DOCSLIB.ORG

Isolation of Enterotoxigenic Staphylococcus Aureus Harboring

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Isolation of Enterotoxigenic Staphylococcus Aureus Harboring Open Veterinary Journal, (2020), Vol. 10(3): 297–307 ISSN: 2226-4485 (Print) Original Research ISSN: 2218-6050 (Online) DOI: http://dx.doi.org/10.4314/ovj.v10i3.8 Submitted: 08/06/2020 Accepted: 25/08/2020 Published: 12/09/2020 Isolation of enterotoxigenic Staphylococcus aureus harboring seb gene and enteropathogenic Escherichia coli (serogroups O18, O114, and O125) from soft and hard artisanal cheeses in Egypt Ola Wagih Hegab*, Eman F. Abdel-Latif and Ashraf Ahmed Moawad Department of Food Hygiene and Control, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt Abstract Background: Soft and hard artisanal cheeses are regularly consumed in Egypt. These products are usually processed from raw milk which may harbor many pathogenic and spoilage microorganisms. Aim: To evaluate the safety of some artisanal cheeses in Egypt, such as Ras, Domiati, and Mish, through chemical and microbiological examination. Methods: One hundred and fifty random samples of traditional Ras, Domiati, and Mish cheeses (50 each) were microbiologically and chemically analyzed. Counts of total bacteria, presumptive coliform, staphylococci, yeast, and mold were estimated. Furthermore, isolation of Escherichia coli and Staphylococcus aureus was performed, followed by PCR confirmation; isolates of E. coli were examined for the presence of virulence genes; on the other hand, the detection of the five classical enterotoxin genes ofS. aureus was performed using multiplex PCR. Regarding chemical analysis, moisture, salt, and acidity content were measured. Correlations between chemical and microbial findings were investigated. Results: Mean counts of total bacteria, presumptive coliform, staphylococci, yeast, and mold were (2 × 108, 3 × 106 and 1 × 107 ), (3 × 105, 5 × 10 and 5 × 102), (1 × 106, 4 × 105and 1 × 105), (3 × 105, 1 × 105 and 5 × 105), and (7 × 103, 4 × 103 and 3 × 104) for Ras, Domiati and Mish cheeses, respectively. Serological identification of suspected E. coli revealed that E. coli O125 was isolated from Ras and Domiati samples, E. coli O18 was recovered from Ras samples, while E. coli O114 was isolated from Mish samples. PCR results revealed that all detected isolates of E. coli were positive for both iss (increased serum survival) and fimH (type 1 fimbriae) genes. Concerning isolated S. aureus, all examined products were harboring S. aureus enterotoxigenic strains, with seb and sed genes being the most common. The mean values of moisture, salt, and acidity were (30.03, 56.44, and 58.70), (3.30, 6.63, and 7.56) and (0.65, 0.68, and 0.50) for Ras, Domiati, and Mish cheeses, respectively. Conclusion: Enterotoxigenic S. aureus harboring seb gene and enteropathogenic E. coli (serogroups O18, O114, and O125) were frequently isolated from soft and hard artisanal cheeses in Egypt. Therefore, strict hygienic measures should be applied during their manufacture, handing, and distribution. Keywords: Domiati, E. coli virulence genes, Mish, Ras, S. aureus enterotoxins. Introduction areas. It is mainly made from raw milk, either cow’s Traditional Egyptian dairy products are an essential or a mixture of cow and buffalo milk, mostly without part of the daily diet in Egypt. Raw milk is the common adding a starter culture, and fermentation and ripening factor in making all traditional products, which usually occur only due to the native flora of raw milk, then it record high sensorial characteristics, as consumers is kept to ripen for 3–8 months till a sharp flavor is mostly choose their dairy products based on its acquired, similar to the Greek Kefalotyri cheese (Awad, sensory properties, regardless if it is made from raw or 2006; El-Fadaly et al., 2015). pasteurized milk (Awad, 2006; El-Ghaish et al., 2010; Domiati or Damietta cheese (Gebnah Domiata) is Ewida and Hussein, 2019). Some traditional products one of the most popular white, soft pickled cheeses. have been traced back to the pharaoh era of 4,000 It is named after the Egyptian seaport city “Dumyât”. BC, and is then handed down from one generation to Typically, it is salty, unlike other pickled cheeses, as the another. There are different types of traditional cheese salt is added directly to the raw milk at the proportion in Egypt and among them are Ras, Domiati, and Mish of 5%–14%, which varies according to season and (Benkerroum, 2012). ripening conditions (Robinson and Tamime, 1991). Ras cheese is a hard cheese commonly known in Egypt Mish is one of the oldest indigenous milk products in as “Romi”. It is one of the artisan type cheeses, which Egypt that has a sharp harsh flavor with a relatively is produced often in small factories located in rural higher salt content and is mostly yellowish brown color. *Corresponding Author: Ola Wagih Hegab. Department of Food Hygiene and Control, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt. Email: [email protected] 297 http://www.openveterinaryjournal.com O. W. Hegab et al. Open Veterinary Journal, (2020), Vol. 10(3): 