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Papers by Jan Narciso

Proceedings of the Florida State Horticultural Society, Dec 1, 2007

ADDITIONAL INDEX WORDS. moist chamber, experimental method, evaluation of antimicrobials There ar... more ADDITIONAL INDEX WORDS. moist chamber, experimental method, evaluation of antimicrobials There are ever increasing numbers of antimicrobial compounds available as treatments to extend shelf-life of minimally processed fruits and to control postharvest decay on fresh market fruit. Most microorganisms are controlled by specifi c compounds or groups of compounds; to ascertain which compounds would be useful on a specifi c organism requires screening many different antimicrobials. A small, moist chamber system was developed that allows for rapid evaluation of many compounds and their effi ciencies to control a specifi c organism or group of organisms.

Canker is a devastating disease for the citrus fresh fruit market and is caused by the pathogenic... more Canker is a devastating disease for the citrus fresh fruit market and is caused by the pathogenic bacterium Xanthomonas citri sub sp. citri (Xcc). Infection occurs by bacterial penetration through physical damage of leaves, peel, and stems, and also by bacterial entry through the stomates of these photosynthetic tissues. The chemical responses to Xcc infection and subsequent canker formation were characterized by high performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) and fluorescence spectroscopy. Analyses of leaf cankers of ‘Marsh’ grapefruit ( Citrus paradisi Macf.) and ‘Hamlin’ sweet orange ( C. sinensis Linn.) showed stimulated production of the structurally related coumarins, umbelliferone, scopoletin, and scoparone. The production of other unidentified coumarins in citrus cankers was also documented. These compounds have been observed under other plant stress conditions in citrus, and it is surmised that these compounds occur as plant defense compounds in response to the resulting tissue damage following Xcc infection.

Proceedings of the Florida State Horticultural Society, Dec 1, 2010

To assist in developing best postharvest practices for handling fruit with canker lesions, a surv... more To assist in developing best postharvest practices for handling fruit with canker lesions, a survey was distributed in summers of 2008 and 2009 to better understand current practices. Approximately 60% of the surveys were returned each year, representing about 55% of total fresh fruit shipments. As expected, the percentage of fruit received from blocks certified canker free declined from 2008 to 2009 as canker spread within the state. Sodium o-phenylphenate was the fruit disinfestation sanitizer most used by 52% of the packers to decontaminate fruit in 2008, but its use declined to 47% in 2009. Use of peroxyacetic acid increased from 21% to 33% over the same period, while chlorine use dropped from 27% to 20%. Most (~50%) of the sanitizers were applied as the fruit were first wetted, but managers were switching more to applying as the fruit were washed or afterwards. For both years, an average of 22 human graders were stationed at different points on the packingline to evaluate each load, with most (83%) increasing to 27 graders when fruit was known to come from a block with canker infection. All but one respondent reported that electronic graders were not useful for removing fruit with canker symptoms. In 2009, packers estimated that 34% of the citrus crop normally packed for the European Union market was disqualified because of canker and that 12% of the product packed for the domestic or Japanese markets was either disqualified, or contained sufficient canker infection to make unprofitable to pack for the fresh market.

Proceedings of the Florida State Horticultural Society, May 3, 2017

Horttechnology, 2005

A comparison of sanitizers for fresh-cut mango (Mangifera indica cv. Keitt) was made. Mangos were... more A comparison of sanitizers for fresh-cut mango (Mangifera indica cv. Keitt) was made. Mangos were obtained from a farm in Homestead, Fla., and stored at 15 °C until processed. Before cutting, fruit were dipped in solutions of either sodium hypochlorite (NaOCl) (200 ppm) or peroxyacetic acid (100 ppm). The cut pieces were dipped in acidifi ed sodium chlorite (NaClO 2) (200 ppm, pH 2.6) or dilute peroxyacetic acid (50 ppm) for 30 seconds. Resulting cut slices were placed in polystyrene clamshell food containers and stored at 5 °C for 21 days. Samples in the clamshells were tested for changes in microbial stability and for quality parameters every 7 days. Results showed that even though the fruit slices were sanitized after cutting, cut fruit microbial populations were related to the method of whole fruit sanitation. After 15-21 days in storage at 5 °C, cut slices from whole fruit sanitized with peroxyacetic acid that were subsequently treated with dilute peroxyacetic acid or acidifi ed NaClO 2 had less contamination [<1 colony-forming unit (cfu) per gram] than samples cut from whole fruit sanitized with NaOCl (<1000 to 3700 cfu/g). These data demonstrate that the method of whole fruit sanitation plays a role in determining the cleanliness of the cut fruit. These sanitizer systems (peroxyacetic acid on whole fruit followed by peroxyacetic acid or acidifi ed NaClO 2 on cut slices) effectively reduced microbial growth and kept microbial counts low on cut fruit surfaces for 21 days when compared to cut fruit slices from NaOCl-treated whole fruit.

