Journal of the American Society for Horticultural Science. American Society for Horticultural Science
The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, ... more The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, and Workshops). The Poster abstract numbers correspond to the Poster Board number at which the Poster will be presented.
Apple fruit (Malus domestica Barkh, ‘Golden Delicious’) is a well known nutritious fruit and its ... more Apple fruit (Malus domestica Barkh, ‘Golden Delicious’) is a well known nutritious fruit and its consumption is highly recommended for a healthy diet. Recent findings reported that apples consumption can cause allergic reactions to some people, especially northern and central European populations, because of the presence of allergens. Allergens are the unique proteins present in plants and many fruit that may cause an overreaction of human immune system. Investigations on apple fruit allergens include allergenicity testing, cultivar comparisons and cultural practices have been conducted by some research groups. Our own proteomic studies demonstrated the presence of many allergen isomers in apples that are also ripening dependent and under the influence of ethylene. In this study, apple fruit harvested at the pre-climacteric stage were allowed to naturally ripen or ripening was stimulated by treatment with 36 µL/L ethylene for 24 h. Postharvest physiological indices including respira...
Banana (Musa AAA group) is one of the most consumed fruit in the world due to its eating quality ... more Banana (Musa AAA group) is one of the most consumed fruit in the world due to its eating quality and nutritional value. Banana fruit quality is dependent on color, flavour (aroma and taste), sweetness and nutritional composition. It has been reported that chlorophyll breakdown and color formation in banana is inhibited by ripening temperatures above 24°C. At this temperature thylakoid membranes are retained resulting in reduced chlorophyll degradation, but faster senescence. In this study, green (immature), untreated banana fruit were obtained from a local whole-sale market and half of the fruit were subjected to ethylene treatment at 10µl/L for 24 hours. After ethylene treatment, both treated and untreated fruit were stored at 20 or 30°C for 7 days. During this period, fruit were sampled after 0, 1, 4 and 7 days of storage and evaluated for color, chlorophyll fluorescence, volatile production and expression of genes related to volatile biosynthesis. Storage at 30°C reduced yellow c...
Apple fruit (Malus domestica Barkh) is a well known climacteric fruit and a good model to study f... more Apple fruit (Malus domestica Barkh) is a well known climacteric fruit and a good model to study fruit ripening and senescence. Ethylene plays an important role in regulating fruit ripening and senescence and directly influences the development of the eating quality of fresh apples, including appearance, color, texture, and flavour. Two studies were conducted. In the first study, apple fruit were harvested at the pre-climacteric stage and allowed to naturally ripen or ripening was stimulated by treatment with 36 μL•L-1 ethylene for 24 h. In the second study, fruit were harvested also at pre-climacteric similar stages and treated with 1-MCP treatment (1 μL•L-1 for 24 h). Postharvest physiological indices, ethylene production and chlorophyll fluorescence were monitored up to 21 d after ethylene treatment or up to 47 d after 1-MCP treatment. Real-time qPCR was employed to investigate gene expression in relation to ethylene perception and biosynthesis at day 0, 7, 13, and 21 for ethylene...
HortScience: a publication of the American Society for Horticultural Science
After a brief description of the ''history of research'' of aroma volatiles of apple and strawber... more After a brief description of the ''history of research'' of aroma volatiles of apple and strawberry fruit, possible reasons for the reduced production of these important quality attributes by particular pre-and postharvest procedures are given. Among the possible physiological factors in association with reduced aroma volatile production, a reduced ethylene sensitivity, a decline in the rate of respiration as well as the content of adenine nucleotides and limited free fatty acids as precursors for aroma volatiles biosynthesis are proposed. A hypothesis about how this sequence of events leads to reduced volatile production is given and finally some suggestions of how to improve volatile synthesis are discussed.
Ethylene plays an important role in regulating fruit ripening and senescence and directly influen... more Ethylene plays an important role in regulating fruit ripening and senescence and directly influences the development of the eating quality of fresh apples, including appearance, color, texture, and flavor. To better understand the regulation of volatile biosynthesis during fruit ripening and to examine the influence of ethylene on expression of volatile biosynthesis genes in fruit, apples harvested at the pre-climacteric stage were allowed to either ripen naturally or ripening was stimulated by treatment with 36 μL•L-1 ethylene for 24. Postharvest physiological indices including respiration, ethylene production and chlorophyll fluorescence were monitored for 21 days. Real-time qPCR was employed to investigate gene expression in relation to ethylene perception and volatile biosynthesis at day 7, 13, and 21 after treatment. The study was repeated over two seasons. After efficiency tests for all designed primers, 20 genes proposed to be involved in volatile biosynthesis in relation to ...
Supplying the increasing demand for flavorful, high quality fresh-cut fruits and vegetables is a ... more Supplying the increasing demand for flavorful, high quality fresh-cut fruits and vegetables is a continual challenge. The complex and dynamic nature of flavor production contributes to the challenge of satisfying consumer expectations. Understanding factors that impact the flavor of fresh-cut products could lead to improved technologies to optimize flavor. In this study the effects of cutting, packaging, and storage on the flavor of ‘Gala’ and ‘Ambrosia’ apple fruit (Malus domestica Barkh.) were determined. The process of cutting fruit increased rate of respiration and release of other volatiles. Respiration of slices was 3-fold greater than that of whole apples, while headspace concentrations of acetate esters and ethanol also increased. Packaging also impacts flavor. When ‘Gala’ apple slices were packaged in solid (S) or micro-perforated (MP) film bags and held at 5C for 14 days, slices held in the MP bags had higher fruit aroma, fruity flavor, perceived sweetness and better textu...
The apple (Malus x domestica Borkh.) is one of the most popular fruit in the world and its consum... more The apple (Malus x domestica Borkh.) is one of the most popular fruit in the world and its consumption is highly recommended for a healthy diet. Polyphenolic compounds of apple fruit play an important role in physiologic functions related to human health. Different polyphenolics have varied biological activities including antioxidant activity. However, information about biological changes in polyphenol compounds during fruit ripening is still lacking. The objectives of this study were to investigate the qualitative and quantitative changes in polyphenolic compounds in apples and to evaluate the effect of 1-MCP treatment on the polyphenolic compounds during fruit ripening. To better understand fruit ripening and effect of 1-MCP on polyphenolic compounds, “Golden Delicious” apples harvested at pre-climacteric stage were allowed to naturally ripen, or ripening was inhibited by 1-MCP treatment (1.0 µL·L-1 for 16 h). Postharvest physiological indices including respiration, ethylene produ...
Proteomics is a systematic approach to study changes in proteins. It provides an essential linkag... more Proteomics is a systematic approach to study changes in proteins. It provides an essential linkage between the transcriptome and metabolome. Despite recent developments, fruit proteomics is still facing major challenges that limit in-depth study. In addition to limited protein sequences available for most fruits, high throughput, reliable and quantitative protein analysis procedure for fruit is also lacking. As a sample preparation step, OFFGEL isoelectric focussing (IEF) offers the ability to fractionate peptides or proteins prior to LC/MS analysis, which has become one of the more popular sample preparation procedures in proteomic research. In order to develop and improve the quantitative fruit proteomic research platform, we conducted a detailed investigation to exam the advantages of OFFGEL in fruit proteomic research using apple, banana and strawberry fruit. We provided technical details concerning sample preparation, trypsin digestion, OFFGEL-IEF, reversed phase nano-LC separa...
HortScience: a publication of the American Society for Horticultural Science
Trends in chlorophyll fluorescence for 'Starking Delicious', 'Golden Delicious' a... more Trends in chlorophyll fluorescence for 'Starking Delicious', 'Golden Delicious' and 'Law Rome' apple (Malus xdomestica Borkh.) fruit were examined during the harvest season, during refrigerated-air (RA) storage at 0 °C, following RA and controlled-atmosphere (CA) storage, and during a poststorage holding period at 22 °C. Fluorescence parameters of minimal fluorescence (Fo), maximal fluorescence (Fm), and quantum yield [(Fm-Fo)/Fm, otherwise denoted as Fv/Fm] were measured. During 'Starking Delicious' fruit maturation and ripening, Fv/Fm declined with time, with the rate of decline increasing after the ethylene climacteric. During RA storage, all fluorescence parameters remained constant for approximately 2 weeks, then steadily declined with time for 'Starking Delicious' fruit. Superficial scald was detected after Fv/Fm had declined from an initial value of 0.78 to ≃0.7. Fv/Fm was consistently higher for CA-stored fruits than for RA-stored frui...
Introduction Corona discharge has been reported to reduce the decay and extend the storage life o... more Introduction Corona discharge has been reported to reduce the decay and extend the storage life of fruits and vegetables. Potential mechanisms by which the corona could affect produce quality include the destruction of ethylene and volatiles, removal of airborne fungal spores, and the production of ozone, negative air ions (NAI) and other reactive species. Ozone and/or NAI have been reported to inhibit or kill pathogenic microbes and reduce decay of fresh produce (Tanimura 1997, 1998). This study evaluated the efficacy of a commercially available corona generation system on produce decay. et al., Materials and Methods An assortment of produce was or was not inoculated with various pathogens and held in two "jacketed" chambers at 10 C and 9598 % RH. Disease development was monitored for up to 3 weeks. The treatment chamber contained a FletcherFresh FE6 air purification system (FE, Hudson, PQ, Canada) equipped with a single corona generating plate made o
A targeted quantitative proteomic investigation employing the multiple reaction monitoring (MRM, ... more A targeted quantitative proteomic investigation employing the multiple reaction monitoring (MRM, SRM) technique was conducted on strawberry fruit at different development stages. We investigated 24 proteins and isoforms from 32 peptides with 111 peptide transitions, which may be involved in the volatile aroma biosynthesis pathway. The normalized protein abundance was significantly changed in coincidence with increased volatile production and advanced fruit maturities. Among them, alcohol acyltransferase (AAT), quinone oxidoreductase (QR), malonyl Co-A decarboxylase, (MLYCD), pyruvate decarboxylase (PDC), acetyl Co-A carboxylase (ACCase), and acyl Co-A synthetase (ACAs) were increased significantly. Several alcohol dehydrogenases (ADHs), and 3-oxoacyl-ACP synthase were significantly decreased. Furthermore, the expression of seven genes related to strawberry volatile production were also investigated using real-time qPCR. Among the tested genes, QR, AAT, ACCase, OMT, PDC and ADH showed increased up-regulation during fruit ripening, while 3-isopropylmalate dehydrogenase (IMD) decreased. Strong correlation between quantitative proteomic data and gene expression suggested that AAT, QR, ACCase, and PDC played critical roles in volatile biosynthesis of strawberry during fruit ripening. Poor correlation between protein abundance and gene expression of ADH was found. Despite intensive research on molecular mechanisms contributing to flavor biosynthesis of strawberry fruit, the complete pathway and regulation have not been fully understood. Our targeted proteomic approach employing LC-MS analysis and MRM technique to quantify proteins in relation to flavor biosynthesis and regulation in strawberry during fruit ripening is novel. Our data revealed the candidate proteins and their quantitative changes in relation to flavor biosynthesis and regulation at different ripeness. In order to provide the biological links among metabolites, gene expression and proteins, quantitative proteomic data is also compared with volatile analysis and gene expression to reveal possible control levels of this important quality trait. Our results demonstrate multiple pathways controlling flavor biosynthesis in strawberry fruit and provide critical insights into the regulation of flavor biosynthesis pathway of any fruit/plant species.
Lactic acid bacteria (LAB) produce a variety of compounds with antimicrobial activity including a... more Lactic acid bacteria (LAB) produce a variety of compounds with antimicrobial activity including acids, alcohols, diacetyl, hydrogen peroxide and bacteriocins. Bacteriocins have attracted many interests due to their potential use as safe and natural food preservatives and antimicrobials for control of spoilage and pathogenic microorganisms. The objective of this study were to isolate and characterize bacteriocinogenic LAB strains, test their antimicrobial effects on common spoilage and pathogenic microorganisms and further investigate selected LAB for use as bio-preservatives on fresh-cut vegetables. Fourteen different horticultural commodities and 11 different dairy products were used to isolate LAB. The antimicrobial properties of cell-free supernatants from LAB isolates were determined using the agar diffusion bioassay with Lactobacillus sakei and Listeria innocua as indicator organisms. The presence of bacteriocins was indicated by inhibition zones following the neutralization of...
Volatile emissions and chlorophyll fluorescence were investigated as potential signals of heat in... more Volatile emissions and chlorophyll fluorescence were investigated as potential signals of heat injury for apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] fruit. 'McIntosh', 'Cortland', 'Jonagold', and 'Northern Spy' apples were exposed to 46 °C for 0, 4, 8, or 12 hours (heat treatments). Following treatments, fruit were kept at 20 °C and evaluated after 1, 2, 4, or 7 days. Heat treatments induced volatile production including ethanol and ethyl acetate. The 8 and 12 hours heat treatments increased ethanol and ethyl acetate production in all four cultivars by as much as 170-and 11-fold, respectively, 1 day after treatments. Heat treatments also reduced ethylene production and chlorophyll fluorescence. Heat for 12 hours caused serious flesh browning. Among the cultivars investigated, 'Northern Spy' and 'McIntosh' were most susceptible to heat stress based on the degree of flesh browning. Correlation coefficients of heat...
Journal of the American Society for Horticultural Science. American Society for Horticultural Science
The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, ... more The Abstracts that follow are arranged by type of session (Posters first, then Orals, Colloquia, and Workshops). The Poster abstract numbers correspond to the Poster Board number at which the Poster will be presented.
Apple fruit (Malus domestica Barkh, ‘Golden Delicious’) is a well known nutritious fruit and its ... more Apple fruit (Malus domestica Barkh, ‘Golden Delicious’) is a well known nutritious fruit and its consumption is highly recommended for a healthy diet. Recent findings reported that apples consumption can cause allergic reactions to some people, especially northern and central European populations, because of the presence of allergens. Allergens are the unique proteins present in plants and many fruit that may cause an overreaction of human immune system. Investigations on apple fruit allergens include allergenicity testing, cultivar comparisons and cultural practices have been conducted by some research groups. Our own proteomic studies demonstrated the presence of many allergen isomers in apples that are also ripening dependent and under the influence of ethylene. In this study, apple fruit harvested at the pre-climacteric stage were allowed to naturally ripen or ripening was stimulated by treatment with 36 µL/L ethylene for 24 h. Postharvest physiological indices including respira...
Banana (Musa AAA group) is one of the most consumed fruit in the world due to its eating quality ... more Banana (Musa AAA group) is one of the most consumed fruit in the world due to its eating quality and nutritional value. Banana fruit quality is dependent on color, flavour (aroma and taste), sweetness and nutritional composition. It has been reported that chlorophyll breakdown and color formation in banana is inhibited by ripening temperatures above 24°C. At this temperature thylakoid membranes are retained resulting in reduced chlorophyll degradation, but faster senescence. In this study, green (immature), untreated banana fruit were obtained from a local whole-sale market and half of the fruit were subjected to ethylene treatment at 10µl/L for 24 hours. After ethylene treatment, both treated and untreated fruit were stored at 20 or 30°C for 7 days. During this period, fruit were sampled after 0, 1, 4 and 7 days of storage and evaluated for color, chlorophyll fluorescence, volatile production and expression of genes related to volatile biosynthesis. Storage at 30°C reduced yellow c...
Apple fruit (Malus domestica Barkh) is a well known climacteric fruit and a good model to study f... more Apple fruit (Malus domestica Barkh) is a well known climacteric fruit and a good model to study fruit ripening and senescence. Ethylene plays an important role in regulating fruit ripening and senescence and directly influences the development of the eating quality of fresh apples, including appearance, color, texture, and flavour. Two studies were conducted. In the first study, apple fruit were harvested at the pre-climacteric stage and allowed to naturally ripen or ripening was stimulated by treatment with 36 μL•L-1 ethylene for 24 h. In the second study, fruit were harvested also at pre-climacteric similar stages and treated with 1-MCP treatment (1 μL•L-1 for 24 h). Postharvest physiological indices, ethylene production and chlorophyll fluorescence were monitored up to 21 d after ethylene treatment or up to 47 d after 1-MCP treatment. Real-time qPCR was employed to investigate gene expression in relation to ethylene perception and biosynthesis at day 0, 7, 13, and 21 for ethylene...
HortScience: a publication of the American Society for Horticultural Science
After a brief description of the ''history of research'' of aroma volatiles of apple and strawber... more After a brief description of the ''history of research'' of aroma volatiles of apple and strawberry fruit, possible reasons for the reduced production of these important quality attributes by particular pre-and postharvest procedures are given. Among the possible physiological factors in association with reduced aroma volatile production, a reduced ethylene sensitivity, a decline in the rate of respiration as well as the content of adenine nucleotides and limited free fatty acids as precursors for aroma volatiles biosynthesis are proposed. A hypothesis about how this sequence of events leads to reduced volatile production is given and finally some suggestions of how to improve volatile synthesis are discussed.
Ethylene plays an important role in regulating fruit ripening and senescence and directly influen... more Ethylene plays an important role in regulating fruit ripening and senescence and directly influences the development of the eating quality of fresh apples, including appearance, color, texture, and flavor. To better understand the regulation of volatile biosynthesis during fruit ripening and to examine the influence of ethylene on expression of volatile biosynthesis genes in fruit, apples harvested at the pre-climacteric stage were allowed to either ripen naturally or ripening was stimulated by treatment with 36 μL•L-1 ethylene for 24. Postharvest physiological indices including respiration, ethylene production and chlorophyll fluorescence were monitored for 21 days. Real-time qPCR was employed to investigate gene expression in relation to ethylene perception and volatile biosynthesis at day 7, 13, and 21 after treatment. The study was repeated over two seasons. After efficiency tests for all designed primers, 20 genes proposed to be involved in volatile biosynthesis in relation to ...
Supplying the increasing demand for flavorful, high quality fresh-cut fruits and vegetables is a ... more Supplying the increasing demand for flavorful, high quality fresh-cut fruits and vegetables is a continual challenge. The complex and dynamic nature of flavor production contributes to the challenge of satisfying consumer expectations. Understanding factors that impact the flavor of fresh-cut products could lead to improved technologies to optimize flavor. In this study the effects of cutting, packaging, and storage on the flavor of ‘Gala’ and ‘Ambrosia’ apple fruit (Malus domestica Barkh.) were determined. The process of cutting fruit increased rate of respiration and release of other volatiles. Respiration of slices was 3-fold greater than that of whole apples, while headspace concentrations of acetate esters and ethanol also increased. Packaging also impacts flavor. When ‘Gala’ apple slices were packaged in solid (S) or micro-perforated (MP) film bags and held at 5C for 14 days, slices held in the MP bags had higher fruit aroma, fruity flavor, perceived sweetness and better textu...
The apple (Malus x domestica Borkh.) is one of the most popular fruit in the world and its consum... more The apple (Malus x domestica Borkh.) is one of the most popular fruit in the world and its consumption is highly recommended for a healthy diet. Polyphenolic compounds of apple fruit play an important role in physiologic functions related to human health. Different polyphenolics have varied biological activities including antioxidant activity. However, information about biological changes in polyphenol compounds during fruit ripening is still lacking. The objectives of this study were to investigate the qualitative and quantitative changes in polyphenolic compounds in apples and to evaluate the effect of 1-MCP treatment on the polyphenolic compounds during fruit ripening. To better understand fruit ripening and effect of 1-MCP on polyphenolic compounds, “Golden Delicious” apples harvested at pre-climacteric stage were allowed to naturally ripen, or ripening was inhibited by 1-MCP treatment (1.0 µL·L-1 for 16 h). Postharvest physiological indices including respiration, ethylene produ...
Proteomics is a systematic approach to study changes in proteins. It provides an essential linkag... more Proteomics is a systematic approach to study changes in proteins. It provides an essential linkage between the transcriptome and metabolome. Despite recent developments, fruit proteomics is still facing major challenges that limit in-depth study. In addition to limited protein sequences available for most fruits, high throughput, reliable and quantitative protein analysis procedure for fruit is also lacking. As a sample preparation step, OFFGEL isoelectric focussing (IEF) offers the ability to fractionate peptides or proteins prior to LC/MS analysis, which has become one of the more popular sample preparation procedures in proteomic research. In order to develop and improve the quantitative fruit proteomic research platform, we conducted a detailed investigation to exam the advantages of OFFGEL in fruit proteomic research using apple, banana and strawberry fruit. We provided technical details concerning sample preparation, trypsin digestion, OFFGEL-IEF, reversed phase nano-LC separa...
HortScience: a publication of the American Society for Horticultural Science
Trends in chlorophyll fluorescence for 'Starking Delicious', 'Golden Delicious' a... more Trends in chlorophyll fluorescence for 'Starking Delicious', 'Golden Delicious' and 'Law Rome' apple (Malus xdomestica Borkh.) fruit were examined during the harvest season, during refrigerated-air (RA) storage at 0 °C, following RA and controlled-atmosphere (CA) storage, and during a poststorage holding period at 22 °C. Fluorescence parameters of minimal fluorescence (Fo), maximal fluorescence (Fm), and quantum yield [(Fm-Fo)/Fm, otherwise denoted as Fv/Fm] were measured. During 'Starking Delicious' fruit maturation and ripening, Fv/Fm declined with time, with the rate of decline increasing after the ethylene climacteric. During RA storage, all fluorescence parameters remained constant for approximately 2 weeks, then steadily declined with time for 'Starking Delicious' fruit. Superficial scald was detected after Fv/Fm had declined from an initial value of 0.78 to ≃0.7. Fv/Fm was consistently higher for CA-stored fruits than for RA-stored frui...
Introduction Corona discharge has been reported to reduce the decay and extend the storage life o... more Introduction Corona discharge has been reported to reduce the decay and extend the storage life of fruits and vegetables. Potential mechanisms by which the corona could affect produce quality include the destruction of ethylene and volatiles, removal of airborne fungal spores, and the production of ozone, negative air ions (NAI) and other reactive species. Ozone and/or NAI have been reported to inhibit or kill pathogenic microbes and reduce decay of fresh produce (Tanimura 1997, 1998). This study evaluated the efficacy of a commercially available corona generation system on produce decay. et al., Materials and Methods An assortment of produce was or was not inoculated with various pathogens and held in two "jacketed" chambers at 10 C and 9598 % RH. Disease development was monitored for up to 3 weeks. The treatment chamber contained a FletcherFresh FE6 air purification system (FE, Hudson, PQ, Canada) equipped with a single corona generating plate made o
A targeted quantitative proteomic investigation employing the multiple reaction monitoring (MRM, ... more A targeted quantitative proteomic investigation employing the multiple reaction monitoring (MRM, SRM) technique was conducted on strawberry fruit at different development stages. We investigated 24 proteins and isoforms from 32 peptides with 111 peptide transitions, which may be involved in the volatile aroma biosynthesis pathway. The normalized protein abundance was significantly changed in coincidence with increased volatile production and advanced fruit maturities. Among them, alcohol acyltransferase (AAT), quinone oxidoreductase (QR), malonyl Co-A decarboxylase, (MLYCD), pyruvate decarboxylase (PDC), acetyl Co-A carboxylase (ACCase), and acyl Co-A synthetase (ACAs) were increased significantly. Several alcohol dehydrogenases (ADHs), and 3-oxoacyl-ACP synthase were significantly decreased. Furthermore, the expression of seven genes related to strawberry volatile production were also investigated using real-time qPCR. Among the tested genes, QR, AAT, ACCase, OMT, PDC and ADH showed increased up-regulation during fruit ripening, while 3-isopropylmalate dehydrogenase (IMD) decreased. Strong correlation between quantitative proteomic data and gene expression suggested that AAT, QR, ACCase, and PDC played critical roles in volatile biosynthesis of strawberry during fruit ripening. Poor correlation between protein abundance and gene expression of ADH was found. Despite intensive research on molecular mechanisms contributing to flavor biosynthesis of strawberry fruit, the complete pathway and regulation have not been fully understood. Our targeted proteomic approach employing LC-MS analysis and MRM technique to quantify proteins in relation to flavor biosynthesis and regulation in strawberry during fruit ripening is novel. Our data revealed the candidate proteins and their quantitative changes in relation to flavor biosynthesis and regulation at different ripeness. In order to provide the biological links among metabolites, gene expression and proteins, quantitative proteomic data is also compared with volatile analysis and gene expression to reveal possible control levels of this important quality trait. Our results demonstrate multiple pathways controlling flavor biosynthesis in strawberry fruit and provide critical insights into the regulation of flavor biosynthesis pathway of any fruit/plant species.
Lactic acid bacteria (LAB) produce a variety of compounds with antimicrobial activity including a... more Lactic acid bacteria (LAB) produce a variety of compounds with antimicrobial activity including acids, alcohols, diacetyl, hydrogen peroxide and bacteriocins. Bacteriocins have attracted many interests due to their potential use as safe and natural food preservatives and antimicrobials for control of spoilage and pathogenic microorganisms. The objective of this study were to isolate and characterize bacteriocinogenic LAB strains, test their antimicrobial effects on common spoilage and pathogenic microorganisms and further investigate selected LAB for use as bio-preservatives on fresh-cut vegetables. Fourteen different horticultural commodities and 11 different dairy products were used to isolate LAB. The antimicrobial properties of cell-free supernatants from LAB isolates were determined using the agar diffusion bioassay with Lactobacillus sakei and Listeria innocua as indicator organisms. The presence of bacteriocins was indicated by inhibition zones following the neutralization of...
Volatile emissions and chlorophyll fluorescence were investigated as potential signals of heat in... more Volatile emissions and chlorophyll fluorescence were investigated as potential signals of heat injury for apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] fruit. 'McIntosh', 'Cortland', 'Jonagold', and 'Northern Spy' apples were exposed to 46 °C for 0, 4, 8, or 12 hours (heat treatments). Following treatments, fruit were kept at 20 °C and evaluated after 1, 2, 4, or 7 days. Heat treatments induced volatile production including ethanol and ethyl acetate. The 8 and 12 hours heat treatments increased ethanol and ethyl acetate production in all four cultivars by as much as 170-and 11-fold, respectively, 1 day after treatments. Heat treatments also reduced ethylene production and chlorophyll fluorescence. Heat for 12 hours caused serious flesh browning. Among the cultivars investigated, 'Northern Spy' and 'McIntosh' were most susceptible to heat stress based on the degree of flesh browning. Correlation coefficients of heat...
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Papers by Jun Song