297–307 Karish cheese is considered as the basic raw material Serological identification of E. coli was done using for such a product. Some other ingredients that may be DENKA SEIKEN CO., LTD. kits. The molecular included in Mish are sour milk, buttermilk, morta (a characterization, and virulence genes detection was byproduct of ghee), different types of pepper (green, performed using PCR, where DNA was extracted from red, and paprika), table salt, and a portion of an old the bacterial isolates using QIAamp® DNA Mini Kit Mish which acts as the starter culture. All ingredients (Catalogue no.51304) according to the instruction are brined under microaerophilic conditions mostly in manual. PCR was done for characterization of 5 genes earthenware containers for more than 1 year to obtain of E. coli using Emerald Amp GT PCR master mix, matured mish, which consists of Mish cheese and Mish Takara (Catalogue No. RR310A), using 5 different slurry (pickling medium), and both are consumed pair of primers (as uniplex PCR) as mentioned in Table (Tamime, 2006). 1. The PCR products were electrophoresed in 1.5% Raw milk used in the production of traditional dairy agarose according to that described in Sambrook et products and harbor a large number of native microflora al.’s (1989) study. that may participate in the development of a desirable Staphylococci count (CFU/g) and S. aureus isolation aroma and an appropriate flavor, but it may also contain were carried out according to the APHA guidelines pathogenic microorganisms such as Escherichia coli, (American Public Health Association) (2004). Staphylococcus aureus, and others that are considered Identification of suspected S. aureus strains as public health hazards, causing a serious food illness (microscopic examination, catalase activity test, and may produce lethal toxins in the food (Awad et al., coagulase test, thermostable nuclease, and anaerobic 2003; El-Ghaish et al., 2010). Moreover, undesirable utilization of mannitol) was carried out according to spoilage organisms may also be found that cause that described in Silva et al.’s (2019) study. Molecular defects and limits the shelf life of these products, characterization of S. aureus strains and enterotoxin rendering them unmarketable. Many other factors may genes detection was done as in E. coli. Six genes of cause an increase in the microbial load of traditional S. aureus (5 enterotoxins done by multiplex PCR and products, such as manufacture, handling, storage, and 23S rRNA) and six pairs (5 as multiplex and 1 pair as even marketing ways, which are still primitive and uniplex PCR) were used (Table 1). unhygienic (Osman et al., 2011). Yeast and mold counts (CFU/g) were conducted The current study was conducted to assess the safety of according to APHA’s guidelines (American Public some traditional cheeses in Egypt, such as Ras, Domiati, Health Association) (2004). and Mish, through chemical and microbiological Statistical analysis examination. The collected data were analyzed using Statistical Package for the Social Sciences Statistics 17 for Materials and Methods Windows. Samples collection Ethical approval One hundred and fifty random samples of Ras, In this study, no experimental live animals were used. Domiati, and Mish cheeses (50 each) were collected All cheese samples were collected directly from the from different Egyptian Governorates. The samples Egyptian local markets. were identified, placed in an ice box, and examined immediately. Results Chemical analysis Chemical analysis Moisture and acidity were analyzed according to the The chemical analysis of the examined samples, AOAC guidelines (Association of Official Analytical including moisture, salt, and acidity, is illustrated Chemists) (2000) and salt according to the APHA in Table 2; for Ras cheese samples, the mean values guidelines (American Public Health Association) were 30.03, 3.30, and 0.65, respectively. The mean (2004). values of Domiati cheese samples were 56.44, 6.63, Microbiological examination and 0.68, respectively, and were 58.70, 7.56, and 0.50, Preparation of food homogenate and decimal dilutions, respectively, for Mish samples. total bacterial count (TBC; CFU/g), presumptive Microbiological examination coliform count (MPN/g), and isolation of E. coli As reported in Table 3, the TBCs of Ras, Domiati, were carried out according to the APHA guidelines and Mish samples were 2 × 108, 3 × 106, and 1 × (American Public Health Association) (2004). 107, respectively, while coliforms were determined Biochemical identification of E. coli (microscopic in 44%, 48%, and 92% of that examined in Ras, examination, oxidase, urea, IMVC, TSI, L-Lysin Domiati, and Mish samples, with a mean values of 3 decarboxylase, carbohydrate fermentation tests, and × 105, 5 × 10, and 5 × 102, respectively. The examined confirmed tests for thermotolerant (fecal) coliforms) samples were positive for E. coli in 8% of Ras cheese was carried out according to Silva et al.’s (2019) samples and in 4% of both Domiati and Mish samples, description. respectively, as shown in Table 5. The serological 298 http://www.openveterinaryjournal.com O.
