Quality and enhancement of bioactive phenolics in cv. Napoleon table grapes exposed to different postharvest gaseous treatments

Ten different gaseous treatments were evaluated for their efficacy in the keeping quality of cv. Napoleon table grapes during 38 days of storage at 0 degrees C followed by 6 days of shelf life at 15 degrees C in air. These storage methods included modified atmosphere packaging (MAP) with and without SO(2) or natural fungicides (hexanal and hexenal), two controlled atmospheres (CA), and intermittent and continuous applications of O(3). As a control, air atmosphere during cold storage was used. Most of the treatments applied kept the postharvest quality of the grapes, although the best results were obtained by the use of a MAP with 5 kPa of O(2) plus 15 kPa of CO(2) plus 80 kPa of N(2). The total anthocyanin content at harvest was 170 +/- 19 microg/g of fresh weight (fw) of grapes, which declined in most of the treatments applied and was reflected in the loss of red color. Peonidin 3-glucoside was detected at all sampling times as the major anthocyanin (always >50% from the total content). Treatments applied kept or decreased the total flavonol content from that measured at harvest (17 +/- 1.4 microg/g of fw of berries). However, an increase of up to 2-fold in total stilbenoid content after shelf life for CA and O(3) treatments was observed. At all sampling times for almost every treatment piceid concentration remained unaltered or slightly changed, whereas large increases were observed after shelf life for resveratrol (1.2 +/- 0.6 microg/g of fw of grapes sampled at harvest), even up to 3- and 4-fold for O(3)-treated grapes and 2-fold for CA-treated ones. Therefore, improved techniques for the keeping quality of cv. Napoleon table grapes during long-term storage seem to maintain or enhance their antioxidant compound content.     

Investigation of volatiles in Charentais cantaloupe melons (Cucumis melo Var. cantalupensis). Characterization of aroma constituents in some cultivars

Volatile compounds of 15 Charentais melon cultivars, known to exhibit differences in their ripening behaviors and in their storage lives (wild, mid, and long shelf life), were investigated. Twenty-eight volatiles (11 esters, 8 sulfur compounds, 6 alcohols, and 3 carbonyl compounds) were isolated by direct dichloromethane extraction and analyzed by means of GC-MS and GC-FID. A considerable reduction in the aroma profile was observed for the long shelf life cultivars, in which total volatiles were 49-87% lower than in the wild or mid shelf life melons. Most of the esters such as ethyl 2-methylbutyrate, ethyl butyrate, ethyl hexanoate, hexyl acetate, and butyl acetate and sulfur compounds such as ethyl 2-(methylthio)acetate, 2-methylthioethanol, ethyl 3-(methylthio)propanoate, 3-(methylthio)propyl acetate, and 3-(methylthio)propanol with low odor values were 2-30-fold lower in long shelf life cultivars than in the others. Discrimination of long shelf life cultivars from wild and mid shelf life melons was achieved by statistical treatment of the data by principal component and variance analysis.     

双孢菇高氧动态气调保鲜参数优化

为提高双孢蘑菇保鲜效果,在(2±1)℃下采用高氧动态气调方法对双孢蘑菇进行贮藏试验,选取第1阶段不同O_2/CO_2比例的气体组分、换气时间、第2阶段不同O_2/CO_2比例的气体组分作为影响因素,考察双孢蘑菇贮藏过程中总色差ΔE、硬度以及感官品质的变化,对双孢蘑菇的动态气调参数进行优化。研究结果显示,第1阶段O_2比例高于80%时,可显著抑制双孢蘑菇ΔE的上升(P0.05);第2阶段80%O_2+20%CO_2气体组分,可使双孢蘑菇的ΔE显著低于其他处理,硬度显著高于其他处理(P0.05);而换气时间则影响较小。最优的动态气调条件为:第1阶段气体组分100%O_2,第3天换气,第2阶段气体组分80%O_2+20%CO_2,双孢蘑菇的ΔE、硬度值和感官品质评分分别为:19.40、6.84×105 Pa和9.52。将此最优动态气调运用于双孢蘑菇的保鲜,研究发现,与静态气调相比,该动态气调显著抑制了双孢蘑菇的呼吸速率与膜结构的损坏,维持了较高的过氧化物酶、抗坏血酸过氧化物酶活性与较低的多酚氧化酶活性,有效抑制了贮藏过程中的酶促褐变,保持了较高的可溶性蛋白含量,并延长其保鲜期至28 d,提高了双孢蘑菇的耐贮性。     

