Marisa M. Wall

Demonstrating Pathogenicity of Enterobacter cloacae on Macadamia and Identifying Associated Volatiles of Gray Kernel of Macadamia in Hawaii

Gray kernel is an important disease of macadamia (Macadamia integrifolia) that affects the quality of kernels, causing gray discoloration and a permeating, foul odor. Gray kernel symptoms were produced in raw, in-shell kernels of three cultivars of macadamia that were inoculated with strains of Enterobacter cloacae. Kochs postulates were fulfilled for three strains, demonstrating that E. cloacae is a causal agent of gray kernel. An inoculation protocol was developed to consistently reproduce gray kernel symptoms. Among the E. cloacae strains studied, macadamia strain LK 0802-3 and ginger strain B193-3 produced the highest incidences of disease (65 and 40%, respectively). The other macadamia strain, KN 04-2, produced gray kernel in 21.7% of inoculated nuts. Control treatments had 1.7% gray kernel symptoms. Some abiotic and biotic factors that affected incidence of gray kernel in inoculated kernels were identified. Volatiles of gray and nongray kernel samples also were analyzed. Ethanol and acetic acid were present in nongray and gray kernel samples, whereas volatiles from gray kernel samples included the additional compounds, 3-hydroxy-2-butanone (acetoin), 2,3-butanediol, phenol, and 2-methoxyphenol (guaiacol). This is believed to be the first report of the identification of volatile compounds associated with gray kernel.

Avocado Fruit Quality Management during the Postharvest Supply Chain

Avocados are a popular subtropical fruit of high economic importance, and the European Union is the biggest importer of the bulk of the fruit coming from countries such as South Africa, Chile, and Israel. The fruit is highly nutritious, being rich in vitamins A, B, C, minerals, potassium, phosphorus, magnesium, iron, and antioxidants. The biggest challenge is that the fruit is highly susceptible to qualitative and quantitative postharvest losses. Successful maintenance of avocado fruit quality during the supply chain depends on many aspects, including adequate orchard management practices, harvesting practices, packing operations, postharvest treatments, temperature management, transportation and storage conditions, and ripening at destination. Postharvest losses are mostly attributed to flesh softening, decay, physiological disorders, and improper temperature management. Management of the supply chain is solely done to provide the fruit with the most favorable conditions to extend storage life, and retain quality and nutritional attributes of the fruit. The focus of this review is therefore to study the findings that have emanated from research done to retain overall avocado fruit quality and to reduce postharvest losses during the supply chain through the adoption of appropriate and novel postharvest technologies.

Withanolides derived from Physalis peruviana (Poha) with potential anti-inflammatory activity

Three new withanolides, physaperuvin G (1), with physaperuvins I (2), and J (3), along with seven known derivatives (4-10), were isolated from the aerial parts of Physalis peruviana. The structures of 1-3 were determined by NMR, X-ray diffraction, and mass spectrometry. Compounds 1-10 were evaluated in lipopolysaccharide (LPS)-activated murine macrophage RAW 264.7 cells. Compounds 4, 5, and 10 with potent nitric oxide inhibitory activity in LPS-activated RAW 264.7 cells, with IC50 values in the range of 0.32-7.8μM. In addition, all compounds were evaluated for potential to inhibit tumor necrosis factor-alpha (TNF-α)-activated nuclear factor-kappa B (NF-κB) activity with transfected human embryonic kidney cells 293. Compounds 4-7 inhibited TNF-α-induced NF-κB activity with IC50 values in the range of 0.04-5.6μM.

Anti-inflammatory and Quinone Reductase Inducing Compounds from Fermented Noni (Morinda citrifolia) Juice Exudates

A new fatty acid ester disaccharide, 2-O-(β-d-glucopyranosyl)-1-O-(2E,4Z,7Z)-deca-2,4,7-trienoyl-β-d-glucopyranose (1), a new ascorbic acid derivative, 2-caffeoyl-3-ketohexulofuranosonic acid γ-lactone (2), and a new iridoid glycoside, 10-dimethoxyfermiloside (3), were isolated along with 13 known compounds (4-16) from fermented noni fruit juice (Morinda citrifolia). The structures of the new compounds, together with 4 and 5, were determined by 1D and 2D NMR experiments, as well as comparison with published values. Compounds 2 and 7 showed moderate inhibitory activities in a TNF-α-induced NF-κB assay, and compounds 4 and 6 exhibited considerable quinone reductase-1 (QR1) inducing effects.

