Use of UV-C irradiation to prevent decay and maintain postharvest quality of ripe 'Tommy Atkins' mangoes

Ripe mangoes 'Tommy Atkins' were exposed to UV-C irradiation for 10 and 20 min, prior to storage for 14 days at 5 or 20 °C and a shelf-life period of 7 days at 20 °C. UV-C-treated fruit maintained better visual appearance than unirradiated controls. UV-C irradiation for 10 min was the most effective regime in suppressing decay symptoms and maintaining firmness during storage at 5 or 20 °C. Such fruit (treated with UV-C for 10 min) showed greater levels of putrescine and spermidine after cold storage than controls and those treated with UV-C for 20 min. Higher levels of sugars and lower levels of organic acids were observed in mangoes treated with UV-C for 20 min. However, the most effective UV-C treatment (10 min) for reducing decay maintained sugar and organic acid levels similar to the controls. No UV-damage was observed on treated fruits after storage. These results indicate that UV-C irradiation could be used as an effective and rapid method to preserve the postharvest life of ripe mangoes without adversely affecting certain quality attributes.     

Effect of Time, Temperature, and Slicing on Respiration Rate of Mushrooms

ABSTRACT:  Respiration rate measurement considering the effects of cutting, temperature, and storage time are important for the shelf life study and modified atmosphere-packaging design of fresh-cut produce. This study investigates in the respiration rate of fresh whole and sliced mushrooms at 0, 4, 8, 12, 16, and 20 °C under ambient atmosphere and different storage times. The O₂ consumption rate increased with temperature and ranged from 22.13 to 102.41 mL/(kg.h) and 28.87 to 143.22 mL/(kg.h) for whole and sliced mushrooms, respectively, in the temperature range tested. Similar trend was observed for CO₂ production rate. Slicing of mushrooms increased the respiration rate by 30% at 0 °C and 40% at 20 °C indicating that the mushrooms are not as sensitive to the stress caused by cutting as other fresh produce. Storage time affected both respiration rate of whole and sliced mushrooms and this effect was prominent at higher temperatures. The respiration rates increased initially for some time, then decreased and reached steady state value at 12, 16, and 20 °C. A 2nd-order polynomial equation was used to fit the respiration rate data as a function of time at each temperature tested.     

Physio-chemical behavior of γ-irradiated garlic bulbs under ambient storage conditions

The present study was undertaken to study the effect of different gamma irradiation doses on storage life of garlic bulbs under ambient storage conditions. Garlic bulbs (cv. PG-18) were irradiated with gamma rays in dose range of 0–0.2 kGy and stored under ambient conditions (Temp 27–35 °C and RH 34–76%). Physical and chemical quality parameters i.e. physiological loss in weight (plw), rotting, sprouting, total soluble solids, firmness, ascorbic acid and allicin content of garlic bulbs was determined fortnightly to assess its storage life. On 195th day of ambient storage, the weight loss of bulbs ranged from 32.22 to 38.48% in all irradiation doses. It was observed that upto 30 days and 150 days, there was no rotting and sprouting, respectively in all the treatments. Firmness, total soluble solids, ascorbic acid and allicin content were significantly different with storage period and irradiation dose levels. It is concluded that garlic bulbs irradiated @ 0.12 kGy of gamma radiation resulted in minimum post-harvest losses along with maintaining their marketable shelf life for 4 months under ambient storage conditions.     

Sugars and organic acids in Japanese plums (Prunus salicinaLindell) as influenced by maturation, harvest date, storage temperature and period

The effects of fruit maturation, harvest date, storage temperature, storage period and shelf life, on the concentrations of individual sugars and organic acids in Japanese plums were investigated. During fruit maturation in 'Amber Jewel' plums, sucrose concentration increased significantly from 101 days after full bloom (DAFB) to 1 week after commercial maturity (136 DAFB) with a non-significant change in the concentration of total organic acids and malic acid, the major organic acid. The changes in concentrations of sugars and organic acids during cold storage of 'Amber Jewel' plums harvested on 129 and 136 DAFB appeared to be independent of harvest date. Storage of 'Amber Jewel' plums at 5 °C accelerated the loss of sucrose and increased the concentrations of fructose and glucose from the 4^th week of storage compared with those stored at 0 °C. 'Blackamber' plums did not undergo any significant increase in the total and individual sugars during 5 weeks storage and subsequent shelf-life of 8 days at 20 °C. Malic acid concentrations declined during storage from 3 weeks onwards with a further substantial loss during ripening at 20 °C. Maturation, harvest date, storage temperature, storage period and shelf-life affect the concentrations of sugars and organic acids in Japanese plums.     

