Bruise susceptibility of banana peel in relation to genotype and post-climacteric storage conditions

The aim of this study was to understand the genotypic factors and post-climacteric storage conditions that affect bruise susceptibility of banana peel. Putative physicochemical indicators of bruise susceptibility, including peel electrolyte leakage (PEL), total polyphenolic content, hardness, water content, and peel thickness, were investigated. Bruise susceptibility is the lowest impact energy needed to produce visible bruising by an object dropped on post-climacteric banana fruit from a pre-determined height, converted into impact energy (20–200 mJ with a 20 mJ increment). The bananas were stored either at 18 °C throughout ripening or at 13 °C between the 2nd and 6th day after ethylene induction. Five cultivars with contrasting susceptibility to impact bruises were used. Neither Grande Naine nor hybrid Flhorban925 bruised at the maximum impact energy (200 mJ) during ripening whatever the storage conditions. A gradient in bruise susceptibility was observed among the other cultivars: French Corne > Fougamou > hybrid Flhorban916. Bruise susceptibility increased during ripening and was higher in bananas stored at 18 °C. The lower ripening temperature resulted in a two-day delay to fruit maturity as well as in bruise susceptibility. Bruise susceptibility was positively correlated with PEL (R = 0.78) and to a lesser extent negatively correlated with hardness (R = −0.45), and was not correlated with polyphenolic content. In conclusion, membrane permeability provides the first clue to understanding bruise susceptibility.     

Temperature effects on peel spotting in ‘Sucrier’ banana fruit

Banana fruit of the cultivar ‘Sucrier’ (Musa acuminata, AA Group) develops peel spotting at a relatively early stage of development (when the peel is about as slightly more yellow than green). Holding ripening bananas at 15 and 18 °C instead of room temperature (26–27 °C) only temporarily reduced spotting, but holding the fruit at 12 °C completely prevented it. The 12 °C treatment resulted in a lower level of total free phenolics, but had no effect on PAL or PPO activity. Transfer of banana fruit previously held at 12 °C to room temperature rapidly increased peel spotting. Transfer of bananas that had some spotting, from room temperature to 12 °C did not prevent further development of the spotting. It is concluded that holding spotless fruit at 12 °C prevents the spotting, although only if they are kept at that temperature, and that PAL and PPO activities seem not rate-limiting.     

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.     

Effect of atmospheric modification, 1-MCP and chemicals on quality of fresh-cut banana

Fresh-cut banana slices have a short shelf-life due to fast browning and softening after processing. The effects of atmospheric modification, exposure to 1-MCP, and chemical dips on the quality of fresh-cut bananas were determined. Low levels of O₂ (2 and 4 kPa) and high levels of CO₂ (5 and 10 kPa), alone or in combination, did not prevent browning and softening of fresh-cut banana slices. Softening and respiration rates were decreased in response to 1-MCP treatment (1 μL L⁻¹ for 6 h at 14 °C) of fresh-cut banana slices (after processing), but their ethylene production and browning rates were not influenced. A 2-min dip in a mixture of 1% (w/v) CaCl₂ + 1% (w/v) ascorbic acid + 0.5% (w/v) cysteine effectively prevented browning and softening of the slices for 6 days at 5 °C. Dips in less than 0.5% cysteine promoted pinking of fresh-cut banana slices, while concentrations between 0.5 and 1.0% cysteine delayed browning and softening and extended the post-cutting life to 7 days at 5 °C.     

Apparent synergism between the positive effects of 1-MCP and modified atmosphere on storage life of banana fruit

Fruit of cv. Gros Michel banana were treated with 1-MCP (1000 nL L⁻¹ for 4 h at 25 °C) and then packed in non-perforated polyethylene (PE) bags for modified atmosphere storage (MAP). The bags were placed in corrugated cardboard boxes and stored at 14 °C. Fruit were removed from cool storage and ripened at room temperature using ethephon. The length of storage life was determined by the change in peel color to yellow, after this ethephon treatment. Fruit treated with 1-MCP + MAP had a storage life of 100 days. The storage life of control fruit (no 1-MCP and no MAP) was 20 days. Fruit held in PE bags without 1-MCP treatment had a 40 day storage life, and the same was found in fruit treated with 1-MCP but without PE bags. 1-MCP is an inhibitor of ethylene action, but also inhibited ethylene production, mainly through inhibition of ACC oxidase activity in the peel. MAP inhibited ethylene production mainly through inhibition of ACC oxidase, both in the peel and pulp. The combination of 1-MCP treatment and MAP storage resulted in much lower ethylene production due to inhibition of both ACC synthase and ACC oxidase activity.     

