STORAGE QUALITY OF MINIMALLY PROCESSED CABBAGE PACKAGED IN PLASTIC FILMS

The effects of packaging and storage at 3C in a refrigerated case on quality changes of minimally processed cabbage were studied. Shredded cabbage samples were packaged in three forms: bags of monooriented polypropylene film (OPP bags) and polyethylene trays overwrapped with a multilayer polyolefin (RD106-PE tray) or with a plasticized PVC film (PVC-PE tray). All types of package effectively controlled the weight loss. The modified atmosphere in PVC-and RD106- PE trays did not change more than 3% as compared with normal atmosphere levels. However, in OPP bags, O₂ reached 2% and CO₂ increased to approximately 13% after 3 days. The microbiological quality during the storage period for all types of packaging was satisfactory. OPP samples were significantly better (p <0.05) in general appearance, wilting and browning but developed an off-odor. No off-odor was detected in samples packaged in PVC and RD106-PE trays. Shelf life for the three packaging forms was estimated.     

PROLONGING THE SHELF-LIFE OF FRESH GREEN CHILE PEPPERS THROUGH MODIFIED ATMOSPHERE PACKAGING AND LOW TEMPERATURE STORAGE

The postharvest quality of green chile fruit was compared after storage in 3 types of packages at 2 temperatures (24C and 8C). Package types were corrugated cardboard boxes, pressed cardboard trays overwrapped with VF-71 polyethylene, or low-density polyethylene (LDPE) bags. Fruit packaged in boxes or overwrapped trays had 24.8% and 10.1% weight loss, respectively, after 1 week of storage at 24C. Fruit packaged in polyethylene bags lost 0.3% weight and remained green. After 1 week at 8C, the weight losses were 3.8%, 1.8% and 0% for the boxed, overwrapped and bagged treatments, respectively. Postharvest quality was maintained up to 4 weeks when fruit were packaged in LDPE bags and stored at 8C. In a second study, steady state O₂ and CO₂ levels were determined inside the LDPE packages as fruit weight and temperature were varied. Storage temperatures were 24C, 16C and 8C. At 8C, steady state O₂ levels ranged from 12.0 kPa to 0.9 kPa, and CO₂ levels ranged from 2.0 kPa to 4.6 kPa as fruit weight was increased from 120 to 480 g. At 24C and 16C, fruit packaged in 480 g units had slower ripening rates than fruit packaged in smaller units; however, fruit stored at 8C remained green the longest, regardless of fruit weight.     

QUALITY OF ‘GALA’ APPLES AS INFLUENCED BY HARVEST MATURITY,STORAGE ATMOSPHERE AND CONCOMITANT STORAGE WITH ‘BARTLETT’ PEARS1

Controlled atmosphere (CA) storage for 45 or 90 days following harvest reduced quality losses for both ‘Gala’apples and ‘Bartlett’pears compared with fruit from regular atmosphere (RA) storage. Fruit stored in CA were firmer, had higher acidity and less color change than fruit from RA storage. Apples and pears stored together in CA maintained good quality and compared favorably with apples or pears stored separately. There was no difference in fruit quality between fruit stored at 1% O₂ and 1% CO₂ compared with fruit stored in 2% O₂ and 3% CO₂. Fruit harvested at a more advanced stage of maturity deteriorated more quickly in storage than earlier harvested fruit. A combination of 45 days in CA followed by 30 days RA resulted in apples that were superior in quality to apples stored for 75 days in RA alone.     

QUALITY CHANGES IN FRESH‐CUT SPINACH (SPINACIA OLERACEA) UNDER MODIFIED ATMOSPHERES WITH PERFORATIONS

ABSTRACT

Fresh‐cut spinach leaves were stored for 4 days at 15C and 75% relative humidity under modified atmosphere packaging to assess the impact of differential in‐pack gas atmospheres generated through different packaging films and variable in‐pack weight on the quality of stored produce. After 4 days of storage, retention of chlorophyll, β‐carotene and ascorbic acid was better in low‐density polyethylene (LDPE) packages than in polypropylene (PP) packages. LDPE film‐packaged samples had higher phenolic content than PP film‐packaged samples. Low in‐pack O₂ (1–2 kPa) along with the buildup of CO₂ (8–10 kPa) seems to have enhanced the retention of antioxidant components, i.e., β‐carotene and ascorbic acid, in LDPE packages. This helped in chlorophyll retention and also prevented formation of oxidation compounds of phenols that otherwise caused browning of cut surfaces. Thus, O₂ and CO₂ permeability of packaging film or in‐pack weight of produce might be such that equilibrated O₂ partial pressures remain near to 1–2 kPa so as to affect a beneficial increase in the phenolic content along with concomitant retention of chlorophyll.