Retention of Folate, Carotenoids, and Other Quality Characteristics in Commercially Packaged Fresh Spinach

ABSTRACT: The effect of storage temperature (4 °C, 10 °C, and 20 °C) on retention of folate, carotenoids, and other quality characteristics in commercially packaged fresh spinach were determined. Based on visual color and appearance, spinach was unacceptable after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Color differences (AE), chlorophyll degradation, fresh weight loss, and microbial populations increased at all storage temperatures and occurred more rapidly at higher temperatures. Peroxidase activity increased but was not significantly ( P > 0.05) affected by storage temperature. Lipoxygenase activity was unaffected by storage time or temperature. Substantial losses of nutrients occurred at each storage temperature. Only 53% of folate in packaged spinach was retained after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Carotenoid losses increased with temperature with only 54%, 61%, and 44%, respectively, of initial detected levels remaining. Vitamin and quality changes were unaffected by presence or absence of packaging.     

Postharvest Aloe vera gel-coating modulates fruit ripening and quality of 'Arctic Snow' nectarine kept in ambient and cold storage

To evaluate the role of Aloe vera gel coating on ripening and fruit quality of nectarine ( Prunus persica L. Batch cv 'Arctic Snow'), the uncoated and coated fruit were allowed to ripen at 20 ± 1 °C in first experiment and in the second experiment, the fruit were stored at 0 ± 0.5 °C and 90 ± 5% RH for 3 and 6 weeks prior to ripening at 20 ± 1 °C. Aloe vera gel-coated fruit kept at ambient or 3 and 6 weeks cold storage reduced respiration rate, ethylene production (62, 37 and 43% respectively), retarded fruit softening, reduced electrolyte leakage (EL), weight loss (65%), levels of ascorbic acid and total antioxidants (24, 9 and 13%) during ripening than control. In conclusion, Aloe vera gel can be used for extending storage life at ambient or cold storage and maintaining quality of 'Arctic Snow' nectarine.     

Inactivation of natural microorganisms in litchi juice by high-pressure carbon dioxide combined with mild heat and nisin

The individual and combined effects of high-pressure carbon dioxide (HPCD), mild heat (MH) and nisin (200 ppm) on the inactivation of natural microorganisms, including aerobic bacteria (AB), yeasts and molds (Y&;M), in litchi juice were evaluated. The samples were treated at a pressure of 10 MPa and temperatures of 32, 42 or 52 °C for 5, 10, 15, 20, 25 or 30 min. Temperature played a prominent role in the inactivation of both AB and Y&;M when combined with HPCD, particularly for AB at 52 °C and Y&;M at temperatures ≥42 °C. Nisin increased the susceptibility of AB to the combined treatment of HPCD and MH (HPCD + MH). A reduction of 4.19 log cycles was achieved by HPCD + MH at 52 °C for 15 min, and complete inactivation of AB was obtained by combination of HPCD, MH and nisin (HPCD + MH + nisin). No significant effect of nisin was found on the inactivation of Y&;M.     

Quality changes of fresh-cut kohlrabi sticks under modified atmosphere packaging

ABSTRACT:  The aim of this study was to determine the effect of different gas compositions on quality attributes and shelf life of kohlrabi sticks stored in modified atmosphere up to 14 d at 0 °C. Two commercial films were tested: oriented polypropylene (OPP) and amide-polyethylene (amide-PE). As a control, a microperforated OPP film was used. In order to study the changes in metabolic activity by minimal processing, the respiration rate and ethylene production at 0 °C were monitored for both intact stems and sticks. Changes in color, chemical parameters, sugars and organic acid contents, and sensorial quality of kohlrabi sticks were evaluated. An initial ethylene production of sticks was 13-fold higher than that of intact stems; meanwhile CO₂ production was 2-fold higher. However after 4 d of storage, a similar respiration rate for stems and sticks was found. Also the ethylene production of sticks and stems was steady around 15 to 20 nL/kg^/h after 10 d. Kohlrabi sticks showed a little change in chemical parameters and very low weight losses during cold storage. Sticks under an equilibrium atmosphere of 7 kPa O₂ and 9 kPa CO₂ at 0 °C reached by amide-PE kept an acceptable sensorial quality for 14 d.     

SPROUT INHIBITION BY GAMMA IRRADIATION IN FRESH GINGER (ZINGIBER OFFICINALE ROSCOE)

ABSTRACT. A study on sprout inhibition by gamma irradiation in fresh ginger of a local variety was carried out. Fresh ginger was irradiated at the doses of 0, 25, 50 and 80 Grays (Gy) and stored at temperature 25-28°C and relative humidity ranging from 76-96% for 4 months. the parameters observed were physiological weight loss, sprouting, external appearance, fungal infection, moisture content, water activity, crude fiber content and total sugar. the results show that irradiation at the doses studied effectively inhibited sprouting in ginger when compared to the nonirradiated samples. However, radiation was unable to extend the shelf-life as all samples started to deteriorate after 2 months storage.     