Physiology and quality response of harvested banana fruit to cold shock

Experiments were conducted to examine softening and quality responses of harvested banana fruit to cold shock treatment intended to extend shelf-life. Fruit were immersed in ice-water for 1 h, then treated with or without 100 μL L^?1 ethylene for 24 h at 24 °C, and finally stored at 20 °C. Fruit firmness, chlorophyll content, ethylene production, respiration rates, contents of pectin, starch and sugar, and the activities of the cell wall modifying enzymes polygalacturonase (PG), pectin methylesterase (PME) and CMCase (cellulase, endo-1,4-β-glucanase) were analyzed. Total amylase activity was also measured. Immersion in ice-water for 1 h effectively inhibited ripening-associated processes, including peel de-greening and pulp softening during storage or ripening. The delay in ripening was also manifest in reduced ethylene production and respiration rates. The inhibition of softening by cold shock treatment was related to decreased PG and PME activities, that is, retardation of pectin solubilization/degradation. Reduced activities of CMCase and total amylase and conversion of starch to sugar by ice-water immersion also contributed to the delay in softening of harvested banana fruit.     

Reduction of energy usage during storage and transport of bananas by management of exogenous ethylene levels

Unripe Australian-grown Cavendish and Lady Finger bananas were stored at 15, 20 and 25 °C in an atmosphere containing 0.001, 0.01, 0.1 and 1.0 μL/L ethylene in air and the green life was determined as the time to reach the respiratory climacteric. As expected, green life increased as the temperature and ethylene concentration decreased. The equation describing the relationship between temperature, ethylene concentration and green life of Cavendish bananas was applied to a five-day 3000 km road transport route from the major tropical production area to the major urban markets. It predicted that bananas transported in the prevailing mean summer temperature of 25 °C would not require refrigeration if the ethylene level did not exceed 0.58 μL/L while transport at the mean winter temperature of 14 °C fruit could withstand a level of about 0.90 μL/L without ripening en route. The equation was also applied to a shipment protocol of 19 days for bananas exported from Central America to southern Europe. This predicted that fruit could be transported without refrigeration if ethylene levels were maintained at 0.04 μL/L during the winter temperature of 17 °C and at 0.002 μL/L at the summer transport temperature of 24 °C. Since a range of technologies are available to maintain such low ethylene levels or reduce the action of ethylene, these findings suggest that the current refrigerated transport of bananas could be minimised or eliminated. The use of higher temperatures in the supply chain would reduce energy consumption with resultant environmental and economic benefits.     

Effect of oxalic acid on ripening attributes of banana fruit during storage

The effect of exogenous oxalic acid treatment on ripening attributes of banana fruit during storage was investigated. Banana fruit were dipped into solutions of 0 (control) or 20 mM oxalic acid for 10 min and then stored at room temperature (23 ± 2 °C) and 75–90% relative humidity. The application of oxalic acid reduced fruit deterioration during storage. The oxalic acid treatment also reduced the rates of respiration and ethylene production, and delayed the decreases in firmness, hue angle, and maximal chlorophyll fluorescence (Fv/Fm) of banana fruit during storage. Furthermore, fruit treated with oxalic acid exhibited higher superoxide dismutase activity and antioxidant capability with a lower production of reactive oxygen species at the late storage period compared with non-oxalic acid-treated fruit. Overall, the oxalic acid treatment was effective in inhibiting postharvest ripening of banana fruit and exhibited the potential for commercial application to store the bananas at room temperature. It can be concluded that the delay in banana fruit ripening associated with oxalic acid treatment could be due to inhibition of respiration and ethylene production rates, and reduction of oxidative injury caused by reactive oxygen species through increased antioxidant activity.     

