Ripening and quality of 'Laetitia' plums following harvest and cold storage as affected by inhibition of ethylene action

The inhibition of ethylene action by 1-methylcyclopropene (1-MCP) extends shelf and storage life of many climacteric fruits. However, 1-MCP appears to have limited effects on stone fruit depending on specie and cultivar. The effects of 1-MCP on ripening and quality of 'Laetitia' plums were determined during ripening at 23ºC following harvest and cold storage. Japanese plums (Prunus salicina, cv. Laetitia) were harvested at mature pre-climacteric stage, cooled to 2ºC within 36 hours of harvest and then treated with 0, 0.05, 0.10, 0.50 or 1.00 muL L-1 of 1-MCP at 1°C for 24 hours. Following treatment, fruits were either held at 23ºC for 16 days or stored at 1ºC for 50 days. Fruits were removed from cold storage at 10-day intervals and allowed to ripe at 23°C for five days. A delay of climacteric respiration and ethylene production by 1-MCP treatment during ripening following harvest and cold storage was associated to a slow rate of fruit softening. 1-MCP treatment also delayed the loss of titratable acidity and changes of flesh and skin color, whereas it had little or no effect on soluble solids content. 1-MCP effects were concentration- and storage duration-dependent and, generally, a saturation fruit response to 1-MCP occurred between 0.5 and 1.0 muL L-1. During ripening, 1-MCP treated fruits attained quality similar to that of controls. Results indicated that 1-MCP treatment may extend shelf life (23ºC) and storage life (1ºC) of 'Laetitia' plums by approximately six and 20 days, respectively.

Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)

An aliphatic-aromatic copolyester of poly(ethylene terephthalate), PET, and poly(ethylene adipate), PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis.

Effect of the structure of commercial poly(ethylene oxide-b-propylene oxide) demulsifier bases on the demulsification of water-in-crude oil emulsions: elucidation of the demulsification mechanism

Water-in-crude oil emulsions are formed during petroleum production and asphaltenes play an important role in their stabilization. Demulsifiers are added to destabilize such emulsions,however the demulsification mechanism is not completely known. In this paper, the performances of commercial poly(ethylene oxide-b-propylene oxide) demulsifiers were studied using synthetic water-in-oil emulsions and model-systems (asphaltenes in organic solvent). No change in the asphaltene aggregate size induced by the demulsifier was observed. The demulsification performance decreased as the asphaltene aggregate size increased, so it can be suggested that the demulsification mechanism is correlated to the voids between the aggregates adsorbed on the water droplets surface.

Poly(ethylene-co-methyl acrylate)/poly(caprolactone) triol blends for drug delivery systems: characterization and drug release

Poly(ethylene-co-methyl acrylate) (EMA) and poly (caprolactone) triol (PCL-T) blends, a biodegradable aliphatic polyester with low molecular weight and moderate water solubility containing diltiazem hydrochloride (DZ) were studied in terms of the thermal and morphological properties, and drug release mechanism. An increase in the PCL-T content in the EMA/PCL-T/DZ films decreased the degree of DZ crystallinity. Drug release from these films is temperature-dependent, and it is possible to modify the drug release rate by adjusting the EMA/PCL-T composition of the blends. The mechanism of drug release is governed by PCL-T melting and PCL-T leaching from EMA matrix.

Ripening of mango fruits. Competition of methods

Mangoes, cv. Imperial, were exposed, in post harvest, to the following methods of ripening: 1) sawdust burning; 2) alcohol vaporization; 3) calcium carbide (acetylene), 4) vapour of ethylene; and, 5) immersion in ethefon. All methods resulted in acceleration of ripening, when compared to controls. Calcium carbide, ethelene and ethefon were the best, methods. Alcohol vaporization also showed good results sawdust burning method showing low efficiency.

Properties of ß-lactamase from Neisseria gonorrhoeae

ß-lactamase activity was studied in Neisseria gonorrhoeae strains. Optimum temperature was found to be 37°C. The enzyme was inactivated at temperatures higher than 60°C, but remained active during storage at low temperatures (4°C, -30°C and -70°C) for two months. Enzyme activity was observed within a pH range of 5.8-8.0, while the optimum pH was 7.0-7.2. Addition of Ni2+, Fe2+, Fe3+, Mn2+ and p-chloromercurybenzoate to the reaction buffer exerted a negative effect upon the activity, whereas Hg2+ and ethylene diamine tetra-acetic acid produced complete inhibition. These results would indicate the presence of -SH groups at the catalytic site of the enzyme.

