Fruit Wax Research Articles

Waxes and plastic film in relation to the shelf life of yellow passion fruit

The high perishability of the yellow passion fruit (Passiflora edulis f. flavicarpa) reduces its postharvest conservation and availability, mainly for in natura consumption. These losses of quality and commercial value occur due to the high respiration and loss of water. This work aimed to evaluate the influence of a modified atmosphere - wax emulsions and plastic film - on the shelf life of the yellow passion fruit. Plastic film (Cryovac D-955, 15 mum thickness) reduced fresh weight loss and fruit wilting, kept higher fruit and rind weight and higher pulp osmotic potential over the storage period. However, it was not efficient in the control of rottenness. Sparcitrus wax (22-23% polyethylene/maleyc resin) caused injury to the fruit, high fruit weight losses and wilting and resulted in lower pulp osmotic potential; this wax lead to a higher concentration of acid and a lower relation of soluble solids/acidity. Among the tested waxes, Fruit Wax (18-21% carnauba wax) was the best, promoting reduced weight loss, wilting and rottenness.

Control of Citrus Green and Blue Molds with Garlic Extracts

Water and ethanol extracts of garlic cloves were applied to artificially inoculated citrus fruits to test their efficacy in the control of Penicillium digitatum and P. italicum, the cause of citrus green and blue mold respectively. Extracts were tested either alone, or in combination with vegetable (sunflower) cooking oil or fruit wax at the rate of (0.1% v/v), using two orange cultivars (Valencia and Shamouti), and grapefruit. Treated fruits were stored at 10 ± 1 ◦ C, and 90–95% relative humidity for 30 days. All concentrations of extracts were more effective than the water control in inhibiting the growth and development of both pathogens, but were not as effective as the fungicide treatment (imazalil 500 ppm + quazatine 1000 ppm). A remarkable increase in the activity of garlic extracts was observed when extracts were mixed with oil. Consequently, the treatment comprising 1% extract plus oil was as effective (100% control) as the fungicide treatment in controlling both green and blue molds on Valencia oranges.

Allelopathic activity of Ammi majus L. fruit waxes

Ammi majus seeds are known to have a strong allelopathic effect due to coumarins. The coumarins were identified and shown to be present in the seed epicuticular waxes. A simple method to study allelopathic compounds leaching from seeds is reported.

Survival of Escherichia coli O157:H7 and Salmonella Muenchen on apples as affected by application of commercial fruit waxes

Survival of Escherichia coli O157:H7, Salmonella Muenchen, and yeasts and molds on apples as affected by application of five commercial apple waxes was investigated. Red Delicious cv. apples at 21 °C were spot inoculated with E. coli O157:H7 and S. Muenchen and spray coated with waxes. Apples sprayed with water served as controls. Apples were dried at either 21 or 55 °C for 2 min before subjecting to microbiological analysis after storage for 0, 1, 3, 6, and 12 weeks at 2 or 21 °C. Drying temperature did not significantly influence populations of E. coli O157:H7 and S. Muenchen. Waxing reduced populations E. coli O157:H7 and S. Muenchen by up to 1.48 log 10 cfu/apple. Compared to untreated apples, treatment of apples with water or waxes resulted in significant ( P≤0.05) reductions in populations of E. coli O157:H7 and S. Muenchen during storage at 2 °C. Reductions on waxed apples stored at 21 °C were not as marked compared to reductions on waxed apples stored at 2 °C. With the exception of one wax, drying temperature did not significantly influence populations of yeasts and molds. Mold populations were less affected by wax applications than were yeasts, and were detected in higher numbers on apples treated with three of the five waxes compared to populations recovered from untreated control apples. None of the waxes evaluated can be relied upon to kill or remove E. coli O157:H7 and Salmonella on apples.

