Nondestructive tests for measuring the firmness of guava fruit stored and treated with methyl jasmonate and calcium chloride

Ripening is one of the most important processes to occur in fruits and involves changes in colour, flavour and texture. An important goal in quality control of fruits is to substitute traditional sensory testing methods with reliable and quantitative methods. In this study, methyl jasmonate (MJ) (220 μL L^?1) and calcium chloride (at 1%) were applied to guava fruits stored at 6 °C. The compression test (CT) and acoustic impact test were used to monitor the shelf life of guavas. The results obtained using both techniques showed that Young’s modulus diminishes as a function of time in all samples; however, the texture of samples treated for 20 days with MJ deteriorated unacceptably, a condition which did not occur in the samples treated with calcium chloride. The control samples had a shelf life of 20 days. In conclusion, it appears that the acoustic impact test is more appropriate than the CT and has the additional advantage of being a nondestructive technique.     

Relationships between volatile production,fruit quality and sensory evaluation of Fuji apples stored in different atmospheres by means of multivariate analysis

Aroma compounds, quality parameters and sensory characteristics of Fuji apples were analysed after 3, 5 and 7 months of storage at 1 °C in normal air (AIR; 210 l m^?3 O₂/0.3 l m^?3 CO₂) and in controlled atmospheres with O₂/CO₂ ratios of 10 l m^?3/10 l m^?3 (ULO1), 10 l m^?3/20 l m^?3 (ULO2) and 30 l m^?3/20 l m^?3 (SCA). After storage the apples were kept at 20 °C for 1, 5 and 10 days. The components that contributed most to the characteristic aroma of Fuji apples were ethyl 2‐methylbutanoate, 2‐methylbutyl acetate and hexyl acetate. The highest aroma compound production was found in ULO1 fruits after 5 months of cold storage and 1 day of shelf‐life. After 3 and 5 months of storage, ULO1 fruits showed the highest firmness after both 1 day and 10 days at 20 °C. After 7 months of storage plus 1 day at 20 °C, ULO2 fruits showed higher titratable acidity and soluble solid content; fruit firmness was also maintained throughout the shelf‐life period. Generally, background and superficial colour were not influenced by storage conditions. A statistically significant correlation was found between aroma compounds, quality parameters and sensory evaluation. Copyright © 2003 Society of Chemical Industry     

Polyamine Accumulation Following Hot-Water Dips Influences Chilling Injury and Decay in'Friar' Plum Fruit

Mature‐green (Prunus salicina Lindl. cv.‘Friar’) plums were treated in water at 40°C for 40 min, 45°C for 35 min, 50°C for 30 min or 55°C for 25 min, stored at 0°C for 35 d plus 9 d of ripening at 20 to 25°C. During cold storage, putrescine and cadaverine accumulated most compared to spermine and spermidine, especially in fruits treated at 45 or 50°C, compared to other treatments. Chilling injury (CI) and decay symptoms were severe in fruits of control, 55 and 40°C‐treated fruits. Decay incidence was also high in fruits stored at room temperature. Chilling injury and decay symptoms were retarded in fruits treated at 45 and 50°C, which also maintained increased polyamines and low ethylene. By the end of their shelf life, only 45 and 50°C‐HWD treated fruits were fit for market.     

Physiological and biochemical changes of different fresh-cut mango cultivars stored at 5 °C

Treatments to inhibit browning, decay and to extend shelf life of ‘Keitt’, ‘Kent’ and ‘Ataulfo’ mango cultivars as a fresh‐cut produce were investigated. Combinations of calcium chloride (CaCl₂), antioxidants [ascorbic acid (AA), citric acid (CA)] and two commercial film coatings resulted in a reduction of browning and deterioration of fresh‐cut mangoes stored at 5 °C, especially for the Ataulfo cultivar. The use of CaCl₂ + AA + CA significantly reduced colour deterioration, loss of firmness and did not affect sensory characteristics of fresh‐cut mango, with a larger effect in the Ataulfo cultivar. In general, these treatments prevented loss of sugar and vitamin C of cubes during storage at 5 °C. Shelf life of this cultivar was 21 days, while that of Keitt and Kent was only 9 and 12 days, respectively. There is a correlation between carotene and vitamin C content of Ataulfo mango and its longer shelf life compared with the other cultivars.     

