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Jennifer R. DeEll and Geoffrey B. Lum

The objective of this study was to investigate the effects of low-oxygen storage and 1-methylcyclopropene (1-MCP) on disorders and quality of ‘Empire’ apples. For 2 years, ‘Empire’ apples were obtained from commercial orchards during their harvesting period. After cooling overnight at 3 °C, the apples were treated with or without 1-MCP (1 µL·L−1) for 24 hours and subsequently stored in controlled atmosphere (CA) with 2.5 kPa O2 (+2 kPa CO2) or 1.5 kPa O2 (+1.2 kPa CO2) for 8 months at 1.5 and 3 °C for the first and second year, respectively. In the second year, a third group of the ‘Empire’ apples was also held in respiratory quotient (RQ)-based dynamic CA storage (SafePod) that reached 0.6 kPa O2 (+0.5 kPa CO2), and half of these apples were treated with 1-MCP (1 µL·L−1) for 24 hours at 3 °C upon removal after 8 months. All apples were then evaluated for disorders and quality after 1, 7, or 14 days at room temperature (RT, 23 to 24 °C). Substantial external CO2 injury, flesh browning, and core browning (up to 38% incidence) developed in ‘Empire’ stored in 2.5 and 1.5 kPa O2 during both years of study. Storage in 1.5 kPa O2 reduced flesh browning in the first year and core browning during the second year in apples without 1-MCP, as compared to storage in 2.5 kPa O2. 1-MCP-treated apples stored in 2.5 or 1.5 kPa O2 had higher overall incidence of disorders than similar fruit without 1-MCP. In contrast, there was negligible incidence (0% to 1%) of these disorders in ‘Empire’ apples held in 0.6 kPa O2, regardless of 1-MCP treatment upon removal. Storage in 0.6 kPa O2 also resulted in the greatest fruit firmness retention while at RT for 14 days. This regime can provide flexibility to postpone 1-MCP treatment until after storage, to prevent increased susceptibility to disorders during storage, without compromising fruit quality. However, results from the RQ-based dynamic CA with 0.6 kPa O2 were from a single season, and further research is needed to confirm these observations.

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Maude Lachapelle, Gaétan Bourgeois and Jennifer R. DeEll

Apple fruit firmness is one of the main attributes indicating fruit quality at harvest. It is affected by numerous factors during the entire growing season. The effects of weather conditions during apple development are often mentioned as a result of their impact on attributes linked to fruit firmness: fruit size, calcium concentration, water content, etc. In this study, the effects of weather conditions on ‘McIntosh’ apple (Malus ×domestica Borkh. cv. McIntosh) firmness at harvest time were analyzed. Fruit were harvested at nine sites in Quebec and Ontario over 15 years (1996–2011). For each case, weather parameters were analyzed from full bloom until harvest, either in monthly subperiods from May until September or in terms of days from full bloom (DFB) until harvest. Regression results highlighted the negative effect of lower air temperature conditions from 31 to 60 DFB, higher air temperature conditions and precipitations from 61 to 90 DFB, and higher temperature conditions from 91 DFB until harvest on ‘McIntosh’ apple firmness level at harvest. Precipitation from 61 to 90 DFB alone explained 39% of ‘McIntosh’ apple firmness variation at harvest time. The prediction of apple firmness at harvest time could be helpful for producers to adjust their marketing and storage strategies according to apple quality level.

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Jennifer R. DeEll and Robert K. Prange

This paper reports preliminary results on the postharvest quality and storage characteristics of several scab-resistant apple cultivars. `Novaspy', `Moira', `Priscilla', `Novamac', `Nova Easygro', `Prima', and `Macfree' were stored for 3 months at 3C in air or standard controlled atmosphere (CA; 4.5% CO2 and 2.5% O2) in 1990 and for 4 months at 0C in air, standard CA, or low-O, CA (LO; 1.5% CO2 and 1.5% O2) in 1991. `Moira', `Prima', and `Priscilla' had very limited storage life. `Moira' was susceptible to bitterpit, scald, core browning, vascular breakdown, and storage rots. `Prima' was susceptible to core browning and vascular breakdown and had a high incidence of storage rots in air storage. `Priscilla' had several defects as a result of insect damage and was susceptible to bitterpit and scald. `Novaspy' stored very well and had virtually no physiological disorders or storage rots. `Novamac, `Nova Easygro', and `Macfree' developed few storage rots and were essentially at the end of their storage life after 4 months, regardless of storage conditions. Firmness in `Novamac' decreased substantially in all storage atmospheres, while `Nova Easygro' and `Macfree' were susceptible to core browning and scald.