Conservation of 'Pedro Sato' guavas under treatment with 1-methylcyclopropene

The search for techniques that extend shelf life of guava (Psidium guajava) fruits, and reduce its postharvest losses is desirable. The objective of this work was to evaluate the effects of concentrations of competitive ethylene antagonist 1-methylcyclopropene (1-MCP) on conservation of 'Pedro Sato' guava fruits. Treatments consisted of 0, 100, 300 or 900 nL L-1 of 1-MCP for 3 hours followed by storage at 25ºC, and 10ºC with 90±5% RH. The application of 900 nL L-1 1-MCP for 3 hours was efficient in delaying loss of skin color, and in keeping fruit firmness at both storage temperatures. The 300 nL L-1 of 1-MCP concentration was efficient in delaying skin color loss only when fruits were stored at 10ºC. The effect of 1-MCP was quite significant on the reduction of rot incidence at both storage temperatures. The respiratory rate was lower in fruits treated with 300 and 900 nL L-1 of 1-MCP during storage at 25ºC. The product was efficient in delaying the ripening of fruits, and the concentration of 900 nL L-1 showed the best effect.

Enzyme activities and pectin breakdown of sapodilla submitted to 1-methylcyclopropene

The objective of this work was to investigate the influence of 1-methylcyclopropene (1-MCP) at 300 nL L-1 on activities of cell wall hidrolytic enzymes and pectin breakdown changes which Sapodilla (Manilkara zapota cv. Itapirema 31) cell wall undergoes during ripening. Sapodilla were treated with ethylene antagonist 1-MCP at 300 nL L-1 for 12 hours and then, stored under a modified atmosphere at 25º C for 23 days. Firmness, total and soluble pectin and cell wall enzymes were monitored during storage. 1-MCP at 300 nL L-1 for 12 hours delayed significantly softening of sapodilla for 11 days at 25º C. 1-MCP postharvest treatment affected the activities of cell wall degrading enzymes pectinmethylesterase and polygalacturonase and completely suppressed increases in beta-galactosidase for 8 days, resulting in less pectin solubilization. Beta-galactosidase seems relevant to softening of sapodilla and is probably responsible for modification of both pectin and xyloglucan-cellulose microfibril network.

Latex production with depolymerizing compounds of actin cytoskeleton in rubber trees

The objective of this work was to assess stimulated latex flow from rubber trees (Hevea brasiliensis) with saturated macrolide (latrunculin A), 1, 5, and 10% potassium iodide in 2% methylcellulose compared with 0.3% ethylene in 2% methylcellulose (check) and 2% methylcellulose (blank). Latex output and contents of pure rubber, total solid, sucrose, inorganic phosphorus, thiol, and Mg2+ were measured. The treatments containing 1% KI or saturated macrolide increased latex yields compared to the blank with 2% methylcellulose alone. The 1% KI or saturated macrolide treatments were equal to that of 0.3% ethylene check treatment. However, 5 and 10% KI were harmful to bark of rubber trees, even caused prolonged tapping panel dryness.

Potassium permanganate effects in postharvest conservation of the papaya cultivar Sunrise Golden

The objective of this work was to evaluate the effects of KMnO4 on the extension of postharvest life of 'Sunrise Golden' papaya, stored under modified atmosphere and refrigeration. Fruit with up to 10% yellow peel were harvested in a commercial orchard in Linhares, state of Espírito Santo, Brazil. Sets of three fruit (unit mass of 289.9±18.5 g) were wrapped in low-density polyethylene films (28 ¼m thick) containing sachets of KMnO4 at 0, 0.5, 1, 1.5, and 2 g per bag. The bags were sealed and stored at 10.4±0.9°C and 90±5% relative humidity for 25 days. After this period, the fruit were removed from the bags and maintained at 21±0.8°C and 90±5% relative humidity until complete ripening. Four days after bag sealing, CO2 concentration stabilized in all treatments, and was higher in bags without KMnO4. In all treatments, fruit reached the climacteric respiratory peak on the third day after bag removal, coinciding with peel color index of 3.5. Increasing the KMnO4 dose reduced the losses in fruit fresh matter, consistency and pulp electrolyte leakage. Potassium permanganate was effective in maintaining the fruit at the pre-climacteric stage during the 25-day storage, and did not interfere with normal ripening after bag removal.

Gene expression profile during coffee fruit development and identification of candidate markers for phenological stages

The objective of this work was to identify genes that could be used as suitable markers for molecular recognition of phenological stages during coffee (Coffea arabica) fruit development. Four cultivars were evaluated as to their differential expression of genes associated to fruit development and maturation processes. Gene expression was characterized by both semi-quantitative and quantitative RT-PCR, in fruit harvested at seven different developmental stages, during three different seasons. No size polymorphisms or differential expression were observed among the cultivars for the evaluated genes; however, distinct expression profiles along fruit development were determined for each gene. Four out of the 28 evaluated genes exhibited a regular expression profile in all cultivars and harvest seasons, and, therefore, they were validated as candidate phenological markers of coffee fruit. The gene α-galactosidase can be used as a marker of green stage, caffeine synthase as a marker of transition to green and yellowish-green stages, and isocitrate lyase and ethylene receptor 3 as markers of late maturation.