PRACTICAL APPLICATIONS

Fresh‐cut spinach leaves have received an enormous demand due to their utility in various traditional Indian preparations. Shelf life and quality of fresh‐cut produce may be greatly reduced due to high rates of respiration. Traditional packaging and handling techniques reduce the shelf life and sensory quality of fresh‐cut spinach. Temperature control and atmospheric modifications help to maintain produce quality by reducing respiration rate and enhance shelf life by minimizing the adverse effects of cutting. This research focused on evaluation of respiratory behavior of fresh‐cut spinach leaves at a temperature commonly encountered during transportation and retail distribution, i.e., 15C, and the effect of different polymeric films and in‐pack weights on produce quality. The results of the study suggest that packaging of fresh‐cut spinach in polymeric film packages could maintain the sensory quality and reduce degradation of various physicochemical constituents. Utilization of the results for proper design of modified atmosphere packages for this highly perishable produce can prove to be extremely beneficial for safe storage and transportation to urban retail markets.     

EFFECT OF SOME GAS MIXTURES ON STORAGE QUALITY OF PLUMS1

Plums were stored in controlled atmospheres (CA) with five gas mixtures of the following O₂:CO₂ percentages; 1:1, 1:4, 4:4, 2:2 and 4:1, for 37 days at 2.5–3C. Fruit treated with CA displayed very low decay incidence at the end of the storage period plus 2 days ripening at 22C in air, in comparison with a very high decay incidence (88%) for control fruits. CA-treated fruit ripened normally, but slowly, after 2 days in ambient conditions. There were no clear differences among CA treatments in the quality attributes of total soluble solids, acidity, firmness or color. Treatment with 1% O₂ nd 4% CO₂, however, resulted in slightly firmer fruit, with higher acidity than the untreated checks.     

CONTROLLED ATMOSPHERE STORAGE AFFECTS QUALITY AND CHILLING SUSCEPTIBILITY OF CUCUMBERS

Controlled atmospheres (CA) maintained the quality of cucumbers better than conventional refrigerated storage at 5C. Elevated levels of CO₂ (3%) and decreased concentrations of O₂ (1 and 15%) also increased the tolerance of cucumbers to chilling exposure. The content of sugars, including fructose and glucose; and organic acids, particularly malic acid, were maintained at higher levels in CA-stored cucumbers than in air-stored samples. The respiration rates (measured as CO₂ production) of cucumber fruit during storage at 5C were markedly suppressed under CA conditions. Contrary to reports in the literature, CA storage was found to be beneficial in reducing chilling injury and maintaining cucumber quality.     

QUALITY OF MINIMALLY PROCESSED LETTUCE AS INFLUENCED BY PACKAGING AND CHEMICAL TREATMENT

Shredded lettuce was packaged in sealed bags of monooriented polypropylene (OPP) film and also in polyethylene (PE) trays overwrapped with a multilayer polyolefin (RD106) or plasticized polyvinyl chloride (PVC) film; and stored at 4C in a refrigerated case during 8 days. Chemical treatment by dipping in a 0.3% ascorbic acid /0.3% citric acid solution did not significantly affect changes in microbial populations or visual sensory attributes. Type of package was not a significant factor for microorganism populations, but was significant (p<0.001) for changes in gas composition and visual sensory attributes. The modified atmosphere within the packages changed from normal air composition to about 1.5% O₂/12% CO₂ for OPP bags and to about 17–18% O₂/1–2% CO₂ for PVC-PE trays and RD106-PE trays after 8 days of storage. The visual sensory quality of the product was retained better in OPP bags than in the other ones.     

Deastringency of Persimmon Fruits by Creating a Modified Atmosphere in Polyethylene Bags

Removal of astringency from persimmons (Diospyros kaki L.) was achieved by enclosing the fruits in air-evacuated polyethylene bags. Reducing the initial in-package air volume created anaerobic conditions by decreasing the O₂ level. Induced anaerobic respiration in-creased the levels of CO₂. acetaldehyde and ethanol, in the atmosphere surrounding the fruit and thereby triggered the deastringency process. Deastringency in air-evacuated polyethylene bags was attained within3–4 days at 20°C. Following the deastringency, the fruits in the bags maintained a high quality and firmness during cold storage and shelf life. Good flavor was maintained for about 10 days at 20°C, but thereafter off-flavor developed due to accumulation of volatiles.     