First Report of Association of Mucor circinelloides on Noni (Morinda citrifolia) in Hawaii

Noni (Morinda citrifolia) is a popular medicinal plant found in tropical or subtropical regions of the world. The fruit and juice extracts have properties that are reportedly therapeutic for diabetes, high blood pressure, and certain types of cancer (1,4). In our studies on noni juice produced from fruit collected from the Kohala and Puna districts of the island of Hawaii from 2008 to 2010, Mucor circinelloides f. sp. circinelloides was isolated from 85% of 157 juice samples and observed with up to 75% incidence on fruit surfaces during fermentation processing in glass jars. Fungal growth, appearing 14 to 21 days in storage at 22°C, was pale yellow to tan brown and was associated with wounded surfaces. Single-spore strains, KN 06-2 (2006; ripe fruit puree) and KN 08-08 (2008; fermented juice; CBS 124110), identified by Centraalbureau voor Schimmelcultures by molecular methods were 97.3% similar in internal transcribed spacer sequence to the type strain (CBS 195.68). M. circinelloides f. sp. circinelloides strains (KN 08-08, KN 09-06, or KN 10-02) (2008 to 2010; fermented juice) were inoculated by pipetting an aliquot of 100 μl of fungus strain spore suspension (1 × 105 to 1.33 × 106 spores/ml) onto firm, yellow maturity noni fruit that were washed, surface disinfected, and either wounded (surface cuts) or nonwounded. Controls consisted of no inoculation and sterile distilled water (SDW) inoculation treatments. Ten to twenty each of wounded and nonwounded fruit comprised each inoculation treatment. Fruit were incubated in acrylic bins with a layer of distilled water at the bottom, and sealed with snap-on lids. The bins were incubated on a lab bench at 22 to 23°C under fluorescent lights. Fruits were evaluated for presence of fungal growth and severity of symptoms. To determine viability of spores on inoculated fruit without symptoms, surfaces were swabbed with sterile cotton swabs dipped in SDW, streaked on potato dextrose agar (PDA) plates, and incubated at 22°C under fluorescent lights. The inoculation experiment was conducted twice. Nonwounded fruit inoculated with M. circinelloides f. sp. circinelloides strains did not result in infections (KN 09-06 and KN 10-02) or produced slight mycelial growth (0 to 20%; KN 08-08). Wounded fruit inoculated with any of the three strains resulted in 85 to 100% infection of moderate severity. There were no infections in noninoculated or SDW treatments of nonwounded or wounded fruit. Kochs postulates were fulfilled with the reisolation of M. circinelloides f. sp. circinelloides from selected fruit exhibiting soft tissue, discoloration, and sporulating yellowish green mycelial growth. Swab washes from asymptomatic surfaces of inoculated nonwounded fruit resulted in the growth of M. circinelloides f. sp. circinelloides on PDA, proving viability of the spores and confirmed that the fungus is primarily pathogenic only on wounded fruit surfaces. To our knowledge, this is the first report of M. circinelloides as a wound pathogen of noni fruit. The quality of fermented noni juice may be affected by the presence of M. circinelloides f. sp. circinelloides but can be remedied by pasteurization that does not affect antitumor properties (unpublished data). This fungus is also a reported pathogen of mango (2) and peach (3). References: (1) J. Li et al. Oncol. Rep. 20:1505, 2008. (2) K. Pernezny and G. W. Simone. Phytopathol. News 34:25, 2000. (3) C. Restuccia et al. J. Food Prot. 69:2465, 2006. (4) M. Y. Wang et al. Acta Pharmacol. Sin. 23:1127, 2002.

