Perforated Bags Research Articles

Modified atmosphere packaging alleviates chilling injury in cucumbers

Abstract Cucumbers (Cucumis sativus L.) packaged in perforated or sealed 31.75 μm (1.25 mil) low density polyethylene (LDPE) bags were found to have less severe chilling injury than nonwrapped fruit in storage at 5 °C and 90–95% relative humidity. The onset of chilling injury was also delayed by the LDPE packaging compared to the nonpackaged control. The concentrations of CO2 increased to 3% while O2 levels decreased to 16% in the sealed bags. Fruit in the sealed bags had the least decay. The O2 and CO2 concentrations inside the perforated bags changed very little from the ambient atmosphere. However, there was a marked difference in the weight loss between nonwrapped cucumbers and fruit from perforated or sealed bags. The weight loss of nonwrapped fruit reached 9% in 18 days while perforated and sealed samples lost less than 1% during the same period. Chilling stress induced increases in putrescine levels in all treatments but the sealed fruit had the highest levels of putrescine. Sealed fruit and perforated fruit also had higher content of spermidine than non-wrapped fruit. These high levels of polyamines may have contributed to the increase of chilling tolerance in fruit from perforated and sealed packages.

Magnetic resonance imaging of persimmon fruit (Diospyros kaki) during storage at low temperature and under modified atmosphere

Abstract Effects of time and storage atmosphere on relaxation properties in persimmon fruit (Diospyros kaki cv Fuyu) were investigated by nuclear magnetic resonance (NMR) imaging during the five weeks following commercial harvest. There were two treatments (n = 4): one in which fruit were hermetically sealed in individual polyethylene bags (modified atmosphere or MA treatment), and another sealed in individual perforated bags (control). Fruit were stored at 7 °C for 4 weeks (conditions conducive to development of chilling-injury), before being removed to 20 °C for 3 days to simulate poststorage shelf conditions. Every week, and at the end of the shelf-life period, a series of 1H NMR images of median transverse and longitudinal planes were acquired from each fruit for calculation of spin-lattice (T1) and spin-spin (T2) relaxation times. Relaxation times associated with the flesh, vasculature and locules in transverse sections, and flesh from basal, median and distal regions of longitudinal sections, were significantly shorter in MA-treated fruit, although no T2 treatment difference was noted with vasculature. MA-treated fruit were further distinguished from controls in that all tissues exhibited a sharp increase in T1 (but not T2) relaxation between the second and third weeks in cold storage. Within a treatment, T1 times in flesh and locules were similar (ca. 1120 ms), and shortest in vascular tissue (1036 ms). T2 was a more sensitive indicator of tissue type (mean values of 71, 101 and 116 ms in the vasculature, flesh and locules of MA-treated fruit, respectively), than T1. However the relative ranking of flesh and locule tissues was time-dependent. There was no gradient in relaxation times between basal, median and distal regions of the fruit. Incipient stages of chilling-injury development were unable to be identified either by visual inspection of time-course images, or variation in relaxation properties. Our observations do indicate, however, that relaxation properties in fruit were strongly influenced by MA conditions. Increased concentrations of soluble metabolites arising from reduced respiration in MA-treated fruit is a possible mechanism consistent with these results, but not removal of a paramagnetic species like O2, where T1 values would be predicted to increase.

Modified-atmosphere Packaging of `Sweetheart' Cherries

Kilogram quantities of `Sweetheart' cherries were stored in HDPE perforated bags (1993, 50.8 μ thickness, OTR = 750 ml·m–2·day–1) or in nonperforated bags (1994, 11 μ thickness, OTR = 5196 ml·m–2·day–1) at 0C. Samples were removed at 1, 2, 4, and 6 weeks of storage and evaluated for fruit and sensory quality. Bag atmospheres after 6 weeks of storage were 10% CO2 and 4.6% O2 for the perforated bags and 3.5% CO2 and 6.6% O2 for the nonperforated bags. Fruit brightness, firmness, and titratable acidity declined during storage. Skin color tended to be redder with the longer storage periods. Sensory evaluation in 1993 showed a decline in overall appearance and flavor with time, but texture and juiciness did not change. Acceptability remained high for the first 4 weeks of storage but dropped at week 6. Surface pitting was noticeable at weeks 4 and 6, particularly from stem bruising.