Load more

Recommended publications
  • Bacteriology of Cheese V. Defects of Blue (Roquefort-Type) Cheese H
    Volume 25 Number 283 Bacteriology of cheese V. Defects of blue Article 1 (Roquefort-Type) cheese October 1940 Bacteriology of cheese V. Defects of blue (Roquefort-Type) cheese H. W. Bryant Iowa State College B. W. Hammer Iowa State College Follow this and additional works at: http://lib.dr.iastate.edu/researchbulletin Part of the Agriculture Commons, and the Dairy Science Commons Recommended Citation Bryant, H. W. and Hammer, B. W. (1940) "Bacteriology of cheese V. Defects of blue (Roquefort-Type) cheese," Research Bulletin (Iowa Agriculture and Home Economics Experiment Station): Vol. 25 : No. 283 , Article 1. Available at: http://lib.dr.iastate.edu/researchbulletin/vol25/iss283/1 This Article is brought to you for free and open access by the Iowa Agricultural and Home Economics Experiment Station Publications at Iowa State University Digital Repository. It has been accepted for inclusion in Research Bulletin (Iowa Agriculture and Home Economics Experiment Station) by an authorized editor of Iowa State University Digital Repository. For more information, please contact [email protected]. October, 1940 Research Bulletin 283 Bacteriology of Cheese v. Defects of Blue (Roquefort-Type) Cheese By H. W. BRYANT AND B. W. HAMMER AGRICULTURAL EXPERIMENT STATION IOWA STATE COLLEGE OF AGRICULTURE AND MECHANIC ARTS DAIRY INDUSTRY SECTION • AMES, IOWA • CONTENTS Summary 112 I n trod u c ti 0 n ______ ____________ ______ ____ _______ ______ _____________________________________ _________________ _______ 113 Methods _______________________________
    [Show full text]
  • Flavor Description and Classification of Selected Natural Cheeses Delores H
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by K-State Research Exchange Culinary Arts and Sciences V: Global and National Perspectives, 2005, ed. Edwards, J.S.A., Kowrygo, B, & Rejman, K. pp 641-654, Publisher, Worshipful Company of Cooks Research Centre, Bournemouth, Poole, UK Flavor description and classification of selected natural cheeses Delores H. Chambers1, Edgar Chambers IV1 and Dallas Johnson2 1The Sensory Analysis Center, Department of Human Nutrition, Kansas State University, Justin Hall, Manhattan, KS 66506-1407, USA 2Department of Statistics, Kansas State University, Dickens Hall, Manhattan, KS 66506, USA Abstract Intensities of 30 flavor attributes were measured for 42 cheeses. Rated intensities of flavor characteristics generally fell in the low to moderate range for all cheeses. Some of the flavor characteristics (dairy fat, dairy sour, dairy sweet, sharp, astringent, bitter, salty, sour, and sweet) were present in all cheeses, and some (cooked milk, animalic, goaty, fruity, moldy, mushroom, and nutty) were specific to only a few of the cheeses evaluated in this study. The flavor of each of the 42 cheeses is described. Similarities in flavor were observed among many of the individual cheeses. Therefore, a clustering scheme was developed to show the overall flavor relationships among the cheeses. Those relationships are schematically represented by a tree diagram. Proximity on the tree diagram indicates a high degree of flavor similarity among the types of cheese. Introduction In most countries, consumption of cheese has been on the rise over the past decades (Richards, 1989; Magretti, 1996; Havrila, 1997; Hoebermann, 1997; Anonymous, 2002).