Volatile emission after controlled atmosphere storage of Mondial Gala apples (Malus domestica): relationship to some involved enzyme activities

Mondial Gala apples were harvested at commercial maturity and stored at 1 degrees C under either air or controlled atmosphere (CA) conditions (2 kPa O2/2 kPa CO2 and 1 kPa O2/1 kPa CO2), where they remained for 3 or 6 months. Data on emission of selected volatile esters, alcohol precursors, and activity of some aroma-related enzymes in both peel and pulp tissues were obtained during subsequent shelf life of fruit and submitted to multivariate analysis procedures. CA storage caused a decrease in the emission of volatile esters in comparison to storage in air. Results suggest that lessened ester production was the consequence of modifications in activities of alcohol o-acyltransferase (AAT) and lipoxygenase (LOX) activities. For short-term storage, inhibition of lipoxygenase activity in CA stored fruit possibly led to a shortage of lipid-derived substrates, resulting in decreased production of volatile esters in spite of substantial ester-forming capacity that allowed for some recovery of fruit capacity for ester emission during the shelf life. For long-term storage, strong inhibition of AAT activity in CA stored fruit in combination with low LOX activities resulted in unrecoverable diminution of biosynthesis of volatile esters.     

Stimulation of gamma-aminobutyric acid production in vine-ripe tomato (Lycopersicon esculentum Mill.) fruits under modified atmospheres

Stimulation of gamma-aminobutyric acid (GABA) production under low O2 and high CO2 conditions (adjusted aerobic atmosphere) under which ethanol fermentation could be avoided was studied. Vine-ripe tomato fruits were stored under hypoxia conditions and adjusted aerobic atmospheres as well as in the air at 15 degrees C for 13 days and at 30 degrees C for 6 days. At 30 degrees C tomato fruit GABA concentration under the adjusted aerobic atmosphere (O2 11%, CO2 9%) was significantly higher by 48% than that in air after 6 days from the start of storage. Increased accumulation of alanine under the adjusted aerobic atmosphere supports the observation that this atmosphere stimulates GABA production. The results demonstrate that the concentration of GABA as a beneficial substance for antihypertensive effects and so on can be increased by storing tomato fruits under adjusted aerobic atmospheres for the first time.     

The role of packaging film permselectivity in modified atmosphere packaging

Modified atmosphere packaging (MAP) is commercially used to increase the shelf life of packaged produce by reducing the produce respiration rate, delaying senescence, and inhibiting the growth of many spoilage organisms, ultimately increasing product shelf life. MAP systems typically optimize O(2) levels to achieve these effects while preventing anaerobic fermentation but fail to optimize CO(2) concentrations. Altering film permselectivity (i.e., beta, which is the ratio of CO(2)/O(2) permeation coefficients) could be utilized to concurrently optimize levels of both CO(2) and O(2) in MAP systems. We investigated the effect of modifying film permselectivity on the equilibrium gas composition of a model MAP produce system packaged in containers incorporating modified poly(ethylene) ionomer films with CO(2)/O(2) permselectivites between 4-5 and 0.8-1.3. To compare empirical to calculated data of the effect of permselectivity on the equilibrium gas composition of the MAP produce system, a mathematical model commonly used to optimize MAP of respiring produce was applied. The calculated gas composition agreed with observed values, using empirical respiration data from fresh cut apples as a test system and permeability data from tested and theoretical films. The results suggest that packaging films with CO(2)/O(2) permselectivities lower than those commercially available (<3) would further optimize O(2) and CO(2) concentration in MAP of respiring produce, particularly highly respiring and minimally processed produce.     