Effect of film and temperature on the sensory, microbiological and nutritional quality of minimally processed cauliflower

The effect of atmosphere modification, generated using three different packaging films, on the quality of cauliflower minimally processed when stored at 4 or 8 °C for up 20 days was evaluated. The colour, texture, weight loss, sensory attributes, as well as microbial counts and sugars and ascorbic acid content were determined. The atmosphere generated with the perforated polyvinylchloride (PVC) film was hardly modified, whereas the other two films (non-perforated PVC and polypropylene films) originated changes in CO₂ and O₂ levels during storage. The different packaging conditions and storage temperature influenced yellowing. An increase in shear force was observed. Weight losses were below 5%. Mesophiles and Pseudomonas counts were below 7 log CFU g⁻¹, the populations being lower with film B and film C than with film A. Cauliflower maintained an acceptable appearance in all the films studied. Total sugars decreased about 27% after 20 days of storage, whereas ascorbic acid did not change.     

Stability of protein digestibility and composition of cowpea (Vigna unguiculata L. Walp.) during sealed storage at different temperatures

Whole grains and flours of two cultivars of cowpea ( Vigna unguiculata ) were stored sealed at steady temperatures of 0, 20 and 55°C, and 11–13% moisture for 7 months. The pH, soluble sugars, free amino nitrogen, titratable acidity, and protein digestibility decreased at 55°C. The changes varied with cultivar and between the flours and the grains stored at 0 and 20°C. All changes, except titratable acidity in white cowpea flour, were strongly correlated with increasing storage temperature.     

Respiratory parameters of onion bulbs (Allium cepa) during storage. Effects of ionising radiation and temperature

The O₂ and CO₂ respiration rates of untreated and irradiated onion bulbs (Allium cepa) at 0.15 and 0.30 kGy were measured at 4, 10 and 20 °C. The O₂ respiration rate increased for 24 h after treatment from 0.19 mmole kg⁻¹ h⁻¹ at 20 °C for control samples up to 0.26 and 0.39 mmole kg⁻¹ h⁻¹ for 0.15 and 0.3 kGy irradiated onions respectively. Respiratory quotient (RQ) increased with temperature. The Q₁₀ of the respiration of the control samples (1.61) was lower than that of any other plant tissue, but it increased with storage duration and irradiation dose. The respiration rate of control onions increased steadily over 25 weeks of storage at 4 °C, while that of the irradiated samples decreased during the same period after a peak observed after irradiation treatment. The apparent K_m for the Menten–Michaelis equation was determined on a new respirometer and averaged 1.6 kPa at 10 °C and 6.3 kPa at 20 °C. However, at this higher temperature (20 °C) apparent K_m varied with O₂ partial pressure, proving that the respiration of onion bulbs does not follow a Menten–Michaelis‐like process. The Fermentative Index (FI) of onions was measured under anoxic conditions as CO₂ production rates in mmole kg⁻¹ h⁻¹ at 4, 10 and 20 °C. © 2000 Society of Chemical Industry     

Effect of temperature and fruit-moisture content on discolouration of dried, sulphured Bon Chretien pears during storage

Summary Discolouration of Bon Chretien pears which had been treated with sulphur dioxide and which had moisture contents of either 16, 18 or 20%, was monitored during storage at 4, 7, 10 and 20 °C. Colour was quantified in terms of CIE L*, a*, b*, hue and chroma. L* was used to predict quality retention. Discolouration was categorized as a decrease in all colour parameters, except a* which increased with storage. Measurement of L* showed that only fruit at 16% moisture content and stored at T ≤ 10 °C retained their original colour. The rate of change in overall colour was observed in the following order at 20 °C, 20% > 18 > 16% moisture content. Fruit with 18 and 20% moisture content could be stored at 10 °C for at least 140 weeks without changing their quality grading. Storage at 20 °C shortened this period to 60 and 27 weeks for fruit at 18 and 20% moisture content, respectively.     