    [Show full text]
  • A Guide to Kowalski's Specialty Cheese Read
    Compliments of Kowalski’s WWW.KOWALSKIS.COM A GUIDE TO ’ LOCALOUR FAVORITE CHEESES UNDERSTANDING CHEESE TYPES ENTERTAINING WITH CHEESE CHEESE CULTURES OF THE WORLD A PUBLICATION WRITTEN AND PRODUCED BY KOWALSKI’S MARKETS Printed November 2015 SPECIALTY CHEESE EXPERIENCE or many people, Kowalski’s Specialty Cheese Department Sadly, this guide could never be an all-inclusive reference. is their entrée into the world of both cheese and Kowalski’s Clearly there are cheese types and cheesemakers we haven’t Fitself. Many a regular shopper began by exclusively shopping mentioned. Without a doubt, as soon as this guide goes to this department. It’s a tiny little microcosm of the full print, our cheese selection will have changed. We’re certainly Kowalski’s experience, illustrating oh so well our company’s playing favorites. This is because our cheese departments are passion for foods of exceptional character and class. personal – there is an actual person in charge of them, one Cheese Specialist for each and every one of our 10 markets. When it comes to cheese, we pay particular attention Not only do these specialists have their own faves, but so do to cheeses of unique personality and incredible quality, their customers, which is why no two cheese sections look cheeses that are perhaps more rare or have uncommon exactly the same. But though this special publication isn’t features and special tastes. We love cheese, especially local all-encompassing, it should serve as an excellent tool for cheeses, artisanal cheeses and limited-availability treasures. helping you explore the world of cheese, increasing your appreciation and enjoyment of specialty cheese and of that Kowalski’s experience, too.
    [Show full text]
  • Cheese Classification, Characterization, and Categorization
    Cheese Classification, Characterization, and Categorization: AGlobalPerspective MONTSERRAT ALMENA-ALISTE1 and BERNARD MIETTON2 1Department of Nutrition and Food Sciences, University of Vermont, Burlington, VT 05405-0086, and Green Mountain Coffee Roasters, Waterbury, VT 05676; 2Expertise Agroalimentaire, 39800 Poligny, France ABSTRACT Cheese is one of the most fascinating, complex, and differentiation of cheese include the variability among diverse foods enjoyed today. Three elements constitute the fundamental processing and aging characteristics that cheese ecosystem: ripening agents, consisting of enzymes and influence both the chemical composition of the fresh microorganisms; the composition of the fresh cheese; and the cheese and its enzymatic potential during ripening. The environmental conditions during aging. These factors determine and define not only the sensory quality of the final cheese fundamental cheesemaking factors include (i) method of product but also the vast diversity of cheeses produced coagulation used to transform the original cheesemaking worldwide. How we define and categorize cheese is a milk into a gel or coagulum (e.g., acid versus rennet); complicated matter. There are various approaches to cheese (ii) acidification characteristics (both rate and time), classification, and a global approach for classification and from the point of setting the milk up through the man- characterization is needed. We review current cheese ufacture of the young or fresh cheese, which define the fi classi cation schemes and the limitations inherent in each of mineralization level of the casein but also moisture loss; the schemes described. While some classification schemes are based on microbiological criteria, others rely on descriptions of and (iii) additional steps during the cheesemaking pro- the technologies used for cheese production.
