Postharvest biology

Green and blue mold, caused by Penicillium digitatum (Pers.) Sacc. and P. italicum Wehmer, respectively, cause significant losses of Satsuma mandarins (Citrus unshiu Marc.) after harvest. The effects of some pre-and postharvest treatments on development of these ...

The effect of hot water dips (53 °C, 2–3 min) on chilling injury (CI) and decay of various citrus fruits was compared with the effect of curing (36 °C, 72 h). Experiments were conducted with grapefruit (Citrus paradisi Macf., cv. Marsh), lemon (Citrus limon. Burm., cv. Eureka), ...

A rapid method, the standard saturated salt solution method (SSM) and the hygrometric instrument method for measuring sorption isotherms of Conference pear flesh tissues at low temperature (1 and 6.5 • C) and high water activity (0.8-1.0) were compared. The rapid pressure controlled method (PCM) could only be used at a minimum temperature of 6.5 • C. It was possible to determine the sorption isotherms by the saturated salt solution method using fans (SSMF) and by the hygrometric instrument method (HIM) at 1 and 6.5 • C. The three methods gave quite similar results, however, it is obvious that the SSMF method results in fewer data points than the other methods. The experimental data show that PCM has the advantage of speed, while HIM allows investigation of the influence of temperature on sorption isotherms below 6.5 • C.

Cultivar segregation according to the sensory perception of their organoleptic characteristics was attempted by using trained panel data evaluated by principal component analysis of 12 plum and four pluot cultivars as a part of our program to understand plum minimum quality. The perception of the four sensory attributes (sweetness, sourness, plum flavor intensity, plum aroma intensity) was reduced to three principal components, which accounted for 98.6% of the variation in the sensory attributes of the tested cultivars. Using the Ward separation method and PCA analysis (PC1 = 49.8% and PC2 = 25.6%), plum and pluot cultivars were segregated into groups (tart, plum aroma, and sweet/plum flavor) with similar sensory attributes. Fruit source significantly affected cultivar ripe soluble solids concentration (RSSC) and ripe titratable acidity (RTA), but it did not significantly affect sensory perception of plum flavor intensity, sourness, sweetness, and plum aroma intensity by the trained panel on fruit harvested above their physiological maturity.

Flesh firmness is used to assess apple (Malus domestica Borkh.) quality both before and after low temperature storage. The effect of fruit temperature on apple firmness at different times during postharvest handling is not known. Experiments were conducted to quantify physical change in apple texture readings with change in fruit temperature. 'Royal Gala', 'Granny Smith', and 'Pacific Rose™' apple fruit were stored at 0°C, while 'Cox's Orange Pippin' was stored at 3°C. At different times during storage, flesh firmness and cortical tensile strength were measured on fruit at storage temperature, after 24 h at 20°C, or after 24 h at 20°C followed by 24 h at the storage temperature. 'Royal Gala', 'Granny Smith' and 'Cox's Orange Pippin' fruit had higher firmness readings at harvest when measured at 20°C than at 0-3°C, but after 50-100 days at 0-3°C firmness and tensile strength readings were greater when measured at 0-3°C than at 20°C. 'Pacific Rose™' had similar firmness and tensile strength readings when measured at 0°C and 20°C. 'Royal Gala' and 'Cox's Orange Pippin' were measured for firmness at different fruit temperatures at harvest and after storage. The relationship between firmness readings and fruit temperature between 0 and 20°C was linear and positive at harvest and linear and negative for stored fruit. Firmness change with temperature was not affected by orchard or harvest maturity. These results suggest that physical changes in firmness with fruit temperature are common for the cultivars studied, and thus could be used to compare firmness values for fruit from different orchards that were measured at different temperatures.

The effect of chitosan on the necrotrophic growth of Botrytis cinerea in bell pepper fruit was investigated. In control tissue, massive fungal colonization was followed by extensive degradation of the pectin component of host walls and middle lamella. Reduction of pectin labelling was also observed in walls distant from invading hyphae. In contrast, cellulose breakdown was limited to small wall areas closely appressed against the pathogen. The disruption of host walls and the reduction of pectin labelling appeared to parallel levels of cell-wall-macerating enzymes isolated from B. cinerea-infected tissue. High levels of polygalacturonase and trace amounts of cellulase were detected in B. cinerea-infected tissue. In chitosan-treated tissue, the preservation of pectin binding sites and the intense and regular cellulose distribution over host walls, suggested that chitosan might have prevented the maceration of host tissue by B. cinerea. Chitosan not only was effective in reducing the production of polygalacturonases by B. cinerea, but also caused severe cytological damage to invading hyphae. This may, in part, explain the limited ability of the pathogen to colonize tissues in the presence of chitosan. © 1997 Elsevier Science B.V.

Apple cv. 'Jonagold' fruit were picked in three different regions of Belgium. In each region one organic and one integrated orchard with identical climatic and soil characteristics was sampled. Fruit were stored in air and under CA conditions (1% O 2 , 2.5% CO 2 ) at 1 • C for 6 months. The acoustic stiffness, firmness, soluble solids contents, acid and sugar contents, and the aroma profile were measured. Quality parameters were analysed right after harvest and storage. At both times an additional shelf-life experiment was carried out to simulate the conditions in the commercial chain.