Effect of gamma irradiation and sulphitation treatments on keeping quality of white button mushroom Agaricus bisporus (J. Lge)

Gamma irradiation, alone and in combination with sulphitation, was tested for preventing the browning and maintaining the quality attributes of the white button mushrooms. Mushrooms were subjected to treatment of gamma irradiation in the dose range of 0.5–2.0 kGy and to combination treatments of sulphitation at a concentration of 0.1% potassium metabisulphite (KMS) and gamma irradiation (dose range 0.5–2.0 kGy) followed by storage at 10 ± 2 °C (RH 85%). A dose of 2.0 kGy significantly reduced the weight loss, prevented browning and mould growth. Cap and veil opening of mushrooms was delayed by 9 days and shelf life was extended by 12 days at a dose level of 2.0 kGy. Sulphitation alone at a concentration of 0.1% KMS was effective in controlling browning only upto 3 days, beyond which both browning and cap opening increased significantly ( P  ≤ 0.05) and the samples were unacceptable after 6 days of storage. No synergistic effect of sulphitation and irradiation was observed with respect to the shelf-life extension of mushroom.     

Preservation and shelf-life extension of shrimps and clams by high hydrostatic pressure

Clam ( Venus gallina ) and shrimp ( Parapenaeus longirostris ) samples were high hydrostatic pressure (HHP) treated at 200, 220 and 250 MPa at 25, 30, 40 and 50 °C for 10 and 20 min. Based on the results of microbial reduction, the best combinations of HHP treatments were determined as 250 MPa, 50 °C, 10 min for shrimps and 220 MPa, 50 °C, 10 min for clams. HHP-treated samples stored at 25 °C (room tempertur) and 4 °C (refrigeration temperature) were analysed. According to the results evaluated, shelf-life of shrimps was found to be 12 and 16 days for storage at room and refrigeration temperatures, respectively, as compared with 4 days for non-HHP-treated samples at 4 °C. Similarly shelf-life for the clam samples was found to be 12 days for storage at room temperature and 18 days for storage at refrigeration temperature as compared with 4 days for non-HHP-treated samples at 4 °C.     

Effect of gamma radiation on the storage of onions used in the dehydration industry

Gamma radiation (8000 rad) of fresh onion bulbs, used in the dehydration industry in Egypt, was investigated. Irradiation reduced sprouting of the fresh bulbs but did not affect the rotting of the bulbs, No effects on sugar content or colour (optical density at 330 nm) of the fresh bulbs and dried onion flakes were observed. The irradiated onion had a noticeably lower ascorbic acid content, pungency (measured as volatile reducing substances) and free amino nitrogen content in comparison with non-irradiated bulbs. Darkening of onion flakes during storage for 8 weeks at 40ºC did not differ when the bulbs were treated with gamma rays before dehydration.     

GAMMA IRRADIATION, HOT WATER AND IMAZALIL TREATMENTS ON DECAY ORGANISMS AND PHYSICAL QUALITY OF STORED NETTED MUSKMELON FRUIT

Nonchemical treatments of gamma irradiation (2 Kilograys) and hot water (57°C) and the fungicide imazalil (1000 ppm) were compared with and without shrink-film wrap for effects on decay and physical quality of netted muskmelon fruit stored at 4°C for 0 through 60 days. Gamma irradiation was ineffective in controlling decay and surface molds, and injurious to physical quality by decreasing firmness, increasing fresh weight loss, membrane leakage and vein track browning. Hot water treatment coupled with shrink-film wrap was effective in controlling decay activity and maintaining physical quality up to 20 days storage. Imazalil coupled with shrink-film wrap controlled the incidence and severity of decay and maintained fruit firmness, moisture loss, membrane permeability and vein track browning for almost 60 days storage.     

CHANGES IN CHEMICAL COMPOSITION OF 'CAVENDISH' BANANA (MUSA ACUMINATA) DURING RIPENING

Green 'Cavendish' bananas were exposed to ethylene for 16 h and the subsequent development of ripening at 20°C was followed in terms of skin color, respiration and ethylene production. At six stages of ripeness, as determined by skin color, pulp tissue was analysed for firmness and for water, protein, fat, individual sugars, starch, dietary fibre, organic acids, ash, soluble solids, pH, vitamin C, thiamin, riboflavin, niacin, carotenes, sodium, potassium, calcium, magnesium, iron and zinc; energy content and edible weight were calculated.     

Metabolic Behavior and Quality Changes of Whole and Fresh Processed Melon

ABSTRACT: Whole fruit and fresh-cut pieces from 4 types of melon were stored for up to 10 d at 0 and 5 °C. After the wound stress period, no differences in the respiration rates were found between intact and the fresh-cut melon. Softness, weight loss, translucency, wound stress, and respiration rate were lower and sensorial quality higher during storage at 0 °C than at 5 °C. Cut cylinders showed a low degree of softness, high translucency, and a poor processing efficiency. Slices showed a higher softness but lower translucency. Trapezoidal sections showed a behavior intermediate between cylinders and slices. For the fresh-cut melon, the best results were obtained with Amarillo trapezoidal sections and a storage temperature of 0 °C.