Effect of chitosan coating in preventing deterioration and preserving the quality of fresh‐cut papaya ‘Maradol’

BACKGROUND: Chitosan can form antimicrobial, semi‐permeable barriers that limit gas exchange and reduces water loss in fruits. Consumer interest in fresh‐cut papaya fruit is leading to increasing demand because of its sensorial and antioxidant properties. However, papaya is a highly perishable product that is prone to loss of weight, loss of firmness and microbial attack. The aim of this study was to evaluate the effect of chitosan coatings on the overall quality of fresh‐cut papaya. Chitosan coatings of low (LMWC), medium (MMWC) and high (HMWC) molecular weights, at concentrations of 0.01 and 0.02 g mL^?1, were applied to fresh‐cut papaya cubes. The treated cubes were stored at 5 °C and changes in quality were evaluated. RESULTS: MMWC maintained the highest color values (L* and b*) and firmness. Chitosan coatings suppressed mesophilic plate count, and the growth of molds and yeast, compared to controls. The MMWC coatings at 0.02 g mL^?1 resulted in the highest antimicrobial activity and decreased the activity of the enzymes polygalacturonase and pectin methylesterase, followed by low and high MW chitosan coatings at 0.02 g mL^?1. CONCLUSION: The application of the MMWC treatment at 0.02 g mL^?1 could be used to reduce deteriorative processes, maintain quality and increase the shelf life of fresh‐cut papaya stored at 5 °C. Copyright © 2008 Society of Chemical Industry     

Growth Potential of Listeria Monocytogenes and Staphylococcus Aureus on Fresh‐Cut Tropical Fruits

The objective of this study was to evaluate the fate of Staphylococcus aureus, Listeria monocytogenes, and natural microbiota on fresh‐cut tropical fruits (pitaya, mango, papaya and pineapple) with commercial PVC film at different storage temperature (5, 13, and 25 °C). The results showed that S. aureus, L. monocytogenes, and natural microbiota increased significantly on fresh‐cut tropical fruits at 25 °C. Both pathogen and natural microbiota were able to grow on fresh‐cut tropical fruits at 13 °C. The maximum population of L. monocytogenes was higher than that of S. aureus on fresh‐cut tropical fruits. L. monocytogenes and S. aureus could survive without growth on fresh‐cut pitaya, mango, and papaya at 5 °C. The population of L. monocytogenes declined significantly on fresh‐cut pineapple at all temperature, indicating composition of fresh‐cut pineapple could inhibit growth of L. monocytogenes. However, S. aureus was still able to grow on fresh‐cut pineapple at storage temperature. Thus, this study suggests that 4 kinds of fresh‐cut tropical fruits (pitaya, mango, papaya, and pineapple) should be stored at low temperature to extend shelf life as well as to ensure the safety of fresh‐cut fruits.     

Low‐temperature conditioning combined with methyl jasmonate treatment reduces chilling injury of peach fruit

BACKGROUND: Peaches are sensitive to low temperature and develop chilling injury (CI) symptoms during refrigerated storage. This CI reduces consumer acceptance of peaches and limits the potential postharvest market life of the fruit. To develop a suitable technique to reduce CI, the effect of a combination of low‐temperature conditioning (LTC) and methyl jasmonate (MJ) treatment on CI of peach fruit was investigated in this study. RESULTS: Freshly harvested firm‐mature peaches were treated with a combination of LTC at 10 or 20 °C and 1 µmol L^?1 MJ and then stored at 0 °C for 5 weeks. The fruits developed CI during storage, manifested as internal browning and flesh mealiness. The combined treatment significantly reduced these CI symptoms and maintained higher fruit quality. The activities of polyphenol oxidase and peroxidase were significantly inhibited while those of superoxide dismutase, catalase and ascorbate peroxidase were induced by the combined treatment. In addition, the activities of phenylalanine ammonia‐lyase and polygalacturonase and the level of total phenolics were enhanced by the combined treatment. CONCLUSION: The combination of LTC and MJ treatment could be a useful technique to reduce CI and maintain quality in peach fruit during cold storage. Copyright © 2009 Society of Chemical Industry     

