Effect of gamma irradiation treatment at phytosanitary dose levels on the quality of ‘Lane Late’ navel oranges

The objectives of this study were to determine the dose tolerance of ‘Lane Late’ navel oranges (Citrus sinensis L. Osbeck) to irradiation for phytosanitary purposes, identify the sensory attributes that may be affected by the treatment, and determine which changes, if any, influence consumer liking. ‘Lane Late’ navel oranges on Carrizo citrange (C. sinensis Poncirus trifoliate) rootstock were irradiated at target dose levels of 200, 400 and 600 Gy (actual absorbed doses were in the range of 100–300, 300–500, and 500–700 Gy, respectively) then stored for 1 d at 5 °C, 3 weeks at 5 °C (to simulate sea shipment to Asia) or 4 weeks (3 weeks at 5 °C and 1 week at 20 °C to simulate distribution to retail following sea shipment). Trained sensory panelists found increased pitting and visual damage in oranges treated at doses of 400 and 600 Gy. Consumer liking scores for appearance were significantly lower for oranges treated at 400 Gy, however, their overall liking scores for those same oranges were not significantly different than control. Color, total phenolic content, vitamin C and ORAC (oxygen radical absorbance capacity) values were not affected by irradiation. Dose effects were seen in terms of visual damage, increased weight loss and increased concentration of certain volatiles and as well as decreased SSC (soluble solids concentration) at doses 400 and 600 Gy. The primary effect of irradiation on fruit quality was external damage and pitting at doses of 400 and 600 Gy. Further research should consider pack configuration and/or combination treatments to possibly mitigate negative irradiation effects on appearance of the fruit.     

Applications of salt solutions before and after harvest affect the quality and incidence of postharvest gray mold of ‘Italia’ table grapes

The efficacy of some potassium and calcium based salts, namely potassium sulphate (PS), potassium sorbate (PSo), potassium carbonate (PC), potassium bicarbonate (PB), calcium sulphate (CS), calcium chelate (CCh), calcium chloride (CC) and calcium silicate (CSi) against gray mold of ‘Italia’ table grapes, was evaluated. In in vitro experiments, PSo, PC, PB, and CCh completely inhibited mycelial growth of Botrytis cinerea at 0.25%. Under artificial inoculation, salts at 1% (immersed or sprayed) showed a variable effect against the pathogen. For natural infection, salt solutions (1%, w/v) were applied according to three strategies: (a) spray (one week) before harvest, (b) immersion after harvest, and (c) combined treatments spray and immersion. The decay incidence of gray mold was evaluated after 30 days at 2 ± 1 °C and 90–95% RH, followed by 7 days of shelf-life at 22 ± 2 °C. All tested salts significantly reduced the decay incidence of gray mold as compared to a water control for the three strategies. The percentages of reduction ranged between 77–100, 91–98, and 61–100% for the preharvest treatment, in combined application, and in the postharvest treatment, respectively. PB and PSo were the most effective salts, completely inhibiting development of gray mold when applied before harvest and as a postharvest treatment. The influence of salts on physical and chemical properties of berry quality including total soluble solids, titratable acidity, pH, color index, weight losses and microbiological profiles was also investigated. New strategies are needed with the critical goal of controlling gray mold of grapes with no fungicide residues. Salts applied just before harvest may be an effective way to minimize gray mold during storage.     

Effect of gamma irradiation on the physico-chemical and visual properties of mango (Mangifera indica L.), cv. ‘Dushehri’ and ‘Fazli’ stored at 20 °C

