Storage Scald Research Articles

QUALITY OF 'CONFERENCE' PEARS AS AFFECTED BY INITIAL LOW OXYGEN STRESS, DYNAMICALLY CONTROLLED ATMOSPHERE AND 1-MCP TREATMENT

‘Conference’ pears in Italy are often subjected to superficial scald in cold storage, impairing their marketing. Among the postharvest methods employed to control scald, some include treatment at harvest with 1-methylcyclopropene (1-MCP), dynamically controlled atmosphere (DCA) and initial low O2 stress (ILOS). This research aimed at studying the influence of these treatments on the quality of ‘Conference’ pears. Treated (300 nl/L 1-MCP, Smartfresh) and untreated pears (control), after 4 weeks at -0.5°C, were stored in controlled atmosphere (CA, 2 kPa O2 + 0.7 kPa CO2), with or without ILOS (0.3-0.5 kPa O2) and in DCA (0.3-0.5 kPa O2 + 0.45 kPa CO2). ILOS was applied twice for 2 weeks with a 3 weeks interval, while monitored with fluorescence sensors (HarvestWatch(TM)). After 4 months of storage, fruit were put at 20°C up to 7 days and evaluated for skin color, pulp mechanical properties (firmness, stiffness, energy-to-rupture), ethylene production (EP), sensory characteristics and storage disorders. Fruit softening and EP were strongly reduced by 1-MCP. Skin yellowing was slowed down by 1-MCP, especially in DCA and ILOS+CA pears which maintained the greenest color throughout the shelf life period. Control fruit stored in DCA and in ILOS+CA at d1 of shelf life had a skin color similar to that of treated pears, showing a quick yellowing with the progress of shelf life period. Treated pears were perceived as firmer and less juicy than control ones regardless of the storage atmosphere. DCA treated pears were more grainy and astringent, and less sweet and aromatic than control DCA fruit. Treated ILOS+CA fruit were perceived as grainy and astringent as control ILOS+CA pears, but less sweet and aromatic. Two types of storage disorders were detected: blackening which was distinguished in two forms (early blackening and black spot) differing for the color and the severity of the disorder. Black spot was developed only in treated DCA fruit (4%); early blackening and black speck were developed in all atmospheres, the former more pronounced in control fruit, with DCA treated pears showing the lowest percentage of early blackening.

CURRENT DPA AND ETHOXYQUIN SITUATION AND ALTERNATIVES TO SUPERFICIAL SCALD CONTROL IN APPLES AND PEARS

Regulations governing the use of chemicals to control diseases and disorders of apples and pears in storage are becoming increasingly stringent, especially in European Union (EU) countries. The European Commission (EC) is currently conducting a review of the active ingredients (AI) of chemicals used in food production under EC Council Directive 91/414. DPA is under a review process and research is being conducting to address the concerns raised in the review. Ethoxyquin is also excluded from the list of AI in Annex I. Commercial supporters have recently come forward so this AI is also now under review. In light of the potential change in regulations, and the concern of fruit packers who market in EU, a survey of international researchers, suppliers and packers was conducted. The aim was to assess the situation in each fruit growing region, to determine which alternatives to antioxidants are being evaluated, gauge the perception about the acceptability of fruit treated with 1-methlycyclopropene (1-MCP) and learn how much packers of different regions are concerned about scald control. The respondents concerned about potential ban on antioxidants are from the countries that export to EU, especially from pear producing regions. Of all the alternatives mentioned by researchers consulted, the ones related to storage under controlled atmosphere (ultra-low oxygen, initial low oxygen stress, and dynamic controlled atmosphere) and 1-MCP are considered as the only sustainable technology to replace DPA. Other alternatives mentioned were ethylene removal, resistant cultivars, inhibition of phospholipase D and combined strategies. Regarding the use of 1-MCP, researchers report that it is a good alternative to current chemicals for control storage scald in apples. Although 1-MCP application to pears provides control of storage scald as well as the reduction in senescent scald, ripening may be inhibited after storage. Researchers are attempting to induce ripening in a number of ways including simultaneous application of 1-MCP and ethylene, conditioning through high temperatures, among others.