Changes in selected quality characteristics of minimally processed carambola (Averrhoa carambola L.) when treated with ascorbic acid

‘B 10’ carambola of ripening stage (RS) 3 and 4 were minimally processed (MP) and then dipped in 0, 15 and 30 mg L^?1 ascorbic acid (AA). The 1‐cm‐thick slices were then dried, packed into cling‐wrapped‐foam tray and stored at 7 °C for 0, 3 and 5 days. Skin colour (L*, C* and h°), flesh firmness, soluble solids concentration, vitamin C content, titratable acidity, pH, degree of browning, polyphenoloxidase (PPO) activity and sensory attributes of MP carambola treated with AA were determined. AA treatment had significant effect in decreasing cut surface browning degree but no significant effect on all the selected quality characteristics of the MP carambola. In the sensory evaluation, flesh colour, sweetness, flavour and overall taste were significantly affected by AA treatment especially at 15 mg L^?1. The RS of fruit significantly affected skin colour (C* and h°), pH and sensory attributes of colour and flavour of the MP carambola. As storage day (SD) progressed, skin colour (C* and h°), flesh firmness and vitamin C content, cut surface browning, PPO activity and all the sensory attributes of MP carambola decreased significantly. Flesh firmness of the MP carambola was affected by the interaction between AA × SD. Sensory attributes of MP carambola were affected significantly by AA × RS. All the sensory attributes of MP carambola positively correlated to each other but negatively correlated with browning degree. PPO activity positively correlated with browning degree. Copyright © 2007 Society of Chemical Industry     

REDUCTION IN MICROBIAL GROWTH AND IMPROVEMENT OF STORAGE QUALITY IN FRESH-CUT PINEAPPLE AFTER METHYL JASMONATE TREATMENT

Maintaining the quality of a fresh‐cut fruit or vegetable product is a major concern and a priority in the development and in the production of fresh‐cut produce products of the industry. The industry has been searching for alternative methods to protect fresh‐cut produce from decay and to prolong shelf life. The objective of this research is to enhance the quality and the shelf life of fresh‐cut pineapple by exposure to methyl jasmonate (MJ). The exposure of the diced pineapple to a MJ emulsion at a concentration of 10 ^?4 M for 5 min in a sealed container decreased microbiological growth by 3 logs after 12 days of storage at 7C, compared with the control pineapple. Methyl jasmonate as vapor or as dip did not affect the firmness or the color of the fruit. Methyl jasmonate may be a practical treatment to ensure the safety and the quality of fresh‐cut pineapple and other fruits and vegetables.     

Abscisic Acid in the Response of ‘Fortune’ Mandarins to Chilling. Effect of Maturity and High-Temperature Conditioning

The possible role of abscisic acid (ABA) and peel colour in chilling tolerance of ‘Fortune’ mandarins has been examined. Fruit stored at 2·5°C, but not at 12°C, showed pitting damage. The degree of damage changed considerably during development and maturity from November until May. Green fruit were more tolerant to chilling injury (CI). After colour break, chilling susceptibility increased from the beginning of December until January and February (the coolest season during the growing period) and declined towards May. This trend did not parallel changes in fruit colour index or free and bound ABA levels, which increased from November until May. At the time of chloroplast transformation to chromoplast a noticeable shift in free but not in bound ABA occurred. During storage, free ABA levels increased in fruits stored at 12°C, but not at 2·5°C. Changes in ABA with storage temperature depended on the stage of maturity of the fruits, but not on their susceptibility to CI. It has also been shown that there was no relationship between ABA content following exposure to 37°C and chilling tolerance. At all stages of maturity, the susceptibility of the fruits to CI and the free ABA levels of the flavedo decreased after conditioning the fruits for 3 days at 37°C. After storage at 2·5°C, the ABA levels of the conditioned fruit were similar or even lower than those of non-conditioned fruit. Treatment of fruit for 3 days with 10 μl litre^-1 ethylene increased free ABA about four times, whereas bound ABA remained nearly constant. This treatment enhanced cold-induced peel damage after prolonged storage. Thus, the ethylene-induced changes in free ABA appear not to be related to the induced changes in chilling susceptibility. The results obtained indicated, therefore, that free and bound ABA appear not to be involved on the adaptative mechanism developed in ‘Fortune’ mandarins to cope with chilling stress. © 1997 SCI.     

Microbial spoilage analysis and its effect on chemical changes and shelf‐life of Norway lobster (Nephrops norvegicus) stored in air at various temperatures

Microbial activity and spoilage of Norway lobster (Nephrops norvegicus) from Greek temperate waters, stored in air at 20, 5 and 0 °C was assessed. Microbial spoilage population, Total Volatile‐Base Nitrogen (TVB‐N), Trimethylamine‐Nitrogen (TMA‐N), pH and organoleptic changes were determined. Shelf‐life of Norway lobster stored at 20, 5 and 0 °C was 24, 72 and 96 h respectively. The product was spoiled due to the development of TVB‐N and melanosis of the carapace, as TVB‐N was apparent from the early stages of storage and correlated very well with microbial growth and shelf‐life. Pseudomonas sp. was the predominant spoilage bacterium. Product rejection coincided with TVB‐N levels of 330–400 mg kg^?1 and Pseudomonas sp. population level of about 5 × 10⁵ cfu g^?1. Pseudomonas sp. and TVB‐N are presumably the Specific Spoilage Organism and the Chemical Spoilage Index of the product.     

Combination of UV‐C Treatment and Metschnikowia pulcherrimas for Controlling Alternaria Rot in Postharvest Winter Jujube Fruit

The potential of using antagonistic yeast Metschnikowia pulcherrimas alone or in combination with ultraviolet‐C (UV‐C) treatment for controlling Alternaria rot of winter jujube, and its effects on postharvest quality of fruit was investigated. The results showed that spore germination of Alternaria alternata was significantly inhibited by each of the 3 doses (1, 5, and 10 kJ m^?2) in vitro. In vivo, UV‐C treatment (5 kJ m^?2) or antagonist yeast was capable of reducing the percentage of infected wounds and lesion diameter in artificially inoculated jujube fruits, however, in fruit treated with combination of UV‐C treatment and M. pulcherrima, the percentage of infected wounds and lesion diameter was only 16.0% and 0.60 cm, respectively. The decay incidence on winter jujube fruits treated with the combination of UV‐C treatment and M. pulcherrima was 23% after storage at 0 ± 1 °C for 45 d followed by 22 °C for 7 d. None of the treatments impaired quality parameters of jujube fruit. Thus, the combination of UV‐C radiation and M. pulcherrima could be an alternative to synthetic fungicides for controlling postharvest Alternaria rot of winter jujube.     

Effect of pre‐ripening chilling temperatures on ripening,shelf life and quality of bananas treated with 1‐methylcyclopropene

Ethylene production, shelf life and fruit quality of Cavendish bananas (cv. Williams), held at different pre‐ripening storage temperatures (5 °C, 10 °C or 15 °C) prior to ethylene and/or 1‐methylcyclopropene (1‐MCP) application, were determined and compared. Levels of ethylene production during ripening were highest for control fruit that had been stored at 5 °C followed by 10 °C and then 15 °C. 1‐MCP treatment (at 300 nL L^?1) had no effect on ethylene production of fruit that had been stored at 10 °C by day 10 of storage, but ethylene production was significantly higher for fruit that had been stored at 15 °C and lower for those stored at 5 °C before 1‐MCP treatment. 1‐MCP also increased shelf life to a greater extent when applied to fruit that had been stored at 10 °C or 15 °C. Even though 1‐MCP had no significant effect on under peel chilling injury, it increased discolouration significantly, regardless of storage temperature. Firmness of 1‐MCP‐treated fruit decreased significantly compared to the control when fruit were held at 5 °C or 15 °C prior to ripening (and 1‐MCP application) but had no effect on fruit stored at 10 °C before ripening. These results indicate that pre‐ripening storage temperature affects ripening, shelf life and quality in both ethylene and 1‐MCP‐treated bananas.     

Quality of mango fruits during storage: effect of synthetic and eco‐friendly films

Mango (Mangifera indica) cv ‘Alphonso’ fruits, harvested 40–50 days after flowering, were stored at 27 ± 1 °C and 65% RH under three conditions of packaging: (1) perforated plastic boxes, (2) wax lined cartons sealed with low‐density polyethylene (LDPE) film, and (3) wax lined cartons sealed with chitosan films. The weight loss, firmness, Hunter colour values and acidity were determined periodically during storage. Sensory analysis was carried out to determine colour, firmness, flavour qualities and also defective spots. Principal component analysis (PCA) of the results indicated that fruits stored in perforated plastic boxes and LDPE film‐sealed cartons differed significantly with respect to mango flavour, firmness and development of defective spots, while those in chitosan film sealed cartons retained the desirable qualities for a longer period (up to 20 days) without developing defective spots. The higher level of carbon dioxide and lower level of oxygen, or lower rate of oxygen transmission, associated with chitosan films delay ripening, and the higher water vapour transmission rate minimizes the rate of transpiration and prevents condensation of water droplets on the film. This helps in establishing equilibrium moisture content of mangoes in the cartons, which, in turn, extends the shelf life of fruits for a longer period. Copyright © 2004 Society of Chemical Industry     

Chemical and microbial stability of high moisture dried apricots during storage

BACKGROUND: This study was conducted to determine the chemical and microbial stability of high moisture (HM) dried apricots during storage at 5, 20 and 30 °C for a period of 8 months. HM dried apricots were obtained by rehydrating dried apricots in ‘water’ and ‘water + H₂O₂’. RESULTS: Analysis of kinetic data suggested first‐order models for loss of SO₂ and non‐enzymatic browning reactions. Higher storage temperatures increased the rate of SO₂ loss and formation of brown colour in HM dried apricots. Results from extensive colour measurements (non‐enzymatic browning, reflectance colour and β‐carotene) revealed that the colour of HM dried apricots stored at 5 °C was almost unchanged during 8 months of storage. The colour of samples stored at 30 °C was unacceptable starting from 2 months of storage. Total mesophilic aerobic bacteria counts decreased 0.7, 1.1 and 1.5 log cycles after 8 months of storage at 5, 20 and 30 °C, respectively. For the same storage period, the decrease in mesophilic bacteria was 0.62 log cycle in samples rehydrated in ‘water + H₂O₂’ and stored at 20 °C. CONCLUSION: These results suggest that HM dried apricots should be stored at temperatures lower than 20 °C to preserve the characteristic golden yellow colour. A relatively low level of SO₂ (1458 mg kg^?1 at 200 g kg^?1 moisture level) was sufficient to prevent the growth of spoilage organisms in HM dried apricots at all three storage temperatures. Copyright © 2008 Society of Chemical Industry     

Antioxidant properties and shelf‐life extension of fresh‐cut tomatoes stored at different temperatures

BACKGROUND: The feasibility of using modified atmosphere packaging (5 kPa O₂ + 5 kPa CO₂) to maintain the antioxidant properties of fresh‐cut tomatoes during shelf‐life was assessed through storage at different temperatures (5, 10, 15 and 20 °C). Health‐related compounds, antioxidant capacity, microbiological counts, physicochemical parameters and in‐package atmosphere of tomato slices were determined. RESULTS: Initial lycopene, vitamin C and phenolic contents and physicochemical parameters of tomato slices were well maintained for 14 days at 5 °C. Lycopene and total phenolic contents were enhanced over time in tomato slices stored at 15 and 20 °C. However, this increase in antioxidant compounds of fresh‐cut tomatoes during storage may be associated with excessive amounts of CO₂ (R² = 0.5679–0.7328) in the packages due to microbial growth. Although keeping tomato slices at temperatures above 10 °C increased their antioxidant content, the shelf‐life of the product was reduced by up 4 days. CONCLUSIONS: A storage temperature of 5 °C is appropriate for maintaining the microbiological shelf‐life of fresh‐cut tomatoes for up to 14 days and also allows the antioxidant properties of tomato slices to be retained over this period, thus reducing wounding stress and deteriorative changes. Copyright © 2008 Society of Chemical Industry     