Ceras para conservação pós-colheita de frutos de abacateiro cultivar fuerte, armazenados em temperatura ambiente

Frutos de abacateiro foram colhidos dia 20/03/97. Selecionou-se 100 frutos uniformes, sendo mantidos 25 frutos para grupo controle - análise de perda de peso e 75 frutos para análises destrutivas - textura, sólidos solúveis totais e pH realizadas a cada 4 dias. Os frutos receberam os tratamentos, com objetivo de aumentar a vida pós-colheita: Cera "Fruit Wax" 1:1 (FW1) e 1:3 (FW2); "Sparcitrus" 1 (SP1) e 1:1 (SP2); Testemunha. Até o 4º dia de armazenamento não houve diferença significativa entre os valores de perda de peso dos tratamentos, sendo que ao final do armazenamento (12º dia) o tratamento SP1 foi superior aos demais, acarretando menor perda de peso dos frutos. Não houve diferença significativa entre os valores de textura analisados dentro de cada dia de armazenamento, mas os valores decresceram durante o armazenamento. Para sólidos solúveis totais não observou-se aumento significativos dos teores durante o armazenamento, sendo que em relação aos tratamentos, apenas no 12º dia para o tratamento FW2 obtiveram-se valores mais elevados do que o SP1. Para o pH não houve diferença significativa entre os valores dentro dos dias de armazenamento, entretanto do ponto de colheita para o 4ºdia de armazenamento, houve diminuição significativa, com exceção do tratamento SP1.

Hypobaric storage removes scald-related volatiles during the low temperature induction of superficial scald of apples

Abstract ‘Law Rome’ and ‘Granny Smith’ apples were stored hypobarically in air at 5 kPa total pressure and also in air or controlled atmosphere (CA) at 1.5 or 3% O2 with 0 or 3% CO2, for 8 months at 1°C. Fruit were placed under hypobaric storage immediately after harvest or after 0.5, 1, 2, 3, 4, 5 or 6 months storage in air at 1°C to determine the effects of delaying imposition of hypobaric storage on ripening and scald development and on the production of α-farnesene and its oxidation product 6-methyl-5-hepten-2-one (MHO). If fruit were placed under hypobaric conditions within 1 month after harvest, scald did not develop. After a 3-month delay, scald development was similar to that for fruit stored continuously in air. Both cvs. produced MHO which accumulated in their epicuticular wax when fruit were placed under hypobaric storage after a 1-month or more delay in air. MHO which had partitioned in the epicuticular wax of fruit stored hypobarically after 2 or more months delay was released upon transfer of fruit to atmospheric pressure of 20°C; MHO accumulated and/or was produced in direct proportion to the delay prior to hypobaric storage. In another experiment with five apple cvs., the production rates of α-farnesene and MHO were low during hypobaric storage, but upon removal of fruit from storage after 7 months, the rates increased over a 7 day period in air at 20°C and then sharply decreased afterward. After storage, α-farnesene and MHO production rates were similar and high for ‘Law Rome’, ‘Mutsu’, ‘Red Delicious’ and ‘Golden Delicious’ apples and were the lowest for ‘Granny Smith’. Scald did not develop on any hypobarically stored fruit whereas it did on all cvs. except ‘Golden Delicious’ stored in air. It was proposed that hypobaric ventilation removes a scald-related volatile substance that otherwise accumulates and partitions into the epicuticular wax of fruit stored in air at atmospheric pressure.

Sanitizing Effects of Fruit Waxes at High pH and Temperature on Orange Surfaces Inoculated with Escherichia coli

ABSTRACTWe determined the bactericidal activity of surface applied waxes on oranges. Effective bactericidal activity of combined alkali and heat treatments was observed on both glass slides and orange fruit surfaces. A five log reduction of Escherichia coli was attained by dipping inoculated glass slides in heated (≥50°C) alkaline (pH 10) wax solution for 4 min. A pH 11, dipping at ≥50°C for ≥2 min achieved similar bactericidal effects. On the fruit surface, wax treatments were effective at the non‐stem scar area. Thus, applied fruit waxes may be useful on raw agricultural commodities to reduce surface microbial contaminants.

Effect of hot water brushing, prochloraz treatment and waxing on the incidence of black spot decay caused by Alternaria alternata in mango fruits

Abstract A combined hot water spray and fruit brushing (hot water brushing–HWB) treatment for 15–20 s was developed for reducing the incidence of postharvest disease caused by Alternaria alternata and improving mango fruit keeping quality. The efficacy of the hot water treatment was tested over a range of temperatures from 48 to 64°C, in combination with prochloraz treatment and fruit waxing. Hot water brushing of fruits significantly reduced decay (infected area) development by A. alternata. But after storage for 3 weeks at 12°C and another week at 20°C, the reduction of disease incidence by HWB and prochloraz treatment (900 μg ml−1) was more effective than by HWB alone. HWB treatment for 15 s improved colour development and was more effective than the common, commercial 5 min dip treatment at 55°C. The combination of fruit HWB and waxing yielded high quality fruits with less decay development.