Mycologia, Nov 1, 1975

The study of volatile fungal metabolites has received increasing attention in recent years and in... more The study of volatile fungal metabolites has received increasing attention in recent years and in his Presidential Address to the British Mycological Society, Hutchinson (1971) summarized the progress made to date. Hutchinson (1971) also attempted to assay the functional significance of volatile compounds produced by fungi. This aspect, however, has been more frustrating than the chemical identification of volatile fungal metabolites. Our laboratory group has been interested in the odors produced by fungi and a number of interesting chemicals have been isolated and identified (Collins and Halim, 1970, 1971, 1972), and techniques followed in these investigations were utilized in the present study. Recently our attention has been directed at species of the genus Penicilliuu. Many species of Penicillium produce characteristic odors, and according to Raper and Thom (1949) they are generally referred to as "musty" or "moldy." These same authors also suggest that odors may have some limited taxonomic value in a number of the Penicillia. For instance, among the Fasiculata, wherever odors are encountered they are generally called "moldy." In some instances, these odors, as we can attest from our own experience, are very intense, e.g., cultures of Penicillium claviforme Bain. In the biverticillately symmetrical forms placed within the P. purpurogenum series, fragrant odors are generally found; while within the Monoverticillata in the P. decumibens series, P. decumbens Thom is described as having a distinctive odor suggestive of soap perfume (Raper and Thom, 1949). This report is concerned

Phytopathology, Feb 1, 2020

Citrus canker (CC), caused by the bacterial pathogen Xanthomonas citri subsp. citri, impacts citr... more Citrus canker (CC), caused by the bacterial pathogen Xanthomonas citri subsp. citri, impacts citrus production in many areas of the world by reducing yields, degrading tree health, and severely blemishing the outer peels of fresh fruit. The relative susceptibility to CC among different species of Citrus varies from the highly susceptible lime (Citrus × aurantifolia), sweet orange (C. × sinensis), and grapefruit (C. × paradisi) to the much less susceptible calamondin (C. × microcarpa) and kumquat (C. japonica). This investigation compares the responses to infection with X. citri subsp. citri of these five genotypes with respect to phenylpropanoid compound profiles and relative increases or decreases of specific compounds postinoculation. In response to X. citri subsp. citri infection, all hosts possessed increased concentrations of phenylpropanoids in leaf tissue, whereas the similarly treated nonhost orange jessamine (Murraya paniculata) did not. Several of the tested genotypes exhibited notably increased production of fluorescent phenylpropanoids, including umbelliferone, herniarin, auraptene, scoparone, and others. The profiles of these compounds and their levels of production varied among the tested species yet all investigated Citrus genotypes exhibited increased concentrations of phenylpropanoids regardless of their degree of susceptibility to X. citri subsp. citri. Kumquat and calamondin, the tested genotypes least susceptible to X. citri subsp. citri, also exhibited the highest levels of the dihydrochalcone 39,59-di-C-glucosyl phloretin, the aglycone portion of which, phloretin, is a known antibiotic, although levels of this compound were not affected by inoculation with X. citri subsp. citri.

Letters in Applied Microbiology, May 1, 2009

It is often difficult to extrapolate information from a Petri dish and apply it to commercial app... more It is often difficult to extrapolate information from a Petri dish and apply it to commercial applications as with antimicrobial assays. Often large volumes of commodities are used for a virtually untested protocol and result in an unnecessary expenditure of time and materials. An intermediate method, where experimental compounds could be tested directly on a specific commodity without expending large quantities of either sample or compound, would be practical and economical. A method was developed that employs the use of a small experimental chamber in which pieces of natural materials (e.g. fruit) can be tested with antimicrobial compounds. This method uses a type of autoclavable incubation chamber with a filter paper base, hydrating sponge pieces and a sterile glass sample platform. The chamber offers a sterile, controlled environment and can be manipulated to serve a number of studies. The chamber results are more analogous to what happens on whole fruit than the Petri dish. This method is presently used to screen for antimicrobial compounds and treatments needed to control serious economic pests compromising Florida's agriculture.