Protease activity in post-mortem red swamp crayfish (Procambarus clarkii) muscle stored in modified atmosphere packaging

Protease activity during storage is thought to be an important contributor to decreased shelf life of fresh seafood. To examine this, three batches of red swamp crayfish ( Procambarus clarkii) tails, placed on trays, were packed with a polyvinyl chloride film (aerobic packaging or AP), under vacuum (vacuum packaging or VP), or under a modified atmosphere (MAP: 80% CO 2/10% O 2/10% N 2), and proteolytic activity was measured on days 0, 1, 3, 6, and 10 during storage at 2 degrees C. The crude extract from the crayfish digestive system (gut) did not have an apparent role in muscle proteolysis as negligible proteolytic activity was detected. However, the loss of calpastatin (the endogenous calpain inhibitor) was identified in MAP-stored muscle samples on day 10, suggestive of high m-calpain activity. Tail samples stored in AP showed no appreciable proteolysis, but those stored in MAP and VP showed significant decreases in the levels of 53, 66, 71, and 110 kDa polypeptides during storage. The observed proteolytic activity and myofibrillar protein degradation did not correspond to muscle textural properties as the MAP samples had an increased toughness ( P < 0.05) after storage for 10 days. These findings suggest that other physicochemical mechanisms are involved in postmortem alteration in the crayfish muscle structure under the packaging systems investigated.     

Effect of hexanal on the shelf life of fresh apple slices.

In this work the effects of hexanal, as a component of packaging atmosphere, on the shelf life of and evolution of naturally occurring microbial populations in fresh apple slices during storage at 4 and 15 degrees C were evaluated. Although hexanal had no bactericidal effects, in all conditions considered, this volatile molecule significantly extended the shelf life. In fact, the presence of hexanal in the storage atmosphere (at 4 degrees C) totally inhibited mesophilic bacteria and considerably prolonged the lag phase of psychrotrophic bacteria. Also, at 15 degrees C, hexanal strongly inhibited molds, yeasts, and mesophilic and psychrotrophic bacteria. Moreover, hexanal led to a yeast selection favoring species having a reduced spoilage potential due to their prevalent respiratory activity. When added to a modified atmosphere (70% N(2) and 30% CO(2)), this molecule was also very effective in preventing browning reactions for at least 16 days at 15 degrees C. No changes in hue angle values were observed in samples packaged in modified atmosphere with hexanal, even after 16 days of storage at 4 degrees C.     

Discrimination of wild and cultured european sea bass (Dicentrarchus labrax) using chemical and isotopic analyses

Recent legislation in the European Union (EC/2065/2001) requires that seafood must provide the consumer with information that describes geographical origin and production method. The present studies aimed to establish methods, based on chemical and stable isotopic analysis, that could reliably differentiate between wild and farmed European sea bass (Dicentrarchus labrax). The study measured fatty acid and isotopic compositions (delta13C and delta18O) of total flesh oil, delta15N of the glycerol/choline fraction, and compound-specific analysis of fatty acids (delta13C) by isotope ratio mass spectrometry. The sample set comprised 10 wild and 10 farmed sea bass from England (wild) and Scotland or Greece (farmed). Discrimination was achieved using fatty acid composition with 18:0, 18:2n-6, 20:4n-6, and 22:6n-3 providing the highest contributions for discrimination. Principal component analysis of the data set provided good discrimination between farmed and wild sea bass where factor 1 and factor 2 accounted for 60% of the variation in the data.     

气调和真空包装对腌制海鳗货架期的影响

该文主要考察25℃下气调和真空包装对腌制海鳗货架期的影响.4个样品分别是M1:空气包装(对照),M2:真空包装,M3:CO2/N2,40%/60%,M4:100%CO2,以挥发性盐基氮,三甲胺,pH值,硫代巴比妥酸值,菌落总数和感官为指标.结果表明,气调包装的货架期为20 d,真空包装为19 d,对照为16 d.对照组细菌增加很快,而M4增加最慢.挥发性盐基氮和三甲胺都随着储存时间延长而增加,在气调包装下的感官质量明显好于对照组.气调和真空包装,特别是100%CO2包装是保藏腌制海鳗的最有效方法.     

