@article{lafountain_johanningsmeier_breidt_stoforos_price_2022, title={Effects of a brief blanching process on quality, safety, and shelf life of refrigerated cucumber pickles}, ISSN={["1750-3841"]}, DOI={10.1111/1750-3841.16112}, abstractNote={AbstractRefrigerated pickles are characterized by crisp, crunchy texture, opaque flesh, and fresh flavor. Typically produced without a thermal process, microbial safety relies on preventive controls, brine composition, and sufficient hold time prior to consumption. We hypothesized that brief blanching of whole cucumbers prior to pickling could provide an additional hurdle for pathogenic microbes without negatively impacting finished product quality. Blanch treatments (15, 90, or 180 s) in 80°C water were conducted in duplicate on two lots of cucumbers prior to cutting into spears, acidifying, and storing at 4°C. Enumeration of total aerobes, lactic acid bacteria, and glucose‐fermenting coliforms was conducted for fresh and blanched cucumber. Texture, color, cured appearance development, and volatile compound profiles were analyzed for fresh and blanched cucumber and corresponding pickle products during refrigerated storage. The 90 s blanch consistently achieved a minimum 2‐log reduction in cucumber microbiota and a predicted 5‐log reduction of Escherichia coli O157:H7 up to 1.1 mm into the cucumber fruit. Blanching had no impact on tissue firmness during refrigerated storage for 1 year (p > 0.098). There were no differences in flavor‐active lipid oxidation products (E,Z)‐2,6‐nonadienal and (E)‐2‐nonenal, and consumers (n = 110) were unable to differentiate between control and 90 s blanched cucumber pickles stored for 62 days. Exocarp color and mesocarp opacity were preserved by the blanching treatment, potentially extending product shelf life. This method offers processors an option for reducing the risk of microbial contamination while maintaining the quality attributes associated with refrigerated cucumber pickles.Practical ApplicationRefrigerated pickles do not undergo thermal processing, which can leave them vulnerable to microbial contamination. This study illustrates that adding a brief blanching step in refrigerated pickle processing can reduce indigenous microbiota without negatively impacting quality attributes. This blanching process could assist pickled vegetable manufacturers in providing additional safeguards for consumers while maintaining a high‐quality product.}, journal={JOURNAL OF FOOD SCIENCE}, author={LaFountain, Lisa J. and Johanningsmeier, Suzanne D. and Breidt, Frederick, Jr. and Stoforos, George N. and Price, Robert E.}, year={2022}, month={Mar} }
 @article{perez-diaz_johanningsmeier_anekella_pagan-medina_mendez-sandoval_arellano_price_daughtry_borges_bream_et al._2021, title={Genotypic and phenotypic diversity among Lactobacillus plantarum and Lactobacillus pentosus isolated from industrial scale cucumber fermentations}, volume={94}, ISSN={["1095-9998"]}, DOI={10.1016/j.fm.2020.103652}, abstractNote={The Lactobacillus plantarum and Lactobacillus pentosus genotypes existing in industrial-scale cucumber fermentations were defined using rep-PCR-(GTG)5. The ability of each genotype to ferment cucumbers under various conditions was evaluated. Rep-PCR-(GTG)5 was the technique capable of illustrating the most intraspecies discrimination compared to the sequencing of housekeeping genes (recA, dnaK, pheS and rpoA), MLST and RAPD with primers LP1, OPL5, M14 and COC. Ten genotypic clusters were defined for the 199 L. pentosus tested and three for the 17 L. plantarum clones. The ability of the 216 clones genotyped and 37 additional cucumber fermentation isolates, of the same species, to rapidly decrease the pH of cucumber juice medium under various combinations of sodium chloride (0 or 6%), initial pH (4.0 or 5.2) and temperatures (15 or 30 °C) was determined using a fractional factorial screening design. A reduced fermentation ability was observed for the L. plantarum strains as compared to L. pentosus, except for clone 3.2.8, which had a ropy phenotype and aligned to genotypic cluster A. L. pentosus strains belonging to three genotypic clusters (B, D and J) were more efficient in cucumber juice fermentation as compared to most L. plantarum strains. This research identified three genetically diverse L. pentosus strains and one L. plantarum as candidates for starter cultures for commercial cucumber fermentations.}, journal={FOOD MICROBIOLOGY}, author={Perez-Diaz, Ilenys M. and Johanningsmeier, Suzanne D. and Anekella, Kartheek and Pagan-Medina, Christian G. and Mendez-Sandoval, Lesley and Arellano, Consuelo and Price, Robert and Daughtry, Katheryne V and Borges, Michelle and Bream, Chloe and et al.}, year={2021}, month={Apr} }