Banana (Musa AAA group) is one of the most consumed fruits in the world. It has been reported that chlorophyll breakdown and color formation in banana is inhibited by ripening temperatures above 24 • C. At this temperature thylakoid membranes are retained resulting in reduced chlorophyll degradation. In this study, green mature, untreated banana fruit were obtained from a local wholesale market and half of the fruit were subjected to ethylene treatment at 10 L L −1 for 24 d. After ethylene treatment, both treated and untreated fruit were stored at 20 • C or 30 • C for 7 d. Fruit were sampled after 0, 1, 4 and 7 d of storage and evaluated for color, chlorophyll fluorescence, volatile production and expression of genes related to volatile biosynthesis. Storage at 30 • C reduced yellow color development in the peel, decreased chlorophyll fluorescence (Fv/Fm), but increased Fo, indicating possible heat stress of the fruit. A total of 19 volatile compounds were identified using SPME/GC/MS. Both ethylene treatment and high temperature enhanced volatile production. The increase of Fo and hexanoate and acetate esters are coincided with the stress of high temperature. Using real time PCR (qPCR), expression of genes related to volatile biosynthesis including branched-chain amino acid transaminase (BCAT), lipoxygenase (LOX), hydroperoxide lyase (HPL), pyruvate decarbolxylase (PDC), alcohol dehydrogenases (ADH, short and medium chains), and alcohol acetyl transferase (AAT) were investigated in both peel and pulp tissues. Among the tested genes, BCAT, HPL, ADH and AAT in peel and pulp tissues increased significantly in response to ethylene and storage at 30 • C. PDC, ADH and BCAT (in pulp tissue) were induced by storage at 30 • C in ethylene-treated fruit. LOX decreased during ripening and storage at 30 • C in the peel, but increased in the pulp tissue of ethylene-treated fruit. This study demonstrates that both ethylene and high temperature influence volatile biosynthesis in banana fruit at the transcriptional level and confirms findings that high temperature causes stress in banana fruit during ripening.

The acridity in Araceae species was not apparently due to the calcium oxalate raphides. Some irritant on the raphide surface caused the acridity, with the raphides apparently functioning to carry the acridity factor. Methanol and methylene chloride extracts from purified raphides did not show any compounds in GC-mass spectrometry (MS) analysis that could be regarded as acrid. The data suggested that a 26 kDa protein, possibly a cysteine proteinase, was the active factor. There were a few other uncharacterized protein bands associated with the raphides that could also be involved. Some amino acid sequence data for the 26 kDa protein was obtained.

Fruit of many citrus cultivars become injured when exposed to low, non-freezing temperatures. In this study we have determined changes in ethylene production and phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) in fruit of three citrus cultivars, 'Fortune' mandarins, and 'Navelina' and 'Valencia' late oranges, with different tolerance to chilling injury (CI) and demonstrated the influence of fruit physiological stage on those stress responses. We have shown that the increase in ethylene production and PAL are cold-induced responses which are only stimulated in fruit of citrus cultivars showing chilling damage and that both responses may occur concomitantly with the development of chilling symptoms. However, the magnitude of these responses was not indicative of the degree of tolerance of a specific cultivar to chilling. The influence of fruit age on both responses was evaluated in the most ('Navelina') and the least ('Fortune') chilling tolerant cultivars. Chilling damage was not developed in 'Navelina' fruit at any physiological stage, but our results in 'Fortune' mandarins, which always developed chilling symptoms, indicated that the induction of PAL in response to chilling was dependent on the fruit physiological stage. Interestingly, increases in both PAL mRNA and activity were barely affected by cold stress in the youngest 'Fortune' fruit harvested in December in spite of its noticeable CI. For a similar CI index, the older the fruit, the higher was the shift in the levels of PAL transcript and in PAL activity in response to cold. In contrast, the cold-induced ethylene production was little affected by the physiological stage of the fruit. #

Making use of the discrete element method (DEM) a study is presented on the influence of mechanical parameters (vibration frequency and acceleration amplitude, apple size, stack height) and fruit properties (apple harvest date, apple temperature, apple acoustic stiffness) on vibration damage of apples. As acceleration input a sine in the vertical direction was used. Realistic parameters of the Kuwabara and Kono [Kuwabara, G., Kono, K., 1987. Restitution coefficient in a collision between two spheres. Jpn. J. Appl. Phys. 26, 1230-1233] contact force model for 'Jonagold' apples and bruise prediction models were applied. As a general conclusion, major influences of mechanical parameters on the vibration damage were identified, in particular stack height and fruit size, and minor influences of fruit properties. Also a detailed study was performed to investigate the relation between apple positions in the stacking and bruise damage. It was demonstrated that the position-bruise damage relation depends on the acceleration amplitude, vibration frequency and stack height. The existence of damage chains within the centre of the apple stack was also identified, that is in accordance with the well-known force chains in bulk materials.

Fifty-one endophytic isolates of Aureobasidium pullulans were obtained from the flesh of sweet cherries and extensively screened to evaluate their biocontrol activity against postharvest rots of sweet cherries and table grapes. Preliminary analysis of all isolates by randomly amplified polymorphic DNA (RAPD) with three different primers showed the presence of a high genetic variability and enabled isolates not showing any genetic difference to be discarded. Thirty-five isolates with different RAPD electrophoresis patterns had a wide range of biocontrol activity against Botrytis cinerea and Monilinia laxa on single-wounded berries of sweet cherries and table grapes with a reduction of decay from 10 to 100%. Two isolates (533 and 547) significantly reduced B. cinerea on table grape berries also when applied 6, 12, and 24 h after the pathogen inoculation. In a 2-year period of investigation (1998 Á/1999), a reduction of total rots ranging from 32 to 80% (sweet cherries) and from 59 to 64% (table grape) was achieved with isolates 533 and 547 applied after harvest. Preharvest applications of isolate 547 significantly reduced postharvest rots of sweet cherries and table grapes by 47 and 38%, respectively. On the whole, isolates 533 and 547 were more effective than A. pullulans L47, a biocontrol agent of postharvest diseases with a known activity. Population studies demonstrated that isolate 547 was able to survive under field conditions, to increase its population during cold storage, and to penetrate the flesh of sweet cherries when applied during flowering. #