    [Show full text]
  • Bacterial Flora of Roquefort Cheese
    BACTERIAL FLORA OF ROQUEFORT CHEESE By ALICE C. EVANS Dairy Bacteriologist, Dairy Division, Bureau of Animal Industry, United States Department of Agriculture INTRODUCTION It is well known that various kinds of hard cheese, such as Cheddar and Emmental, or Swiss, depend on a suitable bacterial flora for their normal development. The two types of cheese mentioned have been studied extensively by a number of investigators. It has been shown that in the manufacture of Cheddar cheese there must be a rapid develop- ment of the lactic-acid bacterium Streptococcus lacticus, and that during the ripening a development of other forms of cocci and lactic bacteria of the bulgaricum 1 type is necessary to produce the typical Cheddar flavor (4).2 In Swiss-cheese manufacture the Bacterium bulgaricum is added, either in pure culture, as a starter, or unwittingly, with the nennet. What other microorganisms are responsible for the characteristic sweetish flavor, and for the development of the * 'eyes"; has not yet been estab- lished, but at any rate the ripening is due to the growth of bacteria, in distinction from the mold-ripened cheeses. It is obvious that in cheeses which are mottled with molds the molds play an important part in the ripening. The mold which ripens Roque- fort cheese, and also Gorgonzola and Stilton cheeses, has been named "Pénicillium roqueforti (Thorn)" (6). Currie (J) has shown that it hydrolyzes fat and the resulting acids have the peppery or burning effect on the tongue and palate which is characteristic of Roquefort cheese. In the making of Roquefort cheese, as in the making of Cheddar cheese, a rapid development of lactic-acid bacteria is necessary to bring about the proper physical condition of the curd in the various stages of manu- facture.
    [Show full text]
  • Types of Cheeses
    Types of Cheeses Asiago cheese is a nutty flavored cheese that hails from Europe. It is named for a region in Italy where it was first produced. This region is known as the Asiago High Plateau, which lies within the Italian Alps. Asiago cheese is produced in two forms as follows: fresh Asiago, also known as Pressato, and mature Asiago, which is called Asiago d´Allevo. Fresh Asiago has an off-white color and is milder in flavor than mature asiago. Mature asiago also has a more yellowish color and is somewhat grainy in texture. Blue cheese is a general classification of cow's milk, sheep's milk, or goat's milk cheeses that have had Penicillium cultures added so that the final product is spotted or veined throughout with blue, blue-gray or blue-green mold, and carries a distinct smell. Some blue cheeses are injected with spores before the curds form and others have spores mixed in with the curds after they form. Blue cheese was initially produced in caves Blue cheeses are typically aged in a temperature- controlled environment such as a cave. The characteristic flavor of blue cheeses tends to be sharp and a bit salty. Due to this strong flavor and smell, blue cheeses are often considered an acquired taste. They can be eaten by themselves or can be crumbled or melted over foods. Cheddar cheese originated in the village of Cheddar, England. A firm, cow's milk cheese that ranges in flavor from mild to sharp and in color from a natural white to pumpkin orange.
    [Show full text]
  • Varieties of Cheese
    Research Library Bulletins 4000 - Research Publications 1980 Varieties of cheese T A. Morris Follow this and additional works at: https://researchlibrary.agric.wa.gov.au/bulletins Part of the Dairy Science Commons, and the Food Processing Commons Recommended Citation Morris, T A. (1980), Varieties of cheese. Department of Primary Industries and Regional Development, Western Australia, Perth. Bulletin 4066. This bulletin is brought to you for free and open access by the Research Publications at Research Library. It has been accepted for inclusion in Bulletins 4000 - by an authorized administrator of Research Library. For more information, please contact [email protected]. CA1 Department of Agriculture, Western Australia. BULLETIN 4066 AGDEX 416/80 Varieties of cheese by T. A. Morris Chief, Division of Dairying and Food Technology VARIETIES OF CHEESE by T. A. Morris Chief, Division of Dairying and Food Technology While Cheddar cheese is by far the main type as far RIPENED CHEESE English speaking countries concerned, it is only as are Cheese ripened by bacteria one of a large number of varieties of cheese which are becoming more universal in production and con- This group includes those cheeses in which most of sumption. In other than English speaking countries the ripening and flavour development is a result of the Cheddar cheese is almost unknown and yet the con- action of bacteria within the cheese. In considering sumption of cheese in some of these countries is very these cheeses it is found that they can be formed into much greater. two sub-groups on the basis of the presence or absence of round holes known as "eyes" in the cheese.