 @article{price_longtin_conley-payton_osborne_johanningsmeier_bitzer_breidt_2020, title={Modeling buffer capacity and pH in acid and acidified foods}, volume={85}, ISSN={["1750-3841"]}, DOI={10.1111/1750-3841.15091}, abstractNote={AbstractStandard ionic equilibria equations may be used for calculating pH of weak acid and base solutions. These calculations are difficult or impossible to solve analytically for foods that include many unknown buffering components, making pH prediction in these systems impractical. We combined buffer capacity (BC) models with a pH prediction algorithm to allow pH prediction in complex food matrices from BC data. Numerical models were developed using Matlab software to estimate the pH and buffering components for mixtures of weak acid and base solutions. The pH model was validated with laboratory solutions of acetic or citric acids with ammonia, in combinations with varying salts using Latin hypercube designs. Linear regressions of observed versus predicted pH values based on the concentration and pK values of the solution components resulted in estimated slopes between 0.96 and 1.01 with and without added salts. BC models were generated from titration curves for 0.6 M acetic acid or 12.4 mM citric acid resulting in acid concentration and pK estimates. Predicted pH values from these estimates were within 0.11 pH units of the measured pH. Acetic acid concentration measurements based on the model were within 6% accuracy compared to high‐performance liquid chromatography measurements for concentrations less than 400 mM, although they were underestimated above that. The models may have application for use in determining the BC of food ingredients with unknown buffering components. Predicting pH changes for food ingredients using these models may be useful for regulatory purposes with acid or acidified foods and for product development.Practical ApplicationBuffer capacity models may benefit regulatory agencies and manufacturers of acid and acidified foods to determine pH stability (below pH 4.6) and how low‐acid food ingredients may affect the safety of these foods. Predicting pH for solutions with known or unknown buffering components was based on titration data and models that use only monoprotic weak acids and bases. These models may be useful for product development and food safety by estimating pH and buffering capacity.}, number={4}, journal={JOURNAL OF FOOD SCIENCE}, author={Price, Robert E. and Longtin, Madyson and Conley-Payton, Summer and Osborne, Jason A. and Johanningsmeier, Suzanne D. and Bitzer, Donald and Breidt, Fred}, year={2020}, month={Apr}, pages={918–925} }
 @article{longtin_price_mishra_breidt_2020, title={Modeling the buffer capacity of ingredients in salad dressing products}, volume={85}, ISSN={["1750-3841"]}, DOI={10.1111/1750-3841.15018}, abstractNote={AbstractThe pH of most acid food products depends on undefined and complex buffering of ingredients but is critically important for regulatory purposes and food safety. Our objective was to define the buffer capacity (BC) of ingredients in salad dressing products. Ingredients of salad dressings were titrated individually and in combination using concentrations typical of dressing products. Titration curves from pH 2 to 12 were generated with sodium hydroxide and hydrochloric acid, which were then used to generate BC curves. A matrix of concentration and pK values for a series of monoprotic buffers approximated the pH of each ingredient. Some buffer series required anion or cation corrections for accurate pH prediction, possibly due to the presence of salts of acid or bases. Most buffers had BC values less than 10‐fold the BC of acetic acid (0.25 β) typically in dressing formulations and had little influence on the final product pH of the dressings tested. Unexpectedly, we found that sugars in dressing formulations, including sucrose or corn syrup, exhibited buffering at pH values greater than 11 (0.035 β and 0.059 β, respectively), which was likely due to weakly acidic hydroxyl groups on the sugar molecules. However, the concentration and pK for buffers above pH 11 or below pH 2 were difficult to quantify due to the BC of water. The BC data may help to quantify the effects of salad dressing ingredients on the final product pH and benefit regulatory agencies and manufacturers in assessing product pH and safety.Practical ApplicationBuffer capacity data for salad dressing ingredients may help determine the influence ingredient addition will have on the final pH of a salad dressing product. The addition of low acid ingredients with little or no buffering may not significantly alter pH. The modeling method may be useful for regulatory purposes to estimate the effects of low acid ingredients on pH changes for food safety and may also be useful for product development of acid and acidified foods.