STORAGE OF ‘SWEETHEART’ CHERRIES IN SEALED PLASTIC FILM1

‘Sweetheart’ cherries were sealed in perforated or nonperforated polyethylene bags and stored for 6 weeks in air at 0C. Samples were removed after 1, 2, 4 and 6 weeks of storage and evaluated for fruit and sensory quality. Volatile analyses were done on samples kept in storage for 2, 4, 6, 8 and 9 weeks. Atmospheres after 6 weeks of storage were approximately 4.6% O₂ and 10% CO₂ for the perforated bags (1993) and 6.6% O₂ and 3.5% CO₂ for the non-perforated bags (1994). Fruit brightness (L* value), firmness and titratable acidity declined during storage. Skin color (hue angle) decreased slightly in redness over the 6-week storage period. Sensory evaluation in 1993 showed a decline in fruit appearance and flavor with storage duration. Texture and juiciness did not change. Acceptability remained high for the first 4 weeks of storage. Twenty-seven volatiles were identified by head-space analysis (1993). Little change occurred in volatile production except for acetaldehyde which increased sharply from week 2 to 4 and ethanol which increased sharply between week 8 and week 9. Butyl acetate behaved much like acetaldehyde. Modified atmosphere packaging maintained high fruit luster and green stems. No differences in fruit quality were observed with bag type, but storage appears to be limited to 4 weeks for ‘Sweetheart’ cherries because of flavor loss.     

Quality of enoki mushrooms as affected by packaging conditions

Fresh enoki mushrooms (100 g) were packaged under various conditions and stored at 10 °C for 14 days. Package atmosphere, weight loss, stipe elongation, surface colour and sensory quality of the mushrooms were measured during storage. Different levels of initial vacuum application did not have a significant influence on the in‐package atmosphere after 2 days. The half‐vacuum package was best in terms of quality preservation of the fresh mushrooms. A polyolefin film with respective gas permeabilities of 166 and 731 ml m⁻² h⁻¹ atm⁻¹ to O₂ and CO₂ established an equilibrated atmosphere of 1.7–2.4% O₂ and 4.1–5.6% CO₂ inside the package at 10 °C. This polyolefin film was shown to contribute to preserving the freshness of the mushrooms. Temperature fluctuations between 5 and 15 °C did not induce a harmful atmosphere inside the polyolefin package, though high temperatures accelerated the quality loss. © 2000 Society of Chemical Industry     

Quality aspects of fresh‐cut ‘long‐storage tomato’ as affected by package,calcium chloride and storage time

In this research, some quality changes during storage at 4 °C were assessed in fresh‐cut fruits of a ‘long‐storage tomato’ landrace, packaged in biocompostable materials (PLA Ingeo tray/NatureFlex? film) or in conventional plastics (PET tray + polypropylene film). The effects of dipping in CaCl₂ on the shelf‐life extension were also assessed. Plants were cultivated both off‐season (greenhouse) and in‐season (open field). CO₂ and O₂ concentration, fruit weight loss, firmness, colour, microbial load were measured at 0, 4, 7, 12 days of storage. Headspace gas changes and fruit weight loss were minimised in conventional package. BIO package prevented water condensation, led to max 5% weight loss and made fruits less susceptible to spoilage. Dipping in CaCl₂ induced better firmness, especially in biopackage. Off‐season fruits had overall lower quality than in‐season fruits; however, these may contribute to extend the production season, with interesting marketing implications for the agri‐food industry.     

EATING QUALITY OF “FUJI” APPLES AFFECTED BY A PERIOD OF COLD AIR AFTER ULO STORAGE

ABSTRACT

Over two subsequent seasons, emission of volatile compounds, consumer acceptability and quality parameters were analyzed in “Fuji” apples. In both seasons, apples were harvested at the same maturity stage and stored for 19 or 30 weeks at 1C and 92% relative humidity under an ultralow oxygen (ULO) atmosphere (1% O₂ + 1% CO₂) or under an ULO atmosphere followed by different periods (2 or 4 weeks) in cold air. The results revealed, for both seasons, that 4 weeks of cold air storage after ULO storage helped to increase the emission of some volatile compounds for both storage period, including characteristic volatile compounds for the variety, and did not have a negative effect on quality parameters. Additionally, the consumer acceptability was superior for those fruits.

PRACTICAL APPLICATIONS

It is well known for various apple varieties that long‐term storage under ULO conditions reduces volatile production resulting in poor flavor and aroma compared with fruits stored in air. Consequently, there is often dissatisfaction among consumers with the flavor of fruits which have been subjected to cold storage. The strategy that is proposed in the present work could be recommended to enhance the aromatic quality of fruit provided by the apple industry and, in consequence, increase its acceptability by consumers.     