Fruit quality of Granny Smith apples picked at different harvest times and treated with 1-MCP

Introduction . Superficial scald is one of the most economically serious postharvest disorders of apples. The optimal harvest window and 1-MCP treatment significantly diminish the risk of storage scald and retain quality of apples stored in a normal atmosphere. Materials and methods . Fruits from three different harvest dates (23rd and 30th September, and 7th October 2008) were treated with 1-MCP (SmartFreshTM ) immediately after harvest, and stored in a normal atmosphere (1 ± 0.5) °C for 180 days followed by a shelf-life period of 7 days at (21 ± 1) °C. Assessments of superficial scald severity, firmness, total soluble solids and titratable acidity were recorded at days 1 and 7 after storage. Organoleptic quality assessments were made after the shelf-life period. Results . 1-MCP treatment was able to control superficial scald before and after shelf life in fruits from the last two harvest times. The highest scald values during shelf life were observed in untreated and 1-MCP-treated fruits from the earliest harvest (3.6 and 2.3, respectively). 1-MCP and early harvest time were determined to have a positive effect on retention of firmness and titratable acidity during storage. Total soluble solids was not affected by 1-MCP treatment. Combination of 1-MCP treatment and mid- or late harvest time gave the best evaluation scores for organoleptic quality. Conclusion . Our results show that 1-MCP treatments of late-harvested “Granny Smith” apples could offer satisfactory results for long-term air storage considering both the absence of superficial scald and retention of fruit quality.

COMPARISON OF CA, 1-MCP AND ETHOXYQUIN TREATMENTS IN ALTERING α-FARNESENE METABOLISM AND REDUCING SUPERFICIAL SCALD OF 'D'ANJOU' PEARS

'd'Anjou' pears were either pretreated directly after harvest with 1-MCP (300 nl L -1 for 24 h at 20°C) or ethoxyquin (2700 g L -1 line spray) and then stored in regular air (RA), or stored in low oxygen CA (0.8 kPa O 2 for 3 months + 2 kPa O 2 /1 kPa CO 2 for 1 month) without pretreatment. Fruit stored in RA without pretreatment were left as control. All fruit were stored at -1°C for four months and α-farnesene, conjugated trienes (CTs), internal ethylene level and fruit firmness were monitored monthly during storage and superficial scald was evaluated 7 d after transferring the fruit to 20°C from cold storage. Superficial scald occurred in control fruit that were stored three months or longer. However, all three treatments of CA, 1-MCP and ethoxyquin prevented scald completely during four months storage. α-Farnesene in fruit peel increased immediately after harvest and remained at high levels in the untreated control fruit. CTs also increased continually in the control. CTs did not accumulate following the ethoxyquin application. However, α-farnesene increased to levels higher than those found in the untreated control. Both 1-MCP pretreatment and CA storage not only eliminated CTs but also significantly decreased α-farnesene accumulation. Both 1-MCP and CA also decreased ethylene production and losses of flesh firmness which ethoxyquin did not. The results indicate that CA, 1-MCP and ethoxyquin prevented scald at different metabolic levels. Ethoxyquin inhibited specific metabolism - the oxidation of α-farnesene to CTs. However, CA and 1-MCP were broad spectrum inhibitors which slowed down the whole metabolic system of fruit, including inhibiting the biosynthesis of α-farnesene. Fruit treated by 1-MCP treatment lost ripening ability.