    [Show full text]
  • Reference Manual for U.S. Cheese
    Reference Manual for U.S. Cheese CONTENTS Introduction U.S. Cheese Selection Acknowledgements ................................................................................. 5 5.1 Soft-Fresh Cheeses ........................................................................53 U.S. Dairy Export Council (USDEC) ..................................................... 5 5.2 Soft-Ripened Cheeses ..................................................................58 5.3 Semi-Soft Cheeses ....................................................................... 60 The U.S. Dairy Industry and Export Initiatives 5.4 Blue-Veined Cheeses ................................................................... 66 1.1 Overview of the U.S. Dairy Industry ...........................................8 5.5 Gouda and Edam ........................................................................... 68 1.2 Cooperatives Working Together (CWT) ................................. 10 5.6 Pasta Filata Cheeses ..................................................................... 70 The U.S. Cheese Industry 5.7 Cheeses for Pizza and Blends .....................................................75 5.8 Cheddar and Colby ........................................................................76 2.1 Overview ............................................................................................12 5.9 Swiss Cheeses .................................................................................79 2.2 Safety of U.S. Cheese and Dairy Products ...............................15 5.10
    [Show full text]
  • (Carica Papaya) PROTEASE in CREAM CHEESE PREPARATION by RESPONSE SURFACE METHODOLOGY
    OPTIMIZATION OF CRUDE PAPAYA (Carica papaya) PROTEASE IN CREAM CHEESE PREPARATION BY RESPONSE SURFACE METHODOLOGY by Nabindra Kumar Shrestha Department of Food Technology Central Campus of Technology Institute of Science and Technology Tribhuvan University, Nepal 2019 Optimization of Crude Papaya (Carica papaya) Protease in Cream Cheese Preparation by Response Surface Methodology A dissertation submitted to the Department of Food Technology, Central Campus of technology, Tribhuvan University, in partial fulfilment of the requirements for the degree of B. Tech. in Food Technology by Nabindra Kumar Shrestha Department of Food Technology Central Campus of Technology Institute of Science and Technology Tribhuvan University, Nepal May, 2019 ii Tribhuvan University Institute of Science and Technology Department of Food Technology Central Campus of Technology, Dharan Approval Letter This dissertation entitled Optimization of Crude Papaya (Carica papaya) Protease in Cream Cheese Preparation by Response Surface Methodology presented by Nabindra Kumar Shrestha has been accepted as the partial fulfilment of the requirement for the B. Tech. degree in Food Technology. Dissertation Committee 1. Head of Department ___________________________________________ (Mr. Basanta Kumar Rai, Assoc. Prof.) 2. External Examiner ___________________________________________ (Mr. Shyam Kumar Mishra, Assoc. Prof.) 3. Supervisor ___________________________________________ (Mr. Bunty Maskey, Asst. Prof.) 4. Internal Examiner ___________________________________________ (Mr. Yadav K.C., Asst. Prof.) Co-supervisor ___________________________________________ (Mr. Ram Shovit Yadav, Asst. Prof.) May, 2019 iii Acknowledgements I would like to express my heartfelt gratitude to my respected guide Asst. Prof. Mr. Bunty Maskey for his kind support, excellent guidance, encouragement and constructive recommendations throughout the work. I am really thankful to Prof. Dr. Dhan Bahadur Karki (Campus Chief, Central Campus of Technology) and Assoc.
    [Show full text]
  • Name That Cheese!
    FOURTH GRADE • LESSON 1 Be Strong! Get your calcium-rich foods! Name That Cheese! cheese on the “Cheese Please” form before Objectives: they taste it. After students have completed all • Students will be able to name at least four observations for this table, they can record what different types of cheese. type of cheese they think is on their “Cheese Please” form. Remind students that the four types Materials Needed: of cheese they are tasting today are identified on • Cheese (four different kinds of cheese made the board. with cows’ milk, with at least one low-fat choice) cut into small chunks – one per student Here are some examples of descriptive words for Examples: Swiss, Colby, low-fat cheddar, each kind of cheese: mozzarella (string cheese) — Swiss: shiny, pale, yellow, large holes, sweet, • Paper plates – one per student sharp, nutty • Note cards to number the stations — Colby: light yellow to rich orange, mild to • Pencils – one per student mellow, lightly sweet to sharp, tangy • Napkins – one per student — Cheddar: light yellow or golden orange, mild, • Four sheets of paper with each cheese type listed delicate • “Cheese Please” forms- one per student — Mozzarella: creamy, white, often molded into shapes, delicate, mild, milky Activity: Divide students into four groups and have them 1. Set up four observation stations around the room. go to their first observation station. Repeat until Number the stations 1-4 using note cards. Each each group has tasted each type of cheese. station will have a different type of cheese for the students to taste. 3. After students have been to all four stations, ask 2.