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Robert K. Prange and Jennifer R. DeEll

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Jennifer R. DeEll and Robert K. Prange

Postharvest quality and sensory attributes of organically and conventionally grown `McIntosh' and `Cortland' apples (Malus domestica Borkh.) stored at 3C in ambient air or in controlled atmospheres were evaluated. Organically grown apples had higher soluble solids concentration than conventionally grown apples, while there were no significant differences in firmness or titratable acids content. Organically grown `McIntosh' were perceived by sensory panelists as firmer than conventionally grown `McIntosh' at harvest but not after storage, which may have been due to maturity differences. No significant differences were perceived in juiciness, sweetness, tartness, and off-flavor of apples at harvest or after storage.

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Jennifer R. DeEll and Behrouz Ehsani-Moghaddam

The main objective of this study was to investigate the effectiveness of preharvest 1-methylcyclopropene (1-MCP) treatment on the development of soft scald in ‘Honeycrisp’ apples. In addition, the effects of preharvest 1-MCP on fruit quality at harvest and after storage were examined. For two consecutive years of study, ‘Honeycrisp’ trees were sprayed preharvest with 1-MCP and fruit were harvested twice during each year. Preharvest 1-MCP treatments had little consistent effect on fruit maturity at the time of harvest. In both years of study, preharvest 1-MCP reduced the incidence of soft scald in ‘Honeycrisp’ apples after air storage at 0 or 3 °C for 5 or 6 months. Soggy breakdown developed only in the second year of study and high incidences were reduced by preharvest 1-MCP treatments. Preharvest 1-MCP often reduced flesh firmness loss in ‘Honeycrisp’ during storage, especially during the second year of study, and with 1-MCP application closer to harvest. Malic acid content was often higher in apples with the preharvest 1-MCP spray closer to harvest. Overall, the most important benefit of preharvest 1-MCP treatments on ‘Honeycrisp’ apples was the reduction in soft scald development. Due to the high potential for substantial fruit losses from this disorder, the use of preharvest 1-MCP sprays on ‘Honeycrisp’ apples could be very advantageous.

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Jennifer R. DeEll and Peter M.A. Toivonen

The objective of this study was to determine if chlorophyll fluorescence could be used as an indicator of anaerobic respiration in broccoli (Brassica oleracea L., Italica group) during modified-atmosphere packaging (MAP). Two types of packages were used, PD-941 bags, which provided optimum MAP conditions for broccoli (≈3 kPa O2 plus 5 kPa CO2), and PD-961EZ bags, which allowed the CO2 to accumulate (≈11 kPa CO2). After 28 days in MAP at 1 °C, the broccoli from both types of bag had similar appearances and weight losses. However, broccoli held in the PD-961EZ bags had developed slight to moderate alcoholic off-odors and had higher ethanol, acetaldehyde, and ethyl acetate content, as compared with broccoli in PD-941 bags. Chlorophyll fluorescence parameters (Fv/Fm, T1/2, Fmd, and ΦPSII) were lower for broccoli held in the PD-961EZ bags than in PD-941 bags, and these differences increased with storage duration. These results indicate that chlorophyll fluorescence is a reliable, rapid, nondestructive indicator of broccoli quality during MAP, and that it could be used to determine if broccoli has developed off-odors without opening the bag and disrupting the package atmosphere.

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Robert K. Prange and Jennifer R. DeEll

Berry crops can include a wide variety of plant species, with the most important temperate North American species in the genera Fragaria, Rubus, and Vaccinium. The preharvest factors affecting the postharvest quality of berry crops can be divided into abiotic and biotic factors. Amongst the abiotic factors, mineral nutrition, especially calcium and nitrogen, water, temperature, and light play important roles in postharvest quality attributes such as size, color, firmness, acidity, and sweetness. Amongst the biotic factors, several postharvest pathogens, which are also present as preharvest pathogens, can cause very significant reductions in postharvest quality. Grey mold (Botrytis cinera) is considered to be the most important pre- and postharvest pathogen in berry crops, but other preharvest pathogens (e.g., Alternaria, Colletotrichum, and Rhizopus) can become major problems, depending on other preharvest factors. In some growing areas, the presence of fruit fly larvae in the fresh fruit reduces the postharvest quality. Other biotic factors can be more subtle in their effects on postharvest quality, such as cultivar, pruning, and pollination.