1-METHYLCYCLOPROPENE (1-MCP) AFFECTS PHYSIOLOGICAL DISORDERS IN 'GRANNY SMITH' APPLES DEPENDING ON MATURITY STAGE

'Granny Smith' apples (Malus domestica Borkh.) are very susceptible to various physiological disorders, superficial scald being the most important. Application of 1-methylcyclopropene (1-MCP) to 'Granny Smith' apples may extend storage life by reducing storage scald, loss of firmness and acidity. However, other skin disorders may be enhanced by 1-MCP. The effect of 1-MCP on the incidence of disorder development and ripening during storage and subsequent shelf life was investigated in 'Granny Smith' apples from different maturity stages (38, 42 and 52% starch degradation). Fruits were exposed to 0 (control) and 0.6 μl·L -1 1-MCP at 1°C during 24 hours. The fruit was evaluated after 120, 180, 210 and 240 days in regular air at 0.5°C, upon removal from storage and after 7 and 14 days at 20°C. Application of 0.6 μl·L -1 1-MCP effectively delayed the ripening rate of the fruit harvested at different times, as indicated by better retention of firmness and titratable acidity. 1-MCP treatment significantly reduced superficial scald. Treated fruit developed scald after 240 days of cold storage, while controls developed scald after 120 days. Core flush incidence was also reduced by 1-MCP treatment, even in the fruit from the latest harvest (52% starch degradation), which was the most affected by this disorder. There was fruit affected by physiological disorders related to calcium deficit, such as bitter pit and lenticel blotch in every evaluation. In early-harvested fruit (38% starch degradation), 1-MCP treated fruit developed less bitter pit and more lenticel blotch, but the incidence of both disorders combined was higher in 1-MCP treated fruit than in control fruit. No significant differences between treatments were detected in optimum- (42% starch degradation) and late-harvested fruit. We conclude that the effect of 1-MCP on different physiological disorders differs with fruit maturity stage. Calcium-related disorders were enhanced in early harvested fruit, especially in the 1-MCP treated fruit and as the length of storage increased.

Contamination of Apple Fruit with Diphenylamine During Storage

Apple fruit are treatmented with diphenylamine (DPA) in the form of a postharvest dip to prevent the development of storage scald. However, DPA residues have been detected on apples not treated with DPA, which is problematic in markets where DPA residues are not acceptable. The objective of this study was to identify sources of DPA contamination and evaluate the effectiveness of ozone to reduce contamination. Concentrations of DPA in the atmosphere of commercial storage rooms was monitored during the storage season and the adsorption of DPA onto wood and plastic bin material, plastic bin liners, foam insulation, and apple fruit was assessed. DPA was sampled from headspace with solid phase micro extraction using 65 μm polyacrylate micro fibers and analyzed using GC-MS. The effectiveness of gaseous treatments of 300 and 800 ppb ozone to reduce DPA contamination on apple fruit and bin material was also determined. DPA was found to volatilize from treated apples and bins into the storage room air, where it was adsorbed onto storage room walls, bins, bin liners and other fruit. DPA was found in the atmosphere of storage rooms containing apples that were not treated with DPA. Wood and plastic bin material, bin liners, and foam insulation all had a high affinity for DPA and were determined to be potential sources of contamination. Ozone reacted with DPA and following gaseous ozone treatments, off-gassing of DPA from wood and plastic bin material and bin liners was reduced. However, ozone was not effective in removing all DPA in contaminated materials and was ineffective in removing DPA from contaminated apples. Due to the pervasive and persistent nature of DPA, fruit should be handled and stored in facilities where DPA is not used to prevent contamination of fruit.

A Perspective on Postharvest Horticulture (1978-2003)