Effect of growth regulators on 'Brookfield' apple gas diffusion and metabolism under controlled atmosphere storage

The objective of this work was to evaluate the effect of growth regulators on gas diffusion and on metabolism of 'Brookfield' apple, and to determine their correlation with quality characteristics of fruit stored in controlled atmosphere. A completely randomized design was used with four replicates. After eight months of storage, the effects of water (control), aminoethoxyvinylglycine (AVG), AVG + ethephon, AVG + naphthaleneacetic acid (NAA), ethephon + NAA, sole NAA, 1-MCP, ethylene absorption by potassium permanganate (ABS), AVG + ABS, and of AVG + 1-MCP - applied at different rates and periods - were evaluated on: gas diffusion rate, ethylene production, respiratory rate, internal ethylene concentration, internal CO2 content, mealiness, and intercellular space. Fruit from the control and sole NAA treatments had the highest mealiness occurrence. Growth regulators significantly changed the gaseous diffusion through the pulp of 'Brookfield' apple, mainly in the treatment AVG + ABS, which kept the highest gas diffusion rate. NAA spraying in the field, with or without another growth regulator, increased ripening metabolism by rising ethylene production and respiration rate, and reduced gas diffusion during shelf life. AVG spraying cannot avoid the ethephon effect during the ripening process, and reduces both the internal space and mealiness incidence, but it is not able to induce ethylene production or to increase respiration rates.

Abscisic acid as a potential chemical thinner for peach

Abstract:The objective of this work was to evaluate the effect of abscisic acid, applied at different rates and different fruit developmental stages, on the thinning of 'Chiripá' peach. Abscisic acid (ABA) at 500 mg L-1 was applied at three stages of fruit development based on lignin deposition: stage 1, at 24 days after full bloom (DAFB); stage 2, at 40 DAFB; and stage 3, at 52 DAFB. Only ABA application at stage 2 - 40 DAFB - reduced fruit set and the number of fruit per plant. Three ABA concentrations (350, 500, and 750 mg L-1) were then applied at 40 DAFB. All rates increased fruit ethylene production and fruit abscission.

Effect of aminoethoxyvinilglycine (AVG) on preharvest fruit drop and maturity of apples

Apple trees cultivars Gala and Fuji were sprayed four weeks before commercial harvest with aminoethoxyvinilglycine (AVG), at doses of 0, 125, or 250 mg L-1, and assessed for preharvest fruit drop, fruit growth, and maturation on tree. In 'Gala', 64 days after AVG spraying, fruit drop for control treatment was 85%, and AVG (at 125 and 250 mg L-1) reduced it to 10%. In 'Fuji', 64 days after AVG spraying, fruit drop for control was 6%, while treatments with AVG (at 125 and 250 mg L-1) increased fruit drop to 10%. AVG was a powerful retardant of fruit maturation for 'Gala' but not for 'Fuji'. In 'Gala', the most affected attribute was the skin background color, followed, in decreasing order, by soluble solids content, the starch index, skin red color, the flesh firmness, and titratable acidity. In 'Gala', only flesh firmness retention was improved by increasing AVG dose from 125 mg L-1 to 250 mg L-1. The AVG at 250 mg L-1 inhibited "Gala" late fruit growth but not 'Fuji'.

Effects of modified atmosphere packaging on ripening of 'Douradão' peach related to pectolytic enzymes activities and chilling injury symptoms

The present study evaluated the effects of modified atmosphere packaging on inhibition of the development of chilling injury symptoms in 'Douradão' peach after cold storage and the possible involvement of cell wall enzymes. Fruits were harvested at the middle stadium of ripening, packed in polypropylene trays and placed inside low density polyethylene (LDPE) bags (30, 50, 60 and 75 µm of thickness) with active modified atmosphere (10 kPa CO2 + 1.5 kPa O2, balance N2). The following treatments were tested: Control: peaches held in nonwrapped trays; MA30: LDPE film - 30 µm; MA50: LDPE film - 50 µm; MA60: LDPE film - 60 µm and MA75: LDPE film - 75 µm. Fruits were kept at 1±1ºC and 90±5% relative humidity (RH) for 28 days. After 14, 21 and 28 days, samples were withdrawn from MAP and kept in air at 25±1ºC and 90±5% RH for ripening. On the day of removal and after 4 days, peaches were evaluated for woolliness incidence, pectolytic enzymes activities. The respiratory rate and ethylene synthesis were monitored during 6 days of ripening. The results showed that MA50 and MA60 treatments had positive effect on the inhibition of the development of woolly texture and reduced pectin methylesterase activity on the ripe fruits, keeping good quality of 'Douradão' peach during 28 days of cold storage. The treatments Control, MA30 and MA75 showed higher woolliness incidence and did not present marketable conditions after 14 days of cold storage.