The effect of γ-irradiation doses (0.3, 0.5, 0.7, 1.0, 6.0, 10.0 kGy) on different physico-chemical and visual properties of two Indian cultivars of mango, cv. ‘Dushehri’ and ‘Fazli’ was observed during storage at 20 °C for the evaluation of delayed ripening and extension of shelf-life. Visually all the irradiated fruit showed greener peel and lighter pulp throughout the storage, however, radiation injuries were present in ‘Dushehri’ treated with 6–10 kGy and in ‘Fazli’ with 1–10 kGy. Loss of fruit due to rotting was less in the irradiated samples, treated up to 1 kGy of both the cultivars. Irradiated fruit of both the cultivars at high doses (6–10 kGy) showed increased sugar content from 0 d, however, all the treated fruit registered a slower rate of increase of sugars with storage compared to the respective controls and those treated with the lower doses of 0.5 and 0.7 kGy attained peak sugar concentration later. Significant (p ≤ 0.05) textural deterioration could be detected immediately after irradiation, in ‘Dushehri’ at doses ≥1 kGy and in ‘Fazli’ at doses ≥0.7 kGy. However, low dose treated fruit (0.3–1 kGy) of both the cultivars softened at a considerably slower rate during storage and registered significantly greater fruit firmness (compression strength) throughout the storage period. Similarly, ‘Dushehri’ treated with 0.3–0.7 kGy and Fazli treated with 0.7 kGy registered significantly greater flesh firmness (shear strength). ‘Dushehri’ treated with 0.3–1 kGy and ‘Fazli’ with 0.5–1 kGy also registered significantly harder and tougher peel, as determined by puncture test, throughout the storage. Scanning electron microscopy (SEM) performed on 3rd and 2nd d of storage of ‘Dushehri’ and ‘Fazli’ respectively, revealed microstructural breakdown at and above 1 kGy in both cultivars. Cell separation could be observed in ‘Fazli’ even at 0.7 kGy. SEM also revealed that the control fruit were in a more advanced stage of ripening than the low dose treated fruit. The study showed the feasibility of low dose γ-irradiation on ‘Dushehri’ (0.3–0.7 kGy) and ‘Fazli’ (0.5 and 0.7 kGy) that induced useful delay in ripening and extension of shelf-life by a minimum of 3 and 4 d, respectively.     

Effect of gamma irradiation on the physico-mechanical and chemical properties of potato (Solanum tuberosum L.), cv. ‘Kufri Sindhuri’, in non-refrigerated storage conditions

The effects of γ-irradiation doses, 0.04, 0.08, 0.12 and 1 kGy, applied at two different postharvest times (5 and 30 days after harvest), were studied on the textural behaviour (puncture force, shear force, work done to puncture and shear, cohesiveness and gumminess), microstructure, reducing sugar, total sugar and tuber losses of potato (Solanum tuberosum L.), cv. ‘Kufri Sindhuri’, during storage at 22 °C (RH: 85–90%). The lowest dose (0.04 kGy) was sufficient to inhibit sprouting in potatoes exposed on day 5 but not in the tubers exposed on day 30. The irradiated, non-sprouted potatoes maintained their appearance during storage. Potatoes irradiated early appeared more sensitive to radiation-induced damage, resulting in excessive loss of tubers at 1 kGy but low doses (up to 0.12 kGy) did not increase the susceptibility of the tubers to rotting. No significant differences between reducing sugar and total sugar contents of the control and low dose irradiated tubers were observed after 120 d. High dose (1 kGy) induced blackening of the bud tissue, increased rotting percentage and poor textural quality. Increasing low doses (up to 0.12 kGy) progressively reduced the textural deterioration in the tubers during storage. The scanning electron micrographs of potatoes irradiated with 0.08–0.12 kGy showed intact cells with rigid cell walls, accounting for the higher textural values registered by the samples. Among the two treatment timings, ‘K. Sindhuri’ irradiated early after harvest (i.e., on day 5) with 0.08–0.12 kGy doses retained higher textural parameters compared to those irradiated after a delay (day 30). The study showed the potential effect of γ-irradiation for enhancing the storage life of potatoes in non-refrigerated storage.     

Influence of environmental conditions on the quality attributes and shelf life of ‘Goldfinger’ bananas

‘Goldfinger’ bananas (Musa accuminata, FHIA-01) were harvested, held for 14–22 d at five temperatures and a constant relative humidity (RH) or at five RHs and a constant temperature and evaluated for quality attributes. The objectives of this work were to: (1) create quality curves for bananas stored at chilling and non-chilling temperatures; (2) create quality curves for bananas stored at a non-chilling temperatures and different RHs; (3) identify which sensory quality attribute limits the shelf life and marketability of bananas when stored at chilling and non-chilling temperatures or at different RHs; and (4) correlate subjective sensory attributes with quantitative quality measurements. Results from this study showed that temperature had a more significant impact on the quality of banana than RH. Bananas stored at temperatures higher than 10 °C were yellower and softer but had lower starch and higher soluble solids and total sugar content than those stored at lower temperatures. When stored at 2, 5 and 10 °C, bananas developed chilling injury (CI) and abnormal ripening when transferred to 20 °C. The most remarkable impact of RH on banana quality was on weight loss, which was significantly higher in fruit held below 80% RH than in fruit held in 87 or 92% RH. CI was the first sensory quality attribute to reach the limit of acceptability in fruit stored at 2, 5 and 10 °C, whereas color changes and softening limited the shelf life of bananas stored at 15 and 20 °C. Changes in color and/or softening were the two main sensory attributes that limited the shelf life of bananas stored at different RHs. Overall, for maximum quality and shelf life bananas should be stored at or above 15 °C and 92% RH. Finally, sensory attributes can be used to estimate peel color, pulp softening and sweetness, while SSC can be used as a reliable and simple method to estimate the total sugar content of bananas stored at different temperatures or different RHs.     