Some postharvest factors associated with the occurrence of chilling injury in banana

Unripe Cavendish banana fruits were stored at 5–7°C under normal or 0.14 normal atmospheric pressure for two weeks, with or without a continuous supply of ethylene, prior to ripening at 20°C. Pulp/peel ratio, colour index and production of volatile were measured following prestorage at chilling temperature, and after reaching ripeness at 20°C. CO₂ and C₂H₄ production were also measured at 20°C. The results show that green fruits had lower pulp/peel ratios than treated green fruits while the reverse was true following ripening at 20°C. Yellow colour development was retarded by 5°C pretreatment, and low pressure storage had no noticeable effect on colour index. Prestorage at 7°C, however, improved colour development slightly. Acetates, butyrates and alcohol produced by fruits prestored at chilling temperature and 0.14 normal atmospheric pressure showed both qualitative and quantitative differences compared with those produced by non-chilled fruits.     

Photochemical Treatment to Improve Storability of Fresh Strawberries

We investigated the effect of pre-storage exposure to shortwave ultra-violet (UV-C) light on the decay and quality of fresh strawberries. Fresh strawberries (cv. Kent, 25% to 50% red) were exposed to UV-C at doses of 0.25 and 1.0 kJ/m² and stored at 4 °C or 13 °C. UV treatment controlled the decay caused by Botrytis cinerea at both temperatures and extended the shelf-life of the fruits by 4 to 5 d. UV-treated fruits had a lower respiration rate, higher titratable acidity and anthocyanin content, and were firmer than the untreated fruits. The percentage of free sugars increased faster in UV-treated fruits at the beginning of the storage period. A lower electrical conductivity in fruits treated with 0.25 kJ/m² suggests a slower rate of senescence compared to the control. A higher electrical conductivity observed with 1.0 kJ/m²suggests damage to the fruits. Overall, UV treatment at 0.25 kJ/m² appears to slow down the ripening and senescence of strawberry fruits stored at 4 °C.     

Kinetics of ascorbic acid degradation and colour change in ground cashew apples treated at high temperatures (100–180 °C)

Ascorbic acid (AA) degradation and colour changes, measured by the lightness index (L*), were determined in cashew apples (at low dissolved O₂ concentrations) heated at high temperature (100–180 °C) in a hermetically sealed cell. A nonisothermal method was developed to estimate thermal degradation kinetics. The results showed that reaction kinetics during heat treatments were well represented by first‐order reactions. The temperature dependence of the kinetic constants was described by an Arrhenius type equation. The activation energy (E_a) for AA degradation and lightness index were 94 ± 3 and 98 ± 3 kJ mol^?1, respectively. The reaction rate constant at 140 °C for AA degradation (64 × 10^?5 ± 3 × 10^?5 s^?1) was twice that for the lightness index change (33 × 10^?5 ± 2 × 10^?5 s^?1). Results allow generating temperature profiles of heat processes that would help preserve the AA of cashew apples as well as control the colour formation during high‐temperature processes.     

Effect of calcium on the storage life of oro (Antiaris africana)

The effects of calcium on the ascorbic acid, chlorophyll, titratable acidity and texture (firmness) of stored oro (Antiaris africana (Mill)) friuits (average weight 100 g ) were studied. Three groups of the fruits were dipped in 20 g litre^?1, 40 g litre^?1 CaCl₂ solutions and deionised water respectively for I0 min. The fourth group, which was untreated, served as the control and was also packaged in heat-sealed cellophane bags. The fruits were displaced and stored at ambient temperature (28 ± 2°C). The calciumtreated fruits which kept better were firmer and had a slight colour change (chlorophyll) which also produced a progressive increase in ascorbic acid level during storage. The titratable acidity of the fruits did not fluctuate as signijcantly as that of the untreated (control) fruits.