}, number={4}, journal={JOURNAL OF FOOD SCIENCE}, author={Longtin, Madyson and Price, Robert E. and Mishra, Ritu and Breidt, Fred}, year={2020}, month={Apr}, pages={910–917} }
 @article{mcmurtrie_johanningsmeier_breidt_price_2019, title={Effect of Brine Acidification on Fermentation Microbiota, Chemistry, and Texture Quality of Cucumbers Fermented in Calcium or Sodium Chloride Brines}, volume={84}, ISSN={["1750-3841"]}, DOI={10.1111/1750-3841.14600}, abstractNote={AbstractCommercial fermentation for bulk preservation of cucumbers relies on natural microbiota and approximately 1 M sodium chloride (NaCl) brines, resulting in large volumes of high‐salt wastewater. An alternative process utilizing 0.1 M calcium chloride (CaCl2) as the only salt was developed to eliminate NaCl from fermentation brines for reduced environmental impact. This study determined the effect of brine acidification on the fermentation microbiota and texture quality of cucumbers fermented in CaCl2 brines. Cucumber fermentations were conducted in sealed glass jars for six independent lots of cucumbers in a randomized complete block design with a full‐factorial treatment structure for brine acidification (acetic acid, hydrochloric acid, or nonacidified) and brining salt (1 M NaCl or 0.1 M CaCl2). Enterobacteriaceae spp. survived longer and were >1 log colony forming units/mL higher in fermenting cucumbers than in brines. Addition of 25 mM acetic acid to fermentation brines (but not the addition of hydrochloric acid at the same pH) reduced Enterobacteriaceae spp. in brines and cucumbers (P < 0.002) during the initiation of fermentation for both brining salts. However, acidification had no effect on texture quality of fermented cucumbers (P = 0.8235). Despite differences in early fermentation microbiota, fermentation of cucumbers in calcium chloride brines under controlled conditions, with or without acidification, resulted in high retention of tissue firmness. These results differ from fermentations in a commercial setting initiated in brines of neutral pH, indicating that production variables, such as air exposure, interact with brining in CaCl2 to negatively affect the texture quality of fermented cucumbers.Practical ApplicationThis study examined the effects of initial brine acidification on the course of lactic acid fermentation and resulting texture quality of cucumbers fermented in calcium or sodium salt brines. Fermentation brines containing acetic acid (the acid in vinegar) reduced the pH of the cucumber and the soil‐associated Enterobacteriaceae spp. most rapidly, and favored the conversion of sugars to lactic acid. Interestingly, the texture quality was not affected by brine acidification, and all cucumbers fermented in calcium brines in the absence of air retained their firmness during fermentation and bulk storage.}, number={5}, journal={JOURNAL OF FOOD SCIENCE}, author={McMurtrie, Erin K. and Johanningsmeier, Suzanne D. and Breidt, Fred, Jr. and Price, Robert E.}, year={2019}, month={May}, pages={1129–1137} }
 @article{dupree_price_burgess_andress_breidt_2019, title={Effects of Sodium Chloride or Calcium Chloride Concentration on the Growth and Survival of Escherichia coli O157:H7 in Model Vegetable Fermentations}, volume={82}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X.JFP-18-468}, abstractNote={HIGHLIGHTS
NaCl and CaCl2 concentrations affected LAB and STEC strains differently. Growth rates at 6% NaCl were reduced for STEC more than LAB in vegetable broth. Extent of growth was reduced for STEC versus LAB for most vegetable fermentations. Death rates were minimally affected by salt type or concentration with lactic acid. Correlations between salt and STEC die-off were inconsistent for fermentation.}, number={4}, journal={JOURNAL OF FOOD PROTECTION}, author={Dupree, Dorothy E. and Price, Robert E. and Burgess, Breanne A. and Andress, Elizabeth L. and Breidt, Frederick}, year={2019}, month={Apr}, pages={570–578} }
