Investigating non-destructive quantification and characterization of pomegranate fruit internal structure using X-ray computed tomography

In this study, X-ray computed tomography (CT) coupled with image analysis techniques was investigated for non-destructive characterization and quantification of internal structure of intact pomegranate fruit (cv. Shani-Yonay). X-ray tomograms of intact fruit were acquired using a V|Tome|X L240 commercial X-ray CT system based on X-ray radiation generated from a source voltage of 200 kV with the electron current set at 100 μA. Two-dimensional (2D) radioscopic images were acquired with a microfocus direct X-ray tube and used to reconstruct three-dimensional (3D) images to quantify volumes occupied by air space, albedo, and arils, using image processing software. The calculated volumes for these fruit fractions were 7.82 ± 1.09, 167.29 ± 16.54, and 182.11 ± 17.04 mL, estimated to contribute 2.22, 46.86 and 50.92% of total fruit volume, respectively. Destructive validation data were similar to non-destructive data, with volumes for albedo and arils of 166.08 ± 14.69 and 170.58 ± 14.25 mL, respectively, contributing 46.07 and 47.32% of total fruit volume. The remaining 6.61% of total fruit volume tested destructively could be due to the presence of air space and calyx. This work has demonstrated the capability of X-ray CT with image analysis as a useful non-destructive technique to study the quantity and distribution of edible and non-edible portions of pomegranate fruit.     

Analysing the energy balances of sugar beet cultivation in commercial farms in Germany

Energy balances are increasingly used to assess the energy efficiency and productivity of agricultural production. In this study, energy balances for sugar beet cultivation in commercial farms in Germany were calculated. 109 farmers with 285 fields were interviewed about the sugar beet cultivation 2004. The energy input and the energy output were calculated with standardised balance-sheet approaches and energy equivalents. Calculated energy balance parameters were the energy gain (energy output less input), the output–input ratio (energy output versus input) and the energy intensity (energy input versus natural yield measured in Grain Equivalents). A factor analysis was performed to explain the variation of the energy balance parameters between the fields by crucial factors for energetic efficiency and productivity. Fields with similarly valued factors were grouped into common clusters by a cluster analysis and a discriminant analysis. The influence of specific growing conditions and cultivation methods on the energy balances were examined for the clusters.Total energy input (median: 17.3 GJ ha⁻¹), energy output (261.7 GJ ha⁻¹), energy gain (244.6 GJ ha⁻¹), output–input ratio (15.4) and energy intensity (87.4 MJ GE⁻¹) revealed a significant variation. The total energy input was significantly lower and the energy yield was significantly higher than in previous studies. Thus, the energy gain and the output–input ratio have clearly risen compared to earlier studies. Today, sugar beet cultivation is energetically more productive and efficient than the cultivation of many other arable crops in Middle Europe.The intensity of the cultivation measures irrigation, catch crop cultivation, tillage and N fertilisation as well as the management of all cultivation measures and the site were determined as crucial factors for energy efficiency and productivity. The intensity of the different cultivation measures influenced the total energy input significantly, but no influence on the energy output was determined. In contrast, the cultivation management (quality and adaptation of cultivation measures) was mainly responsible for the energy output. Whereas the cultivation management mostly explained the energy gain, the factor cultivation management and the factors representing cultivation intensity together were responsible for the output–input ratio.Cluster and discriminant analysis resulted in the formation of 13 clusters. For clusters with an above-average energy gain and output–input ratio, the intensity and in particular the management of cultivation measures were essential for optimising the energy balance.     

Postharvest treatment of polyamines maintains quality and extends shelf-life of table grapes (Vitis vinifera L.) cv. Flame Seedless