Postharvest Ripening of Noni Fruit (Morinda citrifolia) and the Microbial and Chemical Properties of Its Fermented Juice

The physiology of noni (Morinda citrifolia) fruit ripening, as well as the chemical and microbial properties of its fermented juice, were determined. The ripening fruit had a nonclimacteric respiratory pattern (34 mg CO2·kg−1h−1) and no detectable ethylene production. The fungus, Mucor circinelloides, was consistently isolated from fermented juice, with peak populations at 14 d coincident with an increase in headspace CO2 and a decline in pH and soluble solids. Bacterial populations were greatest at 42 d, with Erwinia pyrifoliae and Gluconobacter frateurii isolated from fermented juice. Sugar concentration (64.8 mg·mL−1) decreased by 37% after 7 d, while organic acids (26.6 mg·mL−1) were the highest at 28 d. Major non-volatile acids present in the fermented juice included acetic, ascorbic, dehydroascorbic, galacturonic, malonic, succinic, and tartaric acids.

Effects of chitosan-based coatings containing peppermint essential oil on the quality of post-harvest papaya fruit

Edible coatings comprised of antimicrobial polymers based on chitosan are promising technologies to preserve post-harvest fruit quality. In this study, we investigated the potential utility of a coating made from chitosan modified by N-acylation with fatty acid to preserve post-harvest papaya quality. Peppermint essential oil (EO) was added to the chitosan-based coatings as an antifungal agent. A formulation which contained a high concentration of peppermint EO (1.0%) without chitosan apparently damaged the peel, resulting in higher peel discolouration, less colour development and lower marketability. The most promising treatment was unmodified chitosan (1%) in combination with peppermint EO (0.2%). The fruits treated with this formulation showed

Volatile changes in Hawaiian noni fruit, Morinda citrifolia L., during ripening and fermentation: Volatile changes in Hawaiian noni fruit during ripening and fermentation

BACKGROUND Noni fruit (Morinda citrifolia L., Rubiaceae) has been used in traditional medicine throughout the tropics and subtropics and is now attracting interest in western medicine. Fermented noni juice is of particular interest for its promising antitumor activity. The present study collected and analyzed volatiles released at nine time intervals by noni fruit during ripening and fermentation using headspace autosampling coupled to gas chromatography-mass spectrometry. RESULTS Twenty-three noni volatiles were identified and relatively quantified. In addition to volatiles previously identified in noni, four novel volatile 3-methyl-2/3-butenyl esters were identified via the synthesis of reference compounds. Principle component analysis (PCA) and canonical discriminant analysis (CDA) were used to facilitate multidimensional pattern recognition. PCA showed that ripening noni fruit cluster into three groups, pre-ripe, fully ripe (translucent) and fermented, based on released volatiles. CDA could 83.8% correctly classify noni samples when all ripeness stages were analyzed and 100% when samples were classified into the three PCA groupings. CONCLUSION The results of the present study confirm the identities of 3-methyl-2/3-butenyl esters, both novel and previously identified, through the synthesis of reference compounds. These esters constitute a large percentage of the volatiles released by fully ripe and fermented noni and likely produced from the decomposition of noniosides, a group of unique glucosides present in the fruit.

Determination of the absolute configuration of chaetoviridins and other bioactive azaphilones from the endophytic fungus Chaetomium globosum.

Chemical investigation of an endophytic fungus Chaetomium globosum isolated from leaves of Wikstroemia uva-ursi led to the isolation of two new azaphilones, chaetoviridins J and K (1 and 3), along with five known derivatives (2 and 4-7). The structures of azaphilones were determined by NMR, X-ray diffraction, Moshers method, and CD analysis. The isolated compounds were evaluated for their cancer chemopreventive-potential based on their abilities to inhibit tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB). Compounds 4, 5, 7, and synthetic 8 and 9 inhibit nitric oxide (NO) production with IC50 values in the range of 0.3-5.8 μM. Compounds 4, 5, and 9 also displayed (TNF-α)-induced NF-κB activity with IC50 values in the range of 0.9-5.1 μM.