Effect of storage temperature, time and wrapping materials on the microbiology and biochemistry of ogiri?a fermented-castorseed soup condiment

Wrapping ogini in perforated cellophane bags at 28°C increased its pH value during 7 days' storage. Storage at 10°C decreased microbial numbers in ogiri wrapped with both plantain leaves and cellophane. The temperature rose from 28 to 42°C during natural ogiri fermentation. Samples of ogiri inoculated with Bacillus sp. and a combination of Bacillus and Micrococcus spp. produced the typical ogiri odour.

Influence of freezing method on thaw drip and protein loss of low-voltage electrically stimulated and non-stimulated sheeps' muscle

South African Mutton Merino wethers ( n = 32) were slaughtered, yielding carcasses with a mean weight of 22·18 ± 2·11 kg. Sixteen carcasses were electrically stimulated (ES) (21 V, 60 Hz, 120 s) immediately and all carcasses were chilled at room temperature (16°C) for 3 h and then overnight at 4°C, 95% RH. Both left and right Mm. longissimus lumborum et thoracis were excised and cut into six portions (77 g ± 7·8 g), each placed separately in a polyethylene bag and randomly allocated to five freezing treatments. These were: (1) cryogenic, −65°C; (2) cryogenic, −90°C; (3) walk-in-freezer, −21°C; (4) blast freezer, −21°C; (5) domestic freezer, −25°C. The respective freezing rates were 4·4, 6·4, 0·55, 0·35 and 0·51 cm h −1 to −2·2°C at core depth of 1 cm below the surface. Samples were frozen to core temperatures of −20°C, removed and placed in a storage freezer (−20°C) for 48 h and 2·5 months. Samples were then suspended in perforated bags in a chiller (4°C) to thaw, and drip was collected in outer bags over the periods 0–24, 24–48, 48–72 and 72–96 h and expressed as g (100 g) −1. Freezing methods had significant ( P < 0·01) influences on drip loss in both ES and NES samples. Following storage for 48 h post-freezing at −20°C, total drip (g (100 g) −1) over 96 h of both ES and NES samples for the five freezing treatments were respectively: (1) 7·61 and 4·61; (2) 7·35 and 3·29; (3) 9·44 and 4·68; (4) 9·07 and 5·43; (5) 10·58 and 5·15. Following storage for 2·5 months, the total ES and NES drip were respectively, (1) 11·25 and 9·38; (2) 10·36 and 9·15; (3) 13·72 and 12·65; (4) 13·70 and 12·26; (5) 11·92 and 11·29. Total protein in the drip did not differ between freezing treatments. Differences between ES and NES samples did occur in the 48 h storage group. It is concluded that cryogenic freezing results in less thaw drip than the vapour compression systems. This advantage of cryogenic freezing disappears if meat is stored for long periods at −20°C. Electrical stimulation increases the drip loss in samples frozen for 48 h, but the differences are not significant after 2·5 months frozen storage. Protein losses parallel the drip.