Effect of Epicuticular Waxes of Fruits on the Photodegradation of Fenthion

After treatment lipophilic pesticides tend to diffuse by penetrating the epicuticular wax of fruits. In this way, solar radiation only acts on pesticide molecules after passing through the waxes. The effect of epicuticular waxes of three fruits (orange, nectarine, and olive) on the photodegradation of fenthion was studied. The waxes affected the photodegradation process of fenthion. The decay rate of fenthion increased in the presence of orange and nectarine waxes, while it decreased when olive wax was used. In all waxes, the transformation of fenthion produced mainly fenthion sulfoxide and low amounts of fenthion sulfone. In orange wax, 50% of the initial fenthion was transformed into unknown compounds. In nectarine wax, fenthion was degraded stoichiometrically into fenthion sulfoxide and fenthion sulfone. In olive wax, the photodegradation of fenthion yielded about 80% of fenthion sulfoxide. Keywords: Fenthion; photodegradation; fruits; wax

Scald-related Volatiles in the Epicuticular Wax of Apple Fruit

Volatile compounds produced by apple (Malus domestica Borkh) fruit partition into the cuticle and epicuticular waxes and may play an important role in superficial apple scald. Of these volatiles, α-farnesene, conjugated trienes, hydroperoxides, and 6-methyl-5-hepten-2-one have been identified as playing a crucial role in scald production. Volatiles from the epicuticular wax of four different apple cultivars have been analyzed by gas chromatography/mass spectroscopy. A correlation was found between scald incidence and 6-methyl-5-hepten-2-one content and the 6-methyl-5-hepten-2-one:α-farnesene ratio. α-Farnesene is the most-abundant volatile at the beginning of storage, whereas 6-methyl-5-hepten-2-one is present in minute quantities. These two volatile compounds appear to have an inverse relationship with respect to one another since the levels of 6-methyl-5-hepten-2-one increased and α-farnesene decreased prior to the onset of apple scald. This changing ratio may have been due to an autoxidative process resulting in the breakdown of α-farnesene to 6-methyl-5-hepten-2-one. Analysis of the volatiles emanating from the apple wax revealed a number of compounds associated with aroma that also partition readily into the fruit surface.

The effect of heat treatment on apple epicuticular wax and calcium uptake

Golden Delicious apples (Malus domestica Borkh) were heated for 4 days at 38 °C and then dipped in 2% CaCl2, or dipped in the solution without prior heating. Scanning electron micrographs of the fruit wax layer after three days of 0 °C storage showed that the heated apples had areas of amorphous wax and fewer surface cracks than unheated apples. There was less wax on the surface of heated than on unheated apples. Electron density scan of apple wax showed more calcium in outer than inner wax area of undipped but heated apples, while the opposite obtained in unheated apples. Dips in calcium raised the wax calcium level of the unheated apples more than the heated ones. Plasma emission spectrometry of calcium in apple peel and flesh after 5 months storage at 0 °C showed greater penetration of calcium from the dips into unheated apples, compared to heated apples. It is suggested that during the heat treatment the wax softens and fills in cracks while water loss pulls calcium towards the fruit surface. This continuous wax layer on heated fruit decreases the ability of external calcium to move into the apple.

Aliphatic components of the epicuticular wax of developing saskatoon (Amelanchier alnifolia) fruit

The epicuticular wax of saskatoon fruit (Amelanchier alnifolia Nutt. cv. Smoky) was analyzed at four stages of maturity. Total wax per unit surface area varied during fruit development, with a net decline from the youngest to the most ripe stage. Surface wax ultrastructure, as revealed by scanning electron microscopy, consisted of pinhead-like crystals that decreased with maturity and platelike crystals that increased with maturity. The major aliphatic compounds were alkanes (C23to C29), long chain esters (C36to C42), primary alcohols (C20to C30), and a secondary alcohol (C29). The esters were composed of primary alcohols (C20to C28) and saturated fatty acids (C16to C24). The most abundant wax components at all stages were nonacosan-10-ol and nonacosane. Keywords: serviceberry, saskatoon fruit, epicuticular wax, aliphatic chemistry, ultrastructure.