Salt strategies to control Botrytis mold of ‘Benitaka’ table grapes and to maintain fruit quality during storage

Gray mold is the most common postharvest disease of table grapes in most regions of the world. The effect of eight salts, namely sodium silicate (SSi), sodium sulphate (SS), sodium carbonate (SC), sodium bicarbonate (SB), iron chelate (Fech), iron sulphate (FeS), ammonium bicarbonate (AB), and ammonium oxalate (AO) was determined in vitro on mycelial growth and spore suspension of Botrytis cinerea. In particular, SSi, SC, SB, FeS, and AB completely inhibited pathogen growth at 0.25% concentration. Six salt solutions at 1%, immersion or spray, were tested to verify their effect on grapes artificially inoculated with B. cinerea. All salts significantly reduced the percentage of gray mold as compared to control except for Fech after one week at 22 ± 1 °C. Three salt solutions were applied, in vivo, according to different strategies: (i) spraying before harvest, (ii) immersion after harvest, and (iii) the combination of pre- and postharvest treatments. Water was involved as a negative control while Rovral (a.i. iprodione) and SO₂ served for comparisons. After one month of cold storage at 2 ± 1 °C followed by one week of shelf-life at 22 ± 2 °C, the natural incidence of postharvest mold was mostly caused by B. cinerea. The efficacy of preharvest applications was noticeably high and statistically was not enhanced by further treatments after harvest. Salts applied only after harvest were not effective in suppressing Botrytis mold, with the exception of FeS. The influence of salts on physicochemical properties for berry quality was also monitored. The field application of salts can be considered as an appropriate regime to enhance their activity since no negative impact of their application on quality profile was observed. The incidence of gray mold can be significantly reduced using some salts which are safe for consumers and the environment.     

Changes in volatile production and sensory quality of kiwifruit during fruit maturation in Actinidia deliciosa ‘Hayward’ and A. chinensis ‘Hort16A’

Although volatiles have been previously studied in kiwifruit (Actinidia spp.), there has been no co-ordinated study of volatile release and softening through the full edible period. In this report, the two most important commercial cultivars A. deliciosa ‘Hayward’ and A. chinensis ‘Hort16A’ were evaluated for volatiles released at different ripening stages corresponding to their typical commercial shelf life, and compared to the sensory quality assessed by a trained taste panel. Gas chromatography–mass spectrometry data indicated that large amounts of straight-chain aldehydes and esters were the dominant volatiles in the two cultivars. In particular, butanoates, the main fruity esters in both fruit, significantly increased during ripening and an extremely high level of butanoates was found in the over-ripe fruit. Sensory results indicated that with fruit softening, some of the changes in volatile content could explain changes in fruit flavor detected by a trained panel, and differences in characteristic flavor of the two cultivars. The results have implications for fruit sample handling and volatile assessment.     

The effect of temperature on fruit set,seed set and seed germination in ‘Sonia’ × ‘Hadley’ hybrid Tea-rose crosses

Summary The effect of temperature on fruit set, seed set and seed germination was studied in Sonia × Hadley Hybrid Tea-rose crosses. Sonia mother bushes were grown at constant temperatures (10, 14, 18, 22, 26°C) in the greenhouses of the phytotron until fruit ripening. Fruit set, fruit weight and number of seeds increased as temperature was higher. Optimum temperatures were found for days to fruit ripening (18°C), seed germination (22°C) and number of seedlings per pollinated flower (22°C). Fruit weight and number of seeds were positively correlated. For crossing and the subsequent growing of seed-bearing plants 22°C was the most favourable temperature. Effects of temperature on pollen tube growth, fertilization and seed germination are discussed.     

Characterization of ethylene biosynthesis and its regulation during fruit ripening in kiwifruit,Actinidia chinensis ‘Sanuki Gold’