 @article{jones_price_breidt_2020, title={Escherichia coli O157:H7 Stationary-Phase Acid Resistance and Assessment of Survival in a Model Vegetable Fermentation System}, volume={83}, ISSN={["1944-9097"]}, DOI={10.4315/JFP-19-463}, abstractNote={Escherichia coli O157:H7 (STEC) acid resistance may aid the pathogenâs ability to cross the human gastric barrier and makes it an organism of concern in acidic foods. Our objective was to determine how STEC acid resistance may correlate with survival during vegetable fermentations. Seven E. coli O157:H7 strains were screened to assess acid resistance in simulated stomach-acid at pH 2. The strains were separated into two groups that differed in acid resistance (p < 0.05), with three being acid sensitive and four acid resistant. The growth rates of these strains were measured in a Luria broth at pH values from 4.2 to 6.8. Two strains having similar growth kinetics, B201 (acid sensitive) and B241 (acid resistant), were selected for further analysis. B201 was found to be missing (compared to B241) two glutamic acid decarboxylase regulatory genes required for acid resistance, gadE and gadX. These strains were challenged in lactic acid (100 mM) solutions including cucumber juice (CJ) media at pH 3.3. As expected, B201 was more acid sensitive than B241, and a filtered fermented CJ was more inhibitory than similarly acidified CJ. In competitive growth studies with Lactobacillus plantarum LA445 in CJ, B201 or B241 grew from approximately 104 CFU/mL to 108 CFU/mL within 24 hours but the STEC strains were below the limit of detection by 48 hours. In all fermentations L. plantarum reached 108 CFU/mL by 48 hours. However, in three out of four independent fermentation experiments, strain B201 survived longer than B241. This was possibly due to buffering in B241-LA445 fermentation brines which had increased lactic acid for a given pH compared to B201-LA445. These data indicate that stationary phase acid resistance may not accurately predict STEC survival during vegetable fermentations.}, number={5}, journal={JOURNAL OF FOOD PROTECTION}, author={Jones, Clara M. and Price, Robert E. and Breidt, Fred}, year={2020}, month={May}, pages={745–753} }
 @article{ding_johanningsmeier_price_reynolds_truong_payton_breidt_2018, title={Evaluation of nitrate and nitrite contents in pickled fruit and vegetable products}, volume={90}, ISSN={["1873-7129"]}, DOI={10.1016/j.foodcont.2018.03.005}, abstractNote={Our objective was to investigate nitrate and nitrite contents of acidified and fermented fruits and vegetables. l-ascorbic acid and total phenols were also examined based on the hypothesis that the presence of these antioxidant compounds may influence N-nitrosation reactions upon human consumption. The fermented and acidified vegetable products included 131 samples from multiple lots of 46 different commercially available products. Nitrite was detected in low concentrations (<1.5 mg/100 g) in four acidified (pickled green beans, red cabbage, pickled beets, and pickled mushrooms) and two fermented products (Greek olives and kimchi). Nitrate concentrations ranged from a mean value of 122 mg/100 g for kimchi to undetectable levels in acidified Brussels sprouts. Measures of antioxidant compounds showed that artichoke hearts had the highest total polyphenols (225 mg/100 g), and olive products had between 84 ± 5 mg/100 g (Spanish table olives) and 170 ± 8 mg/100 g (Greek olives). An acidified red pepper product had the highest l-ascorbic acid content of 32 ± 10 mg/100 g, with a low nitrate level of 0.1 ± 0.09 mg/100 g. These results provide new information for evaluating nitrate and nitrite contents in pickled fruit and vegetable products with regard to potential human dietary health consequences.}, journal={FOOD CONTROL}, author={Ding, Zhansheng and Johanningsmeier, Suzanne D. and Price, Robert and Reynolds, Rong and Truong, Van-Den and Payton, Summer Conley and Breidt, Fred}, year={2018}, month={Aug}, pages={304–311} }