STORAGE QUALITY OF BELL PEPPERS PRETREATED WITH HOT WATER AND POLYETHYLENE PACKAGING

Treatments of bell peppers (Capsicum annuum, L) with hot water at 45Cfor 15 min or SSC for 4 min prior to storage at 8C markedly reduced the incidence of fungal infections. However, the hot water treatment induced shriveling during storage. When hot water treated pepper fruits were subsequently placed in low density polyethylene bags, storage quality of these peppers improved tremendously including retention of firmness, reduction of water loss, retardation of color change, and alleviation of chilling injury. Total soluble solids, titratable acidity, and pH values in the pepper fruit were generally not affected by these treatment. A 4 min dip at 53C followed by packaging with 0.065 mm low density polyethylene film was very effective in maintaining pepper quality. This treatment inhibited respiration rate, reduced decay, retained turgidity and green color, and maintained excellent overall quality after 28 days of storage at 8C. Hot water treatment combined with polyethylene film packaging is a promising technique for improving the storage quality of bell peppers.     

Composite starch‐based coatings applied to strawberries (Fragaria ananassa)

Starch‐based coatings were used to the extend storage life of strawberries (Fragaria ananassa) stored at 0°C and 84.8% relative humidity. Effects of coating formulation (including starch type, plasticizer, lipid and antimicrobial agent) were analysed with respect to fruit quality. Plasticizer addition was necessary for film and coating integrity to avoid pores and cracks. Plasticizer presence reduced weight losses and maintained surface colour of fruits. Amylomaize coatings showed lower water vapour and gas permeabilities and decreased weight losses for longer periods than corn starch ones. Coatings with sorbitol showed lower permeabilities than glycerol ones. Coatings with antimicrobial agents decreased microbial counts, extending storage life of coated fruits by 10 to 14 days in comparison to the control. The addition of 2 g/l sunflower oil to the formulations decreased the water vapour permeability of starch‐based films, maintained the surface colour of coated fruits and controlled effectively fruit weight losses during storage. Lipid addition minimized the effects of starch and plasticizer types. Composite starch‐based coatings showed selective gas permeability (CO₂ higher than O₂) which helps to delay senescence of fruits.     

QUALITY OF PINK TOMATOES (cv. BUFFALO) AFTER STORAGE UNDER CONTROLLED ATMOSPHERE AT CHILLING AND NONCHILLING TEMPERATURES

Greenhouse-grown pink tomatoes (cv. Buffalo) were stored in air or in a controlled atmosphere (CA) of 4% O₂ plus 2% CO₂, to study the effect of CA at chilling and nonchilling temperatures on fruit quality characteristics. Tomatoes could be stored in CA at 12C for three weeks with no major changes in fruit appearance. CA was effective in delaying color development and ripening at this temperature. The soluble solids content was lower after CA storage, but no significant differences in firmness, pH or titratable acidity were observed between storage in air or CA. Storage in CA at 12C was also effective in reducing decay. However, at 6C, fruit showed high incidence of decay after both air and CA storage. CA did not alleviate chilling injury symptoms relative to air-stored samples and may have caused CO₂ injury. Water loss was greater under CA at both temperatures.     

QUALITY OF 'ANJOU' PEARS FROM VARIABLE OXYGEN AND HIGH CARBON DIOXIDE CONTROLLED ATMOSPHERE STORAGE

Loss of ‘Anjou’ pear quality after 90 days of storage (60 days at 1.5% O₂ and <1.0% CO₂ then 30 days at 4% O₂) wasapparent in this study. Distinct color changes from green to yellow in the peel and a more yellow flesh, coupled with a loss of firmness, for ‘Anjou’ pears even afteronly a short period (30 days) in elevated O₂ was evident. Use of elevated CO₂ (3%), in CA storage, resulted in a greener peel and firmer pears with less change in flesh color, and superior stem condition after 150, or 210, days of storage compared with pears from 1.5% O₂ and <1% CO₂. After controlled atmosphere and an addition 30 days of storage in regular atmosphere, quality differences in ‘Anjou’ pears from the different atmospheres (1.5% O₂ and 1.0% CO₂; variable O₂;1.5% O₂ and 3.0% CO₂) was even more manifest. Pears in elevated O₂, displayed reduced firmness, finish and stem condition and enhanced shrivel. Pears in 3.0% CO₂, compared favorably in all quality considerations with pears from a normal (1.5% O₂ and <1.0% CO₂) atmosphere. No pithy brown core was evident in ‘Anjou’ pears regardless of storage atmosphere.     