Investigations were carried out to verify the potential of putrescine and spermidine as a postharvest dip treatment for maintaining quality and extending storage life of table grapes (Vitis vinifera L.) cv. Flame Seedless during the 2012 and 2013 seasons. Grape clusters were manually harvested at the commercial mature stage and were dipped in different concentrations (0.0, 0.5, 1.0 and 1.5 mM) of putrescine and spermidine, and then stored at 3–4 °C, and 90–95% RH. Evaluation of physico-chemical parameters and other fruit quality attributes were made at 0 day (before treatment) and at 30, 45, 60 and 75 days of storage. Putrescine and spermidine at the lowest dose (0.5 mM) effectively maintained berry firmness, peel colour (L*, C*, h°) and stabilized anthocyanins as well as suppressing the activity of pectin methylesterase and reducing the rate of electrolyte leakage. The polyamines also retarded the degradation of TSS and TA while maintaining higher total phenol content and reduced decay incidence. Putrescine and spermidine at 1.0 mM exhibited almost similar effects with a 0.5 mM dose. The highest doses (1.5 mM) of both polyamines showed detrimental effects, especially on weight loss, decay incidence, rachis browning and organoleptic properties, as found in the control group, which was commercially acceptable only up to 45 days. Furthermore, analysis of linear regressions and correlations showed that many quality parameters were interdependent. The postharvest dip treatment of spermidine or putrescine at a dose of 0.5 mM for 5 min could be an effective means for prolonging storage and increasing shelf-life of ‘Flame Seedless’ grapes.     

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.     

UV-C light inactivation kinetics of Penicillium expansum on pear surfaces: Influence on physicochemical and sensory quality during storage

UV-C inactivation kinetic data of Penicillium expansum on intact and wounded pear disks were determined. P. expansum conidia (0.5 mL, 1.6 × 10⁷ CFU/mL) were spot inoculated onto intact and wounded pear tissue with skin (excised disks), treated with UV-C doses ranging 0.101–3.06 kJ/m² at 23 °C and surviving conidia were enumerated. Changes in selected physicochemical parameters and sensory quality following UV-C treatment of whole pears were determined immediately after treatment, and 4 and 8 weeks of storage at 4 °C. A greater UV-C intensity was required for similar inactivation levels of P. expansum populations on wounded pear disks (3.1 kJ/m² for 2.7 log reduction) compared to intact pear disks (1.7 kJ/m² for 2.8 log reduction). No significant difference in % weight loss, or soluble solids content and texture was observed between UV-C treated and untreated pears. However, browning was observed on UV-C treated pear surfaces after 4 and 8 weeks along with changes in flavor and texture. An increase in consumer preference was noticed for the untreated control pears after 4 weeks storage.     

Effectiveness of 1-MCP treatments on ‘Bartlett’ pears as influenced by the cooling method and the bin material

Wooden bin-stored ‘Bartlett’ pears (Pyrus communis L.) were hydrocooled (HC) or forced-air cooled (FAC) and immediately treated or not with 1-methylcyclopropene (1-MCP) for 24 h. 1-MCP gas concentrations used were 0, 0.3 or 0.6 μL L^?1 (called 0, 0.3 and 0.6, respectively). Fruit were subsequently kept at 20 °C for 20 d or stored at ?0.5 °C and 95% RH for 60, 90, 120 or 150 d. After cold storage, fruit were kept at 20 °C for up to 16 d for further ripening. In another experiment, pears stored in wooden bins (W) or plastic bins (P) were all hydrocooled, treated or not with 0.5 μL L^?1 1-MCP (called 0.5 and 0, respectively), stored at ?0.5 °C and 95% RH for 0, 30, 60, 90 or 120 d, and transferred to 20 °C for further ripening. In FAC pears, increasing 1-MCP concentrations usually resulted in delayed increases in ethylene production and lower ethylene production rates, as well as delayed softening. In contrast, HC-0.3 pear firmness did not differ from that of HC-0 fruit after cold storage. Generally, HC-0.3 pears displayed higher ethylene production and lower firmness values than FAC-0.3 pears after a 7-d exposure to 20 °C, regardless the length of cold storage. FAC-0.6 pears always showed lower ethylene production rates and higher flesh firmness values than HC-0.6 fruit. Soluble solids concentration was not consistently affected by 1-MCP. FAC-0.3 and HC-0.6 fruit showed higher titratable acidity values than HC-0 fruit after 0, 60, 120 and 150 d of cold storage plus 7 d at 20 °C. Effectiveness of 1-MCP treatments on HC pears was influenced by the bin material; P-0.5 pears were firmer than W-0.5 pears after 7 d at 20 °C, regardless the length of the cold storage. HC-0.5 fruit exposed to ?0.5 °C for 90 d reached eating quality (firmness ≤23 N) by day 7 if placed in W, and by day 21 when stored in P. Results and previous evidence suggest that wet wooden bin material may represent a major though unpredictable source of 1-MCP sorption that could bind a significant percentage of the 1-MCP applied. When used at relatively low doses 1-MCP partial removal by wet wooden bins can compromise the application effectiveness for controlling ethylene action.     

