Search

Although new storage technologies have been emerging in recent years, preservation of pear (Pyrus communis L.) remains a challenge for suppliers. Maintenance of desired organoleptic properties throughout cold storage using non-chemical strategies has been investigated and the use of edible coatings has shown potential to delay fruit quality deterioration during cold storage. Thus, the objective of this study is to evaluate the impact of pectin coatings including plant extracts, in &ldquo, Rocha&rdquo, pear (Pyrus communis L. cv. Rocha) preservation. A four-month pilot scale assay was performed in both dynamic controlled atmosphere (DCA) (&minus, 0.5 &deg, C, 0.5% O2, and 0.4% CO2) and normal atmospheric (NA) conditions (2 &deg, C). For each storage condition, the following three coatings were tested: pectin (3% w/v) (PCT), pectin (3% w/v) + strawberry tree leaves extract (9.5 mg/mL) (CT1), and pectin (3% w/v) + apple pomace extract (16 mg/mL) (CT2). Volatile compounds, potentially related to aroma or ripening status of &ldquo, pear, were monitored alongside with conjugated trienols (CTs) and maturity parameters. The combination of DCA conditions and the application of pectin coatings were able to reduce the release of Rocha pear volatiles associated with ripening status, (particularly esters and sesquiterpenes), as well as reduce CTs, which could contribute to the preservation of Rocha pear for longer periods.

Storage techniques, such as low temperature and modified atmosphere packaging, are efficient in keeping visual quality of ready-to-eat (RTE) products such as processed leafy vegetables throughout the supply chain, but studies on appearance often neglect the effect of different storage conditions on their nutritional properties. The effects of initial O2 partial pressure (20, 10, 5 and 2.5 kPa O2) in packages and storage time (14 d) on RTE rocket leaves on the bioactive compounds, phenolics, ascorbic acid, and antioxidant activity were determined. Kinetic models were applied to allow the assessment and prediction of the influence of initial partial pressure on nutritional composition. The results show that lowering package initial O2 partial pressure from 20 kPa to 5–10 kPa reduced the respiration rate by 53 and 38%, respectively. However, antioxidant activity and ascorbic acid content showed most effects with an initial O2 of 5 kPa. The kinetic parameters are relevant to help predict phytochemical changes during storage under different package O2 partial pressures. To obtain an overall quality, the application of intermediate atmospheres would be beneficial.

Fresh-cut wild rocket (Diplotaxis tenuifolia L.) represents a very interesting ready-to eat (RTE) product with a high market value. Scarce information is available on product freshness and on quality attribute deterioration during storage. The aim of this work was to evaluate the respiration rate and functional quality of rocket salad when packaged under passive atmosphere composition in two different permeability bags. Wild rocket was packaged on two different sealed polypropylene bags: macroperforated (P) and a non-permeable (NP) film bag. Bags were stored at 4°C during 15 days and the O2 and CO2 concentrations inside the bags, the respiration rate, the functional quality (ascorbic acid, phenolic compounds, anthocyanins, and chlorophyll) and microbial load of RTE rocket were evaluated at five different time points. Results showed that NP packages generated a passive modified atmosphere, with continuous decrease of O2 concentration (close to anaerobiosis by 14 days) and with increasing CO2 levels up to ca. 8 kPa after 5 days. Rocket preserved in this type of bag showed higher respiration rate in the first 2 days, when compared with rocket packaged in P bags. The evolution of carbon dioxide and oxygen concentration in both systems did not exhibit significant impact in the ascorbic acid and chlorophyll content. A positive effect of oxygen availability inside P packages was observed on total phenolic compounds and total anthocyanin concentration of rocket leaves, but simultaneously higher microbial contamination by day 5 in comparison with NP packages.