The goals of postharvest research and extension are to maintain quality and safety and minimize losses of horticultural crops and their products between production and consumption. Reduction of postharvest losses increases food availability to the growing human population, decreases the area needed for production, and conserves natural resources. Strategies for loss prevention include use of genotypes that have longer postharvest life, use of an integrated crop management system that results in good keeping quality, and use of proper postharvest handling systems that maintain quality and safety of the products. Thus, most horticulturists are involved to some extent in some aspects of postharvest horticulture, at least as consumers desiring fruit and vegetables with good flavor and nutritional quality and ornamentals with attractive appearance and long postproduction life. Most accomplishments of postharvest horticulture have resulted from interdisciplinary, collaborative efforts among horticulturists and other plant biologists working with food scientists and engineers, marketing economists, consumer scientists, and other researchers and extensionists. Interactions among postharvest horticulturists and their colleagues from other disciplines are facilitated through the American Society for Horticultural Science (ASHS) Postharvest Working Group and the International Society for Horticultural Science (ISHS) Commission on Quality and Postharvest Horticulture. Also, many postharvest horticulturists participate regularly in ISHS International Postharvest Conferences, the Gordon Research Conferences on Postharvest Physiology, and the International Controlled Atmosphere Research Conferences, which have been held every 4 years since 1969. The Australasian Postharvest Conferences are held every 2 years in Australia or New Zealand. Results of postharvest research have been published in ASHS journals beginning with volume 9 of the Proceedings of the American Society for Horticultural Science published in 1913, as well as in a wide range of plant science, food science and technology, agricultural engineering, and other journals. A specialized abstracting journal titled Postharvest News and Information was initiated in 1990 and has been published bimonthly by CAB International. In 1991, Elsveir Science Ltd. initiated the journal Postharvest Biology and Technology, which has grown steadily (under the leadership of G.E. Hobson, R.P. Cavalieri, and I.B. Ferguson) in its ranking among journals and in frequency of publication to a monthly schedule in 2003. Published information covers the continuum from postharvest biology to technology of a broad range of horticultural crops and their products. When ASHS celebrated its 75th anniversary in 1978, Professor Don Dewey, Michigan State University, reviewed the accomplishments of postharvest horticulture since 1903 under the title “Three Remarkable Generations of Postharvest Horticulture” (Dewey, 1979). Interest in postharvest horticulture within ASHS began early and expanded quickly as evidenced by the number of papers focused on postharvest physiology and quality that were published in the ASHS Proceedings. He reviewed the history of identifying ethylene as a gas that influences plant growth and development, fruit ripening, and senescence of harvested plant organs. He predicted correctly that “there seems little doubt but that ethylene will play a major role in our future work and publications.” He also identified postharvest disorders (physiological and pathological) as an important research area that received much attention from postharvest horticulturists between 1903 and 1978. Identifying preharvest and postharvest factors that influence incidence and severity of physiological disorders remained an active research area during the past 25 years (Ferguson et al., 1999; Hodges, 2003). Important discoveries have concerned the nature of chilling injury (Saltveit, 2000; Wang, 1990), the control of storage scald on apple, the cause of bent-neck in cut roses, and the role of calcium (Bangerth, 1979) or other elements in tomato blossom-end rot, tipburn in lettuce, and flesh breakdown in apple. However, in most cases the underlying molecular and physiological causes are yet to be discovered. Dewey (1979) concluded his presentation by challenging

118 1-MCP Controls Superficial Scald and Delays Softening in `Cortland' Apples

`Cortland' is an apple cultivar with inherent poor storeability because of excessive vulnerability to the development of superficial scald in long-term storage. The objectives of this investigation were to evaluate the potential of the potent ethylene action inhibitor 1-methylcyclopropene (1-MCP; EthylBloc®) to counteract this constraint and to develop some basic procedures for its exposure. Eight hours after harvest, fruit were exposed to 1.0 mL·L–1 1-MCP for 0, 3, 6, 9, 12, 16, 24, or 48 h at 3, 13, or 23 °C. Following exposure, fruit were placed at 0 to 1 °C in air for 120 days, after which time they were removed to 20 °C and held 7 days for post-storage assessment of ripening and to allow development of physiological disorders. In general, and within our experimental limits, the higher the temperature of 1-MCP exposure the shorter the required exposure time to obtain similar effects. The desired effectiveness of 1-MCP could be achieved by exposing fruit for at least 3 h at 23 °C, for 6 h at 13 °C, or for 9 h at 3 °C. 1-MCP-treated apples were consistently 2 kg firmer than untreated apples. Scald incidence in untreated fruit after 120 days at 0 to 1 °C and 7 days at 20 °C was 100%, whereas 1-MCP reduced scald by 95% in treatments of long enough duration at any particular temperature.