 @article{price_parsons_kathariou_2018, title={RNA Helicase Mediates Competitive Fitness of Listeria monocytogenes on the Surface of Cantaloupe}, volume={4}, ISSN={["2311-7524"]}, DOI={10.3390/horticulturae4040040}, abstractNote={Listeria monocytogenes is a foodborne pathogen that is implicated in numerous outbreaks of disease (listeriosis) via fresh produce. The genetic features of L. monocytogenes that allow adherence and growth on produce remain largely uncharacterized. In this study, two non-motile transposon mutants were characterized for attachment, growth, and survival on the surface of cantaloupe rind. One of the mutants, L1E4, harbored a single transposon insertion in a DEAD-box RNA helicase gene (lmo0866 homolog), while the other, M1A5, harbored an insertion in a gene from a flagellum biosynthesis and chemotaxis gene cluster (lmo0694 homolog). When inoculated alone, neither mutant was significantly impaired in growth or survival on the surface of cantaloupe at either 25 or 37 °C. However, when co-inoculated with the wildtype parental strain, the RNA helicase mutant L1E4 had a clear competitive disadvantage, while the relative fitness of M1A5 was not noticeably impacted. Genetic complementation of L1E4 with the intact RNA helicase gene restored relative fitness on cantaloupe. The findings suggest that the DEAD-box RNA helicase encoded by the lmo0866 homolog is critical for relative fitness of L. monocytogenes on cantaloupe. Mutant L1E4 was pleiotropic, being not only non-motile but also cold-sensitive and with reduced hemolytic activity, warranting further studies to elucidate the role of this helicase in the competitive fitness of L. monocytogenes on produce.}, number={4}, journal={HORTICULTURAE}, author={Price, Robert and Parsons, Cameron and Kathariou, Sophia}, year={2018}, month={Dec} }
 @article{huggins_minrovic_corey_jacobs_melander_sommer_zurawski_melander_2017, title={1,2,4-Triazolidine-3-thiones as Narrow Spectrum Antibiotics against Multidrug-Resistant Acinetobacter baumannii}, volume={8}, ISSN={["1948-5875"]}, DOI={10.1021/acsmedchemlett.6b00296}, abstractNote={With only two new classes of antibiotics developed in the last 40 years, novel antibiotics are desperately needed to combat the growing problem of multidrug-resistant and extensively drug resistant bacteria, particularly Gram-negative bacteria. Described in this letter is the synthesis and antibiotic activity of 1,2,4-triazolidine-3-thiones as narrow spectrum antibiotics. Optimization of the 1,2,4-triazolidine-3-thione scaffold identified a small molecule with potent antibiotic activity against multiple strains of multidrug-resistant and extensively drug-resistant Acinetobacter baumannii. This small molecule also shows single dose, in vivo activity in a Galleria mellonella infection model with A. baumannii and represents a promising start in the development of a class of drugs that can target this bacterial pathogen.}, number={1}, journal={ACS MEDICINAL CHEMISTRY LETTERS}, publisher={American Chemical Society (ACS)}, author={Huggins, William M. and Minrovic, Bradley M. and Corey, Brendan W. and Jacobs, Anna C. and Melander, Roberta J. and Sommer, Roger D. and Zurawski, Daniel V. and Melander, Christian}, year={2017}, month={Jan}, pages={27–31} }
 @article{fan_breidt_price_perez-diaz_2017, title={Survival and Growth of Probiotic Lactic Acid Bacteria in Refrigerated Pickle Products}, volume={82}, ISSN={["1750-3841"]}, DOI={10.1111/1750-3841.13579}, abstractNote={AbstractWe examined 10 lactic acid bacteria that have been previously characterized for commercial use as probiotic cultures, mostly for dairy products, including 1 Pediococcus and 9 Lactobacilli. Our objectives were to develop a rapid procedure for determining the long‐term survivability of these cultures in acidified vegetable products and to identify suitable cultures for probiotic brined vegetable products. We therefore developed assays to measure acid resistance of these cultures to lactic and acetic acids, which are present in pickled vegetable products. We used relatively high acid concentrations (compared to commercial products) of 360 mM lactic acid and 420 mM acetic acid to determine acid resistance with a 1 h treatment. Growth rates were measured in a cucumber juice medium at pH 5.3, 4.2, and 3.8, at 30 °C and 0% to 2% NaCl. Significant differences in acid resistance and growth rates were found among the 10 cultures. In general, the acid resistant strains had slower growth rates than the acid sensitive strains. Based on the acid resistance data, selected cultures were tested for long‐term survival in a simulated acidified refrigerated cucumber product. We found that one of the most acid resistant strains (Lactobacillus casei) could survive for up to 63 d at 4 °C without significant loss of viability at 108 CFU/mL. These data may aid in the development of commercial probiotic refrigerated pickle products.}, number={1}, journal={JOURNAL OF FOOD SCIENCE}, author={Fan, Sicun and Breidt, Fred and Price, Robert and Perez-Diaz, Ilenys}, year={2017}, month={Jan}, pages={167–173} }