薄膜气调包装对枇杷果实冷藏期间呼吸和品质性状的影响

通过对呼吸速率、总可溶性固形物、可滴定酸、pH值、果肉硬度、维生素C、失重率和品质及感官指标的变化进行分析，研究了薄膜气调包装对枇杷(Eriobotrya japonica Lindl.，品种：解放钟）果实冷藏期间呼吸和品质特性的影响，气调包装用的薄膜为低密度聚乙烯薄膜(LDPE，厚度20 μm)，以打孔的低密度聚乙烯薄膜包装为对照。结果表明，低密度聚乙烯薄膜包装枇杷果实后，3～4 d后可维持一个相对稳定的适宜枇杷贮藏的O₂和CO₂的气体浓度，即CO₂(4.8±0.67)%，O₂(11.5±0.85)%；薄膜气调包装结合低温可明显地降低枇杷果实的呼吸速率；薄膜气调包装可以最大限度地减小冷藏期间的枇杷果实的失重率、果肉硬度、维生素C、总可溶性固形物、可滴定酸和固酸比的变化，维持枇杷的新鲜品质，延长货架期。因此，低密度聚乙烯薄膜（LDPE，厚度20 μm）气调包装可用于枇杷的贮藏保鲜。     

Active package for wild strawberry fruit (Fragaria vesca L.)

An antimicrobial active package has been developed to improve the safety and quality of wild strawberries, as well as extending their shelf life. The fruits were packed in equilibrium-modified atmosphere packaging (EMAP), and the effect on Botrytis cinerea growth and on the quality parameters of the fruit by the addition of different amounts of 2-nonanone, an antifungal volatile compound naturally present in strawberries, was investigated during storage at 10 and 22 degrees C. The temperature of 10 degrees C was chosen as the temperature used at points of sale, and 22 degrees C was chosen as the control temperature. Fungal growth was inhibited in all cases, possibly due to the synergistic effect of high CO2 partial pressures and the presence of the antifungal compound. Weight, soluble solids, titrable acidity, and anthocyanin losses were retarded by the presence of 2-nonanone. This effect was more pronounced as the 2-nonanone concentration was increased at both temperatures. Therefore, an active package that releases 2-nonanone inhibits fungal decay and delays the senescence of highly perishable wild strawberry fruit.     

Health-promoting compounds in broccoli as influenced by refrigerated transport and retail sale period

Total aliphatic and indole glucosinolates, phenolic compounds (flavonoids and hydroxycinnamoyl derivatives), and vitamin C contents were evaluated in freshly harvested broccoli (Brassica oleracea L., var. italica, cv. Marathon) inflorescences. These were film-wrapped and stored for 7 days at 1 degrees C to simulate a maximum period of commercial transport and distribution. After cold storage, inflorescences were kept for 3 days at 15 degrees C to simulate a retail sale period. For wrapping, low-density polyethylene (LDPE) of 11 microm thickness was used. Gas composition was about 17% O(2) and 2% CO(2) during cold storage and about 16% O(2) and 3-4% CO(2) during shelf life within packages. The predominant glucosinolates were 4-methylsulfinylbutyl-glucosinolate (glucoraphanin), 3-indolylmethyl-glucosinolate (glucobrassicin), and 1-methoxy-3-indolylmethyl-glucosinolate (neoglucobrassicin). The predominant hydroxycinnamoyl derivatives were identified as 1,2,2'-trisinapoylgentiobiose, 1,2-diferuloylgentiobiose, 1,2'-disinapoyl-2-feruloylgentiobiose, and 3-O-caffeoyl-quinic (neochlorogenic acid). Results showed major losses at the end of both periods, in comparison with broccoli at harvest. Thus, the respective losses, at the end of cold storage and retail periods, were 71-80% of total glucosinolates, 62-59% of total flavonoids, 51-44% of sinapic acid derivatives, and 73-74% caffeoyl-quinic acid derivatives. Slight differences in all compound concentrations between storage and retail sale periods were detected. Distribution and retail periods had minimal effects on vitamin C. Weight loss was monitored at the end of both periods.     

