal infections and delayed in vitro germination of Botrytis cinerea conidia. After 2 days at 20 °C, treated fruit had lower amount of phenolics than the control. Neither the heat nor UV-C irradiation modified the total sugar content, although the combined treatment decreased it slightly relative to the control. Titratable acidity increased through storage at 20 °C in all fruit, but no differences between control and treated fruit were detected. The combination of UV-C and heat treatments enhanced the benefits of applying each treatment separately, and could be useful to improve and extend strawberry fruit postharvest life. Copyright © 2004 Society of Chemical Industry
Use of UV-C light to reduce Botrytis storage rot of table grapes
Postharvest Biology …, 1998
Single table grape berries (Vitis 6inifera L. cv. Italia) were irradiated with ultraviolet-C (UV-C) doses ranging from 0.125 to 4 kJ m − 2 and inoculated with Botrytis cinerea. The pathogen was inoculated on artificial wounds at different times (0, 24, 48, 72, 96 and 144 h) after irradiation and the berries were stored either at 21 or 3°C. To check the influence of UV-C irradiation on the wound-healing processes, trials using berries wounded just before the UV-C irradiation and inoculated at different times were also performed. Significantly lower numbers of infected berries and lesion diameter were found in berries treated with UV-C doses ranging from 0.125 to 0.5 kJ m − 2 . There was also a significantly lower level of disease in berries inoculated after 24 -48 h than in those inoculated just after (10 -15 min) the UV-C treatment. Thus, pretreatment with low UV-C doses followed by artificial inoculation with B. cinerea reduces postharvest grey mould of table grapes, suggesting induced resistance to the disease, both in berries wounded before and after irradiation. The microbial epiphytic population on UV-C-treated berries was also monitored. Results showed a significantly higher increase in the population of yeasts (including yeast-like fungi) and bacteria on berries irradiated with 0.25 and 0.5 kJ m − 2 than on unirradiated control berries.
The Use of Fungicide Alternatives for Controlling Postharvest Decay of Strawberry and Orange Fruits
Journal of Plant Protection Research, 2008
Control measures of postharvest diseases of strawberry and navel orange fruits using hydrogen peroxide, calcium chloride and chitosan were evaluated under in vitro and in vivo conditions. All tested concentrations of chemicals used were able to reduce the linear growth and spore germination of B. cinerea; R. stolonifer; P. digitatum and P. italicum. Complete inhibition of linear growth and spore germination was obtained with concentrations of 1.5 and 2.0% of all treatments. Under storage conditions, significant reduction in descending order of mould incidence was observed in strawberry and orange fruits treated with ascending concentrations of calcium chloride, hydrogen peroxide and chitosan. Obtained data revealed significant reduction in mould incidence in fruits when treated by calcium chloride and chitosan 12h before artificial inoculation with the mould pathogens, while hydrogen peroxide showed the opposite result. The present study demonstrated that the application of hydrogen peroxide is superior to treatment with calcium chloride or chitosan enhanced the control activity against mould pathogens which as it expressed was as either percentage of diseased fruits or decay development as rotted tissue weight of strawberry and navel orange. The applied tested chemical might act as contact and systemic fungicides which have a protective or therapeutic effect.
Pre-storage hypobaric treatments delay fungal decay of strawberries
Postharvest Biology and Technology, 2013
Fungal decay is a major cause of postharvest losses in strawberries. The traditional approach for controlling fungal decay is the use of fungicides. However, the use of fungicides has been questioned as a sustainable and safe method, and is also prohibited in many countries. One potential physical method for reducing fungal decay is application of a short-term hypobaric treatment prior to storage. In this study efficacy of postharvest hypobaric treatments to control natural rot development in strawberries was evaluated. Strawberries were treated with hypobaric pressures (25 kPa a , 50 kPa a and 75 kPa a) for 4 h at 20 • C and subsequently stored at 20 • C or 5 • C. A 50 kPa a treatment consistently delayed rot development in samples stored at either temperature confirming that the technique has potential as a non-chemical treatment. Moreover 50 kPa a treatments did not affect weight loss and firmness at either 20 • C or 5 • C. An initial increase in respiration rate was observed in 50 kPa a treated samples potentially indicating mild stress due to hypobaric treatment. An in vitro fungal study found that 50 kPa a treatment for 4 h did not affect the rate of radial growth of colonies of Botrytis cinerea and Rhizopus stolonifer, providing further evidence that the potential mechanism of hypobaric treatment is induction of the defence system within the fruit rather than a direct effect on fungal viability. Further molecular and biochemical research is required to evaluate the possible stimulation of resistance in fruit through short-term hypobaric treatments.