High oxygen levels promote peel spotting in banana fruit

We studied the effect of high oxygen on early peel spotting in ‘Sucrier’ bananas held at 25 °C and 90% RH. Fruit first ripened to colour index 3–4 (about as yellow as green) and were then held in containers with a continuous gas flow of 18 ± 2 kPa (control) or 90 ± 2 kPa oxygen. High oxygen promoted peel spotting. The in vitro activities of phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO), measured both in the whole peel and in peel spots, were lower in high oxygen than in the controls. The level of total free phenolics, both in the whole peel and in peel spots, was lower in the high oxygen treatment. Dopamine content in the peel spots decreased rapidly, earlier in the high oxygen treatments than in controls. It is concluded that peel spotting was not correlated with in vitro PAL and PPO activities. Decrease in dopamine levels correlated with peel spotting, indicating that it might be used as a substrate for the browning reaction.     

The effects of ethylene, 1-MCP and AVG on sprouting in sweetpotato roots

Exogenous ethylene is commonly used as a commercial sprouting inhibitor of potato tubers. The role of ethylene in the control of sprouting of sweetpotato roots, however, is not known. The aim of this study was to investigate the role of ethylene in control of sprouting in sweetpotato roots by observing the effect of an ethylene synthesis inhibitor, aminoethoxyvinylglycine (AVG), and the ethylene antagonist, 1-methylcyclopropene (1-MCP), in the presence and absence of exogenous ethylene on root sprouting and associated sugar accumulation. Continuous exposure to 10 μl L⁻¹ ethylene, 24 h exposure to 625 nl L⁻¹ 1-MCP or dipping in 100 μl L⁻¹ AVG all inhibited sprout growth in sweetpotato roots of two varieties over 4 weeks of storage at 25 °C. The observations that both ethylene on its own and 1-MCP, which inhibits ethylene action, inhibit sprout growth indicate that while continuous exposure to exogenous ethylene leads to sprout growth inhibition, ethylene is also required for sprouting. In potato tubers ethylene is required to break dormancy, while continuous exposure inhibits sprout growth.Monosaccharide concentrations in ethylene, 1-MCP or AVG treated roots were lower than in untreated roots, and for ethylene treated roots this was associated with higher respiration rates. This is consistent with the activation of some additional process by ethylene which uses energy through sugar metabolism. 1-MCP and AVG both inhibited this increase in respiration rate and counteracted the decrease in monosaccharide concentrations. 1-MCP presumably counteracts the ethylene stimulation of this process, while the effect of AVG is attributed to its possible inhibitory effects on protein synthesis.     

Rheological and chemical predictors of texture and taste in dessert banana (Musa spp.)

To be able to account for sensory qualities earlier in the assessment of a new banana hybrid in a selection scheme, predicting the sensory perception of banana texture and taste by instrumental parameters was investigated. Thirteen cultivated banana and four new triploid hybrids were characterized by sensory profiling, and rheological and chemical analyses. Multilinear regressions were used to calibrate predictions using 13 cultivated bananas, and the quality of predictions was validated using four hybrids. The sensory characteristics sourness and sweetness were predicted by titratable acidity (R² = 0.68) and pH (R² = 0.66). Malate and citrate were the main contributors to sweetness and sourness. Astringency was predicted by total tannins (R² = 0.55). Rheological parameters from texture profile analyses (stress at fracture, fracturability) were more suitable than pulp puncture force to predict the sensory texture properties firmness (R² = 0.47) and melting (R² = 0.60). These textural properties were predicted by titratable acidity and dry matter content (R² = 0.62). Predictions of mealiness, adhesiveness, and heterogeneity were not efficient. Differences of 3.6–3.7 meq 100 g⁻¹ FW in titratable acidity or of 0.30 g 100 g⁻¹ FW in malate or citrate were required to ensure a detectable difference in sourness or sweetness (p = 0.9). Pulp puncture force needed to differ by a minimum of 0.9 N before a difference in firmness could be perceived by the panelists. In conclusion, while models to predict sourness and sweetness can now be used for high throughput phenotyping, we recommend additional tests for other sensory attributes.     