Use of activated carbon inside modified atmosphere packages to maintain tomato fruit quality during cold storage

Ethylene triggers the ripening process of tomato affecting the storage durability and shelf life (loss of quality) and inducing fruit decay. In this paper, an active packaging has been developed on the basis of the combination of modified atmosphere packaging (MAP) and the addition of granular-activated carbon (GAC) alone or impregnated with palladium as a catalyst (GAC-Pd). A steady-state atmosphere was 4 and 10 kPa for O2 and CO2 in control packages, while it was 8 and 7 kPa for O2 and CO2 in treated ones. The addition of GAC-Pd led to the lower ethylene accumulation inside packages, while the higher was obtained in controls. The parameters related to ripening showed that treated tomatoes exhibited a reduction in color evolution, softening, and weight loss, especially for GAC-Pd treatment. Moreover, these treatments were also effective in delaying tomato decay. After sensorial panel, tomatoes treated with GAC-Pd received the higher scores in terms of sweetness, firmness, juiciness, color, odor, and flavor. Results from the GC-MS analysis of the MAP headspace showed that 23 volatile compounds were identified in control packages, with these volatiles being significantly reduced in MAP-treated packages, which was correlated to the odor intensity detected by panelists after bag opening.     

Controlled-atmosphere effects on postharvest quality and antioxidant activity of cranberry fruits

The effects of controlled-atmosphere (CA) storage on the firmness, respiration rate, quality, weight loss, total phenolics and flavonoids contents, and total antioxidant activities of the Pilgrim and Stevens cultivars of cranberries (Vaccinium macrocarpon Aiton) have been studied during storage in atmospheres of 2, 21, and 70% O(2) with 0, 15, and 30% CO(2) (balance N(2)); and 100% N(2) at 3 degrees C. Elevated CO(2) concentrations decreased bruising, physiological breakdown, and decay of berries, thereby reducing fruit losses. Respiration and weight loss of fruits decreased, but fruit softening increased, at higher CO(2) concentrations. Accumulations of acetaldehyde, ethanol, and ethyl acetate varied by cultivar and storage atmosphere but were generally highest in the 2 and 70% O(2) and 100% N(2) atmospheres and increased in response to elevated CO(2) concentrations. Overall, the 30% CO(2) plus 21% O(2) atmosphere appeared optimal for the storage of cranberries. Sensory analysis is required, however, to confirm that accumulations of fermentation products at this atmosphere are acceptable for consumers. Stevens fruits had a higher phenolics content and total antioxidant activity than Pilgrim fruits. The storage atmosphere did not affect the content of total phenolics or flavonoids. However, the total antioxidant activity of the fruits increased overall by about 45% in fruits stored in air. This increase was prevented by storage in 30% CO(2) plus 21% O(2).     

Browning evaluation of ready-to-eat apples as affected by modified atmosphere packaging

The color and polyphenol oxidase (PPO) activity of fresh-cut Golden delicious apples were evaluated throughout cold storage under modified atmospheres. The shelf life of cut apples was extended to several weeks, especially when an initial atmosphere of 90.5% N(2) + 7% CO(2) + 2.5% O(2) and plastic pouches of 30 cm(3)/cm(2) x bar x 24 h were used. Under these conditions, a maximum 62% PPO activity depletion was observed. In all cases, the faster the initial PPO activity decays, the less the color changes. A fractional conversion first-order model was proposed for predicting color changes in minimally processed apples. Browning was better described through lightness (L) (k(L) = 0.017 - 0.07 day(-1)) and color difference (Delta E*) values (k(Delta E) = 0.015 - 0.073 day(-1)), which fitted the model with enough accuracy.     

Combined effect of modified atmosphere packaging and addition of rosemary (Rosmarinus officinalis), ascorbic acid, red beet root (Beta vulgaris), and sodium lactate and their mixtures on the stability of fresh pork sausages

The effects of rosemary, in combination with ascorbic acid, red beet root, and sodium lactate, as well as their mixtures, on the inhibition of both lipid and pigment oxidation of fresh pork sausages packaged in a modified atmosphere were studied. Sausages (240) were packaged in a 80% O2 + 20% CO2 gas mixture and analyzed for CIE a, metmyoglobin, TBARS, psychrotrophic aerobes, and sensory discoloration and off-odor throughout 20 days of storage at 2 +/- 1 degrees C. The mixture of rosemary + ascorbic acid + sodium lactate + red beet root extract extended the shelf life of fresh pork sausages from 8 to 16 days. Results demonstrated that all of the components of the mixture contributed to obtaining the maximum delay in color and/or odor decay, due to a combined inhibitory action on both pigment and lipid oxidation, as well as on microbial growth.     