Ethylene biosynthesis in kiwifruit, Actinidia chinensis ‘Sanuki Gold’ was characterized using propylene, an ethylene analog, and 1-methylcyclopropene (1-MCP), an inhibitor of ethylene perception. In fruit harvested between a young stage (66 days after pollination) (DAP) and an early commercial harvesting stage (143 DAP), 2 days of exposure to propylene were sufficient to initiate ethylene biosynthesis while in fruit harvested at commercial harvesting stage (154 DAP), 4 days of propylene treatment were required. This observation suggests that response of ethylene biosynthesis to propylene treatment in kiwifruit declined with fruit maturity. Propylene treatment resulted in up-regulated expression of AC-ACO1, AC-ACO2, AC-SAM1 and AC-SAM2, prior to the induction of AC-ACS1 and ethylene production, confirming that AC-ACS1 is the rate limiting step in ethylene biosynthesis in kiwifruit. Treatment of fruit with more than 5 μL L^?1 of 1-MCP after the induction of ethylene production subsequently suppressed ethylene production and expression of ethylene biosynthesis genes. Treatment of fruit with 1-MCP at harvest followed with propylene treatment delayed the induction of ethylene production and AC-ACS1 expression for 5 days. These observations suggest that in ripening kiwifruit, ethylene biosynthesis is regulated by positive feedback mechanism and that 1-MCP treatment at harvest effectively delays ethylene production by 5 days.     

Hydrogen ion concentration affects quality retention and modifies the effect of calcium additives on fresh-cut ‘Rocha’ pear

‘Rocha’ pear (Pyrus communis L.) was used as a model system to assess the effect of pH of dipping solutions on quality retention of fresh-cut fruit and its interaction with calcium additives. Pear slices were dipped for 60 s in a buffer solution at pH 3.0, 5.0 or 7.0 and stored at 4.5 °C for 13 days. In other experiments, pear slices were dipped for 60 s in buffer solutions containing 250 mM of calcium ascorbate, lactate, chloride, and propionate, at pH 3.0 or 7.0, and stored at 4.5 °C for 6 days. Browning and softening were more intense in slices dipped in a solution at pH 3.0 than at pH 5.0 or 7.0, but microbial growth was lower in slices treated at pH 3.0. The effect of calcium additives depended on the anion and significant interactions between the effects of calcium salt and pH were observed. Calcium ascorbate was very effective in preserving color and reducing microbial growth irrespective of pH, but enhanced pectin solubilization and tissue softening at pH 3.0. Slices treated with 250 mM calcium propionate or calcium lactate were softer and had higher electrolyte efflux when treated at pH 3.0 than at pH 7.0. Calcium lactate enhanced browning and reduced microbial growth at pH 3.0 but did not affect color or microbial counts at pH 7.0. All calcium treatments enhanced electrolyte leakage. pH of the dipping solution can affect, per se, the quality of fresh-cut fruit. The choice of calcium additives to prevent undesirable changes on visual and sensory quality of cut produce should involve pH ranges that provide the expected benefits.     

Investigating the potential of a humidification system to control moisture loss and quality of ‘Crimson Seedless’ table grapes during cold storage

The potential of humidifying cold storage rooms to control moisture loss and quality of table grapes in different package designs was studied. Fruit were stored in cold rooms (−0.33 ± 0.32 °C or −0.12 ± 0.32 °C) with humidifier (95.0% RH) or no humidification (90.3% RH) respectively. Room humidification resulted in a 7.5% and 9.0% increase in RH inside the clamshell and open-top punnets multi-scale packages respectively in comparison to non-humidified storage, while there was no significant change in RH inside the 4.5 kg carry bag multi-packaging. The grapes were assessed for weight loss and SO₂ injury at intervals during a 35 d period. After 21 d of cold storage under humidification, weight loss of grapes was significantly higher (P < 0.05) in packages with open-top punnets than clamshell punnets and carry-bags. After 35 days in non-humidified cold storage, grape weight losses were 1.45 ± 0.32%, 1.62 ± 0.21% and 2.01 ± 0.57% for the 4.5 kg carry-bag, 5 kg clamshell punnet and 5 kg open-top multi-packages, respectively. When fruit were stored inside the same types of multi-packages under humidification, the corresponding weight losses were 0.97 ± 0.34%, 1.08 ± 0.27% and 2.00 ± 0.57%. Cold storage humidification reduced the rate of stem dehydration and browning; however, it increased the incidence of SO₂ injury in table grape bunches and caused wetting of the packages.     

Effect of sustained deficit irrigation on physicochemical properties,bioactive compounds and postharvest life of pomegranate fruit (cv. ‘Mollar de Elche’)

In this study, the influence of sustained deficit irrigation (SDI; 32% of reference evapotranspiration (ET₀)) on physicochemical and sensory quality and bioactive compounds of pomegranates stored for 30, 60 and 90 days in air at 5 °C + 4 days at 15 °C, at each storage period, was studied and compared to a control (100% ET₀). Fruit from SDI had higher peel redness and greater firmness, soluble solids contents, vitamin C (27%), phloretin (98%) and protocatechuic acid (10%) levels, and total antioxidant capacity (TAC) (46%) than the control. Cold storage and shelf-life did not induce significant changes in soluble solids, pH, titratable acidity, and chroma and Hue. SDI fruit had retarded development of chilling injury (CI) symptoms, which appeared after 60 days of storage in comparison to 30 days in the controls. Anthocyanins, catechin, phloretin and protocatechuic, caffeic, p-coumaric and caffeic acids contents had greater increases in SDI fruit than in controls throughout the postharvest life. TAC was significantly (P < 0.05) correlated to anthocyanins, gallic acid and total vitamin C contents. Generally, after long term storage, the fruit grown under SDI showed higher sensory and nutritional quality, more health attributes and a longer shelf-life (up to 90 days at 5 °C + 4 at 15 °C) than fruit irrigated at 100% ET₀.     