Temperature and relative humidity effects on quality,total ascorbic acid,phenolics and flavonoid concentrations,and antioxidant activity of strawberry

The physical qualities and antioxidant components of ‘Jewel’ strawberry fruit stored in 75, 85 or 95% relative humidity (RH) at 0.5, 10 and 20 °C for 4 days were studied. Overall fruit quality declined more rapidly at 20 °C, especially at 95% RH. Weight loss of fruit was negligible for 2 days at all temperatures but it increased at 10 °C in the lowest RH and increased rapidly from day 3 at 20 °C especially with lower RH. Firmness was maintained, or even increased, at 0.5 or 10 °C, while soluble solids concentrations (SSC) decreased at higher storage temperatures. Red color, assessed using chroma, hue and lightness, and anthocyanin concentrations were relatively unchanged at 0.5 or 10 °C but increased rapidly at 20 °C as fruit ripened. Firmness, SSC and color were not affected by RH. Total phenolic compounds were slightly higher at 20 °C than at other temperatures at all RHs. Total ascorbic acid concentrations of the fruit remained similar for the first 2 days of storage, then declined in fruit stored at 0.5 and 20 °C, but remained unchanged at 10 °C at all RHs. Total flavonoid content of fruit did not change over time at all temperatures. The total antioxidant activity of fruit was higher at 10 °C than at 0.5 and 20 °C on day 3, and no effect of RH was detected. In conclusion, while the best temperature for long-term storage is 0.5 °C, quality could be maintained at 10 °C for acceptable periods of time for marketing and may be associated with better nutritional quality.     

Effect of 60Coγ-irradiation doses on nutrients and sensory quality of fresh walnuts during storage

Fresh Liaohe walnuts (Juglans regia cv. Liaoning4) were given ⁶⁰Coγ-irradiation doses of 0, 0.1, 0.5, 1.0 and 5.0 kGy and stored at 0 ± 1 °C for 120 d. The concentrations of fat, protein, fatty acid, soluble sugar, water and vitamin E (V_E), peroxide value (PV) and the sensory quality were determined at regular intervals during storage. Irradiation at 0.1, 1.0 and 5.0 kGy accelerated lipid oxidation, increased the PV, and decreased the sensory quality and V_E content of walnuts during storage. However, an irradiation dose of 0.5 kGy resulted in less oxidative degradation, reduced PV, and maintained a higher V_E concentration and better sensory quality of walnuts during the 90 d storage. We conclude that a dose of 0.5 kGy is the optimal dose for the preservation of fresh walnuts over a 90 d storage period.     

Thiabendazole residue loading in dip,drench and wax coating applications to control green mould and chilling injury on citrus fruit