Degreening behavior in ‘Fallglo’ and ‘Lee × Orlando’ is correlated with differential expression of ethylene signaling and biosynthesis genes

Two citrus types (‘Fallglo’ and ‘Lee × Orlando’) exhibiting differential fruit degreening response when treated with ethylene were selected. Fruit were harvested at commercial maturity but at different developmental periods (Harvest I, II and III). Rate of color change was greater in ‘Fallglo’ than in ‘Lee × Orlando’ when fruit were treated with 5 μL L⁻¹ of ethylene for 24 h. After 24 h of transfer of fruit to ethylene-free storage, rate of change decreased in ‘Fallgo’ and exhibited varied response in ‘Lee × Orlando’ depending on harvest date. ‘Fallglo’ fruit from Harvests I and II were completely degreened at the end of storage for 7 d; however ‘Lee × Orlando’ were not and were green in color. No difference in seedling triple response was observed between ‘Fallglo’ and ‘Lee × Orlando’ and sequences of the four ethylene receptors were identical between them. Expression of genes involved in ethylene biosynthesis and signaling pathways were studied in flavedo to test if differences in these pathways were correlated with differential ethylene sensitivity of the citrus types. Basal levels of ACS2 and ACO expressions declined as maturity progressed, and ethylene-induced expression of ACS1 and ACO were influenced by fruit maturity. At Harvests I and II, ethylene-induced increase in ACS1 and ACO expressions and ACC levels were greater in ‘Fallglo’ than in ‘Lee × Orlando’. Ethylene treatment influenced MACC content only during Harvest I in ‘Lee × Orlando’. MACC levels were generally higher in ‘Lee × Orlando’ than in ‘Fallglo’. Expressions of ETR1 and ETR2 were ethylene responsive in ‘Fallglo’ and only ETR1 expression was ethylene responsive in ‘Lee × Orlando’. Ethylene had more impact on ETR1 expression in ‘Fallglo’ than in ‘Lee × Orlando’. Ethylene had a negative effect on ETR3 expression which was more pronounced in ‘Lee × Orlando’ than in ‘Fallglo’. Expressions of ERS1, CTR1, EIN2, EIL1 and EIL2 were not affected by ethylene in both citrus types. Expression of chlorophyllase gene and rate of total chlorophyll degradation were higher in ‘Fallglo’ than in ‘Lee × Orlando’ during ethylene treatment. Differential degreening behavior of ‘Fallglo’ and ‘Lee × Orlando’ correlated with peel maturity, and factor(s) downstream of ethylene signaling but upstream of ethylene biosynthesis play a role in the differential sensitivity.     

Effect of ethylene degreening on the development of postharvest penicillium molds and fruit quality of early season citrus fruit

The effect of commercial degreening with ethylene gas on fruit susceptibility and quality and development of postharvest green (GM) and blue (BM) molds on early season citrus fruit was investigated. Each cultivar was harvested with different peel color indexes (CI). Fruit were exposed for 3 d to 2 μL L⁻¹ ethylene at 21 °C and 95–100% RH before or after artificial inoculation with Penicillium digitatum or Penicillium italicum. Control fruit were kept at the same environmental conditions without ethylene. Fruit were stored at either 20 °C for 7 d or 5 °C for 14 d and disease incidence (%) and severity (lesion diameter) were assessed. No significant effect of commercial degreening was observed on fruit susceptibility to both GM and BM on citrus cultivars inoculated after degreening. Likewise, no significant effect was observed on disease incidence on citrus cultivars inoculated before degreening and stored at either 20 °C for 7 d or 5 °C for 14 d. In contrast, in cultivars like ‘Clemenules’ mandarins and ‘Navelina’ oranges, degreening significantly increased the severity on fruit with higher initial CI (−3.6 and 1.7, respectively). GM and BM severity on degreened and control ‘Clemenules’ mandarins incubated at 20 °C for 7 d was 146 and 118 mm and 56 and 46 mm, respectively. In general, commercial degreening did not significantly affect external and internal quality attributes of citrus cultivars. Commercial degreening after inoculation of less green (more mature) fruit showed a trend to increase mold severity, presumably through an aging effect (acceleration of peel senescence).     