Effective and efficient design of modified atmosphere packaging (MAP) systems for ready-to-eat (RTE) products requires knowledge on produce respiration rate under various temperatures and oxygen levels. In order to model the respiratory behavior of RTE rocket leaves under different storage conditions, leaves respiration rate was measured during storage under four initial oxygen partial pressures (2.5; 5; 10 and 20 kPa O2) and three temperatures (0, 5 and 10 °C), for 10 days. The respiratory quotient was determined and found to range between 0.6 and 1.3. Temperature showed a significant impact on respiration rate and the effect of oxygen partial pressures was found to be temperature-dependent. The oxygen pressure effect on respiration rate was accurately described using Michaelis–Menten kinetics, without inhibition by carbon dioxide, and the effect of temperature was well modeled by exponential functions. Monte Carlo simulation allowed quantification of the relative impact of the reduction of oxygen pressure and temperature on the decrease in respiration rate and the potential shelf life increase of RTE rocket leaves. Temperature contributed to more than 80% of the Michaelis–Menten model variance while oxygen pressure contributed only with 13%. The model obtained is a useful tool for defining packaging and storage conditions for a shelf-life extension of rocket leaves.

Lysophosphatidylethanolamine (LPE) is a naturally occurring lipid with regulatory effects in senescence and ripening. When applied exogenously to horticultural crops, LPE affects growth, development, and postharvest longevity. The effects of exogenously applied LPE have been studied in a range of plant organs in more than a dozen horticultural species. The claimed horticultural benefits include delayed leaf senescence, stimulation of ripening in table grape, acceleration of color development and extension of shelf-life in cranberry and tomato, and increased vase life of cut flowers. Responses to LPE application are found to vary dramatically within horticultural commodity, developmental stage, and organ type. Effects on ethylene responses are contradictory. LPE inhibits phospholipase D and is reported to affect the activity of enzymes relevant for produce quality, such as phenylalanine ammonia lyase and acid invertase. The biochemical mode of action of LPE is poorly understood. In particular, a mechanism by which a plant growth regulator might delay senescence of plant organs and accelerate ripening-related changes is not obvious. The horticultural, physiological and biochemical effects of LPE are reviewed in an attempt to highlight the knowledge gaps regarding the putative regulatory role of exogenously applied LPE.

Second-order polynomial models were used to relate the independent variables, temperature, relative humidity and storage time, to the quality attributes (electrolyte leakage, chlorophylls, weight loss, humidity and headspace gas composition inside packages before and after packaging) of ready-to-eat spinach leaves. Results show that while waiting for processing the best conditions to assure high quality spinach leaves before packaging were 4 °C, 83 % RH and 4 h. The weight loss of spinach leaves was time-dependent: increasing the exposure time under these conditions decreased the amount of wet leaves before packaging. Under the same conditions, the electrolyte leakage was lower (4.63 %) and the chlorophyll content (45.44) was higher. After packaging and while waiting for dispatch, temperature most affected the package headspace atmosphere. Indeed, an increase in storage temperature from 3 to 7 °C led to a significant increase in respiration. The best combination of conditions in the high-care room was 3 °C, 74 % relative humidity for a maximum of 1 day before dispatch. In this case, the moisture content (0.46 %) and electrolyte leakage (4.16 %) were lower and the chlorophyll content (43.37) and oxygen concentration inside the packages of ready-to-eat spinach leaves (19.55 kPa) were higher.

The effect of calcium application and solution pH on ready-to-eat (RTE) baby-leaf spinach ( Spinacia oleracea L.) texture and structure preservation was studied. Spinach leaves were treated with calcium chloride, calcium lactate and calcium propionate, at two different pH conditions (5 and 7), packaged and stored for 7 days at 5 °C. After 24 h, the leaves crispness increased 49 and 29% for leaves treated with calcium chloride and lactate at pH 5 and the elasticity increased 100% after calcium propionate treatment at pH 7. During spinach shelf-life, the tissue flexibility decreased (20–60%) for all calcium treatments at pH 5 and 7 while tissue crispiness increased (7–40%) only for calcium treatments under pH 7. The electrolyte leakage increased throughout storage and was higher for all calcium treated samples when compared with controls. The chlorophyll content slightly decreased (12%) by the end of product shelf-life and did not differ according the calcium treatments. Total vitamin C content was lower in leaves treated with calcium chloride at pH 5 (31%) and pH 7 (19%) while the remaining treatments did not affect vitamin C content. The different calcium additives tested for potential texture quality maintenance did not provide the expected benefits on baby spinach leaves but increasing solution pH from 5 to 7 lead to an increased firmness by the end of shelf-life.