リンゴ‘スターキング・デリシャス’果実の食味保持と揮発性成分生成に及ぼすポリエチレン包装の影響

Starking Delicious' apple fruit (Malus domestica Borkh.) were packaged hermetically in low density polyethylene bags of 30 and 50 μm thicknesses, and stored for 11 weeks at 8°C. Oxygen concentrations in 30 and 50 μm thick bags ranged from 1215% and 5 9% ; carbon dioxide concentrations 4% and 56%, respectively. The polyethylene packaging inhibited carbon dioxide and ethylene evolution. Softening of apples in 30 and 50 μm thick bags was retarded 2 and 4 weeks, respectively, compared with the fruits in perforated bags.The characteristic volatiles of apple, such as butyl acetate and 2-methylbutyl acetate were produced at the beginning of storage. In perforated bags, the production of these esters was high on early period of the storage. But, as senescence of the fruit proceeded, ethyl alcohol and ethyl esters became the dominant volatiles. In the 50 μm thick package, the production of ethyl alcohol and ethyl estars, which are non-characteristic aromatic compounds for apple, was enhanced shortly after packaging; whereas production of butyl acetate and 2-methylbutyl acetate was decreased. These changes in the production of aromatic compounds resulted in an off-flavor. In the 30 μm thick package, the production of butyl acetate and 2-methylbutyl acetate was slightly inhibited, whereas ethyl alcohol and the esters were low during storage.

Effects of Storage Temperature and Packaging Films on the Deterioration of Mustard

To determine the effect of packaging and storage temperature on the postharvest life and quality of mustard, it was stored at 1, 4, and 15 C (34, 40, and 60 F) in either perforated polyethylene bags, Cryovac D-955 60-gauge or 100-gauge heat-shrinkable films, or not-bagged. Packaging mustard in perforated bags and Cryovac films significantly reduced weight loss over nonbagged mustard. Bag type had a highly significant effect on CO2 concentration in atmosphere within bags of mustard, with higher CO2 concentrations occurring in the bags made of Cryovac film. Bagged mustard was stored for 12 days at either 1 C (34 F) or 4 C (40 F) with excellent results, whereas nonbagged mustard was unacceptable after only five days in storage. Quality of all mustard was poor after only five days in storage at 15 C (60 F). Bagging significantly increased the incidence of decay and yellow discoloration of mustard stored at 15 C (60 F). Sensory evaluations indicated bagging and storing mustard for extended periods (12 days) did not affect the flavor and quality of cooked mustard.

EFFECT OF MOISTURE CONTENT AND STORAGE TEMPERATURE ON THE VIABILITY OFBAMBUSA TULDASEED

SUMMARY Bamboos are attractive plantation species but as seed is only available in quantity during sporadic periods of gregarious flowering it is important to develop effective storage techniques. Tests with 3 incubation temperatures and 4 substrata showed the optimum conditions to evaluate viability involved germination at 30°C between two layers of paper. Seeds stored at their original moisture content of 26% lost germination capacity within 2 months but when moisture content was reduced to 10.2% and 6.6% percentage germination after 12 months was 57% and 70% respectively. Seeds stored in perforated polythene bags failed to retain germination capacity for 12 months at all tested temperatures. Storage in sealed polythene bags at ambient room temperature, 5°C, 15°C and 30°C gave percentage germinations of 70%, 80%, 82% and 24% respectively. The seeds exhibited orthodox behaviour and could possibly be stored for longer durations with proper handling and drying techniques.

Effect of a Bacterial Ethylene Absorbent on Keeping Quality of Apples Removed from CA Storage

Using 'Starking Delicious' apple fruits which have been in commercial CA store for 4 months and transferred to air, effect of a bacterial ethylene absorbent on the keeping quality of the fruits was investigated, comparing with commercial catalytic metal ethylene absorbent (chemical agent). Each of the 10kg fruits was sealed with or without absorbents in bags of 0.03mm thickness of polyethylene, and held at 1 °C and 20 °C.The bacterial absorbent showed ethylene removing ability which was almost comparable to the chemical agent at 20 °C, but much lower ability at 1 °C. The chemical agent removed ethylene even at low temperature. Ethylene disappeared once in the bags with both absorbents, but accumulated considerably in the latter half of the holding period at 20 °C.Concentrations of oxygen and carbon dioxide in the bags were little affected with both absorbents. Decrease of organic acid content, softening and discoloration of flesh were retarded by sealing in bags as compared with the fruits in perforated bags, but significant additional effect of both absorbents was not found as compared with package without ethylene absorbents.