Journal of Food Safety, Nov 1, 2001

Contamination of refrigerated juice products in gable-top cartons can occur by filamentous fungi ... more Contamination of refrigerated juice products in gable-top cartons can occur by filamentous fungi that are present in the paperboard. A method was developed to assay the mycoflora of paperboard carton material used in beverage packaging. This method involved direct plating on an agar surface of 1 cm 2 carton pieces rather than disintegration of carton material in a blender prior to plating. When compared to the standard disintegration method traditionally used for monitoring contamination of paperboard, the new method is less cumbersome, more efficient, and reduces opportunities for contamination. The number of colonies produced by the direct plating method was greater than or equal to the modified standard disintegration method. Direct plating also resulted in a larger number of different genera isolated. Une contamination de jus de fruits refrigeres peut se produire par des champignons filamenteux presents dans le carton d'emballage. Dans cette etude, une methode de dosage de la microflore du materiau cartonne utilise dans l'emballage des boissons est evaluee. Cette methode comprend un ensemencement direct sur une surface d'agar de morceaux de carton de 1cm 2 preferable a la desagregation du materiau dans un mixer avant ensemencement. Comparee a la methode traditionnelle de desagregation, cette nouvelle methode est plus commode, plus efficace et reduit les risques de contamination. Le nombre de colonies detectees par ensemencement direct est superieur ou egal a celles obtenues par la methode classique et les genres isoles sont plus nombreux.

Proceedings of the Florida State Horticultural Society, 2013

EDIS, 1969

Contamination of refrigerated juice products in gable-top cartons may occur by filamentous fungi ... more Contamination of refrigerated juice products in gable-top cartons may occur by filamentous fungi that are present in the paperboard. The method presently used by the food industry to assess the amount of fungal contamination in the paperboard carton material is cumbersome and inefficient (1). To ascertain what types of fungal organisms are present in paperboard containers used to hold foods and beverages with an extended shelf-life, a direct-plating method was developed which is efficient, accurate and utilizes little in the way of time and resources (2). This method incorporates routinely used mycological techniques, including medium and incubation procedures which insure that conditions for fungal growth are optimal and results will be reliable. This document is FSHN04-07, one of a series of the Food Science and Human Nutrition Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: August 2004. http...

Ficus whitefly, Singhiella simplex (Singh), is a significant pest of ficus plants, especially wee... more Ficus whitefly, Singhiella simplex (Singh), is a significant pest of ficus plants, especially weeping fig, Ficus benjamina L. Ficus whitefly is a relatively new exotic pest established in several counties in Florida since 2007. The pest can cause complete ficus plant defoliation when left uncontrolled. WashGard is a plant based wax product. The main ingredient in WashGard, carnauba wax, has been widely applied as a polish, food preservative, and to reduce sunburn in apples. But in recent years it has been used as an adjuvant to increase the adherence of copper sprays to citrus tree leaves. The adjuvant prolongs the time that copper residue remains on the leaves thereby improving the management of citrus canker disease which is caused by the bacterium Xanthomonas axonopodis . Studies have shown that WashGard application could reduce piercing-sucking insect feeding such as the Asian citrus psyllid, Diaphorina citri Kuwayama, the vector of citrus greening disease. In this study, we app...

Fungi metabolize polycyclic aromatic hydrocarbons by a number of detoxification processes. Preval... more Fungi metabolize polycyclic aromatic hydrocarbons by a number of detoxification processes. Prevalent fungal detoxification pathways for aromatic compounds include the formation of sulfated and glycosylated conjugates. Furanocoumarins, a class of aromatic compounds, are important for their diverse biological activities and clinical applications. The 6,7dihydroxybergamottin (DHB), 6,7-epoxybergamottin (EB), and bergamottin (BM) are three major furanocoumarins in grapefruit, and their metabolism in humans is involved in the "grapefruit/drug interactions." The metabolism by fungi of these furanocoumarins has received little research attention. In our study, the metabolism by Aspergillus niger of DHB, EB, and BM has been investigated. Aspergillus niger metabolized EB, DHB, and BM into a water-soluble sulfate conjugate possibly using etherase- and sulfotransferase-like enzyme activities. In addition, A. niger showed a specificity in metabolizing furanocoumarins, in which the fun...

Citrus canker caused by the pathogenic bacterium, Xanthomonas citrisubsp. citri (Xcc) , poses a s... more Citrus canker caused by the pathogenic bacterium, Xanthomonas citrisubsp. citri (Xcc) , poses a serious threat to citrus production in Florida, especially for the fresh fruit market. Xcccauses severe damage to fruit, stem, and leaf tissues, and although much has been learned about the complex interactions between the infecting bacteria and these citrus plant tissues, chemical responses in host trees to this infection has yet to be fully explored. To address this issue, initial investigations were made of the changes in the phytochemical compositions of canker-infected leaves of greenhousegrown grapefruit trees. These changes were monitored by HPLC-fluorescence spectroscopy, where particular attention was given to the detection of coumarins (C) and furanocoumarins (FC). Such analyses showed that physical abrasion of grapefruit leaves dramatically decreased the levels of certain Cs and FCs, and that subsequent Xccinfections triggered the production of other Cs and FCs.

