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Jan Narciso and Anne Plotto

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 acidified sodium chlorite (NaClO2) (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 acidified NaClO2 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 acidified NaClO2 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.

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Anne Plotto and Jan A. Narciso

Organic foods are produced using agricultural practices that emphasize renewable resources and conservation of soil and water. Horticultural crops are grown and processed without synthetic fertilizers, pesticides, ingredients and processing aids. Crops or ingredients derived from genetic engineering, and use of ionizing radiation are prohibited in organic production. The challenge is to deliver produce that has the same safety, quality and shelf life as conventional products, with a limited array of tools available for sanitation and postharvest treatments. Organic operators, professionals servicing the industry, as well as researchers involved in organic production practices, should be aware of all the points in the process of storing, handling and transforming horticultural crops where accidental contamination could occur, and thus compromise organic integrity. This presentation summarizes the major points of the National Organic Program for processing and handling, and gives suggestions for postharvest research. For example, finding organic alternatives for postharvest decay control is critical to maintain food safety. Additionally, ingredients compatible for fresh cut and produce coatings must be developed for the organic market for food safety and competitiveness.

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Elizabeth Baldwin, Jan Narciso, Randy Cameron and Anne Plotto

Strawberry fruit were harvested on three different dates from the Strawberry Association plot (cv. Festival), a commercial farm (cv. Camino Real), and at the University of Florida Gulf Coast Research and Education Center (cv. Sweet Charlie), in central Florida in 2005 and 2006. Fruit were transported to the USCSPL in Winter Haven, Fla., sorted, dipped for 10 s in treatment solutions, drained and stored in commercial clam-shells at 15 to 19 °C. Percentage of decay (number of fruit with lesions) was monitored during storage. There were 10 fruit per replicate clamshell, and three to four replicates per treatment for each harvest. Treatments included three size classes of galacturonic acid (GA) oligomers with a degree of polymerization (DP) ranging from 1–13, 8–24, and 22–46 and undigested polygalacturonic acid at 0.2% in 50 mmol LiOAC, LiOAC/NaOAC, with 22% ETOH, or KOAC buffer (all buffers at pH ≈4.4), prepared by enzymatic digestion followed by differential pH and alcohol precipitation. The main pathogens found on these fruit were Rhizopus stolonifer and Botrytis cinera at 1×105 cfu/g fruit in 2005 and 5×107 in 2006. The medium range oligomers (DP 8-24) reduced decay significantly compared to buffer alone or to the lower or higher DP GA oligomers, and elicited ethylene production. Oligomers in this pectin size class have previously been reported to elicit ethylene and plant defense responses in plant tissues.

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Anna Marín, Anne Plotto, Lorena Atarés and Amparo Chiralt

Lactic acid bacteria (LAB) have been shown to prevent the growth and activity of several postharvest pathogen fungi in fruit and vegetables because of their ability to produce antimicrobial metabolites. Edible coatings (ECs) can be used as carriers of LAB and could provide an alternative natural preservation method. The effectiveness of Lactobacillus plantarum against fungal decay on grapes applied together with EC was studied. Different formulations with or without L. plantarum were considered, using pregelatinized potato starch (PS) or sodium caseinate (NaC) as main components of the coating matrices. In some of the formulations, oleic acid (OA) was added as a surfactant. The population dynamics of the bacterium and its ability to control fungal decay were studied together with the assessment of fruit quality. NaC-based formulations improved survival of L. plantarum on fruit surface after 7 days of storage in comparison with a water control. On the other hand, L. plantarum in PS-based formulation without OA reduced Botrytis incidence more than when applied in NaC formulation or in water. Coatings had little effect on berry quality (weight, color, firmness, and soluble solids content) of grapes throughout storage, although some of the coated samples maintained acidity and maturity index during storage better than others. Therefore, LAB applied in ECs could provide a viable biocontrol method for postharvest disease in grapes.