Rethinking Apple Scald: New Hypothesis on the Causal Reason for Development of Scald in Apples

Superficial scald is still one of the most important postharvest physiological disorders in apples. Commercial control of this disorder has been accomplished by selecting resistant cultivars, treating fruit with DPA and ethoxyquin, using oil-soaked fruit wraps and storing the fruit under low O2. However, the causal reason for scald development is still a mystery. Research has indicated that the scald-promoting factor or inducing compound may be formed or accumulated in apple cuticle then rediffused back into the hypodermis, thereby causing damage. Hydroperoxides, auto-oxidative product from α-farnesene, have been thought to be the toxic compounds, inducing scald; however, it is not explained how the hydroperoxides move from the cuticle to the hypodermis. The identification and dynamic changes of 6-methyl-5-heptene-2-one as a natural volatile in apple fruit during ripening were made, which accumulated in higher quantitaty in cuticular wax than in headspace. The close relationship between the chloroplast breakdown and amount of α-farnesene changes, the induction of scald-like symptom on the surface of apple fruit by 6-methyl-5-heptene-2-one and the sensitivity of fruit to this ketone damage were investigated. Our results suggest that the accumulation of 6-methyl-5-heptene-2-one in the cuticular wax of apple fruit might be the causal reason for scald development in apples.

Heat Treatment Affects Epicuticular Wax Structure and Postharvest Calcium Uptake in `Golden Delicious' Apples

`Golden Delicious' apples (Malus domestica Borkh) were pressure-infiltrated at harvest with a 4% CaCl2 solution either without prior heat treatment or following 4 days at 38C. Examination of the apple surfaces from both treatments by low-temperature scanning electron microscopy revealed that heat treatment changed the pattern of epicuticular wax. The epicuticular wax of nonheated fruit exhibited numerous deep surface cracks that formed an interconnected network on the fruit surface. The epicuticular wax of heat-treated fruit did not exhibit a similar network of deep cracks. This apparent obstruction or elimination of deep cracks may limit the CaCl2 solutions from entering the fruit. The heated fruit contained significantly less Ca than the fruit that were pressure-infiltrated with CaCl2 solutions but not heated. These results indicate that cracks on the fruit surface may be an important pathway for the penetration of CaCl2 solutions.

371 TRITERPENES IN GRAPEFRUIT EPICUTICULAR WAX

The purpose of this study was to identify compounds in the wax of fruit obtained from different canopy positions for possible relationships to chilling injury development. Both exterior and interior canopy grapefruit wax extracts were separated by thin layer chromatography into four lipid classes: alkanes, aldehydes, linear alcohols and triterpenes. The triterpene class consisted of three subclasses: triterpenols (TOH), triterpenones (TON) and triterpenol acetates (TAC). Each triterpene subclass was analyzed by gas chromatography and their component structures estimated by comparison of retention times with authentic standards. Derivatives were prepared for each subclass: TOH were oxidized to TON, TON were reduced to TOH, and TAC hydrolyzed to TOH. Structures were verified by gas chromatography-mass spectra of components and their derivatives as well as spectra of authentic standards and their derivatives. There was a higher level of TON in interior compared with external canopy fruit. The three major TON were a amyrone, β amyrone and friedelin. α amyrone was also shown to be a major component of the wax of `Valencia' orange, a fruit not subject to chilling injury when produced in Florida

The morphology of epicuticular wax and albedo cells of orange fruit in relation to albedo breakdown

SummaryChanges in the morphology of albedo cells of ‘Leng’ navel and ‘Valencia’ (Citrus sinensis (L.) Osbeck) orange fruit, in relation to fruit development and to the structural basis of albedo breakdown (creasing), were examined by scanning electron microscopy of frozen- hydrated plant material. In albedo tissue sampled from fruit affected by albedo breakdown the fracture paths developed across cell layers in a radial direction, normal to the direction of the stress. The fracturing of albedo tissue was due predominantly to the separation of adjacent cells rather than the cleavage of individual cells, and was, therefore, characteristic of anisotropic tissue. Although separation of albedo cells was also observed in unaffected fruit, it was assumed that the number of cell separations did not exceed a critical threshold required to initiate fracture formation in the tissue. We suggest that changes in the cohesion of adjoining cells at the middle lamella predisposes the fruit to albedo breakdown. The rind of...