Green mould (caused by Penicillium digitatum) is a major cause of postharvest losses in citrus. Residue loading of thiabendazole (TBZ) with application methods typically used in South African packhouses and green mould control was studied. TBZ was applied curatively and protectively in dip, drench and wax coating treatments and fruit were inoculated with a TBZ-sensitive or a TBZ-resistant isolate of P. digitatum. The dip treatments consisted of TBZ concentrations of 0–2000 μg mL⁻¹; fruit were dipped for 60 s at 22 °C at a pH of 7. Residues differed between fruit batches and ranged from 0.5 to 1.7 μg g⁻¹ at 1000 μg mL⁻¹ TBZ. Curative dip treatments almost completely controlled green mould (>96% at 1000 μg mL⁻¹ TBZ). The residue level needed for 75% curative control ranged from 0.06 to 0.22 μg g⁻¹, depending on citrus type. Protective treatments were unreliable and control varied from 17% to 97.9% at 1000 μg mL⁻¹ TBZ between fruit batches. Drench treatments consisted of exposure times of 30, 60 and 90 s with 1000 or 2000 μg mL⁻¹ TBZ. Average TBZ residues were 2.14 μg g⁻¹ for Clementine mandarin fruit and 3.50 μg g⁻¹ for navel orange fruit. Green mould control on navel orange fruit resulted in 66–92%, 34–90% and 9–38% control for curative treatments after 6 and 24 h and protective treatments, respectively, depending on fruit batch. Wax with 4000 μg mL⁻¹ TBZ was applied at 0.6, 1.2 and 1.8 L wax ton⁻¹ fruit. Chilling injury was evaluated after fruit storage at −0.5 °C for 40 days. Average TBZ residues loaded was 1.3, 1.3 and 2.7 μg g⁻¹ at the recommended 1.2 L ton⁻¹ for Satsuma mandarin, Clementine mandarin and Valencia orange fruit, respectively. Protective treatments showed lower infection levels (14–20%) than curative treatments (27–40%) for Valencia orange fruit. The same trend was observed with Satsuma (92–95% curative; 87–90% protective) and Clementine mandarin fruit (82–90% curative; 59–88% protective), but control was relatively poor. TBZ application in wax exceeded 5 μg g⁻¹ at higher wax loads (1.2 and 1.8 L ton⁻¹). Wax treatments showed a significant reduction in chilling injury; TBZ had an additive effect. TBZ resistant isolates could not be controlled.     

Effect of fruit moving speed on predicting soluble solids content of ‘Cuiguan’ pears (Pomaceae pyrifolia Nakai cv. Cuiguan) using PLS and LS-SVM regression

Visible (Vis)/near infrared (NIR) spectroscopy is an excellent technique for non-destructive fruit quality assessment. This research was focused on evaluating the use of Vis/NIR spectroscopy for measuring soluble solids content (SSC) of intact ‘Cuiguan’ pears (Pomaceae pyrifolia Nakai cv. Cuiguan) on-line. Also, the effect of fruit moving speed on SSC measurements was investigated. Diffuse transmission spectra were collected using a fiber spectrometer equipped with a 3648-element linear silicon CCD array detector in the wavelength range of 345–1040 nm, and all sample spectra were collected three times at different fruit moving speeds of 0.3 m s^?1, 0.5 m s^?1 and 0.7 m s^?1. Spectral pre-processing such as derivative, standard normal variate transformation (SNV) and multiplicative scatter correction (MSC) was used before calibration. Partial least squares (PLS) and least squares support vector machines (LS-SVM) were used to develop calibration models for SSC. The results show that fruit moving speed has few effects on spectra and model performance at a fruit moving speed of 0.3–0.7 m s^?1. At 0.5 m s^?1, the best model for SSC was PLS regression coupled with original spectra, its coefficient of determination (R²) and root mean square error of prediction (RMSEP) being 0.916% and 0.530%, respectively.     

Effect of hyperbaric pressure and temperature on respiration rates and quality attributes of tomato

Previous work with hyperbaric treatment of tomato focused on application at lower temperature (13 °C). In this work, hyperbaric treatment at varying pressure levels (i.e., 0.1, 0.3, 0.5, 0.7 and 0.9 MPa) at ambient temperature (20 °C) was tested as a potential alternative to conventional refrigerated storage (0.1 MPa at 13 °C) to preserve tomato quality. The experiments were divided into 3 phases: (1) 4 day of hyperbaric treatment, (2) 5 day of post-treatment ripening, and (3) 10 day of post-treatment ripening. Respiration rate (RR) of the tomatoes was continuously monitored during the course of the hyperbaric treatments. Quality attributes were assessed immediately after removal from the hyperbaric treatments and after 5 and 10 day ripening at 20 °C after removal from the treatments. Hyperbaric treatments at ≥0.3 MPa resulted in RR equal or higher than the RR in control fruit (0.1 MPa at 20 °C). The lowest RR was obtained from tomato stored at 0.1 MPa at 13 °C. Hyperbaric treatment at 0.5, 0.7 and 0.9 MPa significantly reduced weight loss, retained color, firmness, total soluble solid (TSS), titratable acidity (TA) and TSS:TA ratio at similar levels as the tomato treated at 13 °C and 0.1 MPa. Firmness after treatment was highest for fruit from 0.1 MPa at 13 °C and from 0.5, 0.7 and 0.9 MPa at 20 °C. The higher firmness advantage declined by 5 day of ripening after treatment, with higher firmness only being retained for fruit from the 0.9 MPa at 20 °C and the 0.1 MPa at 13 °C treatments. After 10 day ripening, firmness was similar for all treatments. Lightness (L*) and hue angle were greater for all treatments compared with the 0.1 MPa at 20 °C treatment. However, only the greater hue angle difference was maintained after 5 day of ripening. After 10 day ripening, no significant differences were found in color attributes. Only 0.1 MPa at 13 °C retained higher soluble solids, lower titratable acidity and higher TSS:TA ratios after treatment and after 5 day ripening. At 10 day of ripening none of the quality attribute differences noted were retained for any of the treatments. These results show that the only consistent effect of hyperbaric treatment at 0.5, 0.7 and 0.9 MPa was to reduce weight loss and enhance firmness retention up to 5 day ripening after treatment.     

Modeling the effect of preharvest weather conditions on the incidence of soft scald in ‘Honeycrisp’ apples

‘Honeycrisp’ apples show a high susceptibility to physiological disorders such as soft scald. The objective of this study was to identify weather parameters during fruit development that influence soft scald development in ‘Honeycrisp’ apples. Soft scald susceptibility of ‘Honeycrisp’ has been linked to weather conditions during specific periods of the growing season, referenced by given phenological stages. Using weather data and fruit quality analysis data from three sites in Ontario, two sites in Quebec and one site in Nova Scotia for three seasons (2009–2011) and four additional sites in Ontario from 2002–2006, a model for soft scald incidence (SSI) was built to predict the susceptibility of ‘Honeycrisp’ apples prior to storage. This model used primarily two weather variables during three sub-periods of fruit development to accumulate a SSI index (%) during the growing season, from full bloom to harvest time. Relatively wet conditions during phenological stages from full bloom until 10 mm diameter (precipitation > 0.5 mm) and from 10 mm until 50% of final caliber (precipitation > 6.0 mm), cool conditions (temperature < 15 °C) from full bloom until 10 mm diameter, and warm conditions (temperature > 20 °C) from 50 to 80% of final size are conditions that resulted in increased soft scald susceptibility for ‘Honeycrisp’ apples. The SSI model may be used by producers to establish more appropriate marketing and storage strategies depending on levels of susceptibility to soft scald development predicted prior to storage.     

Low oxygen levels and light exposure affect quality of fresh-cut Romaine lettuce

Modified atmosphere packaging (MAP) has the potential to extend the shelf-life of fresh-cut lettuce mainly by limiting the oxidation processes. However, exposure to light conditions has been described as causing browning and quality loss. The influence of O₂ partial pressures (pO₂) and light exposure during storage on the shelf-life of fresh-cut Romaine lettuce was studied. Fresh-cut lettuce was exposed daily during storage to different light conditions: light (24 h), darkness (24 h) and photoperiod (12 h light + 12 h darkness). Changes in respiration rate, headspace gas composition, sensory quality, colour, electrolyte leakage, stomatal opening, water loss, texture and compositional constituents related to browning such as vitamin C and individual and total phenolic compounds were evaluated. Different weight samples (75–275 g), packaged with an initial pO₂ of 0.5–2.0 kPa balanced with N₂, reached pO₂ from 0.1 to 1.5 at the steady-state. Atmospheres with low pO₂ (0.2–0.5) at the steady-state preserved lettuce quality by the control of browning and the prevention of off-odours and off-flavours. Light exposure during storage positively influenced the number of open stomata (74% in light vs 24% in darkness) which contributed slightly to weight loss. Consumption of O₂ in samples exposed to light differed significantly from those stored in photoperiod or darkness (10.6 ± 7.0, 18.3 ± 3.5 and 25.8 ± 8.6 nmol O₂ kg^?1 s^?1, respectively). Packages exposed to light showed higher pO₂ compared with packages stored in darkness while those exposed to photoperiod had intermediate values. Moreover, location of the packages in the shelves affected package headspace gas composition and thus, packages near the front of the shelves showed higher pO₂ than those at the back. The different light conditions did not influence the content of vitamin C or the individual and total phenolic compounds. This study shows that under light conditions respiration activity was compensated by photosynthesis resulting in a higher pO₂. Thus, browning of fresh-cut Romaine lettuce can be promoted by light exposure during storage as it increases headspace pO₂.     

Lemongrass essential oil incorporated into alginate-based edible coating for shelf-life extension and quality retention of fresh-cut pineapple

The effects of different concentrations (0.1%, 0.3% and 0.5%, w/v) of lemongrass essential oil incorporated into an alginate-based [sodium alginate 1.29% (w/v), glycerol 1.16% (w/v) and sunflower oil 0.025% (w/v)] edible coating on the respiration rate, physico-chemical properties, and microbiological and sensory quality of fresh-cut pineapple during 16 days of storage (10 ± 1 °C, 65 ± 10% RH) were evaluated. Coated fresh-cut pineapple without lemongrass and uncoated fresh-cut pineapple were stored under the same conditions and served as the controls. The results show that yeast and mould counts and total plate counts of coated samples containing 0.3 and 0.5% (w/v) lemongrass were significantly (p < 0.05) lower than other samples. However, the incorporation of 0.5% (w/v) lemongrass in coating formulation significantly (p < 0.05) decreased the firmness and sensory scores (taste, texture and overall acceptability) of fresh-cut pineapples. Therefore, the results indicate that an alginate-based edible coating formulation incorporated with 0.3% (w/v) lemongrass has potential to extend the shelf-life and maintain quality of fresh-cut pineapple.     

Optimization of postharvest ultrasonic treatment of strawberry fruit

Freshly harvested strawberry fruit were treated at ultrasonic powers from 250 to 450 W at a constant frequency of 40 kHz for different times (5–15 min). Response surface methodology (RSM) based on a two factors three level central composite design was applied to optimize ultrasonic treatments on decay incidence, microbial population and quality maintenance of strawberries. According to response surface analysis, the optimal treatment parameters were an ultrasonic power of 250 W and treatment time of 9.8 min. Decay incidence and quality parameters of strawberries treated at the determined optimum conditions were compared with a water treatment during storage for 8 d at 5 °C. An ultrasonic treatment was found to be effective in inhibiting decay incidence and preserving quality in strawberries, and these results suggest that such a treatment may provide an alternative for extending shelf-life and maintaining quality of strawberry fruit.     

Ethanol vapor treatment maintains postharvest storage quality and inhibits internal ethylene biosynthesis during storage of oriental sweet melons

In order to evaluate the effect of ethanol vapor treatments (0.5 mL/kg and 3 mL/kg) on postharvest storage at 23 °C, quality of oriental sweet melons, and to clarify the mechanism of the inhibition of senescence, we investigated physiological and quality changes induced by ethanol vapor, decay incidence, internal ethylene concentration (IEC) and ethylene-related enzymes activities as well as gene expression. Both ethanol vapor treatments, irrespective of concentration, significantly (P < 0.5) delayed skin color changes, retarded softening and suppressed fruit decay in ethanol vapor-treated fruit. Between the two treatments, 0.5 mL/kg of ethanol vapor maintained better quality in storage than that of 3 mL/kg. Compared with the control, both ethanol vapor treatments resulted in different profiles and composition of aromatic volatile compounds of fruit during storage, and a significant increase of ethyl esters, including ethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl 2-methylbutanoate, 3-(methylthio) propionate and 2-phenethyl acetate, and five new ethyl esters were also detected. Both treatments increased alcohol acyl-transferase (AAT) activity levels, which peaked earlier than in the control, but there were no significant differences in activities of alcohol dehydrogenase (ADH). Both treatments significantly (P < 0.5) suppressed internal ethylene concentrations (IEC) during storage at 23 °C, which was evident from reducing 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) activities, and inhibiting ACC biosynthesis, and the effect of the 0.5 mL/kg treatment was better than that of 3 mL/kg. Real-time quantitative PCR (Q-PCR) analysis showed that the expression patterns of CM-ACO1, CM-ACO2, CM-ACS1 and CM-ACS2 were consistent with ethylene production during storage. These results suggest that postharvest ethanol vapor treatments markedly delayed the senescence of harvested oriental sweet melons, maintained better quality in storage and improved levels of volatile aroma compounds, especially the ethyl esters, through suppressing the expression of particular members of ethylene-forming enzyme gene families as well as ethylene biosynthesis, and the effect is dose dependent.     

Application of optical coherence tomography to non-destructively characterise rind breakdown disorder of ‘Nules Clementine’ mandarins

The feasibility of optical coherence tomography (OCT) for imaging histological changes associated with the development of a progressive rind breakdown (RBD) disorder of ‘Nules Clementine’ mandarin (Citrus reticulate Blanco.) was investigated. The investigation utilised fruit with different levels of the disorder, carefully selected from a batch of fruit stored for eight weeks at 8 ± 0.5 °C. Images of healthy and RBD-affected intact mandarin fruit were acquired using a Thorlabs OCT system based on a broadband 930 nm source. OCT provided high resolution 2D images of fruit rind to a depth of about 1.1 mm. Immediate and non-destructive acquisition of images showing histological and microstructural features in intact rind tissues was demonstrated. The oil glands stayed intact in unaffected fruit and gradually collapsed in RBD affected fruit. At advanced stages of the disorder, the collapsed oil glands became increasingly deformed and flattened. The study showed that OCT is a promising technique for immediate, real-time and non-destructive acquisition of images showing histological and microstructural rind features of ‘Nules Clementine’ mandarin fruit.     

Influence of fertilisation and harvest time on fuel quality of giant reed (Arundo donax L.) in central Italy

The perennial grass giant reed (Arundo donax L.) has been proposed as a promising biomass energy crop in southern Europe. The aim of this study was to investigate the effects of two fertilisation levels (F = 200–80–200 N–P–K kg ha^?1; UF = 0–0–0 N–P–K kg ha^?1) and two harvest times (A: autumn, W: winter) on the biomass quality of giant reed as a solid fuel for combustion. Different aged crops grown in central Italy (latitude 43°40′N, and longitude10°19′E) in the period of 1996–2005 were collected and analysed. Our results confirmed that giant reed biomass is characterized by a high content of ash and silicon. Giant reed showed an increase in ash content from F to UF and from A to W. The production of biomass from fertilised crops harvested in the autumn may thus be a good method for reducing the ash content by about 20%. The results also showed an improvement in biomass combustion quality in 10-year-old crops due to a lower ash content and higher SiO₂/K₂O and CaO/K₂O ratios, which could contribute to a lower slagging tendency. This research should help to improve our knowledge of the chemical composition of giant reed and presents possible agronomic strategies to combine a high biomass yield with good combustion quality.     

Effect of radiation intensity on the outcome of postharvest UV-C treatments

Studies on the use of UV-C radiation of fresh produce have focused on the selection of appropriate doses (energy per unit area) for different commodities, but little attention has been placed on the effect of radiation intensity (dose per unit time). In this study, tomatoes (Solanum lycopersicum cv. Elpida) and strawberries (Fragaria × ananassa cv. Camarosa), were harvested (breaker and 100% of surface red color respectively) and treated with 4 kJ m⁻² of UV-C, at low (3 W m⁻²) or high (33 W m⁻²) radiation intensities. Untreated fruits were used as controls. After the treatments and at different storage times the incidence of postharvest rots and the changes in fruit physical and chemical properties were determined. UV-C treatments reduced decay, with the effects being were more marked in fruit exposed to high intensities. Mold counts were unaffected by the treatments, suggesting that improved disease control did not result from greater germicide effect. In both fruit species exposure to UV-C radiation delayed ripening, evidenced as lower color development, pigment accumulation and softening. UV-C-treated fruit maintained better quality than the control. In strawberry, high intensity treatments were more effective to prevent deterioration than in tomato where the differences between UV-C treatments were subtler. Soluble solids, titratable acidity and ethanol soluble antioxidants were not affected regardless of the UV-C intensity. Consumer tests showed higher preference of fruit treated at high UV-C intensity. Results show that in addition to the applied dose, radiation intensity is a main factor determining the effectiveness of UV-C treatments and should not be over-sighted. For a given dose, increasing radiation intensity may in some cases maximize the benefits of UV-C on fruit quality, while significantly reducing the treatments time.