516 Does Diphenylamine Reduce Chilling Injury in Green Bell Peppers?

Diphenylamine has been used to reduce low-temperature-induced storage scald of apples for decades. Its effectiveness in reducing scald has been attributed to its antioxidant properties. Oxidative reactions have also been implicated in chilling injury of other commodities, including green bell peppers (Capsicum annuum L.). Diphenylamine was applied as a dip at rates of 500 to 2000 ppm to green bell peppers prior to storing them for 7 days at 1 °C. The development of sheet pitting, the most common visible symptom of chilling injury in bell peppers, was inhibited almost completely by diphenylamine. Diphenylamine, however, only slightly reduced the chilling-induced decrease in chlorophyll fluorescence ratios. Darkening of the vascular tissues of the calyxes and seed darkening, which are also symptoms of chilling injury, were not prevented by diphenylamine. Thus, diphenylamine either did not get into all of the sites of oxidative reactions or some of the manifestations of chilling injury are initiated by processes other than oxidative ones.

Effects of low preharvest temperature on scald susceptibility and biochemical changes in `Granny Smith' apple peel

An over-tree mist system provided evaporative cooling of the `Granny Smith' apple fruit. The temperatures of fruit under mist, control (without mist) and air were recorded from 1 September until harvest. Fruit were harvested when 30, 60, 80, 100, 120 and 160 h at less than 10°C had been recorded. Fruit maturity indices (flesh firmness, soluble solids, titratable acidity, starch index, internal ethylene concentration and color), lipid composition, membrane permeability, antioxidant concentration and activity were evaluated at harvest and after 60, 120 and 180 days of storage at 0°C plus 7 days at 20°C. Superficial scald was evaluated after storage and a shelf life period. Maturity indices significantly changed during the harvest period. However, there was no significant difference between maturity indices of fruit under mist and control at the same harvest date. Fruit at the first harvest date without mist had accumulated 30 h at less than 10°C and 100% of them developed storage scald, while fruit of the same harvest date under mist had accumulated 60 h at less than 10°C and developed 82% scald. Superficial scald decreased to 16% on fruit exposed to T<10°C for 100 h and was negligible on fruit exposed to T<10°C for 120–160 h. Total lipids, waxes and fatty acids of apple peel increased with duration of temperature less than 10°C. Unsaturated fatty acids significantly increased on fruit with 100–160 h exposure to less than 10°C. Fruit exposed to less than 100 h at less than 10°C had higher electrolyte leakage of peel tissue discs than fruit with more than 100 h at less than 10°C. The concentration and activity of peel antioxidants significantly increased with the low temperature duration before harvest.

What Components of Chlorophyll Fluorescence are Related to Storage Scald in Apple?

Chlorophyll fluorescence of three cultivars of apple, representing fruits that are considered highly susceptible (`Cortland'), moderate- to highly susceptible (`Red Delicious'), and resistant (`Empire') to superficial scald were studied in relation to scald development during storage. The preclimacteric harvested fruits from each variety were divided into two equal lots, lot one was treated with DPA (1000 ppm) and all the fruits (treated and untreated) were air-stored in separate bins at 0°C for 4 months. Chlorophyll fluorescence parameters, minimal fluorescence (Fo), maximal fluorescence (Fm) and the ratio of (Fm – Fo)/Fm, and various quenching components of variable fluorescence were measured at regular intervals during storage. The maximal level of fluorescence (Fm) at harvest varied between varieties; it was highest in `Empire', followed by `Red Delicious' and `Cortland', respectively. DPA dip treatment seemed to have no influence on chlorophyll fluorescence at harvest. Decline in Fm was found to be related to scald development during storage. The data on fluorescence quenching pattern and kinetics in relation to development of storage scald will be discussed. Changes in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{O}_{2}^{-}\) \end{document} radical (a possible cause of apple scald) scavenging system during storage will also be presented.

Yield Increased and Fruit Disorders Decreased with Repeated Annual Calcium Sprays on 'Anjou' Pears

Yield of 'Anjou' pears, Pyrus communis L, was increased with repeated annual (9-13 years) calcium chloride (CaCl2) sprays. The incidence of fruit disorders (alfalfa greening and cork spot ) was decreased by CaCl2 sprays with or without Regulaid but some minor calcium spray phytoxicity occurred on fruit and leaves. Fruit calcium concentrations in peel and cortex were increased with calcium chloride sprays; however, these sprays had little or no effect on leaf weight, fruit size, leaf Ca concentrations, tree vigor, shoot growth, fruit firmness, soluble solids, titratable acids, fruit color, fruit rots, or storage scald. This study suggested that long-term calcium chloride sprays of 60.5 g Ca per 100 liters of water or 33 to 44 kg CaCl2 per ha should provide the pear grower with a means of not only controlling fruit disorders but also for increasing 'Anjou' pear yield.