Modified-atmosphere retail packaging of discovery apples

An experimental modified-atmosphere packaging system was used to compare the atmospheric compositions that developed within sealed packs made from a range of films of different permeability properties. The effects of these conditions were then related to the primary quality attributes, i.e. background skin colour and flesh firmness, and the sensory quality of Discovery apples. Concentrations of CO₂ and O₂ within packs were dependent on the permeability of the film and the holding temperature. In packs sealed with low density polyethylene films and held at 20°C, equilibrated atmospheres containing 3-5% CO₂ and 5-6% O₂ developed within 1-2 days. Softening and yellowing of fruit was markedly retarded. In packs sealed with some less permeable films, atmospheres containing 12-20% CO₂ and 0.9-4% O₂ developed within 1-2 days, resulting in retarded softening and yellowing of the fruit but also a high incidence of tainting. Possible commercial applications, benefits and limitations of modified-atmosphere packaging are discussed.     

Physiological responses and quality attributes of ‘Kyoho’ grapes to controlled atmosphere storage

This research studied the physiological responses and quality attributes of Kyoho grapes (Vitis vinifera X V. labrusca) to controlled atmosphere storage. The grapes were stored for up to 60 days in 95% relative humidity with four different conditions, 4% O₂+9% CO₂, 4% O₂+30% CO₂, 80% O_2, and air, as control. The examined physiological responses and quality attributes included polyphenol oxidase (PPO) activity, ethanol concentration, fruit detachment force (FDF), firmness, color, soluble solid content (SSC), titratable acidity (TA), ascorbic acid concentration (Vc), and sensory quality. PPO activity, FDF drop and decay incidence when stored in 4% O₂+30% CO₂ were more effectively controlled, but unacceptable alcoholic flavor and browning were detected after 45 days, compared with those stored in 4% O₂+9% CO₂ or 80% O₂. The fruits kept in 4% O₂+9% CO₂ or 80% O₂ had good quality during 60 days of storage. The results suggested that high O₂ atmosphere exhibited a potential for maintaining the quality of ‘Kyoho’ grapes during long-term storage.     

Storage studies of tomato and bell pepper using eco‐friendly films

Tomato (Lycopersicon esculentum) and bell pepper (Capsicum annuum), packaged in cartons (approximately 0.35 kg per box) covered with either eco‐friendly chitosan film or synthetic petroleum‐based low‐density polyethylene (LDPE) film, were stored at room temperature (27 ± 1 °C) and 65 ± 3% relative humidity (RH). Fruits were withdrawn periodically and changes in physico‐chemical, instrumental and sensory characteristics were analysed. During storage, oxygen levels showed only marginal changes, while CO₂ levels showed a gradual increase, especially so in LDPE film‐covered cartons. The fresh weight loss, colour, firmness, formation of defective spots and shrivelling showed greater changes for unpackaged fruits as well as for those in LDPE film‐covered cartons, in comparison with fruits stored in chitosan film‐covered cartons, which retained many of the desirable attributes. Principle component analysis of data from sensory or instrumental sensory analyses indicated segregation of samples stored under different conditions with respect to both desirable and undesirable attributes. The fruits showed greater deterioration, including the loss of characteristic bell pepper odour, when packaged in cartons covered with LDPE films, while those packaged in chitosan film retained more of the desirable quality attributes for a longer period. Copyright © 2006 Society of Chemical Industry     

Storage studies of mango packed using biodegradable chitosan film

The effect on the quality of mango fruits (Mangifera indica) during modified atmosphere packaging was investigated. The fruits were kept in carton boxes whose top surface was covered with either chitosan film or with low-density polyethylene (positive control) or kept as such (control) and stored at room temperature (27ǃ °C at 65% RH). The CO₂ and O₂ levels measured on day 3 were 23-26% and 3-6%, and at the end of the storage period they were 19-21% and 5-6%, respectively. Various quality parameters such as colour, chlorophyll, acidity, vitamin C, carotenoid and sugar contents were studied. The fruits stored as such had a shelf-life of 9ǃ days, whereas those stored in low-density polyethylene showed off-flavour due to fermentation and fungal growth on the stalk and around the fruits, and were partially spoiled. On the other hand, fruits stored in chitosan-covered boxes showed an extension of shelf-life of up to 18 days and without any microbial growth and off-flavour. Being biodegradable and ecofriendly, chitosan films are useful as an alternative to synthetic packaging films in the storage of freshly harvested mangoes.