    [Show full text]
  • The Effect of Adjusting PH on Stretchability and Meltability to White Brined Nabulsi Cheese
    American Journal of Applied Sciences 6 (4): 543-550, 2009 ISSN 1546-9239 © 2009 Science Publications The Effect of adjusting PH on Stretchability and Meltability to White Brined Nabulsi Cheese 1Ayman Suliman Mazahreh, 2Jihad M. Quasem, 3Ali Faleh Al-Shawabkeh and 4Ibrahim Abdullah Afaneh 1Al-Balqa Applied University, Princes Alia University College, P.O. Box 941941 Amman 11194 Jordan 2Al-Balqa Applied University, Zarqa University College, Zarka, Jordan 3 Department of Basic Sciences, Faculty of Engineering Technology, Al-Balqa Applied University, P.O. Box 15008 Amman 11134 Jordan 4Department of Food Processing, Al-Quds University, P.O. Box 20002, Jerusalem, Via Israel Abstract: Problem statement: Boiled white brined (Nabulsi cheese) is the mostly consumed in Jordan; this cheese should show meltability and high stretchability in order to fit in the production of high quality Kunafa and other popular local sweets and pastries.The most outstanding characteristic of Nabulsi cheese is the long keeping ability (more than one year) without cooling, since it is preserved in concentrated brine (up to 25%). Approach: This work was based on the hypothesis that it would be possible to imply meltability and stretchability to the cheese by adjusting pH to the original brine that may specifically act on cross linking bonds of casein. A new apparatus for measuring the actual stretchability was designed and constructed; measurements on different cheeses proved its validity and reliability to measurement stretchability up to 80cm. Detailed treatments revealed the success of the proposed assumption in inducing meltability and stretchability to cheese processed and preserved according to the traditional methods. Results: The following results were obtained: It is possible to imply a low but acceptable level of stretchability and meltability through adjustment of the pH in the range of 5.4-5.8 by adding calculated amount of citric acid considering the buffering capacity of the cheese and storing it for few weeks to reach equilibrium.
    [Show full text]
  • Queso Fresco Cheese Treated with SFE at 120 Bar, 40°C for 30 Minutes For
    EFFECT OF REDUCED SODIUM CHEESE ON THE GROWTH OF PATHOGENIC BACTERIA AND INACTIVATION OF LISTERIA INNOCUA ON CHEESES USING SUPERCRITICAL FLUID EXTRACTION WITH CO2 A Thesis presented to the Faculty of California Polytechnic State University, San Luis Obispo In Partial Fulfillment of the Requirements for the Degree Master of Science in Agriculture, Specialization in: Food Science and Nutrition by Suyapa Padilla Antunez April 2016 © 2016 Suyapa Padilla Antunez ALL RIGHTS RESERVED ii COMMITTEE MEMBERSHIP TITLE : Effect of Reduced Sodium Cheese on the Growth of Pathogenic Bacteria and Inactivation of Listeria Innocua on Cheeses Using Supercritical Fluid Extraction with CO2 AUTHOR: Suyapa Padilla Antunez DATE SUBMITTED: April 2016 COMMITTEE CHAIR: Amanda Lathrop, Ph.D. Associate Professor of Food Science and Nutrition COMMITTEE MEMBER: Rafael Jimenez-Flores, Ph.D. Professor of Dairy Products Technology Center COMMITTEE MEMBER: Luis Castro, Ph.D. Assistant Professor of Food Science and Nutrition iii ABSTRACT Effect of Reduced Sodium Cheese on the Growth of Pathogenic Bacteria and Inactivation of Listeria Innocua on Cheeses Using Supercritical Fluid Extraction with CO2 Suyapa Padilla Antunez Listeria monocytogenes continues to challenge the dairy industry in causing post-process contamination of cheeses. To reduce risk of contamination, it is crucial to understand the growth and survival of pathogenic bacteria in cheese products and to develop post-process mitigation strategies. This study evaluated the fate of pathogens in reduced and regular sodium Mozzarella cheese, and the potential of Supercritical Fluid Extraction with CO2 (SFE) to reduce Listeria innocua on Mozzarella and Queso Fresco. The survival of L. monocytogenes, Salmonella, and E.coli O157:H7 (2-3 log CFU/g) in reduced sodium Mozzarella (1.62%), compared to regular sodium Mozzarella cheese (2.15%) at 4ºC and 12ºC for 90 and 30 days, respectively, was evaluated.
    [Show full text]