Effects of cinnamon extract,chitosan coating,hot water treatment and their combinations on crown rot disease and quality of banana fruit

The antifungal activities of cinnamon extract (CE), piper extract (PE) and garlic extract (GE) were evaluated on banana crown rot fungi (Colletotrichum musae, Fusarium spp. and Lasiodiplodia theobromae) in vitro. The assay was conducted with extracts of CE, PE and GE with concentrations of 0, 0.1, 0.5, 1.0, 5.0, 10.0 and 0.75 g L⁻¹ of carbendazim (CBZ) on potato dextrose agar at room temperature. CE completely inhibited conidial germination and mycelial growth of all fungi at 5.0 g L⁻¹. PE totally suppressed mycelial growth of all fungi at 5.0 g L⁻¹ and conidial germination at 10.0 g L⁻¹ except for Fusarium spp. GE had no significant effects but low concentrations (0.1 and 0.5 g L⁻¹) enhanced germ tube elongation of the three fungi. The ED₅₀ values were higher for mycelial growth than for conidia except for Fusarium spp. Combined treatments were investigated on crown rot development in banana fruit (Musa AAA group ‘Kluai Hom thong’). Treatments included 5.0 g L⁻¹ CE, 1% (w/v) chitosan solution, hot water treatment (HWT, 45 °C for 20 min), CE plus chitosan, CE plus HWT and 0.75 g L⁻¹ of CBZ, applied before and after inoculation of the fruit. Crown rot development was assessed during storage at 13 °C for 7 weeks. Disease development was least (25%) on CE treated fruit after inoculation compared to CBZ but was higher when CE was applied before inoculation. Chitosan significantly delayed ripening as in terms of peel color, firmness, soluble solids and disease severity. CE showed no negative effects on quality of fruit. CE plus HWT caused unacceptable peel browning.     

Induction of ripening capacity in ‘Packham's Triumph’ and ‘Gebhard Red D’Anjou’ Pears by temperature and ethylene conditioning

Methods were tested for rapid induction of ripening capacity in ‘Packham's Triumph’ and ‘Gebhard Red D’Anjou’ pears in order to facilitate early marketing. Fruit of each cultivar were harvested at the onset of maturity and conditioned to develop ripening capacity by exposure to 100 μL L⁻¹ ethylene at 20 °C for 0, 24, 48, or 72 h, followed by varying durations of temperature conditioning at −0.5 or 10 °C. Ripening capacity was tested by measuring fruit firmness after 7 d at 20 °C after completion of conditioning treatments. Fruit firmness was also measured after conditioning but before ripening, and was designated “shipping firmness,” indicative of the potential for the fruit to withstand transport conditions without physical injury. With temperature conditioning at −0.5 °C only, ‘Packham's Triumph’ pears needed 45 d to develop ripening capacity, while ‘Gebhard Red D’Anjou’ pears were not capable of fully ripening after 60 d, the longest duration tested. Using ethylene only, 72 h exposure was necessary to develop full ripening capacity in both cultivars, and adequate shipping firmness was maintained. Using temperature conditioning at 10 °C, ripening capacity in ‘Packham's Triumph’ and ‘Gebhard Red D’Anjou’ developed within 10 and 20 d, respectively, but shipping firmness in ‘Gebhard Red D’Anjou’ was compromised at 20 d. In both cultivars, 24 or 48 h in ethylene followed by 5 d at 10 °C induced ripening capacity while maintaining adequate shipping firmness.     