Temperature Conditioning and Surface Treatments of Grapefruit Affect Expression of Chilling Injury and Gas Diffusion

`Marsh' Grapefruit (Citrus paradisi Macf.) were temperature conditioned (7 days at 15C), wiped with hexane, treated with squalene, squalane, or safflower oil (all 10% in hexane), or waxed with a commercial fruit wax (Flavorseal) to determine their effects on weight loss, chilling injury (Cl) symptoms on the peel, and gas exchange. Following 3 weeks of storage at SC, wiping fruit with hexane resulted in a significant decrease in weight loss, but not CI. Temperature conditioning and Flavorseal independently inhibited weight loss and Cl development. Squalene inhibited CI development, but not weight loss. Chilling injury on fruit treated with squalene or Flavorseal was similar in appearance, but significantly less common than that on nontreated fruit. Grapefruit peel accounted for 92% of the gas diffusion of fruit, and resistance coefficients for peel and whole fruit were similar. Less ethane diffused into fruit that were: temperature-conditioned compared with nonconditioned, hexane wiped compared with nonhexane-wiped, and squalene-treated compared with nonsqualene treated fruit. Ethane influx was significantly restricted into squalane- and squalane-treated fruit compared with Flavorseal- or safflower oil-treated fruit. Oxygen and CO2 influx was significantly reduced by Flavorseal, safflower oil, squalene, and squalane. Squalane was the most restrictive of ethylene efflux followed by safflower oil, squalene, and Flavorseal. All of these surface treatments are known to reduce CI on grapefruit. These data indicate that water loss is less important to the development of Cl than has been previously suggested, and that the beneficial effects of squalene are not the result of an inhibition of water loss. Permeability of grapefruit peel to gases other than H2O vapor may also influence the expression of Cl.

Effects of antagonistic microorganisms on the post‐harvest development of Colletotrichum gloeosporioides on mango

Potential microbial antagonists of Colletotrichum gloeosporioides were isolated from blossom, leaves and fruit of mango and screened using a series of assay techniques. In total 648 microorganisms, including bacteria, yeasts and filamentous fungi, were isolated and tested for their inhibition of growth of C. gloeosporioides on malt extract agar. In vitro, 121 organisms inhibited the fungus and were tested further for their ability to affect conidial germination. Of these isolates, 45 bacteria and yeasts inhibited germination. These were inoculated onto mangoes artificially infected with C. gloeosporioides and assessed for their potential to reduce the development of anthracnose lesions. Seven isolates were chosen for use in a trial in the Philippines using freshly harvested fruit. This final screening procedure yielded two potential candidates for further trials, isolate 204 (identified as Bacillus cereus) and isolate 558 (identified as Pseudomonas fluorescens). In post‐harvest trials under commercial conditions, isolates 204 and 558 were both tested in combination with different application methods including the addition of adhesive material, peptone, fruit wax or sucrose polyester. Application of isolate 204 did not reduce disease development, whereas application of 558 significantly reduced anthracnose development. No additional benefit was achieved by incorporating the bacteria in adhesive material, peptone, fruit wax or sucrose polyester.

Surface waxes from olive fruits

The chloroform-soluble waxes of green and black olive fruits ( Olea europaea cv Coratina) contain alkanes (C 23–C 33), saturated and unsaturated alkyl esters (C 38–C 56), aldehydes (C 24–C 30), methyl phenyl esters, triacylglycerols, alcohols (C 22–C 28), fatty acids (C 16–C 28), and pentacyclic triterpenols and triterpenoid acids. Oleanolic acid and triacylglycerols are the major components. Uvaol and erythrodiol, present in substantial amount in wax from green olives, were present only in trace amounts in that from black olives.

Gas Permeability of Fruit Coating Waxes

The permeability to O2, CO2, C2H4, and water vapor was determined for 19 commercial fruit wax coatings, four ingredients thereof, and one shrink-wrap film. For the commercial coatings, the O2permeability at 50% relative humidity and 30C ranged from 470 to 22,000 ml (STP) × mil/(m2 × day × atm) (1 mil = 0.0254 mm) with CO)2. permeability two to eight times as high. Permeability to noncondensable gases tended to be higher for coatings made from carnauba wax than for those made from shellac and rosin. Commercial fruit wax had sufficiently low noncondensable gas permeability to account for large reductions in the respiration rate of coated fruit. Wax coatings could be improved if permeability were controlled: