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Richard A. Holley - One of the best experts on this subject based on the ideXlab platform.

  • antagonistic effects of lactobacillus reuteri against escherichia coli o157 h7 in white Brined Cheese under different storage conditions
    Journal of Dairy Science, 2021
    Co-Authors: Anas A Alnabulsi, Amin N. Olaimat, Tareq M Osaili, Mutamed M Ayyash, Saba B Oqdeh, Ziad W Jaradat, Richard A. Holley
    Abstract:

    This study aimed to investigate the survival of the foodborne pathogen Escherichia coli O157:H7 in white-Brined Cheeses as influenced by the presence of Lactobacillus reuteri. The white Cheeses were made from pasteurized bovine milk inoculated with E. coli O157:H7 (cocktail of 3 strains) to achieve ∼5 log10 cfu/g with absence or presence of Lb. reuteri (∼6 log10 cfu/g). Cheese samples were Brined in 10% or 15% NaCl solution and stored at 10°C and 25°C for 28 d. The white-Brined Cheeses were assessed for salt content, pH, water activity (Aw), and numbers of E. coli O157:H7, Lb. reuteri, nonstarter lactic acid bacteria (NSLAB), yeasts, and molds. Results showed that E. coli O157:H7 survived in Cheese stored in both brine solutions at 10°C and 25°C regardless of the presence of Lb. reuteri. A substantial reduction was observed in Cheese stored in 10% NaCl brine at 25°C, followed by Cheese stored in 15% NaCl brine at 10°C by 2.64 and 2.16 log10 cfu/g, respectively, in the presence of Lb. reuteri and by 1.02 and 1.87 log10 cfu/g, respectively, in the absence of Lb. reuteri under the same conditions. The pathogen in brine solutions survived but at a lower rate. Furthermore, the growth of Lb. reuteri and NSLAB were enhanced or slightly decreased in Cheese and brine by 28 d, respectively. The salt concentrations of Cheese ranged from 4 to 6% and 5 to 7% (wt/wt), during 28-d ripening in 10 and 15% brine, respectively. Values of pH and Aw slightly increased at d 1 after exposure to brine and reached 4.69 to 6.08 and 0.91 to 0.95, respectively, in all treatments. Therefore, the addition of Lb. reuteri can be used as a biopreservation method to inhibit the survival of E. coli O157:H7 in white-Brined Cheese when combined with the appropriate temperature, NaCl level, and storage time.

  • antimicrobial activity of chitosan coating containing zno nanoparticles against e coli o157 h7 on the surface of white Brined Cheese
    International Journal of Food Microbiology, 2020
    Co-Authors: Anas A Alnabulsi, Ghadeer F. Mehyar, Amin N. Olaimat, Tareq M Osaili, Amani Sawalha, B A Albiss, Mutamed M Ayyash, Richard A. Holley
    Abstract:

    Abstract White Brined Cheese may serve as an ideal medium for the growth of foodborne pathogens including E. coli O157:H7. The objectives of this study were i) to evaluate the inhibitory effects of zinc oxide (ZnO) nanoparticles against E. coli O157:H7 at 10 or 37 °C using broth dilution; ii) to address the post-process contamination of white Brined Cheese with E. coli O157:H7 by using chitosan coating with or without ZnO nanoparticles during storage for 28 d at 4 and 10 °C; and iii) to study the physicochemical characteristics of chitosan coating containing ZnO nanoparticles. ZnO nanoparticles at ≥0.0125% inhibited the growth of three E. coli O157:H7 strains at both 37 and 10 °C. The chitosan coating with or without ZnO nanoparticles significantly reduced the initial numbers of E. coli O157:H7 in white Brined Cheese by 2.5 and 2.8 log CFU/g, respectively, when stored at 4 °C or by 1.9 and 2.1 log CFU/g, respectively, when stored at 10 °C. The chitosan-ZnO nanoparticle coating was not significantly different (p > 0.05) but was slightly better than chitosan alone as an active, smart packaging material in food applications.

  • factors affecting the viability of staphylococcus aureus and production of enterotoxin during processing and storage of white Brined Cheese
    Journal of Dairy Science, 2020
    Co-Authors: Anas A Alnabulsi, Amin N. Olaimat, Tareq M Osaili, Mutamed M Ayyash, Roa A Abunaser, Murad A Alholy, Khaled M Kadora, Richard A. Holley
    Abstract:

    ABSTRACT Staphylococcus aureus is a major foodborne pathogen that causes severe disease in humans. It is commonly found in milk and dairy products, particularly in fresh Brined Cheese. Our aim was to investigate the behavior of Staph. aureus and enterotoxin production during the storage of white-Brined Cheese prepared with or without a starter culture and stored in a 10 or 15% NaCl brine at 10°C and 25°C for 28 d. NaCl concentration, water activity, pH, and number of Staph. aureus and lactic acid bacteria were determined in Cheese and brine. Only 1 of 4 Staph. aureus strains (ATCC 439) was positive for enterotoxin production, and its production was detected in unsalted UHT milk, but not in salted milk or in any of the Cheese treatments held at 37°C for 1, 3, or 7 d. Staphylococcus aureus grew in the Cheese stored in both brines at 10°C and 25°C, regardless of the presence of a starter culture, although the latter significantly reduced Staph. aureus growth in Cheese or its brine at 10°C. Staphylococcus aureus numbers were increased by 2.26 and 0.47 log10 cfu/g in Cheese stored in 10 and 15% NaCl brine, respectively, in the presence of starter culture, and by 2.78 and 2.96 log10 cfu/g, respectively, in the absence of starter culture at 10°C. Nonetheless, the pathogen grew, but at a lower number in the brines. The salt concentration of Cheese stored in 10% brine remained at approximately 5% during storage; however, in 15% brine, the salt concentration increased to almost 8% (wt/wt) by 28 d. The addition of a starter culture, high salt concentration, low temperature, and pH (∼5.2) had inhibitory effects on the growth of Staph. aureus. Moreover, lactic acid bacterial numbers increased considerably in Cheese and brine by d 28. The use of starter cultures, salt (15%), and low storage temperature (10°C) reduced the growth of Staph. aureus, and salt may have prevented enterotoxin production in white-Brined Cheese.

  • Effects of chitosan coating containing lysozyme or natamycin on shelf-life, microbial quality, and sensory properties of Halloumi Cheese Brined in normal and reduced salt solutions
    Journal of Food Processing and Preservation, 2017
    Co-Authors: Ghadeer F. Mehyar, Anas A. Al Nabulsi, Mohammed Saleh, Amin N. Olaimat, Richard A. Holley
    Abstract:

    The effects of chitosan (C) coating with or without lysozyme (L) or natamycin (N) on shelf-life, microbial quality, and sensory properties of Halloumi Cheese held at 3 °C or 25 °C in 5%, 10% or 15% (w/v) NaCl were examined. Coatings increased Cheese shelf-life by ≥ 5 days than the control when Brined in 5% and 10% NaCl at 3 °C but did not affect the shelf-life of Cheese in 15% NaCl. Nonetheless, coatings reduced psychrotrophs, anaerobes, lactic acid bacteria, and yeasts and molds by 1.8 to 2.2 log in 15% Brined Cheese. Reductions of microbial species contaminating Halloumi Cheese at 10% and 15% brine were not significantly different with CL and CN coatings throughout storage at 3 °C. Coatings did not adversely affect sensory properties of Cheese. Therefore, brine concentration could be reduced to 10% for CL and CN-coated Cheeses. Practical applications Results support the possibility of reducing the high salt concentration in brine solution of Halloumi Cheese by using a chitosan coating containing lysozyme or natamyc in which provided similar shelf-life and microbial stability. The coatings did not adversely affect the sensory properties of Cheese and can be applied by a simple step during processing which facilitates their use in the food industry.

  • M:FoodMicrobiology Safety Survival of Escherichia coli O157:H7 during Manufacture and Storage of White Brined Cheese
    2016
    Co-Authors: Tareq M Osaili, Amin N. Olaimat, Reyad R Shaker, Mohammad Taha, Anas A. Al-nabulsi, Richard A. Holley
    Abstract:

    Abstract: Escherichia coli O157:H7 is a major foodborne pathogen that causes severe disease in humans. Survival of E. coli O157:H7 during processing and storage of white Brined Cheese was investigated. Cheeses were prepared using pasteurized milk inoculated with a 4 strain E. coli O157:H7 cocktail (7 log10 CFU/g) with or without yogurt starter culture (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus) and stored in 10 % or 15 % NaCl brine at 10 and 21 ˚C for 28 d. NaCl concentration, water activity (aw), pH, and numbers of E. coli O157:H7 and lactic acid bacteria (LAB) were determined in Cheese and brine. E. coli O157:H7 was able to survive in Cheese stored in both brines at 10 and 21 ˚C regardless of the presence of starter LAB, although the latter significantly enhanced E. coli O157:H7 reduction in Cheese or its brine at 10 ˚C. E. coli O157:H7 numbers were reduced by 2.6 and 3.4 log10 CFU/g in Cheese stored in 10 % and 15 % NaCl brine, respectively, in the presence of starter LAB and by 1.4 and 2.3 log10 CFU/g, respectively, in the absence of starter LAB at 10 ˚C. The pathogen survived, but at lower numbers in the brines. The salt concentration of Cheese stored in 10 % brine remained about 5 % during ripening, but in 15 % brine, the NaCl level increased 1.6 % to 8.1 % (w/w) by 28 d. Values of pH and aw slightly decreased 1 d after exposure to brine and reached 5.5 to 6.6 and 0.88 to 0.94, respectively, in all treatments

Barbaros Özer - One of the best experts on this subject based on the ideXlab platform.

  • changes of proteolysis and angiotensin i converting enzyme inhibitory activity in white Brined Cheese as affected by adjunct culture and ripening temperature
    Journal of Dairy Research, 2014
    Co-Authors: Didem Sahingil, Barbaros Özer, Huseyin Avni Kirmaci, A A Hayaloglu, O Simsek
    Abstract:

    The effects of use of adjunct cultures (Lactobacillus helveticus and Lb. casei) and ripening temperatures (6 or 12 °C) on proteolysis and angiotensin-I converting enzyme (ACE)-inhibitory activity in white-Brined Cheeses were investigated during 120 d ripening. Proteolysis was monitored by urea-polyacrylamide gel electrophoresis (urea-PAGE) and reversed phase-HPLC (RP-HPLC) of water-insoluble and -soluble fractions of the Cheeses, respectively. Urea-PAGE patterns of the samples revealed that the intensities of the bands representing casein fractions decreased in the experimental Cheeses, being more pronounced in the Cheeses made with adjunct cultures. Similarly, peptide profiles and the concentrations of individual and total free amino acids were influenced by both the adjunct cultures and ripening temperatures. The ACE-inhibitory activity of the water-soluble extracts of the Cheeses were higher in the Cheeses made using adjunct cultures (especially Lb. helveticus) and ripened at 12 °C. The ACE-inhibitory activity did not decrease during ripening. The contribution of Lb. helveticus to the development of proteolysis and ACE-inhibitory peptide activities were higher than that of Lb. casei. To conclude, the use of Lb. helveticus as adjunct culture in white-Brined Cheese and ripening at 12 °C would be recommended to obtain white-Brined Cheese with high ACE-I-inhibitory peptides activity and higher levels of preoteolysis.

  • changes in volatile composition proteolysis and textural and sensory properties of white Brined Cheese effects of ripening temperature and adjunct culture
    Dairy Science & Technology, 2014
    Co-Authors: Didem Sahingil, A A Hayaloglu, O Simsek, Barbaros Özer
    Abstract:

    The effects of ripening temperature and adjunct cultures (Lactobacillus helveticus and Lactobacillus casei) on the volatile compounds and sensory and textural properties of white-Brined Cheese were investigated. Three batches of Cheese were produced: Cheese A was inoculated with only Cheese starter culture (Lactococcus lactis subsp. lactis plus Lactococcus lactis subsp. cremoris), Cheese B was inoculated with Cheese starter culture plus Lactobacillus helveticus and Cheese C was inoculated with Cheese starter culture plus Lactobacillus casei. Cheeses were ripened at 6 or 12 °C and analyzed at 30-day intervals up to 120 days of ripening. The use of adjunct culture and ripening temperature significantly influenced the pH and proteolysis of Cheeses (P < 0.05). Acids, ketones and alcohols were found at high levels in all three Cheeses. Volatiles were significantly influenced by the use of the adjunct cultures, ageing and to some extent ripening temperature (P < 0.05). Textural parameters of the Cheeses were significantly affected by the adjunct culture during ripening (P < 0.05). The sensory scores of the Cheese samples decreased during the ripening period. An age-related bitterness was detected by the panellists in 90 or 120-day-old Cheeses with added adjunct cultures. In conclusion, the use of adjunct culture and ripening at 12 °C enhanced the volatile composition and changed the texture profiles of the Cheeses.

  • simultaneous use of transglutaminase and rennet in white Brined Cheese production
    International Dairy Journal, 2013
    Co-Authors: Barbaros Özer, Huyla Yaman, Ayse Gursoy, Ali Adnan Hayaloglu, Leyla şener
    Abstract:

    Abstract The effects of renneting temperature (30 °C or 34 °C) on textural properties, proteolysis and yield of white-Brined Cheese made by simultaneous use of microbial transglutaminase (mTG) and rennet were investigated. Incorporation of mTG resulted in higher yield values for experimental Cheeses than for the control Cheeses at both renneting temperatures. The total solids contents of the Cheeses treated with mTG were remarkably lower than the control Cheeses; but the former Cheeses had higher protein-in-dry matter levels. The TPA profiles of the Cheeses showed that the incorporation of mTG led to modification in the textural properties. The development of proteolysis in the Cheeses treated with mTG was slightly slower than the control Cheeses at both coagulation temperatures. To conclude, the specific action of mTG on milk proteins could be successfully exploited to modify the textural properties and to increase the yield of white-Brined Cheese.

  • the effects of incorporating wild type strains of lactococcus lactis into turkish white Brined Cheese beyaz peynir on the fatty acid and volatile content
    International Journal of Dairy Technology, 2011
    Co-Authors: Barbaros Özer, Huseyin Avni Kirmaci, A A Hayaloglu, Mustafa Akcelik, Nefise Akkoc
    Abstract:

    The development of free fatty acids (FFA) and volatile flavour compounds in the Turkish white-Brined Cheese Beyaz peynir made by using three wild strains of Lactococcus lactis subsp. lactis was investigated over 90 days. Results showed that production of both FFA and flavour compounds in the control (PK1) and experimental Cheeses (MBLL9, MBLL23 and MBL27) was strain dependent. The hydrolysis of milk fat was more evident in the Cheese made using Lc. lactis subsp. lactis MBL27. Considering the production of fat breakdown compounds and acidification activities of the strains MBLL23 and MBL27, the combination of these strains could be proposed for the production of white-Brined Cheese.

  • proteolytic properties of turkish white Brined Cheese beyaz peynir made by using wild type lactococcal strains
    International Journal of Dairy Technology, 2011
    Co-Authors: Huseyin Avni Kirmaci, Barbaros Özer, A A Hayaloglu, Mustafa Akcelik, Nefise Akkoc
    Abstract:

    The development of proteolysis in white-Brined Turkish Cheese made by using wild strains of Lactococcus lactis subsp. lactis (namely MBLL9, MBLL23 and MBL27) was monitored for 90 days. Proteolysis in Cheeses was investigated using urea-PAGE gel electrophoresis of pH 4.6-insoluble and RP-HPLC of both 70% ethanol-insoluble and 70% ethanol-soluble nitrogen fractions. Results indicated that developments of proteolysis in the experimental Cheeses were strain dependent. The degradation of casein fractions was more evident in the Cheeses made using strain MBLL23. The lowest levels of proteolysis and development of acidity were obtained in the Cheese made using strain MBLL9.

A A Hayaloglu - One of the best experts on this subject based on the ideXlab platform.

  • role of using adjunct cultures in release of bioactive peptides in white Brined goat milk Cheese
    Lwt - Food Science and Technology, 2020
    Co-Authors: Ali Kocak, Tuba Sanli, Elif Ayse Anli, A A Hayaloglu
    Abstract:

    Abstract A mixed commercial starter culture containing Lactococcus lactis subps lactis and Lactococcus lactis subsp cremoris (Cheese A, control) was combined with three adjunct cultures including Lactobacillus casei (Cheese B), Lactobacillus plantarum (Cheese C) and Lactobacillus bulgaricus (Cheese D) in the manufacture of white Brined Cheese using goat's milk. Use of adjunct culture was not significantly affected pH and gross chemical composition except for nitrogenous compounds; however, use of adjunct cultures in Cheese manufacture showed a potential increase in ACE-inhibitory and antioxidant activity parallel to the increase in water-soluble nitrogenous compounds until the 60th day of ripening. The highest antioxidant and ACE-inhibitory activity was detected in Cheese D (62.55%) and Cheese B (51.95%), respectively. All Cheese samples showed almost similar peptide profile; however, quantitative differences were observed. In conclusion, use of adjunct cultures in white-Brined goat-milk Cheese manufacturing contribute to increase in ACE-inhibitory activity and antioxidant activity.

  • characterisation of macedonian white Brined Cheese effect of raw or heat treated caprine milk
    International Journal of Dairy Technology, 2018
    Co-Authors: Erhan Sulejmani, A A Hayaloglu
    Abstract:

    This research analysed the use of raw and pasteurised milk in the production of Macedonian white caprine milk Cheese. Pasteurisation resulted in a considerable decrease in the nitrogen fractions, urea-polyacrylamide gel electrophoresis of caseins, peptide profiles and volatiles during the maturation period. Forty-five volatile components were detected, including twelve acids, fourteen esters, six ketones, three alcohols, four terpenes and six other compounds. It was deduced that pasteurisation of milk for the manufacture of artisanal white-Brined Cheese delayed the evolution of volatiles, which are related to the unique flavour of the Cheese.

  • changes of proteolysis and angiotensin i converting enzyme inhibitory activity in white Brined Cheese as affected by adjunct culture and ripening temperature
    Journal of Dairy Research, 2014
    Co-Authors: Didem Sahingil, Barbaros Özer, Huseyin Avni Kirmaci, A A Hayaloglu, O Simsek
    Abstract:

    The effects of use of adjunct cultures (Lactobacillus helveticus and Lb. casei) and ripening temperatures (6 or 12 °C) on proteolysis and angiotensin-I converting enzyme (ACE)-inhibitory activity in white-Brined Cheeses were investigated during 120 d ripening. Proteolysis was monitored by urea-polyacrylamide gel electrophoresis (urea-PAGE) and reversed phase-HPLC (RP-HPLC) of water-insoluble and -soluble fractions of the Cheeses, respectively. Urea-PAGE patterns of the samples revealed that the intensities of the bands representing casein fractions decreased in the experimental Cheeses, being more pronounced in the Cheeses made with adjunct cultures. Similarly, peptide profiles and the concentrations of individual and total free amino acids were influenced by both the adjunct cultures and ripening temperatures. The ACE-inhibitory activity of the water-soluble extracts of the Cheeses were higher in the Cheeses made using adjunct cultures (especially Lb. helveticus) and ripened at 12 °C. The ACE-inhibitory activity did not decrease during ripening. The contribution of Lb. helveticus to the development of proteolysis and ACE-inhibitory peptide activities were higher than that of Lb. casei. To conclude, the use of Lb. helveticus as adjunct culture in white-Brined Cheese and ripening at 12 °C would be recommended to obtain white-Brined Cheese with high ACE-I-inhibitory peptides activity and higher levels of preoteolysis.

  • changes in volatile composition proteolysis and textural and sensory properties of white Brined Cheese effects of ripening temperature and adjunct culture
    Dairy Science & Technology, 2014
    Co-Authors: Didem Sahingil, A A Hayaloglu, O Simsek, Barbaros Özer
    Abstract:

    The effects of ripening temperature and adjunct cultures (Lactobacillus helveticus and Lactobacillus casei) on the volatile compounds and sensory and textural properties of white-Brined Cheese were investigated. Three batches of Cheese were produced: Cheese A was inoculated with only Cheese starter culture (Lactococcus lactis subsp. lactis plus Lactococcus lactis subsp. cremoris), Cheese B was inoculated with Cheese starter culture plus Lactobacillus helveticus and Cheese C was inoculated with Cheese starter culture plus Lactobacillus casei. Cheeses were ripened at 6 or 12 °C and analyzed at 30-day intervals up to 120 days of ripening. The use of adjunct culture and ripening temperature significantly influenced the pH and proteolysis of Cheeses (P < 0.05). Acids, ketones and alcohols were found at high levels in all three Cheeses. Volatiles were significantly influenced by the use of the adjunct cultures, ageing and to some extent ripening temperature (P < 0.05). Textural parameters of the Cheeses were significantly affected by the adjunct culture during ripening (P < 0.05). The sensory scores of the Cheese samples decreased during the ripening period. An age-related bitterness was detected by the panellists in 90 or 120-day-old Cheeses with added adjunct cultures. In conclusion, the use of adjunct culture and ripening at 12 °C enhanced the volatile composition and changed the texture profiles of the Cheeses.

  • the effects of incorporating wild type strains of lactococcus lactis into turkish white Brined Cheese beyaz peynir on the fatty acid and volatile content
    International Journal of Dairy Technology, 2011
    Co-Authors: Barbaros Özer, Huseyin Avni Kirmaci, A A Hayaloglu, Mustafa Akcelik, Nefise Akkoc
    Abstract:

    The development of free fatty acids (FFA) and volatile flavour compounds in the Turkish white-Brined Cheese Beyaz peynir made by using three wild strains of Lactococcus lactis subsp. lactis was investigated over 90 days. Results showed that production of both FFA and flavour compounds in the control (PK1) and experimental Cheeses (MBLL9, MBLL23 and MBL27) was strain dependent. The hydrolysis of milk fat was more evident in the Cheese made using Lc. lactis subsp. lactis MBL27. Considering the production of fat breakdown compounds and acidification activities of the strains MBLL23 and MBL27, the combination of these strains could be proposed for the production of white-Brined Cheese.

Tareq M Osaili - One of the best experts on this subject based on the ideXlab platform.

  • antagonistic effects of lactobacillus reuteri against escherichia coli o157 h7 in white Brined Cheese under different storage conditions
    Journal of Dairy Science, 2021
    Co-Authors: Anas A Alnabulsi, Amin N. Olaimat, Tareq M Osaili, Mutamed M Ayyash, Saba B Oqdeh, Ziad W Jaradat, Richard A. Holley
    Abstract:

    This study aimed to investigate the survival of the foodborne pathogen Escherichia coli O157:H7 in white-Brined Cheeses as influenced by the presence of Lactobacillus reuteri. The white Cheeses were made from pasteurized bovine milk inoculated with E. coli O157:H7 (cocktail of 3 strains) to achieve ∼5 log10 cfu/g with absence or presence of Lb. reuteri (∼6 log10 cfu/g). Cheese samples were Brined in 10% or 15% NaCl solution and stored at 10°C and 25°C for 28 d. The white-Brined Cheeses were assessed for salt content, pH, water activity (Aw), and numbers of E. coli O157:H7, Lb. reuteri, nonstarter lactic acid bacteria (NSLAB), yeasts, and molds. Results showed that E. coli O157:H7 survived in Cheese stored in both brine solutions at 10°C and 25°C regardless of the presence of Lb. reuteri. A substantial reduction was observed in Cheese stored in 10% NaCl brine at 25°C, followed by Cheese stored in 15% NaCl brine at 10°C by 2.64 and 2.16 log10 cfu/g, respectively, in the presence of Lb. reuteri and by 1.02 and 1.87 log10 cfu/g, respectively, in the absence of Lb. reuteri under the same conditions. The pathogen in brine solutions survived but at a lower rate. Furthermore, the growth of Lb. reuteri and NSLAB were enhanced or slightly decreased in Cheese and brine by 28 d, respectively. The salt concentrations of Cheese ranged from 4 to 6% and 5 to 7% (wt/wt), during 28-d ripening in 10 and 15% brine, respectively. Values of pH and Aw slightly increased at d 1 after exposure to brine and reached 4.69 to 6.08 and 0.91 to 0.95, respectively, in all treatments. Therefore, the addition of Lb. reuteri can be used as a biopreservation method to inhibit the survival of E. coli O157:H7 in white-Brined Cheese when combined with the appropriate temperature, NaCl level, and storage time.

  • antimicrobial activity of chitosan coating containing zno nanoparticles against e coli o157 h7 on the surface of white Brined Cheese
    International Journal of Food Microbiology, 2020
    Co-Authors: Anas A Alnabulsi, Ghadeer F. Mehyar, Amin N. Olaimat, Tareq M Osaili, Amani Sawalha, B A Albiss, Mutamed M Ayyash, Richard A. Holley
    Abstract:

    Abstract White Brined Cheese may serve as an ideal medium for the growth of foodborne pathogens including E. coli O157:H7. The objectives of this study were i) to evaluate the inhibitory effects of zinc oxide (ZnO) nanoparticles against E. coli O157:H7 at 10 or 37 °C using broth dilution; ii) to address the post-process contamination of white Brined Cheese with E. coli O157:H7 by using chitosan coating with or without ZnO nanoparticles during storage for 28 d at 4 and 10 °C; and iii) to study the physicochemical characteristics of chitosan coating containing ZnO nanoparticles. ZnO nanoparticles at ≥0.0125% inhibited the growth of three E. coli O157:H7 strains at both 37 and 10 °C. The chitosan coating with or without ZnO nanoparticles significantly reduced the initial numbers of E. coli O157:H7 in white Brined Cheese by 2.5 and 2.8 log CFU/g, respectively, when stored at 4 °C or by 1.9 and 2.1 log CFU/g, respectively, when stored at 10 °C. The chitosan-ZnO nanoparticle coating was not significantly different (p > 0.05) but was slightly better than chitosan alone as an active, smart packaging material in food applications.

  • factors affecting the viability of staphylococcus aureus and production of enterotoxin during processing and storage of white Brined Cheese
    Journal of Dairy Science, 2020
    Co-Authors: Anas A Alnabulsi, Amin N. Olaimat, Tareq M Osaili, Mutamed M Ayyash, Roa A Abunaser, Murad A Alholy, Khaled M Kadora, Richard A. Holley
    Abstract:

    ABSTRACT Staphylococcus aureus is a major foodborne pathogen that causes severe disease in humans. It is commonly found in milk and dairy products, particularly in fresh Brined Cheese. Our aim was to investigate the behavior of Staph. aureus and enterotoxin production during the storage of white-Brined Cheese prepared with or without a starter culture and stored in a 10 or 15% NaCl brine at 10°C and 25°C for 28 d. NaCl concentration, water activity, pH, and number of Staph. aureus and lactic acid bacteria were determined in Cheese and brine. Only 1 of 4 Staph. aureus strains (ATCC 439) was positive for enterotoxin production, and its production was detected in unsalted UHT milk, but not in salted milk or in any of the Cheese treatments held at 37°C for 1, 3, or 7 d. Staphylococcus aureus grew in the Cheese stored in both brines at 10°C and 25°C, regardless of the presence of a starter culture, although the latter significantly reduced Staph. aureus growth in Cheese or its brine at 10°C. Staphylococcus aureus numbers were increased by 2.26 and 0.47 log10 cfu/g in Cheese stored in 10 and 15% NaCl brine, respectively, in the presence of starter culture, and by 2.78 and 2.96 log10 cfu/g, respectively, in the absence of starter culture at 10°C. Nonetheless, the pathogen grew, but at a lower number in the brines. The salt concentration of Cheese stored in 10% brine remained at approximately 5% during storage; however, in 15% brine, the salt concentration increased to almost 8% (wt/wt) by 28 d. The addition of a starter culture, high salt concentration, low temperature, and pH (∼5.2) had inhibitory effects on the growth of Staph. aureus. Moreover, lactic acid bacterial numbers increased considerably in Cheese and brine by d 28. The use of starter cultures, salt (15%), and low storage temperature (10°C) reduced the growth of Staph. aureus, and salt may have prevented enterotoxin production in white-Brined Cheese.

  • M:FoodMicrobiology Safety Survival of Escherichia coli O157:H7 during Manufacture and Storage of White Brined Cheese
    2016
    Co-Authors: Tareq M Osaili, Amin N. Olaimat, Reyad R Shaker, Mohammad Taha, Anas A. Al-nabulsi, Richard A. Holley
    Abstract:

    Abstract: Escherichia coli O157:H7 is a major foodborne pathogen that causes severe disease in humans. Survival of E. coli O157:H7 during processing and storage of white Brined Cheese was investigated. Cheeses were prepared using pasteurized milk inoculated with a 4 strain E. coli O157:H7 cocktail (7 log10 CFU/g) with or without yogurt starter culture (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus) and stored in 10 % or 15 % NaCl brine at 10 and 21 ˚C for 28 d. NaCl concentration, water activity (aw), pH, and numbers of E. coli O157:H7 and lactic acid bacteria (LAB) were determined in Cheese and brine. E. coli O157:H7 was able to survive in Cheese stored in both brines at 10 and 21 ˚C regardless of the presence of starter LAB, although the latter significantly enhanced E. coli O157:H7 reduction in Cheese or its brine at 10 ˚C. E. coli O157:H7 numbers were reduced by 2.6 and 3.4 log10 CFU/g in Cheese stored in 10 % and 15 % NaCl brine, respectively, in the presence of starter LAB and by 1.4 and 2.3 log10 CFU/g, respectively, in the absence of starter LAB at 10 ˚C. The pathogen survived, but at lower numbers in the brines. The salt concentration of Cheese stored in 10 % brine remained about 5 % during ripening, but in 15 % brine, the NaCl level increased 1.6 % to 8.1 % (w/w) by 28 d. Values of pH and aw slightly decreased 1 d after exposure to brine and reached 5.5 to 6.6 and 0.88 to 0.94, respectively, in all treatments

  • survival of escherichia coli o157 h7 during manufacture and storage of white Brined Cheese
    Journal of Food Science, 2014
    Co-Authors: Tareq M Osaili, Amin N. Olaimat, Anas A Alnabulsi, Reyad R Shaker, Mohammad Taha, Richard A. Holley
    Abstract:

    Escherichia coli O157:H7 is a major foodborne pathogen that causes severe disease in humans. Survival of E. coli O157:H7 during processing and storage of white Brined Cheese was investigated. Cheeses were prepared using pasteurized milk inoculated with a 4 strain E. coli O157:H7 cocktail (7 log10 CFU/g) with or without yogurt starter culture (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus) and stored in 10% or 15% NaCl brine at 10 and 21 ˚C for 28 d. NaCl concentration, water activity (aw), pH, and numbers of E. coli O157:H7 and lactic acid bacteria (LAB) were determined in Cheese and brine. E. coli O157:H7 was able to survive in Cheese stored in both brines at 10 and 21 ˚C regardless of the presence of starter LAB, although the latter significantly enhanced E. coli O157:H7 reduction in Cheese or its brine at 10 ˚C. E. coli O157:H7 numbers were reduced by 2.6 and 3.4 log10 CFU/g in Cheese stored in 10% and 15% NaCl brine, respectively, in the presence of starter LAB and by 1.4 and 2.3 log10 CFU/g, respectively, in the absence of starter LAB at 10 ˚C. The pathogen survived, but at lower numbers in the brines. The salt concentration of Cheese stored in 10% brine remained about 5% during ripening, but in 15% brine, the NaCl level increased 1.6% to 8.1% (w/w) by 28 d. Values of pH and aw slightly decreased 1 d after exposure to brine and reached 5.5 to 6.6 and 0.88 to 0.94, respectively, in all treatments.

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  • effects of a commercial oat β glucan concentrate on the chemical physico chemical and sensory attributes of a low fat white Brined Cheese product
    Food Research International, 2004
    Co-Authors: Pantelis Volikakis, Costas G Biliaderis, Costas Vamvakas, Gregory K Zerfiridis
    Abstract:

    Abstract Low-fat white-Brined Cheese was manufactured by a traditional procedure from bovine milk (70% fat reduction) containing two levels of an oat β-glucan concentrate (CEBA Foods AB) at 0.7% and 1.4% (w/w). For comparison two controls – a full-fat and a low-fat product without addition of the β-glucan concentrate – were also examined. The results indicated that as the fat content of Cheese milk decreased, the fat, moisture in non-fat solids (MNFS) and yield values significantly decreased, and the moisture and total nitrogen values increased. The products fortified with the β-glucan concentrate exhibited higher yield values and significantly lower pH (at 60 and 90 days of storage) than the control samples. In accordance with the latter values, the HPLC analysis showed that incorporation of the β-glucan concentrate into the low-fat Cheese milk led to a significant increase in the production of lactic, acetic and butyric acid throughout Cheese ripening. Also, the extent of proteolysis in the treatments supplemented with the hydrocolloid significantly increased, especially at 60 and 90 days and was higher than the respective values of the control products. With regard to the rheological properties of the Cheeses, incorporation of the β-glucan concentrate brought about amelioration in all the textural parameters of the low-fat product, as determined by large deformation mechanical testing and sensorial analysis; significant correlations ( p

  • low fat white Brined Cheese made from bovine milk and two commercial fat mimetics chemical physical and sensory attributes
    International Dairy Journal, 2002
    Co-Authors: Ehab Romeih, Costas G Biliaderis, Alexandra Michaelidou, Gregory K Zerfiridis
    Abstract:

    The composition, proteolysis, sensory and texture characteristics of low-fat white-Brined Cheeses (∼60% fat reduction) made from bovine milk and containing two commercial hydrocolloid-fat replacers (1% w/w Simplesse® D-100 and 0.125% w/w Novagel™ NC-200) were examined throughout aging for 90 d. For comparison, the low-fat variant without fat replacers (L) and the full-fat Cheese (F) were also studied. All the low-fat products showed reduced values for MNFS and yield, whereas the moisture and protein content significantly increased; however, the Cheeses containing fat replacers had higher moisture and yield values than the L product. The extent of proteolysis and lipolysis in the low-fat white-Brined Cheeses made with the fat replacers significantly increased compared to the F Cheese. The kinetics of αs1-and β-casein degradation as well as the evolution of the peptide profile (reversed phase HPLC) were not largely affected by the hydrocolloids. For the Cheeses containing fat replacers, the mean values of TPA (texture profile analysis) parameters and the maximum stress (σmax at 80% deformation on uniaxial compression) were significantly less than those of the L Cheese, showing a great improvement in Cheese texture when the fat replacers were included. The textural attributes of the product made with Novagel™ resembled more closely those of the F Cheese. Significant correlations (p<0.05) with negative slopes were obtained between the variables reflecting the degree of proteolysis and instrumental (TPA) texture parameters; such relationships were even stronger when the data were analyzed for each type of Cheese separately. The rheological measurements showed an improvement in the low-fat Cheeses containing fat replacers, but this was not clearly evident by sensory testing. Overall, the full-fat white-Brined Cheese was perceived as more elastic, less salty and had higher flavor and odor intensity scores than all low-fat variants. Although Simplesse® (S) had a marked improving effect on Cheese appearance, the product was rated as a harder Cheese than its full-fat counterpart.