Relationships among bloom dates, ethylene climacteric initiation dates, and maturity-related storage disorders of Jonathan apples grown in Australia

Abstract One-hundred full bloom Jonathan apple flowers were tagged on each of five trees in each of two orchards on five dates: 9, 14, 19, 24 and 30 October 1988 (5000 tagged flowers). Three apples/bloom date/tree (150 fruits) were collected in late February and held at 20°C in individual fruit respirometers until the ethylene climacteric (EC) was initiated. The balance of the bloom-tagged apples were picked in March and held in air at 0°C until August. Mean EC dates for the late February sample were 145 ± 3 days after the five bloom dates. The chronologically oldest fruits, those that developed from early blooming flowers, were the most advanced in maturity at harvest, had the highest incidence of low-temperature breakdown (LTB) and the lowest incidence of storage scald (scald). The chronologically youngest fruits, those that developed from late bloom flowers, were the least advanced in maturity at harvest, had the lowest incidence of LTB and the highest incidence of scald.

A survey of the relationships among accumulated orchard hours below 10 °C, fruit maturity, and the incidences of storage scald on 'Starkrimson Delicious' apples

Incidences of storage scald were recorded in three seasons for 'Starkrimson Delicious' apples sampled 137, 144 and 151 d after full bloom and stored for 150 d in air at 0 °C at several North American locations. Severity of storage scald was inversely related to fruit maturity (determined by starch index) and the number of accumulated hours when orchard air temperature was below 10 °C between 100 d after full bloom and harvest. Key words: Malus domestica, climate, fruit maturity, physiological disorder, apples

Postharvest and Storage Factors Affecting Superficial Scald and Core Flush of ‘Granny Smith’ Apples

Abstract Initial O2 stress (IOS) treatments in 0% to 0.5% O2, followed by ultra low O2 (ULO) storage (O2&lt;1.7%, in 0°C, 92–96% RH, of ‘Granny Smith’ apples (Malus domestica Borkh) reduced fruit susceptibility to storage scald allowing satisfactory control of the disorder after 9 months of storage with 300 mg.1-1 diphenylamine (DPA). Storage factors increasing scald were the reversion from ULO to air storage twice during 9 months of ULO storage, and the omission of an IOS treatment prior to ULO storage. When storage included IOS treatments and continuous ULO, the inclusion of the fungicide (Rovral) 1-isopropylcarbamoyl-3-(3,5-dichlorophenyl) hydantoin, manufactured by Rhome Poulene, Lyon, France, increased scald, compared to treatments in calcium chloride (CaCl2) or DPA, and 1500 mg.1-1 of DPA compared to treatments in water and (CaCl2) increased core flush. Susceptibility to storage scald was reduced by low ethylene levels during storage in 3.0% CO2 + 3.5% O2 but not during storage in ULO 0.5% CO2 + 1.0% O2. The incidence of core flush, however, was reduced by low ethylene levels during storage, regardless of the CA storage treatment.

Effect of Low-oxygen Atmosphere on Storage Scald and Quality Preservation of ‘Delicious’ Apples

Abstract Studies of low-O2 storage of ‘Delicious’ apple fruit (Malus domestica Borkh.) were conducted in Oregon (1981), Washington (1982), and British Columbia (1981 and 1982). A combination of 1% O2 with 1% CO2 was the most promising for control of storage scald and quality preservation of ‘Delicious’ apple fruit grown in Oregon. A combination of 1% O2 with &lt;0.03% CO2 effectively reduced or eliminated the incidence of storage scald and preserved dessert quality of apples grown in Washington. Early-harvested apples from British Columbia developed a high incidence of storage scald after 7 months of storage in 1% O2 with 0.05% CO2. Apples harvested at commercial maturity, however, developed only slight or minimal storage scald symptom after 7 months of storage in 1 and 0.5% O2 with 0.05% CO2. A high incidence of low-O2 injury (i.e., ribbon-like, depressed skin browning) was found in fruit from Oregon stored for 9 months in 0.5% O2 (with or without CO2) and in 1.0% to 1.5% O2 with &lt;0.03% CO2. No low-02 injury was found in fruit from Washington or British Columbia after low-O2 storage.