Influence of the combination of different atmospheres on diphenylamine,folpet and imazalil content in cold-stored ‘Pink Lady®’ apples

‘Pink Lady^®’ apples were harvested at commercial maturity, treated with three different agrochemical products, and stored at 1 °C under either air or controlled atmosphere conditions (2 kPa O₂ + 2 kPa CO₂ and 1 kPa O₂ + 1 kPa CO₂) for 13 and 27 weeks, followed by 4 weeks storage in air at 1 °C. Diphenylamine, folpet and imazalil contents in both the skin and flesh were simultaneously determined after cold storage plus simulated marketing periods of 1 and 7 d at 20 °C. After 27 weeks plus 7 d, diphenylamine and folpet levels in apple skin were lower for fruit stored in low O₂ (2 kPa) or air than for those kept under ultra-low O₂ (1 kPa). An additional storage period of 4 weeks in air reduced diphenylamine and folpet contents in whole apples stored for 13 weeks in the low O₂ controlled atmosphere. For imazalil, the same result was obtained in apple skins stored for 27 weeks under an ultra-low O₂ controlled atmosphere. Differences in diphenylamine and folpet contents were found for skin and flesh samples throughout the simulated marketing period, but there were observable differences in imazalil contents only for flesh samples.     

The development of females of the potato root eelworm, (Heterodera rostochiensis Woll.) on ‘tuber-pieces’ of susceptible and resistant potatoes

A method is described for determining the degree of resistance shown by potatoes to a non-aggressive biotype of the potato root eelworm, Heterodera rostochiensis Woll., using tuber slices inoculated with H. rostochiensis larvae. The degree of resistance assessed by this method was found to agree well with the results obtained by root screening. The tuber piece method of testing for resistance could be used when root screening is impracticable or in conjunction with it.     

Responses to temperature of fruit dry weight,oil concentration,and oil fatty acid composition in olive (Olea europaea L. var. ‘Arauco’)

Correlative studies in olive using data from different locations or years suggest that temperature can modulate crop oil yield and oil composition. However, there are no published studies of manipulative experiments that demonstrate a direct role for temperature as a regulator of oil yield and oil quality in olive. The objectives of this study were to: i) elucidate the effect of temperature during the fruit oil accumulation phase on fruit dry weight, oil concentration and fatty acid composition; and ii) identify the developmental window within the oil accumulation phase exhibiting the greatest sensitivity to temperature and that with the highest fruit capacity to recover from the temperature treatments. Two branch-level experiments were conducted in a commercial orchard at Los Molinos (La Rioja, Argentina) using var. ‘Arauco’. Both experiments were conducted during the oil accumulation phase by enclosing fruiting branches in transparent plastic chambers with individualized temperature control. The first experiment; known as the four month long experiment, employed four temperature treatments that were applied for a single period of four months: a control at ambient temperature, two heating levels (5 °C and 10 °C warmer than the control), and a cooling level (5 °C cooler than the control). The second experiment consisted of four separate successive one month long treatment periods, in each of which two temperature treatments were applied: control and heating (ca. 7 °C higher than control). In the four month long experiment, fruit dry weight was not affected by average temperatures in the 16–25 °C range, but it was reduced with further increases in temperature. Oil concentration decreased linearly at 1.1% °C⁻¹ across the whole range (16–32 °C) of average seasonal temperatures explored, while oleic acid concentration decreased 0.7% °C⁻¹ over the same range. In the one month long experiment, 30 days of temperatures ca. 7 °C above ambient had a permanent negative effect on oil concentration at final harvest, particularly when the exposure to high temperature took place at the beginning of oil accumulation. By contrast, oleic acid concentration at the end of the treatment interval fell with increasing temperature but it could recover after treatment was removed in all periods except the first one. These results show that high temperatures during the oil accumulation phase may negatively affect olive oil yield and quality in warm regions, particularly if the high-temperature event occurs early in the phase. Additionally, the response of oleic acid concentration (%) to temperature under our experimental conditions was found to be opposite to that of many annual oil-seed crops.