AdditionAl index words. flavonoid, limonoid, alkaloid, carotenoid, ascorbic acid, total phenolic ... more AdditionAl index words. flavonoid, limonoid, alkaloid, carotenoid, ascorbic acid, total phenolic content 'Hamlin' orange juices were prepared using one of following methods: 1) freshly squeezed with a commercial food service squeezer (fresh), 2) freshly squeezed and pasteurized (fresh/pasteurized), and 3) processed with industrial extractor and pasteurized (processed). Samples were taken from the juices directly after extraction and again after 4 d of juice storage at 5 °C for analysis of flavonoids, limonoids, alkaloids, carotenoids, ascorbic acid and total phenolic content. Processed juice had higher levels of insoluble solids, but lower levels of peel oil in comparison to fresh juice regardless of pasteurization. The majority of flavonoid glycosides including hesperidin, narirutin, narirutin 4´-glucoside, 6,8-di-Cglucosyl apigenin and isosakuranetin rutinoside, which are rich in the albedo and segment membranes, occurred at the highest levels in processed juice. In contrast, the polymethoxylatedflavones associated with peel oil, such as quercetagetin hexamethyl ether, sinensetin, nobiletin, tetramethylscutellarein, heptamethoxyflavone and tangeretin occurred at the highest levels in the fresh juices. Limonoids (limonin glucoside, limonin aglycone, nomilin glucoside, nomilinic acid glucoside, and nomilin aglycone), alkaloids (feruloyl putrescine and an unknown alkaloid) and carotenoids (zeaxanthin, lutein, ß-cryptoxanthin, α-carotene and ß-carotene) occurred at higher levels in the processed juice than in the fresh juice regardless of pasteurization. The processed juice had higher total phenolic content but lower ascorbic acid content than the fresh juices. Thermal pasteurization increased the contents of the polymethoxylated flavones, but decreased the contents of carotenoids. During 4-d storage at 5 °C, 20% to 80% of hesperidin, narirutin, narirutin 4´-glucoside and isosakuranetin rutinoside precipitated in the processed juice but not the fresh juice. Mention of a trademark or proprietary product is for identification only and does not imply a guarantee or warranty of the product by the U.S. Department of Agriculture. The U.S. Department of Agriculture prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status *Corresponding author; phone:

AdditionAl index words. ClO2, timed-release, weight loss, fruit firmness Chlorine dioxide (ClO2),... more AdditionAl index words. ClO2, timed-release, weight loss, fruit firmness Chlorine dioxide (ClO2), a strong oxidizing and sanitizing agent, is used as a postharvest sanitizer for fruits and vegetables and is generally applied on a packing line using a ClO2 generator. The objective of this research was to study the physiological responses of strawberries to ClO2 when applied to the fruit using a crystalline form packaged in a “sachet” attached to a polyethylene clamshell. The ClO2 was released gradually during storage and distribution. Strawberries were packed in commercial clamshells, with or without ClO2 treatments, and stored at 1 and 5 °C for 14 d to simulate cold storage/shipping conditions and at 10 and 20 °C for 7 d to simulate refrigerated and non-refrigerated shelf conditions. The effect of ClO2 on strawberries was assessed by determining weight loss, firmness, surface color, soluble solids content (SSC), titratable acidity (TA), respiration rate, and ethylene production. Chl...

This research studied different edible coatings for quality preservation of zucchini slices desti... more This research studied different edible coatings for quality preservation of zucchini slices destined for fresh-cut consumption or for cooking. In the first experiment, antioxidants, including calcium ascorbate (CAA), cysteine (CYS) or ethanol (ET) in edible coatings made from chitosan (CHIT), chitosan + glucose (CHIT + GLUC), whey protein concentrate (WPC), soy protein isolate (SPI), carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC) and soy bean oil (SB) were tested for effects on appearance and weight loss of the zucchini slices stored at 6 °C and 20 °C. In a second experiment, the best coatings from the initial experiment (CHIT, HPMC, SPI, and SB including CAA + ET as antioxidants) were tested for effects on color of fresh-cut zucchini slices stored at two different temperatures (6 °C and 12 °C). The effectiveness of CHIT, SPI, with or without antioxidants, was observed best and HPMC and SB were eliminated from further testing. The use of antioxidants contributed...

Phytopathology®, 2019