Steady-state levels of hydrogen peroxide and activities of catalase and peroxidase were measured in the peel and pulp of zucchini squash (Cucurbita pepo L., cv., Giambo) during storage at 10 • C or 0 • C for two weeks. No visible damage occurred during this storage time; epidermal brown pits become visible later, at day 20 in fruit stored at 10 • C and at day 15 in those stored at 0 • C. In order to analyze the early effects of the chilling-induced oxidative stress during zucchini storage, rates of succinate oxidation, alternative oxidase activity, membrane fluidity and phospholipid composition were also measured in mitochondria isolated from the zucchini pulp. A decrease in hydrogen peroxide levels, an increase in the activity of detoxifying enzymes, a recovery of chilling-induced mitochondrial membrane fluidity and an increase in alternative oxidase (AOX) activity were detected in the early stages of zucchini storage at 10 • C. The peroxidase and the AOX activities of the pulp of zucchini stored at 0 • C were also found to increase but to a lesser extent and later during storage, suggesting that these fruit can also activate these ROS regulatory systems, possibly preventing the occurrence of early visible damage in the peel but not the occurrence of cold stress.

Papaya fruit postharvest losses up to 75% have been reported to Hawaii shippers by mainland USA wholesalers and retailers. These losses are often blamed on decay, however, this decay can be associated with storing color-break fruit for more than 3 weeks at 10°C or lower temperatures. A number of non-pathological fruit disorders are seen in retail markets, with some confusion amongst personnel as to the cause. 'Soft' fruit, for example, can be caused by mechanical impact injury of ripening fruit and by fruit with low flesh calcium at harvest that can ripen at twice the normal rate. The requirements for the ripening and storage of papaya are discussed. Evaluation of postharvest losses is considered in relation to the variation and limitations in ripening and storage facilities in the current handling system. There is a need to develop methods to predict papaya fruit yield and size distribution to allow orderly marketing and to accurately sort fruit as to their internal stage of ripening. © 1997 Elsevier Science B.V.

Insights into the relative importance of various aspects of product quality can be provided through quantitative analysis of consumer preference and choice of fruit. In this study, methods previously used to establish taste preferences for kiwifruit and conjoint approaches were used to determine the influence of three key aspects of avocado quality on consumer liking and willingness to purchase fruit: dry matter percentage (DM), level of ripeness (firmness) and internal defects (bruising). One hundred and seven consumers tasted avocados with a range of DM levels from ∼20% (minimally mature) to nearly 40% (very mature), and at a range of fruit firmness (ripeness) stages (firm-ripe to soft-ripe). Responses to bruising, a common quality defect in fruit obtained from the retail shelf, were examined using a conjoint approach in which consumers were presented with photographs showing fruit affected by damage of varying severity. In terms of DM, consumers showed a progressive increase in liking and intent to buy avocados as the DM increased. In terms of ripeness, liking and purchase intent was higher in avocados that had softened to a firmness of 6.5 N or below (hand-rating 5). For internal defects, conjoint analysis revealed that price, level of bruising and incidence of bruising all significantly lowered consumers' future purchase decision, but the latter two factors had a greater impact than price. These results indicate the usefulness of the methodology, and also provide realistic targets for Hass avocado quality on the retail shelf.

Treatment of tomato fruit (Lycopersicon esculentum L. cv Prisca) with 1-methylcyclopropene (1-MCP), a potent inhibitor of ethylene action, delayed colour development, softening, and ethylene production in tomato fruit harvested at the mature green breaker, and orange stages. 1-MCP treatment also decreased the mRNA abundance of phytoene synthase 1 (PSY1), expansin 1 (EXP1), and 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase 1 (ACO1), three ripening-related tomato genes, in mature green, breaker, orange, and red ripe fruit. These results demonstrate that the ripening process can be inhibited both on a physiological and molecular level, even at very advanced stages of ripening. The effects of 1-MCP on ripening lasted 5-7 days and could be prolonged by renewed exposure.

Central broccoli heads (cv. de Cicco) were harvested and treated with UV-C light (4, 7, 10, or 14 kJ m −2). All treatments delayed yellowing and chlorophyll degradation at 20 • C but the irradiation dose of 10 kJ m −2 allowed retaining the highest chlorophyll content yet had lower amounts of pheophytins than every treatment other than 7 kJ m −2. This dose was selected to analyze the effect of UV-C on postharvest broccoli senescence at 20 • C. The UV-C treatment delayed yellowing, chlorophyll a and b degradation, and also the increase in pheophytins during storage. The activity of chlorophyll peroxidase and chlorophyllase was lower in UV-C treated broccoli. Instead, Mg-dechelatase activity increased immediately after the treatment, but after 4 and 6 d this activity was lower in UV-C treated florets than in controls. Treated broccoli also displayed lower respiration rate, total phenols and flavonoids, along with higher antioxidant capacity. The results suggest that UV-C treatments could be a useful non-chemical method to delay chlorophyll degradation, reduce tissue damage and disruption, and maintain antioxidant capacity in broccoli.

The effect of cold storage on antioxidant profile and the antioxidant activity of five sweet orange genotypes [Citrus sinensis (L.) Osbeck], three blood (pigmented) varieties with different anthocyanin contents ('Tarocco Messina', 'Tarocco Meli' and 'Moro') and two blond varieties ('Ovale' and 'Valencia late'), stored at 6 ± 1 • C for 65 d was investigated. During fruit storage, anthocyanins, hydroxycinnamic acids, vitamin C, flavanones and total phenolics were determined, and juice antioxidant capacity was measured by two different in vitro tests (DPPH scavenging activity and inhibition of induced linoleic acid peroxidation). The results showed an increase in anthocyanins, flavanones and hydroxycinnamic acids and a slight decrease in vitamin C in the blood oranges. Cold storage negatively affected flavanone concentration, while positively influenced vitamin C in blond orange varieties. Both antioxidant activity tests showed an increase in antioxidant capacity during storage caused mainly by phenolic accumulation (blood oranges) and vitamin C increase (blond oranges). Finally, correlations between antioxidant activity and total or individual phenolic components were examined.