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Xiuxiu Sun, Elizabeth Baldwin, Mark Ritenour, Anne Plotto and Jinhe Bai

Warm field temperatures can often result in poor peel color of some citrus varieties, especially early in the harvest season. Under these conditions, Florida oranges, temples, tangelos, and K-Early citrus fruit are allowed to be treated with Citrus Red No.2 dye (CR2) to help produce a more acceptable peel color. Unfortunately, CR2, the commercial colorant used in Florida, has been listed as a group 2B carcinogen by the European Union (EU) and the International Agency for Research on Cancer (IARC). Although not likely dangerous at levels used on citrus, and on a part of the fruit that is not ingested, there is a negative health perception, and thus, a need for natural or food grade alternative colorants to replace CR2 for use on citrus. This research demonstrated that three out of five oil-soluble natural red/orange colorants resulted in peel colors somewhat similar to the industry standard CR2. These three (annatto extract, paprika extract, and paprika oleoresin) were selected for further in vivo studies. The stability of the natural colorants along with CR2 was evaluated by applying them on test papers and then on fresh ‘Hamlin’ oranges. All natural colorants were found to be easily oxidized and faded when applied on test papers. However, coating the colored surfaces with carnauba wax apparently inhibited oxidation and the subsequent discoloration of the surface. When applying the natural colorants to ‘Hamlin’ oranges before waxing, the treatments retained the improved color after storage in the dark at 5 °C, simulating cold storage. However, only annatto extract maintained a stable color when subsequently stored in a simulated market condition, at 23 °C exposed to 300 lx of standard fluorescent white light.

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Anne Plotto, Mina R. McDaniel and James P. Mattheis

Aroma and flavor characters of `Gala' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. `Gala'] were identified by 10 trained panelists. A vocabulary of 13 aroma descriptors and 16 flavor descriptors were used to characterize changes in controlled atmosphere (CA) and air, or regular atmosphere (RA) storage over 20 weeks. When compared with RA storage, the intensity of fruity (pear, banana, and strawberry) and floral descriptors decreased after 10 weeks in CA for whole and cut fruit aroma and flavor. During the entire storage period under CA, aroma of cut apples retained high vegetative and citrus characters but had a less intense anise aroma. Sourness and astringency were significantly higher for CA-stored apples, and sweetness was significantly lower. A musty note was perceived in whole apples stored in CA for 20 weeks. Aroma of whole fruit stored for 16 weeks in CA followed by 4 weeks in RA was higher in fruitiness, banana, floral, and anise characters when compared with apples stored 20 weeks in CA. There was no difference between fruit stored in CA followed by RA versus CA stored apples for flavor and aroma of cut fruit. Changes in descriptor ratings during storage are discussed in relation to gas chromatography and olfactometry data obtained with the Osme method.

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Anne Plotto, Mina R. McDaniel and James P. Mattheis

Changes in the odor-active volatile compounds produced by `Gala' apples [Malus ×sylvestris (L.) Mill. var. domestica (Borkh.) Mansf. `Gala'] were measured after 4, 10, and 20 weeks storage at 1 °C in regular atmosphere (RA) or controlled atmosphere (CA), and 16 weeks in CA followed by 4 weeks in RA. Aroma was evaluated using the gas chromatography-olfactometry method Osme. Production of volatile esters decreased along with corresponding fruity aromas during CA storage. Hexyl acetate, butyl acetate, and 2-methylbutyl acetate were emitted in the largest amounts and perceived with the strongest intensities from RA-stored fruit. While hexyl acetate and butyl acetate concentrations and aroma intensities decreased during CA storage, 2-methylbutyl acetate remained at the RA concentration until apples had been stored 16 weeks in CA. Perception intensities of methylbutyrate esters with apple or berrylike odors decreased less than straight chain esters in CA-stored fruit. 4-Allylanisole, ß-damascenone, and 1-octen-3-ol, as well as an unknown compound with a watermelon descriptor, were perceived more in RA-stored fruit than in CA-stored apples. Factor analysis indicated the importance of these compounds in `Gala' apples stored 4 weeks in RA. Even though these compounds do not have an apple odor, they contribute to fresh `Gala' aroma.

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Céline Jouquand, Craig Chandler, Anne Plotto and Kevin Goodner

The aim of this study was to understand the flavor components of eating quality of several strawberry (Fragaria ×ananassa Duch.) genotypes grown in Florida over two harvest seasons. Five selections and one cultivar of the University of Florida Breeding program as well as two new cultivars from Australia (Rubygem and Sugarbaby) harvested on different dates from the same grower were evaluated by sensory evaluation. Festival, the main strawberry cultivar grown in Florida, had low ratings for flavor and sweetness in January and March. Selection FL 00-51 and ‘Rubygem’ had relatively high and consistent ratings for flavor and sweetness compared with the other selections. Genotypes with low flavor ratings were always judged as “not sweet enough” by the panelists, thus linking flavor to sweetness preference. Instrumental analysis confirmed that typically these selections had low soluble solids content (SSC) and/or high titratable acidity (TA), thus explaining their lack of sweetness. Volatile compounds that varied only quantitatively did not seem to influence the flavor rating except for ‘Sugarbaby’. This cultivar contained between seven and 40 times less total ester content than the other selections and was disliked by panelists despite its high sugar content and perceived sweetness. It was perceived as having an artificial peach- or blueberry-like flavor. A principal component analysis was performed with chemical parameters (SSC, TA, and volatile content) and selections over the two harvest seasons. Chemical composition was mainly influenced by harvest date, except for FL 00-51. This selection maintained high volatile content and SSC throughout the seasons, explaining consistently high flavor ratings.

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Alan Chambers, Pamela Moon, Yuqing Fu, Juliette Choiseul, Jinhe Bai, Anne Plotto and Elizabeth Baldwin

Fragaria vesca is a diploid strawberry species that produces gourmet, aromatic fruits with only limited commercial production because of its relative obscurity. Most F. vesca research focuses on genetics and fruit aroma, but yield and fruit quality data across diploid accessions are lacking. Sixteen F. vesca accessions were grown in replicated field plots in southern Florida to measure field performance and fruit quality over multiple harvests during a single growing season. Accessions ‘Reine des Vallees’, ‘Baron Solemacher’, ‘Fragolina di Bosco’, and ‘Reugen’ all had significantly higher yield (115–140 g/plot/week) and fruit number (117–139 fruit/plot/week) compared with ‘Bowlenzauber’, ‘Attila’, ‘Ali Baba’, and ‘Pineapple Crush’ (31–57 g/plot/week and 32–60 fruit/plot/week) during peak production. Total average yield ranged from 240 g (‘Pineapple Crush’) to 1194 g (‘Baron Solemacher’) per plot of 10 plants. Fruit number and fruit yield were highly correlated (R 2 = 0.96) for all accessions, and there was no significant difference in fruit weight among accessions through the entire season. Total soluble solids ranged from 10.9 to 13.5 °Brix, and fructose, glucose, sucrose, and total sugars ranged from 15.3 to 22.1, 13.5 to 20.0, 0.1 to 2.7, and 29.7 to 42.5 mg/g, respectively, fresh weight. Acidity ranged from 1.00% to 1.18% citric acid and was not consistently significantly different among accessions over multiple harvests. Forty-two aroma compounds were putatively identified over three harvests for each accession and included mostly esters and ketones with a few alcohols, terpenes, and aldehydes. The majority of these compounds were similarly abundant over harvests and among accessions with a few exceptions, including methyl anthranilate. These results are the first in-depth study of yield and fruit quality for a large number of F. vesca accessions that could lead to increased cultivation of this species for local markets.

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Anne Plotto, Anita N. Azarenko, Mina R. McDaniel, Patrick W. Crockett and James P. Mattheis

Eating quality of `Gala' and `Fuji' apples (Malus domestica Borkh.) from multiple harvests and storage durations was assessed using an untrained consumer panel. Apples were harvested at weekly intervals for 6 weeks and stored in air. Changes due to harvest maturity and storage for overall liking (OL), sweetness, tartness, firmness, and flavor intensity were evaluated over 8 months. A multivariate factor analysis revealed multicollinearity for OL, sweetness, and flavor intensity ratings in both cultivars. These attributes had the highest loadings in the first factor, explaining 51% and 52% of the variance of `Gala' and `Fuji' data sets, respectively, and were interpreted as a quality factor. Tartness and firmness had the highest loadings in the second factor for `Gala', explaining an additional 23% of the variability and reducing that cultivar's data set to two factors. For `Fuji', however, tartness and firmness were independent and included in factors 2 and 3, respectively. Factors 2 and 3 were interpreted as maturity factors, which explained 23% and 12% of the variance. The plots of the mean factor scores provided a multivariate technique to illustrate that panelists could differentiate between the stages of maturity of apples. Canonical correlations were calculated between the sensory and instrumental data. Only firmness measurements were correlated with sensory ratings for firmness (r = 0.53 and 0.44 for `Gala' and `Fuji', respectively).