Long-term storage of Pink Lady apples modifies volatile-involved enzyme activities: consequences on production of volatile esters

Pink Lady apples were harvested at commercial maturity and stored at 1 degrees C and 92% relative humidity under either air or controlled atmosphere conditions (2 kPa O 2:2 kPa CO 2 and 1 kPa O 2:1 kPa CO 2) for 27 weeks. Data on the emission of volatile compounds and on the activity of some related enzymes in both skin and flesh tissues were obtained during subsequent shelf life at 20 degrees C. Major effects of storage atmosphere and poststorage period were observed on the emission of volatile esters and their precursors. Changes in the production of volatile esters were partly due to alterations in the activity of alcohol o-acyltransferase, but the specific esters emitted by fruit after storage also resulted largely from modifications in the supply of the corresponding substrates. Samples stored under air were characterized by higher availability of acetaldehyde, whereas those stored under CA showed enhanced emission of the alcohol precursors ethanol and 1-hexanol (2 kPa O 2) and 1-butanol (1 kPa O 2), with accordingly higher production of ethyl, hexyl, and butyl esters. Multivariate analysis revealed that a large part of the observed differences in precursor availability arose from modifications in the activity of the enzymes considered. Higher pyruvate decarboxylase activity in air-stored fruit possibly accounted for higher acetaldehyde levels in these samples, while storage under 1 kPa O 2 led to significantly decreased lipoxygenase activity and thus to lessened production of 1-hexanol and hexyl esters. Low acetaldehyde availability together with enhanced hydroperoxide lyase and alcohol dehydrogenase levels in these fruits are suggested to have led to higher emission of 1-butanol and butyl esters.     

孵化前期二氧化碳调控对蛋鸡种蛋孵化胚胎的影响

为探究孵化前期高浓度CO2调控对蛋鸡种蛋孵化的影响机制,该研究以京红1号蛋鸡种蛋为试验对象,在孵化前期（0～10 d）处理组通过补充CO2的方式保持1%浓度,处理组在（0～10 d）期间通过CO2调控系统实时补充CO2;对照组CO2浓度小于0.25%,对比研究了1%浓度CO2处理对种蛋孵化的影响。结果表明,CO2处理组与对照组的受精蛋孵化率无显著性差异（P>0.05）;第9天和第12天CO2处理组的胚胎质量和相对胚胎质量显著高于对照组（P<0.05）;第3天、第6天和第9天CO2处理组的蛋白pH值显著低于对照组（P<0.05）;第11天,CO2处理组和对照组尿囊绒毛膜（CAM,Chorioallantoic Membrane）血管发育密度无显著性差异（P>0.05）;第0天、第6天、第12天两组的蛋壳和胚胎钙含量不存在显著差异。在蛋鸡种蛋孵化前期（0~10 d）保持1%浓度的CO2,降低了蛋白pH值,加速了胚胎发育,但未影响孵化率。     

Production of volatile compounds by Fuji apples following exposure to high CO2 or low O2

The emission of volatile compounds by Fuji apples following short- or long-term exposure to high CO(2) was studied. The production of ethanol, methyl and ethyl esters, octanal, nonanal, and decanal was enhanced while the production of C(3)-C(6) alcohols, propyl, butyl, pentyl, and hexyl esters and butanal decreased in fruit exposed to 10 kPa O(2) + 20 kPa CO(2) at 20 degrees C for up to 12 days. The impact of high CO(2) exposure on volatile production was dependent on fruit maturity at harvest. Apples stored for 8 months in an ultralow O(2)-controlled atmosphere (CA) (0.5 kPa O(2) + 0.05 kPa CO(2)) or high CO(2) CA (1.5 kPa O(2) + 3 kPa CO(2)) at 0.5 degrees C had reduced production of most volatiles, especially butyl and hexyl esters, as compared to fruit stored in air. Two exceptions were ethanol and ethyl acetate for which the production was enhanced by both CA regimes. Treatment with the antioxidant diphenylamine prior to storage prevented most of the high CO(2)-induced and ultralow O(2)-induced changes in volatile production. The results of this study do not indicate that changes in volatile production following the exposure of Fuji apples to high CO(2) are causally related to the development of CO(2) injury.