To improve fertilisation recommendations in organic farming systems and nitrate vulnerable zones, the response of white cabbage to the application of increasing rates of mineral N (0, 90 and 180 kg ha-1) fertiliser in combination with increasing rates (0, 20 and 40 t ha-1) of an organic fertiliser from the composting process (182 days) of the solid fraction (SF) of dairy cattle slurry, was assessed in the summer season in NW Portugal. Cabbage yield was strongly related to mineral N application with an N recovery rate over 70%, but was not associated to SF compost application, except for treatments without mineral N fertilisation where cabbage dry weight increased (P

Cabbage (B. oleracea var. capitata) response to 0 and 30 t/ha of mature cow and horse manure compost (C1: C/N=16.5) and of composted dairy cattle slurry solid fraction with different maturation periods and C/N ratios (C2: C/N=18.4; C3: C/N=21.8) and, incorporated into the soil one month before planting (B) and at planting (P), was evaluated throughout a randomized block design experiment. At the site, a mineral fertilized cabbage experiment was also carried out, with 180 kg ha-1 of mineral N. All crops were evaluated 0, 20, 34, 48 and 62 days after planting. The mineral fertilized cabbage showed increased growth rate compared to the organic crops with a final yield of 79.6 t/ha. The timing of compost application did not significantly affect crop growth, except for C2. Organic cabbage yield with the compost treatment C2B and compost C1 (mean of both application dates) were respectively 49.7 and 51.8 t/ha. Yield of crops grown with C2P and C3 were lower (mean of 36.9 t/ha) compared to C2B and C1 and were not significantly different from unfertilized crops (28.7 t/ha). Dry matter content was lower for mineral fertilized crops (9.2%) than for organic crops (mean 12.2%) and differences between the percentage of crop waste residues of organic (25.6%) and mineral fertilized (29.8%) crops were not statistically significant. The apparent compost N efficiency rate decreased from 13.7 to 11.2 and 9.2%, whereas N immobilization period increased from 37 to 42 and 45 days, respectively for C1, C2 and C3. Consequently, N uptake decreased from 99.7 (C1) to 89.8 (C2) and 79.5 kg/ha (C3). The N recovery rate for the mineral N application in the mineral fertilized cabbage crop was 55.3% (N uptake of 99.5 kg/ha). This study shows that as the C/N of the composts decreased, the period of N immobilisation decreased and the apparent compost N efficiency rate by the crop increased. Consequently, during the cabbage growing period more mineral N was available from the mineralisation of composts with a lower C/N ratio, as well as for the earlier compost application for the mature compost C2.

'Rocha' pear (Pyrus communis L.) was used as a model system to assess the effect of pH of dipping solutions on quality retention of fresh-cut fruit and its interaction with calcium additives. Pear slices were dipped for 60. s in a buffer solution at pH 3.0, 5.0 or 7.0 and stored at 4.5°C for 13 days. In other experiments, pear slices were dipped for 60. s in buffer solutions containing 250. mM of calcium ascorbate, lactate, chloride, and propionate, at pH 3.0 or 7.0, and stored at 4.5°C for 6 days. Browning and softening were more intense in slices dipped in a solution at pH 3.0 than at pH 5.0 or 7.0, but microbial growth was lower in slices treated at pH 3.0. The effect of calcium additives depended on the anion and significant interactions between the effects of calcium salt and pH were observed. Calcium ascorbate was very effective in preserving color and reducing microbial growth irrespective of pH, but enhanced pectin solubilization and tissue softening at pH 3.0. Slices treated with 250. mM calcium propionate or calcium lactate were softer and had higher electrolyte efflux when treated at pH 3.0 than at pH 7.0. Calcium lactate enhanced browning and reduced microbial growth at pH 3.0 but did not affect color or microbial counts at pH 7.0. All calcium treatments enhanced electrolyte leakage. pH of the dipping solution can affect, per se, the quality of fresh-cut fruit. The choice of calcium additives to prevent undesirable changes on visual and sensory quality of cut produce should involve pH ranges that provide the expected benefits.

Cantaloupensis melons are aromatic and fast senescing, whereas Inodorus have less odor and are slower senescing. Modified atmosphere packaging (MAP) is used to reduce respiration rate and extend shelf-life but may alter the synthesis of volatile compounds. We assessed the effects of passive MAP and controlled atmosphere (CA; 5 kPa O 2 + 10 kPa CO 2 ) upon quality and volatile production by fresh-cut 'Cantaloupe' and 'Honeydew' melons, stored at 5°C for 14 days. O 2 concentration inside the MAP packages decreased during the 14 days, to 11.1 and 14.2 kPa, in 'Cantaloupe' and 'Honeydew', respectively. CO 2 levels increased to 11.3 and 7.9 kPa during storage, for 'Cantaloupe' and 'Honeydew', respectively. In MAP, during the first 4 days of storage, cantaloupe cubes softened at a higher rate (2.0 N.day -1 ) than 'Honeydew' cubes (0.9 N.day -1 ). Conversely in CA, fresh-cut 'Honeydew' softened faster (1.9 N.day -1 ) than fresh-cut 'Cantaloupe' (0.9 N.day -1 ) which, softened faster between days 4 and 7 (2.1 N.day -1 ). Initial 'Cantaloupe' respiration was 17.5 ml CO 2 .kg -1 .h -1 , which increased to 63.8 and 43.4 ml CO 2 .kg -1 .h - 1 when stored in CA and MAP, respectively. Initial respiration of 'Honeydew' melon was 7.7 ml CO 2 .kg -1 .h -1 and increased to 55.5 and 30.0 ml CO 2 .kg -1 .h -1 when stored in CA and MAP, respectively. Volatile compounds that are known to be flavor-important in melons, were extracted using Stir Bar Sorptive Extraction (SBSE) and quantified via GC-MS. The production of acetate esters increased in both melons stored in MAP, but decreased in 'Cantaloupe' under CA conditions. Non-acetate esters increased in both cultivars and storage conditions. Alcohols, initially more abundant in 'Honeydew', underwent a decrease throughout storage. Aldehydes, initially more abundant in 'Cantaloupe', decreased in both melons for MAP but not in 'Honeydew' stored in CA. Lower O 2 availability in fresh-cut fruit, stored under CA conditions utilized in this experiment, likely suppressed some of the acetate esters relevant to the aroma of fresh-cut melon.

Melon ( Cucumis melo L.) is a widely consumed fruit whose major biologically active compounds are the vitamins C, pro-vitamin A, and folic acid, the phenolic phytochemicals and the toxic cucurbitacins. Levels of biologically active compounds in melon vary widely and are affected by genotype and environmental conditions during production and post-harvest handling, with strong interactions between cultivar and environmental effects. Ascorbic acid levels are generally reduced by processing methods. β-Carotene concentration also varies widely with genotype and is affected by processing conditions. Phenolics are generally preserved during storage and processing of raw materials but can be enhanced by roasting. Cucurbitacin levels, although negligible in commercial cultivars, may become important in pharmacological or ethnobotanical applications.

Wounding increases the hydrolysis of phospholipids mediated by phospholipase D (PLD) in plant tissues. Subsequent reactions may originate flavor-related aldehydes and alcohols. Lysophosphatidylethanolamine (LPE) is a naturally occurring phospholipid capable of inhibiting phospholipase D in vitro. The effect of LPE on the quality and volatile profile of fresh-cut melon was investigated. Cantaloupe melons (Cucumis melo L. 'Fiesta') were processed into cubes, vacuum-infiltrated with 200 μg L-1 of LPE, packaged in plastic clamshells and stored at 5°C for 9 days. The activities of phospholipase D (PLD) and C (PLC), respiration and ethylene production rates, color, firmness, soluble solids content (SSC), and volatile production were measured during storage at 5°C for 9 days. LPE significantly reduced the activity of PLD and PLC one day after the treatment but the effect was transient. LPE did not affect ethylene production and had a negligible effect on the respiration rate of melon cubes. Firmness and SSC were not affected by the treatment but LPE induced a very small increase in hue angle. LPE did not affect the major classes of volatiles in melon -esters and alcohols -but reduced the accumulation of aldehydes typical of wounding after the first day of storage. In conclusion, LPE did not help in the quality retention of fresh-cut melon but had a specific inhibitory effect on aldehyde production.