Relationship of IAD index to internal quality attributes of apples treated with 1-methylcyclopropene and stored in air or controlled atmospheres

The research was conducted to evaluate the relationship between I_AD index (index of absorption difference between 670 and 720 nm) values and internal quality attributes of apples treated with 1-methylcyclopropene (1-MCP) and stored in air and controlled atmospheres (CA). Apples of ‘8S6923’ (Aurora Golden Gala™), ‘Fuji’ and ‘Royal Gala’ were tested. The results with Aurora Golden Gala™ show that I_AD index values were maintained at higher levels if the fruit were stored in CA and that 1-MCP had no significant effect on retaining at-harvest values. The I_AD values correlated with chlorophyll a content in the peel (R² = 0.95, P < 0.0001), but not with chlorophyll b content, internal ethylene levels, firmness or titratable acidity. ‘Royal Gala’ apples showed a similar response to Aurora Golden Gala™ apples, showing no correlation between I_AD index values and internal quality attributes of those apples when treated with 1-MCP and/or CA. In contrast, ‘Fuji’ apples showed a relationship between I_AD index value changes and internal ethylene concentrations (R² = 0.67, P < 0.05) and titratable acidity changes (R² = 0.89, P < 0.01), but not firmness. These results suggest that when 1-MCP and/or CA are applied to apples after harvest, that I_AD index values do not consistently correlate to any internal quality attributes other than peel chlorophyll a content.     

Efficacy of 1-MCP treatment in tomato fruit: 1. Duration and concentration of 1-MCP treatment to gain an effective delay of postharvest ripening

‘Raf’ tomato fruit were harvested at the mature-green stage and treated with 1-methylcyclopropene (1-MCP) at 0.5 (for 3, 6, 12 or 24 h) or 1 μl l⁻¹ for 3 or 6 h. Fruit were stored at 10 °C for 7 days and a further 4 days at 20 °C for a shelf life period. All 1-MCP treatments reduced both ethylene production and respiration rate and in turn retarded the changes in parameters related to fruit ripening, such as fruit softening, colour (a^*) change, and increase in ripening index (TSS/TA ratio). These effects were significantly higher when 1-MCP was applied at 0.5 μl l⁻¹ for 24 h. In order to obtain the maximum benefit from 1-MCP, this treatment would be the most suitable for commercial purposes.     

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.     

Ripening and sensory analysis of Guatemalan-West Indian hybrid avocado following ethylene pretreatment and/or exposure to gaseous or aqueous 1-methylcyclopropene

Previous reports showed that both gaseous and aqueous 1-methylcyclopropene (1-MCP) delay ripening of avocado (Persea americana Mill.), but there are no reports of the influence of 1-MCP on its sensory attributes. The objective of this study was to evaluate the effects of ethylene pretreatment and/or exposure to gaseous or aqueous 1-MCP on fruit ripening and sensory attributes of ‘Booth 7’ avocado, a Guatemalan-West Indian hybrid. Separate experiments were conducted during two seasons (2008 and 2009) with fruit harvested at preclimacteric stage in October (early season) and in November (late season). Fruit from Season 1 were exposed to ethylene (4.07 μmol L⁻¹) for 12 h at 20 °C, and stored for more 12 h at 20 °C in an ethylene-free (ethylene, <0.1 μL L⁻¹) room prior to treatment with either aqueous (1.39 or 2.77 μmol L⁻¹ a.i.) or gaseous (3.15 or 6.31 nmol L⁻¹ a.i.) 1-MCP. Ripening was monitored and firmness, respiration, ethylene production and weight loss were measured. Texture profile analysis and sensory analysis were performed on ripe fruit only (firmness, 10–15 N). Fruit from Season 2 were not exposed to ethylene pretreatment but treated only with aqueous 1-MCP 24 h after harvest. Fruit were assessed exclusively for sensory analysis when ripe (firmness, 10–15 N). Treatment with either 1-MCP formulation effectively delayed ripening from 4 to 10 d for early-season fruit, and from 4 to 6 d for late-season fruit. Higher concentrations of 1-MCP of either formulation had the greatest effect on selected pulp textural parameters of early-season fruit; the gaseous formulation had greater effect on late-season fruit quality than the aqueous formulation. In general, sensory panelists ratings of overall liking were not affected by 1-MCP treatment. Both aqueous and gaseous 1-MCP formulations delayed ripening of the Guatemalan-West Indian ‘Booth 7’ avocado without significant loss in appearance or in sensory attributes and, therefore, could be considered for use as a postharvest treatment for this hybrid.