Low Oxygen Effects on Dessert Quality, Scald Prevention, and Nitrogen Metabolism of ‘d’Anjou’ Pear Fruit during Long-term Storage1

Abstract ‘d’Anjou’ pears (Pyrus communis L.) harvested at optimum maturity, 6.4 kg flesh firmness, were stored in 0.5, 1.0, 1.5, 2.0, 2.5 and 5.0% O2 with CO2 concentration were maintained at 0.01 to 0.03%. Other samples were stored in commercially recommended concentrations of 2-2.5% O2 and 0.8-1.0% CO2 (i.e., regular CA), and conventional air storage. Temperatures of −1.1°C (30°F) were maintained in all cabinets throughout the 8 month storage. Oxygen concentration below 1.5% maintained the dessert quality of fruit and reduced the incidence of superficial storage scald after 8 months of storage. Fruit stored at 1.0% O2 for 8 months did not develop scald even after returning to air storage for 30 days. Oxygen concentration above 2% without CO2 had no beneficial effect on dessert quality or scald control. Regular CA storage also maintained dessert quality, but had only slight effect on scald control. Fruit stored below 2% O2 softened slower, lost titratable acids and free amino acids more slowly, and accumulated protein more slowly than samples stored at higher O2 levels for 8 months. Regular CA fruit changed similarly to those from the 1.0% and 1.5% O2 treatments. Overall fruit metabolism in 0.5% O2 was markedly retarded during the 5 to 8 month storage period.

Influence of Apple Bloom Date on Maturity and Storage Quality of ‘Starking Delicious’ Apples1

Abstract Tree cages were used to modify temperature around ‘Starking Delicious’ apple (Malus domestica Borkh.) trees and to establish 4 bloom dates: April 2, 15 and May 7, 22. Determination of soluble solids, acid, firmness and chlorophyll indicated that the time from bloom to maturity was longer for fruit from earlier than normal bloom. Fruit from delayed bloom accumulated less soluble solids than that from normal or earlier bloom dates. Ultimate fruit size decreased with each successive bloom. Fruit from the 2 early bloom dates apparently was harvested before the preclimacteric minimum. Fruit from delayed bloom was harvested after initiation of the climacteric. Loss of fruit firmness in storage increased with successive harvests. Storage scald and green fruit color were associated with warm night temperatures just before harvest rather than with length of growing season.

The Predominant Role of Calcium as an Indicator in Storage Disorders in Cleopatra Apples

SummaryExperiments with Cleopatra apple trees growing on Mailing 7 rootstocks in pot culture were conducted over a period of seven years. The trees were subjected over the years to a wide variety of treatments related to the nutrient supply, consisting of various levels and combinations of calcium, magnesium, phosphorus, nitrogen and potassium. The study considered the influence of nutrition on the mineral element composition of the fruit and on the storage disorders bitter pit, breakdown, scald and fungal rotting. Statistical analysis of the results indicated a predominant role for calcium in inhibiting bitter pit development, and also showed that calcium was the only mineral element of importance as an indicator of other storage disorders. Under conditions of adequate nutrition, a direct role for magnesium and potassium is unlikely. Principal component analysis, followed by varimax rotation of the first three component axes, proved to be a most useful mathematical technique for studying interrelationshi...

Preharvest Application of Ethephon on Scald and Quality of Stored ‘Delicious’ Apples1

Abstract (2-Chloroethyl)phosphonic acid (ethephon) applied 3 weeks before normal harvest hastened most of the changes commonly associated with maturation and ripening of ‘Delicious’ apples. Red color development, increase in soluble solids, water core development and decreased susceptibility to storage scald were all hastened by the ethephon treatment.