Citrus fruit are relatively non-perishable, and can normally be stored for long periods of 6-8 weeks. However, the development of various types of rind disorders limits the postharvest storage capability, and causes massive commercial losses. In the present study, we found that modified atmosphere packaging (MAP) in "bag-in-box" Xtend ® films (XF) effectively reduced the development of chilling injury (CI) as well as other types of rind disorders that are not related to chilling, such as rind breakdown, stem-end rind breakdown (SERB) and shriveling and collapse of the button tissue (aging). In all cases, microperforated films (0.002% perforated area) that maintained CO 2 and O 2 concentrations of 2-3 and 17-18%, respectively, inside the package were much more effective in reducing the development of rind disorders than macroperforated films (0.06% perforated area), which maintained CO 2 and O 2 concentrations of 0.2-0.4 and 19-20%, respectively. In both types of package, the relative humidity (RH) was ∼95%. No major differences were found between the effectiveness of polyethylene (PE) and XF packages, despite the fact that XF prevents water condensation inside the bags. Overall, microperforated and macroperforated XF packages reduced rind disorders not related to chilling (rind breakdown, SERB and aging) after 5 weeks of storage at 6 • C and 5 days of shelf life conditions by 75 and 50%, respectively, in 'Shamouti' orange, and by 60 and 40%, respectively, in 'Minneola' tangerines. Similarly, microperforated and macroperforated XF packages reduced the development of CI after 6 weeks of cold storage at 2 • C and 5 days of shelf life conditions by 70 and 35%, respectively, in 'Shamouti' oranges and by 75 and 45%, respectively, in 'Star Ruby' grapefruit. Furthermore, storage of unwrapped 'Shamouti' oranges in high RH (95%) also reduced rind disorders by 40-50%, similarly to the effects of the macroperforated films. In the light of these data, we suggest that MAP reduces the development of rind disorders in citrus fruits via two modes of action: the first, which is common to both microperforated and macroperforated films is by maintaining the fruit in a high RH environment; the second, which is specific to the microperforated film, involves maintaining a modified atmosphere environment with elevated CO 2 and lowered O 2 levels.

A novel edible bio-film was prepared and its effects on preserving strawberries were investigated. The film covering the fruit surface contained Cryptococcus laurentii (10 9 cfu mL −1 ) in combination with alginate (2%, w/v), glycerol (2%, w/v), palmitic acid (0.5%, w/v), glycerol monostearate (0.5%, w/v), and ␤-cyclodextrin (0.5%, w/v). Microorganism viability of the bio-film underwent no obvious change during 20 d storage. Furthermore, the addition of C. laurentii as antagonist in the films aided inhibition of mold growth, and maintenance of strawberry commercial quality throughout storage. Sodium alginate film entrapped with C. laurentii had no significant effects on external color parameters and anthocyanins of strawberries during storage. In contrast, it significantly reduced microbial decay, decreased weight loss, maintained the firmness of the strawberries, and improved the quality and storage properties of the fruit.

Chemical composition (titratable acidity, moisture content, crude fibre, colour, pH, soluble solids, sugars, organic acids) and flavour changes during ripening of jackfruit (Artocarpus heterophyllus L.) cultivar J3 were evaluated. Significant (p < 0.05) changes in titratable acidity and colour was obtained, but no significant changes were found in moisture and crude fiber contents during ripening. Total soluble solids and total sugars increased significantly (p < 0.05) throughout the ripening process. Total soluble solids at the top portion of the fruit were significantly (p < 0.05) higher than middle and bottom portions of the same fruit. A high content of malic acid was found in unripe fruit (day 1). In contrast, ripened fruit (days 5 and 6) contained a high amount of citric acid. Overall, the total amount of organic acids was found to decrease from the early to later stage of ripening. A total of 23 volatile compounds were tentatively identified by GC and GC-MS. The number of peaks was observed to increase throughout the ripening process. In this study, data obtained suggest that the ripening process of jackfruit was at its optimum at day 5 after harvest.

The flesh quality profile of Gold cultivar pineapple and the influence of packaging conditions on fruit pieces were studied as tools to prop up homogeneous, reproducible, and endurable quality of fresh-cut pineapple. Physicochemical, mechanical and antioxidant attributes, as well as the aroma profile of the natural occurring volatiles were determined for three cross-sections cut along the pineapple. The influence of packaging conditions using passive modified atmosphere (AIR) with and without an alginate coating and two active modified atmospheres (low oxygen, LO: 12 % O 2 , 1% CO 2 and high oxygen, HO: 38% O 2 ) at 5 °C on the quality of the freshcut fruit was also assessed. Soluble solids content (SSC), titratable acidity (TA), water content, vitamin C and phenolic compounds content, as well as POD activity in the bottom third of the fruit were significantly higher (p<0.05) than in other sections, while L* and b* color parameters were smaller. In general, the mechanical response of pineapple flesh to penetration, cut, compression and/or extrusion forces did not significantly vary among pieces from different sections of the fruit, except for the shear test, which showed the largest resistance in pineapple pieces cut from the bottom third of the fruit. In addition, twenty volatile compounds were identified and quantified from the fresh pineapple aroma profile. The most abundant volatile compounds were methyl butanoate, methyl 2-methyl butanoate and methyl hexanoate, whereas the most odor active volatiles of pineapple aroma were methyl 2-methyl butanoate, ethyl 2-methyl butanoate, ethyl hexanoate and 2,5-dimethyl-4methoxy-3(2H)-furanone. The same aroma profile constituents were found in the three cross-sections of the fruit, but the total volatiles content increased from the top to the bottom third of the fruit (7560 to 10910 µg/kg). The concentration of the main odor active volatiles as well as their relative content varied along the fruit. On the other hand, AIR, LO and HO atmospheres allowed the preservation of SSC, TA, pH and color of fresh-cut pineapple for two weeks without differences among packaging atmospheres. Vitamin C content and antioxidant capacity were smaller in fruit pieces packed under HO atmosphere than in LO or AIR, but no changes were observed along storage. Total phenols content and juice leakage differed among packaging conditions and along storage. Alginate coating helped to reduce juice leaked from pineapple pieces, while high CO 2 concentrations were likely to promote it. Shear test hardness and work were bigger for pineapple pieces cut from the bottom third than other parts of the fruit; however, mechanical characteristics of the fruit were not modified during storage. Moreover, volatile compounds content reached a maximum during the second week of storage, and depleted thereafter. The use of passive modified atmosphere and alginate coatings could favor longer withhold of odor active volatile compounds and antioxidant attributes in the fresh-cut fruit, with reduced juice leakage along storage at 5 °C. Adequate mixing procedures during fresh-cut pineapple preparation, accounting for quality attributes differences along the fruit, are needed for homogeneous and reproducible quality of fresh-cut pineapple.

Postharvest degradation of minimally processed mangoes limits the marketability of fruit. The effect of heat treatments applied to whole 'Keitt' mango fruit on physical, physiological and biochemical quality of minimally processed mangoes was studied. Whole mangoes were subjected to hot water dipping (HWD) at 46 or 50 • C for 30 or 75 min, cooled for 15 min, minimally processed and stored at 6 • C for 9 d. Sensory analysis, firmness, color, acidity, pH, total soluble solids (TSS), ascorbic acid, total carotenoids, malondialdehyde (MDA) and respiration rate (RR) were investigated. A global beneficial effect of HWD 50 • C/30 min was observed. This treatment was the only one to maintain the acceptability of fresh-cut mangoes for 6 d, the yellow color, expressed by b* value, for 9 d and the firmness for 3 d compared to the control. Moreover, HWD 50 • C/30 min increased the total carotenoids content after 3 d compared to the control. Although the ascorbic acid content decreased during storage, HWD 50 • C/30 min is the less degrading condition of the heat treatments. Lipid peroxidation, estimated by MDA content, was less important for HWD 50 • C/30 min. Finally, the RR of whole mangoes treated by HWD 50 • C/30 min was lower than in the other treatments and could be used as an indicator of product shelf-life. This study selected the HWD 50 • C/30 min as the optimal heat treatment to improve the quality of fresh-cut 'Keitt' mangoes.

This review covers some recent advances for the maintenance of fresh-cut fruit quality with respect to the use of chemical compounds, including plant natural antimicrobials and antioxidants, as well as calcium salts for maintaining texture. It focuses especially on the use of natural preservatives, which are of increasing interest because of toxicity and/or allergenicity of some traditional food preservatives. The difficulties in the application of these substances on fresh-cut fruit without adversely affecting sensory characteristics of the product are reviewed. Edible coatings are presented as an excellent way to carry additives since they are shown to maintain high concentrations of preservatives on the food surfaces, reducing the impact of such chemicals on overall consumer acceptability of fresh-cut fruit.

Coating of tomato fruit with gum arabic has been found to enhance their shelf-life and postharvest quality. Gum arabic in aqueous solutions of 5, 10, 15 and 20% was applied as a novel edible coating to green-mature tomatoes which were stored at 20 • C and 80-90% RH for 20 d. Fruit coated with 10% gum arabic showed a significant (P ≤ 0.05) delay in changes of weight, firmness, titratable acidity, soluble solids concentration, ascorbic acid content, decay percentage and colour development compared to uncoated control fruit. Sensory evaluation proved the efficacy of 10% gum arabic coating by maintaining the overall quality of tomato fruit during the storage period. The results suggest that by using 10% gum arabic as an edible coating, the ripening process can be delayed and the storage life of tomatoes stored at 20 • C and at the breaker stage can be extended up to 20 d without any spoilage and off-flavour.

The minimal processing industry for fruit and vegetables needs appropriate selection of raw materials and operation of improved sustainable strategies for reducing losses and providing high quality and safe commodities. The most important target for keeping overall quality of these commodities is a decrease in microbial spoilage flora as these cause both decay and safety problems. Every step in the production chain will influence microbial load and the implementation of an accurate disinfection program should be the main concern of commercial processing. The only step that reduces microbial load throughout the production chain is washing disinfection, and the keys are proper handling and optimizing existing techniques or a combination of them. Chlorine is a common efficient sanitation agent but there is the risk of undesirable by-products upon reaction with organic matter and this may lead to new regulatory restrictions in the future. Moreover, its efficacy is poor for some products. Consequently the minimal processing industry wants safer alternatives. Several antimicrobial washing solutions, O 3 , UV-C radiation, intense light pulses, super high O 2 , N 2 O and noble gases, alone or in combination, are presently considered promising treatments. However, change from use of conventional to innovative sanitizers requires knowledge of the benefits and restrictions as well as a practical outlook. This review addresses some recent results obtained with these eco-innovative sanitizers on fresh-cut plant commodities.

The effects of four pre-packaging UV-C illumination doses (1.6, 2.8, 4.8 and 7.2 kJ m −2 ) on quality changes of watermelon cubes stored up to 11 days at 5 • C were studied. Non-treated cubes were used as a control. Higher UV-C doses induced slightly higher CO 2 production throughout the storage period, while no changes in C 2 H 4 production were monitored. However, UV-C did not significantly affect the final gas partial pressures within modified atmosphere packages where levels of 3-6 kPa O 2 and 13-17 kPa CO 2 were reached for all treatments. UV-C decreased microbial counts just after illumination. After 11 days at 5 • C, mesophilic, psycrophilic and enterobacteria populations were significantly lower in UV-C treated watermelon. Slight changes in CIE colour parameters were observed. According to sensory quality attributes, control and low UV-C treated cubes (1.6 and 2.8 kJ m −2 ) can be stored for up to 11 days at 5 • C while the maximum shelf-life of moderate to high UV-C treated fruit was 8 days at 5 • C. Control cubes showed a 16% decrease in lycopene content after 11 days at 5 • C similar to that found for the high UV-C treatment. However low UV-C treated watermelon cubes preserved their initial lycopene content (2.8 kJ m −2 ) or it was slightly decreased (1.6 kJ m −2 ). UV-C radiation did not significantly affect the vitamin C content while catalase activity and total polyphenols content considerably declined throughout the storage period. However, total antioxidant capacity markedly increased, independently of UV-C doses. As a main conclusion, UV-C radiation can be considered a promising tool for keeping overall quality of fresh-cut watermelon.

A novel edible coating based on Aloe vera gel, accordingly to our developed patent (SP Patent Filed P200302937), has been used as postharvest treatment to maintain sweet cherry quality and safety. During cold storage, uncoated fruit showed increases in respiration rate, rapid weight loss and colour changes, accelerated softening and ripening, stem browning and increased microbial populations, these processes being more intense during the shelf life periods. On the contrary, sweet cherry treated with A. vera gel significantly delayed the above parameters related to postharvest quality losses, and storability could be extended. The sensory analyses revealed beneficial effects in terms of delaying stem browning and dehydration, maintenance of fruit visual aspect without any detrimental effect on taste, aroma or flavours. As far as we aware, this is the first time A. vera gel is used as an edible coating in fruit, which would be an innovative and interesting means for commercial application and as alternative of the use of postharvest chemical treatments.

Consumers are increasingly demanding fruit of consistent high quality. Mechanical damage, which can occur during harvesting, packing house operations, handling and transport, represents a serious hazard to quality and has the potential to significantly reduce the value of the product. Dynamic forces during fruit transport and handling cause by far the most bruise damage. This paper reviews 45 years of research in the area of impact damage during transport and handling of apples. Because the amount of research on the impact damage of apples is considerable, an attempt was made to classify the research in categories.

An overview is given of near infrared (NIR) spectroscopy for use in measuring quality attributes of horticultural produce. Different spectrophotometer designs and measurement principles are compared, and novel techniques, such as time and spatially resolved spectroscopy for the estimation of light absorption and scattering properties of vegetable tissue, as well as NIR multi-and hyperspectral imaging techniques are reviewed. Special attention is paid to recent developments in portable systems. Chemometrics is an essential part of NIR spectroscopy, and the available preprocessing and regression techniques, including nonlinear ones, such as kernel-based methods, are discussed. Robustness issues due to orchard and species effects and fluctuating temperatures are addressed. The problem of calibration transfer from one spectrophotometer to another is introduced, as well as techniques for calibration transfer. Most applications of NIR spectroscopy have focussed on the nondestructive measurement of soluble solids content of fruit where typically a root mean square error of prediction of 1 • Brix can be achieved, but also other applications involving texture, dry matter, acidity or disorders of fruit and vegetables have been reported. Areas where more research is required are identified.

Little is known about the biochemistry of the marron (Castanea sativa cv Marrone fiorentino) when it is soaked in water for the curing process; the immersion treatment time is still empirical and based on traditional knowledge. A study was carried out by keeping marrons in water for 7 d at 14 • C. Tap water and acid water (pH 3) were used in the following water/marron ratios 1:1, 1:2, and 3:2. After curing, the marrons were moved to air storage at room temperature (20 • C and 90% RH) for 1 week (shelf-life), and at 0 • C and 90% RH for 60 d. A large accumulation of carbon dioxide in the head space of the glass jar where the marrons were kept, was observed during water soaking, above all in samples in acid water with a water/marron ratio 1:2. In the first 5 d of water curing, a significant increase in acetaldehyde concentration and phenol content was measured in the marron pulp and subsequently, both compounds declined. Ethanol decreased slightly or remained constant. During the following week of shelf-life, the lowest respiration rate was measured in 1:1 and 1:2 samples while the highest rate was measured in acid water samples. SSC (solid soluble contents) increased in marrons soaked in acid water but remained constant under shelf-life conditions. SSC, ethanol, acetaldehyde and polyphenols did not change following storage at 0 • C for 2 months, but acid water samples showed a higher percentage of decayed marrons. Finally, it is possible to define some technological parameters. The immersion time of marrons in water must be at least 5 and no longer than 7 d, in order to avoid cell destruction. A water/marron ratio of 1:1 is advised. Using acid water, the samples with the ratios of 1:2 and 1:1 showed higher polyphenol and sugar contents. However, the metabolic response of these marrons was assumed to be a "stress response" to acid water.

The risk of undesirable by-products from chlorine disinfection in fresh-cut industries, together with its limited efficacy, has led to a search for alternative agents. The aim of this study was to test several alternative putative antimicrobial substances to reduce Escherichia coli O157:H7, Salmonella spp. and Listeria spp. populations on fresh-cut apple. Carvacrol, vanillin, peroxyacetic acid, hydrogen peroxide, Nacetyl-l-cysteine and Citrox were selected for their results in in vitro assays against E. coli O157:H7 and Listeria spp., to be tested on fresh-cut apple plugs. Apple flesh was inoculated by dipping in a suspension of a mix of the studied pathogens at 10 6 cfu mL −1 , and then treated with the antimicrobial substances. All treatments were compared to deionized water and a standard sodium hypochlorite treatment (SH, 100 mg L −1 , pH 6.5). Pathogen population on apple plugs was monitored for up to 6 days at 10 • C. Bacterial reductions obtained by peroxyacetic acid (80 and 120 mg L −1 ), vanillin (12 g L −1 ), hydrogen peroxide (5, 10, 20 mL L −1 ) and N-acetyl-l-cysteine (5 and 10 g L −1 ) were similar or higher than reduction obtained by SH. In addition, bacterial populations were maintained at low levels throughout storage. No cells of any of the pathogens were detected in the peroxyacetic acid, hydrogen peroxide, Citrox and SH washing solutions after apple treatment. Peroxyacetic acid, hydrogen peroxide and N-acetyl-l-cysteine could be potential disinfectants for the fresh-cut industry as an alternative to chlorine disinfection. However, their effect on sensory quality and effectiveness under commercial processing conditions should be evaluated.

The effect of preharvest soil application of potassium on the development of the physiological disorder called internal browning (IB) in harvested pineapple fruit was studied. Potassium was applied as a soil dressing at 4-20 g of K 2 O per plant in three split applications at 8, 24 and 40 weeks after planting. Fruit were harvested 19 months after planting and were harvested at two maturity stages, classified as color break (CB) or half ripe (HR) and stored at 7 • C and 95% RH for 15 days followed by 5 days at 25 • C to simulate commercial handling. IB was more severe in HR than in CB fruit. Application of potassium reduced IB in fruit of both maturities. Maximum response was achieved with 16 g of K 2 O per plant. Phenolic content of CB and HR fruit from plants treated with potassium was reduced up to 38 and 39%, respectively. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities varied according to the stage of maturity with higher activities in the ripe fruit. Potassium treatment promoted a progressive and more accentuated decrease of PPO activities in HR when compared to CB fruit. Similarly, PAL and POD activities were lower in fruit from plants treated with potassium as was the incidence of IB. This work showed that soil applications of potassium to growing pineapple plants could improve fruit quality.

Strawberries (Fragaria × ananassa Duch., cv. Selva) were heat-treated in an air oven (45 • C, 3 h). After treatment, the fruit were stored at 0 • C for 0, 7 or 14 d, and then held for 2 d at 20 • C. Respiration rate, hydrogen peroxide level, potassium leakage, antioxidant capacity, ascorbic acid, superoxide dismutase (SOD), ascorbate peroxidase (APX) and pyrogallol peroxidase (POD) activities were measured. Heat-treated fruit showed lower decay and less tissue damage than control fruit as judged by changes in ion leakage, respiration rate and pyrogallol peroxidase (POD). Heat-treated fruit also presented lower levels of H 2 O 2 than control fruit during storage. In addition, antioxidant capacity was higher in heat-treated fruit both after 1 d at 20 • C or 7 d at 0 • C. Ascorbate peroxidase (APX) and superoxide dismutase (SOD) activity were not affected immediately after the treatment. However, higher activity was found in heat-treated fruit during storage, indicating that the heat treatment produced changes in the oxidative metabolism of the fruit. Interestingly, the main differences were not observed immediately after the treatment but during the storage. The differential responses observed in the case of heat-treated fruit during storage could protect the fruit against reactive oxygen species generated during senescence or pathogen attack.

The effect of storage temperature on physicochemical, microbial and sensory quality of minimally processed durian (Durio zibethinus Murray) was determined at 28 • C for 3 days and 4 • C for 35 days. When held at 28 • C, the pulp retained its colour but softened rapidly after 24 h and became acidic (pH 4.71) after 2 days of storage due to the formation of citric, succinic, acetic and lactic acids. Sucrose decreased concomitantly with increase in glucose and fructose contents during storage. For fruit stored at 4 • C, no noticeable changes in pH occurred. Following 1 week of storage, there was a progressive increase in glucose, fructose and sucrose contents concomitant with the increase in total soluble solids. The firmness increased significantly (P < 0.05) at the end of storage. The organic acid content remained constant throughout storage with a minor increase in tartaric acid detected. Titratable acidity of the fruit correlated well with the shift in organic acid profile instead of pH. Sensory evaluation revealed off-odour development on day 14 for fruit stored at 4 • C. The off-flavour increased to an unacceptable point on day 28 of storage. The minimally processed durian fruit could be held at 4 • C for 14 days with acceptable microbiological count and without off-odour development. At ambient temperature, minimally processed durian could only be stored for 1 day after which the pulp became acidified.

Bacillus subtilis isolates F1, L2, and L2-5, isolated from citrus fruit surfaces were evaluated for control of citrus green and blue molds caused by Penicillium digitatum and P. italicum , respectively. These isolates were evaluated alone, or in combination with sodium bicarbonate (SB) or hot (45 8C) water treatment on artificially inoculated 'Valencia' and 'Shamouti' orange cultivars. Treated fruit were stored at 109/1 8C, and 90 Á/95% relative humidity (RH) for 4 weeks. When applied alone, all isolates performed significantly better than the water control in checking the incidence of both green and blue molds, but were not as effective as the fungicide (quazatine plus imazalil) treatment. Isolate F1 was more effective than L2 and L2-5 in this respect. A significant increase in biocontrol activity of all isolates was observed when isolates were combined with SB, or when applied following hot water treatment. The treatments comprising F1 combined with SB or F1 applied following hot water treatment was as effective as the fungicide treatment, which gave 100% control of both green and blue molds on both cultivars. #

Edible coatings based on high molecular weight chitosan combined with oleic acid were used to preserve quality of cold-stored strawberries cv. Camarosa. Physicochemical properties, fungal decay and respiration rates of samples were determined during cold storage. In addition, water vapour barrier properties and the sensory quality of coated samples were analysed. Coatings had no significant effects on acidity, pH and soluble solids contents of strawberries throughout storage. In contrast, coatings slowed down changes in the mechanical properties and slightly modified respiration rates of samples. Addition of oleic acid not only enhanced chitosan antimicrobial activity but also improved water vapour resistance of chitosan-coated samples. Sensory analysis showed that coating application led to a significant decrease in strawberry aroma and flavour, especially when the ratio oleic acid:chitosan was high in the film.

A new strain of Metschnikowia pulcherrima (MACH1) was studied for its efficacy as a biocontrol agent against Botrytis cinerea, Penicillium expansum and Alternaria alternata on apples stored for 8 months at 1 • C. The results of two semi-commercial trials demonstrated the efficacy of the biocontrol strain MACH1. In order to understand the mechanism of action involved, the yeast strain was investigated for its competitive ability for iron against postharvest pathogens of apple. M. pulcherrima strain MACH1 was cultivated on PDA with different concentrations of iron (supplemented as FeCl 3 ) against A. alternata and B. cinerea. The yeast strain MACH1 produced a wider pigmented inhibition zone against both pathogens in low iron amendments while less inhibition was measured with increased iron concentrations. At the coloured inhibition zone, B. cinerea and A. alternata conidia did not germinate and mycelial degeneration was observed. In addition, a high reduction in infection by both pathogens was recorded in apples treated with M. pulcherrima strain MACH1 supplemented with low iron amendments compared to higher iron concentrations. The same experiments were carried out in vivo and in vitro against P. expansum. M. pulcherrima strain MACH1 amended with low iron concentration (5 g mL −1 FeCl 3 ), showing modest lesion diameter reduction and no effect on P. expansum under increased iron and without iron amendments. This study illustrated that iron depletion by the yeast strain MACH1 under low iron conditions could reduce the growth of some postharvest pathogens in vitro and in vivo. Although, iron depletion seems to be a primary mode of action against the postharvest pathogens studied, other mechanisms of action cannot be excluded in the biocontrol employed by M. pulcherrima strain MACH1.

Edible coatings with antimicrobial agents can extend the shelf-life of fresh-cut fruit. The effect of lemongrass, oregano oil and vanillin incorporated in apple puree-alginate edible coatings, on the shelf-life of fresh-cut 'Fuji' apples, was investigated. Coated apples were packed in air filled polypropylene trays and wrapped with polypropylene film. Changes in headspace atmosphere, color, firmness, sensory quality and microbial growth were measured during 21 days storage at 4 • C. A significant reduction in the rates of O 2 depletion and CO 2 production was observed in samples containing high concentrations of essential oils. Ethylene production in the coated apples remained below 50 L L −1 , while production of this gas increased continuously in uncoated apples and those coated without essential oils during storage. Apples coated with apple puree-alginate exhibited ethanol and acetaldehyde formation in the first week. Coatings with calcium chloride and N-acetylcysteine helped to maintain firmness and color, while lemongrass containing coatings induced severe texture softening. Vanillin containing coatings (0.3% w/w) were the most effective in terms of sensory quality after 2 weeks storage. All antimicrobial coatings significantly inhibited the growth of psychrophilic aerobes, yeasts and molds. The antimicrobial effect of essential oils against L. innocua inoculated into apple pieces before coating was also examined. Lemongrass (1.0 and 1.5% w/w) and oregano oil containing coatings (0.5% w/w) exhibited the strongest antimicrobial activity against L. innocua (4 log reduction).

Sorption isotherm experiments in the high RH range (80-100%) were carried out at 1, 6.5, 10.5 and 18.5 • C for different parts (inner cortex, outer cortex tissues and cuticle) of early and late picked 'Conference' pears after 1 and 6 months of storage in controlled atmosphere conditions. Experiments were implemented successfully with the pressure-controlled method, in which samples were submitted to an air-flow of very high velocity (∼10 m/s) for 48 h. The results showed no significant effect of picking date and storage period. The effect of temperature was evident in the RH range above 91% for the inner cortex tissue, but much less for the outer cortex tissue. The difference in sorption isotherms of different tissues is quite obvious. The cuticle showed a non-hygroscopic behaviour, while the inner and outer cortex tissues showed the opposite. The inner cortex tissue had a higher water holding capability than the outer cortex tissue, which indicates the more protective properties of the latter against temperature and relative humidity fluctuations during storage. The water content change versus water activity was also stronger in the case of inner cortex tissue. In an attempt to relate the moisture distribution (water content) to the water status (potential) in pears and, to understand water movement in fresh fruit, a detailed modelling of the cellular structural properties and of the intercellular space is a necessity.

The effects of individual shrink film wrapping with two polyolefin films (BDF-2001 and D-955) and skin coating with a sucrose polyester (SPE) Semperfresh™ on the shelf life and quality of soft-seeded &#x27;Ganesh&#x27;pomegranates (Punica granatum L.) stored at 8, 15 and 25° C ...

Application of exogenous ethylene, irrespective of the method of application, caused intensification of mesocarp discoloration in avocado fruit (Persea americana Mill.) during cold storage of all cultivars tested. 'Ettinger' fruit treated with Ethrel (2-chloroethyl phosphonic acid) prior to packing and storage developed severe chilling injury (CI) symptoms, expressed as mesocarp discoloration after 3 weeks at 5°C. 'Fuerte' fruit treated with ethylene gas (100 ml l − 1 ) for 24 h at 20°C prior to storage at 5°C exhibited mesocarp discoloration, which increased dramatically during shelf life at 20°C. 'Fuerte' fruit treated in cold storage with a continuous low ethylene dose (4 ml l − 1 ) developed severe browning in the fruit pulp after 3 weeks at 5°C. 'Hass' fruit treated with 50 ml l − 1 ethylene, for 12, 24 or 48 h at 5°C showed a gradual increase in mesocarp discoloration after 3 weeks in cold storage plus shelf life; the 48 h ethylene-treated fruit exhibited the most severe pulp browning. Use of absorbent sachets that removed ethylene from modified atmosphere (MA) packaging reduced mesocarp discoloration and decay development in 'Hass' fruit after 5 weeks storage at 5°C. Application of 1-methylcyclopropene (1-MCP), reduced mesocarp discoloration, decay development and polyphenol oxidase activity, whereas this enzyme activity was induced in ethylene-treated fruits that were cold stored for 4 weeks.