Defense by symbiotic crustacea of host corals elicited by chemical cues from predator.

Observations and experiments carried out on a coral reef off the Pacific coast of Panamá demonstrated that shrimp (Alpheus lottini) and crab (Trapezia spp.) symbionts that protect their host coral (Pocillopora elegans) can detect an approaching sea star predator (Acanthaster planci) by chemical cues. Simulated feeding attacks by Acanthaster in sealed transparent bags elicited only 0.5 defensive responses (snipping at spines and tube feet, jerking the sea star, and snapping) per 3 min; defensive behavior increased significantly to 4 and 5 responses, respectively, for Acanthaster in perforated bags and for Acanthaster in direct contact with coral. Neutralized (boiled) Acanthaster elicited only 3 defensive interactions per 3 min compared with 12 interactions for live Acanthaster. Simulated feeding attacks by Oreaster, a non-corallivorous sea star, elicited only 0.5 defensive responses per 3 min, whereas Oreaster introduced with "Acanthaster water" increased the level of defensive responses to 7. These results suggest that chemical, and to a lesser extent visual (physical presence and movements of sea star), cues stimulate the defensive behavior of the symbiotic crustaceans. The ability to detect a predator at a distance is probably advantageous because in responding only to an actual threat it minimizes the time the defending symbionts spend in an exposed position on the terminal branches of the host coral and because it alerts the crustaceans to sea stars feeding at night.

Storage of fresh asparagus

Abstract Fresh asparagus spears stored in unperforated polyethylene bags had lower weight loss and improved appearance when compared with spears stored in perforated bags. Ascorbic acid concentration dropped from 39.1 mg to 17.6 mg/100 g fresh weight after 6 weeks. Loss of ascorbic acid was initially rapid but slowed after the first 2 weeks of storage. High storage temperatures (4° and 6°C) resulted in greater ascorbic acid loss than lower temperatures (0° and 2°C). Fibre and toughness did not alter markedly during storage. Visual assessment of spears indicated that storage of fresh asparagus in unperforated polyethylene bags at 2°–4°C for periods of up to 4 weeks is possible. Precooling asparagus before storage reduced the rate of deterioration during a shelf-life period at 12°C and is recommended as a routine treatment for fresh asparagus for export from New Zealand. Stored asparagus had a shorter shelf life after a simulated transit period than fresly cut spears, so storage of asparagus before exportin...

Effects of γ‐irradiation on quality and enzyme activities of prepacked cut chicory

SummaryThe effects of γ‐irradiation on quality and enzyme activities of prepacked cut chicory were investigated. Freshly cut slices of chicory were washed, centrifuged and packed in polythene bags. These samples were γ‐irradiated and stored in the dark at 10°C. The samples were tested organoleptically and the peroxidase and polyphenoloxidase activities were determined. The chlorogenic acid content was also measured.The results showed that, as far as the keeping quality of the prepacked chicory was concerned, 100 krad irradiation was superior to both the 0 krad and the 300 krad treatment, but irradiation in perforated bags (high O2 content) increased discolouration (browning). Peroxidase and polyphenoloxidase activities did not change for about two days after irradiation in the perforated or non‐perforated bags. These activities increased strongly in the non‐irradiated series. Some chicory was treated with cystein and NaCl in order to inhibit some of the discolouration, but rotting of this sample occurred sooner than in non‐irradiated samples. No difference in the chlorogenic acid content was found as a result of irradiation.

Shelf life of raw French-fry potato strips in consumer bags

Pre-peeled raw French-fry strips are highly perishable and have a very short shelf life at warm temperatures. An adequate shelf life for retailing can be obtained only through refrigeration at 40° F. or lower. Pre-peeled potatoes packaged in either perforated or nonperforated polyethylene bags kept for less than 1 day at 85° F., from 3 to 6 days at 50°, whereas at 32° they kept from 12 to 15 days in perforated bags, and at least 15 days in nonperforated bags