Research, Society and Development, 2021
It is common to combine methods to increase the shelf life of a raw material or product. In this study, we sought to understand the relationship between ultraviolet (UV) radiation and sodium hypochlorite (NaOCl) in attenuating the proliferation of fungus and its deteriorating effect on strawberries. The UV light intensities of 125, 250 and 400 Watts (W) and sodium hypochlorite were tested in concentrations 0.5, 1.0 and 1.5 ppm. The strawberries were sprayed with sodium hypochlorite solutions and then kept for 1 minute in UV light chambers, to then be stored in transparent sealed plastic containers. The strawberry samples with the longest life were those that were sprayed with 0.5 and 1.0 ppm sodium hypochlorite solution combined with exposure to 125 W UV light. These samples had a shelf-life extension of about five days compared to strawberries without any kind of treatment. Thus, it is possible to state that this combination is efficient in cleaning the fruit without causing damage.
Quality of heat-treated strawberry fruit during refrigerated storage
Postharvest Biology and Technology, 2002
Strawberries cv. Selva were heat-treated in an air oven (45°C, 3 h) and then stored at 0°C for 0, 7 or 14 days. Afterward, fruits were placed at 20°C and monitored after 24, 48 or 96 h and the effect of heat treatment on the following parameters was recorded: weight loss, external color, anthocyanin content, firmness, titratable acidity, total and reducing sugars, fruit decay and count of colony forming units (CFUs) for bacteria and molds. Heat-treated fruits showed higher hue angle than controls, indicating the delay of red color development. The treatment diminished fruit lightness (L*), although the effect reverted during holding at 20 or at 0°C. The application of the treatment caused an initial weight loss close to 2% but afterwards, heat-treated fruits showed lower weight loss rate at 20°C. Heat-treated fruits had lower acidity than controls, but there was no difference in the content of total sugars between control and treated fruits. Heated fruits were slightly firmer at the end of the treatment, and they softened less than controls after 24 h at 20°C. Heat-treated fruits remained firmer than controls after 7 days of cold storage, and the relative difference in softening persisted after 48 h at 20°C. However, no difference in treated and control fruit firmness was observed after 14 days of storage at 0°C and following 48 h at 20°C. In the absence of storage, heat-treated fruits showed lower decay at 20°C than controls. After 7 days at 0°C followed by 72 h at 20°C, the percentage of decayed fruits was lower in heat-treated than in control fruits. The treatment decreased the initial bacterial population, but did not modify the amount of mold initially present. After 7 days of cold storage, the CFU number for bacteria were lower in treated than in control fruits. This difference was still significant after 48 h at 20°C. In the case of molds, heat-treated fruits that were stored for 7 or 14 days at 0°C and then transferred to 20°C for 48 h showed lower CFU value than controls.
Use of combined UV-C and heat treatments to improve postharvest life of strawberry
Strawberry is a rapidly decaying fruit and much of the postharvest research on strawberry is devoted to the development of methods to improve its postharvest shelf life. Physical treatments involving a low UV-C dose (4.6 kJ·m -2 ) and heat treatment (45 °C, 3 h in air oven) have been assayed both separately and in a combined fashion on strawberries (Fragaria x ananassa 'Seascape') 70-80% surface red. After treatments, fruit were kept at 20 °C for 2 d and fruit quality characteristics such as surface color and lightness, anthocyanin content, total phenol and sugar content were measured. Also, the development of surface fungal infections was monitored to quantify the effect of treatments. For both the heat and combined treatments, development of surface hue was delayed, a result in accordance to the observed reduced rate in anthocyanin increment; for these same treatments, lightness loss was also delayed. Fruit treated with the combined physical treatment showed a steady phenol content along the running time compared with the decrease found in those on which the treatments were assayed separately. No significant differences among treatments were observed in the total sugar content except for day 2. Over the experimental time (7 d after harvest), combined physical treatment drastically reduced surface fungal infections. Based on these results, a potential synergistic effect from the combination of both treatments can be foreseen for most parameters studied, thus suggesting an innovative physical method to improve postharvest life (i.e. prolong shelf life and maintain quality parameters), which might prove to be cheap, simple and market-appealing as well.
UV Hormesis in the preservation of Fresh Fruits and Vegetables: Control of Postharvest Diseases
Introduction Fresh fruits and vegetables are highly perishable and maintain an active metabolism in the postharvest phase. The major factors causing early termination of the storage life of fresh produce are fungal infection, senescence and transpiration. Storage diseases, especially those caused by fungal pathogens, are responsible for substantial postharvest losses. Public pressure to reduce the use of fungicides to control storage diseases and the evolution of fungicide-tolerant strains of postharvest pathogens have stimulated the development of new approaches to combat fungal pathogens. They include : activation of the natural defense mechanisms of the harvested produce, use of non-toxic and natural biocides, the use of biological antagonists and genetic transformation (1). The intrinsic and variable resistance of fruits and vegetables to postharvest diseases might be associated with one or a combination of properties of the host. The disease resistance of the crop includes both...