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Jennifer R. DeEll, Jennifer T. Ayres and Dennis P. Murr

This study evaluated the effects of 1-methylcyclopropene (1-MCP) on ‘Empire’ and ‘Delicious’ apples (Malus ×domestica) in commercial controlled atmosphere (CA) storage for 12 months and in commercial cold storage for 6 months. Apples were harvested and delivered by growers to a local commercial storage facility. Four different grower lots were chosen for each of three ‘Empire’ and two ‘Delicious’ storage rooms. Fruit were treated with 1-MCP (≈0.8–1.0 ppm) for 24 hours, while control fruit samples were held in a similar nearby storage room. After treatment, control samples were placed with matching 1-MCP-treated samples into either CA (2.5% O2 + 2.5% CO2 at 2.2 °C or 0 °C for ‘Empire’ and ‘Delicious’, respectively) or air storage at 0 to 1 °C. Initial maturity was relatively uniform among the grower lots, with internal ethylene concentration (IEC) averaging less than 1 ppm for ‘Empire’ and 2 to 3 ppm for ‘Delicious’. IEC was lower in apples treated with 1-MCP after air (3 or 6 months) or CA (6, 9, or 12 months) storage, but this effect was reduced after a 14-day ripening period at 22 °C, and was less dramatic in fruit from CA than from air storage. Apples treated with 1-MCP were also firmer than non-treated fruit upon removal from air or CA storage, and this difference became greater with increased poststorage time at 22 °C. 1-MCP-treated apples stored in air had higher soluble solids concentration (SSC), while there was no significant effect of 1-MCP on SSC in fruit held in CA. Core browning developed in ‘Empire’ held in air for 6 months or in CA for 9 or 12 months, and in ‘Delicious’ after 9 or 12 months in CA. 1-MCP decreased the incidence of core browning in ‘Empire’, but increased the incidence in ‘Delicious’. There was no significant effect of 1-MCP on the incidence of internal browning and storage rots, which developed in both cultivars.

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Jennifer R. DeEll, Jennifer T. Ayres and Dennis P. Murr

This study evaluated the effects of 1-methylcyclopropene (1-MCP) concentration (1000 vs. 625 ppb) and treatment delays (3, 7, and 10 days after harvest) on the ripening and incidence of storage disorders in ‘McIntosh’ apples from three harvest times in 2004. Apples were stored in air at 0 °C to 1 °C for 3 and 6 months or in controlled atmosphere (CA) storage at 3 °C for 6 and 9 months. Apples treated with 1-MCP and held in air or CA storage were firmer than those not treated, but this difference in firmness was less with later harvests, more delay before 1-MCP treatment, and longer storage time. Apples treated with 1000 ppb 1-MCP were often firmer than those treated with 625 ppb after 6 months of storage and/or 7 days at 22 °C. Ethylene and carbon dioxide (CO2) production were reduced in apples treated with 1-MCP, especially in fruit from the first harvest and those treated 3 days after harvest. Fruit treated with 1000 ppb 1-MCP showed a slower increase in ethylene production than those treated with 625 ppb during 14 days at 22 °C after storage. CO2 production was the lowest in ‘McIntosh’ apples treated with 1000 ppb 1-MCP 3 days after harvest, but fruit treated with 625 ppb also exhibited lower respiration than those not treated. Storage disorders were most prevalent in ‘McIntosh’ apples stored for 6 months in air at 0 °C to 1 °C, whereas fruit from the first harvest treated with 1-MCP 3 days after harvest developed the fewest disorders. 1-MCP reduced the incidence of superficial scald, flesh browning, core browning, and senescent breakdown, while 1-MCP concentration and treatment delay had varying effects. This research has provided the basis for Canadian registration of SmartFreshSM use on apples at 1000 ppb 1-MCP and for the requirement that treatment be within 3 days of harvest.