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Chiefly it is figured that the underreporting rate is as much as 95-96%. Only a low percentage of individuals with gastro intestinal diseases contact a physician. Moreover, the responsible agent is found in only a little ratio of investigated cases (Notermans and Hoogenboom-Verdegaal, 1992). Baird-Parker (1994) showed some causes for the elevated occurence of food borne disease. The elevation is likely the result of a combination of elements, including: improved reporting and statistical intellects due to alterations in reporting systems; shifts in agricultural practices; changes in food production and food utilization practices; identification of newly developing food originated pathogens; and vulnerability of populations to infections. Foodborne diseases are more probably to be life endangering for the immune-compromised aged individuals vulnerable by underlying health problems (Oblinger, 1988).Some microorganisms are ubiquitous in nature, habitating in soil and on vegetation and on animal carcasses. Some bacterial pathogens can reside in the intestinal tracts of animals and humans. Therefore, pathogens can introduce raw foods easily. The primary demand for foodborne disease of microbial root is that the organisms related gain access to a food and once present, the storage environment of food are efficient of encouraging development or survival. The capability of some potentially life frightening pathogens to endure or proliferate below refrigeration and in decreased oxygen environments, and in some levels the low number essential for disease output, signal the seriousness of the possible hazards.
Food originated diseases can be separated as (i) intoxications, (ii) toxin-regulated infections; and (iii) infections when microbes occupy and reproduce in the intestinal mucosa or other types of tissues (Anon, 1988). Intoxications are stimulated by consumption of foods containing either toxic chemicals or toxins created by microorganisms.
Bacteria that develop entero-toxins during colonization and development in the intestinal tract are the reason of toxin-mediated infections. Infectious or contagious microorganisms such as Salmonella, Campylobacter and Shigella can cause troubles if present even in low counts. Significant figures of Clostridium perfringens and Bacillus cereus must be consumed to develop intoxication (Notermans et al., 1994). The causal agents of food borne diseases may also be such entities as 'viable non-culturable' varieties of infective bacteria (Baird-Parker, 1994). Campylobacter jejuni has the distinctive characteristic of degenerating into a coccoid, non-culturable form in culture after a short period of inoculation (Saha et al., 1991). Microbe quantities of only 500 cells are efficient to have illness in man (Robinson, 1981). Researches for the identification and recovery of the coccoid Campylobacteria have established debatable results. Saha et al. (1991) isolated seven of sixteen non-culturable Campylobacter strains after transition through rat gut. Medema et al. (1992) experimentally proved that retrieval of the coccoid cells after transition through gut might be poor by using one day old chickens as animal models. Beumer et al. (1992) executed a wide series of works with non-culturable Campylobatter jejuni cells and stated that the presence of culturable cells is not possible when using simulated gastric, ileum and colon environments.
It has been subdivided foodborne pathogens and food related disease-causing factors into three groups according to the hazards they present: (i) severe diseases caused by Clostridium botulinum, Salmonella cholerae-suis, S. typhi, S. paratyphi A, Shigella spp., Vibrio cholerae, Hepatitis B virus and several mycotoxins; (ii) low risk rates with drastically spreading diseases caused by pathogenic microorganisms such as Escherichia coli, Listeria monocytogenes, Salmonella spp.; and (iii) moderate risks with average spread, with causal agents such as e.g. Bacillus cereus, Campylobatter jejuni, Clostridium perfn'ngens, Staphylococcus aureus, Vibrio parahaemolyticus, Yersinia enterocolitica. Table I constitutes the dominant bacteria as causative factors of foodborne diseases.
Notermans et al. (1994) showed a literature survey of particular or cumulative bacteria that have seemed to cause foodborne diseases over the last two dacades. These bacteria are represented in Table 2. Moulds exhibit in certain raw materials and processed foods can develop mycotoxins when developing under favourable circumstances (Notermans et al., 1992). Mycotoxins are heat stable mutagenic and they are very toxic in nature when orally consume. They are also carcinogenic and inducing different diseases in man and animals (WHO, 1976). Table 3 represents the predominant mycotoxins. Viruses are obligate intracellular parasites that cannot reproduce in food. The bulk of foodborne viruses important to human health are exhibit in the human intestine and are frequently transferred by food or water polluted with fecal material. Seafood consumed from water contaminated with human ravages is one of the most common vectors of human viral diseases. Hepatitis A virus has been the causal agent in outbreaks of contagious hepatitis diseases are generally transmitted by oysters, salads, cold meats, milk and milk products. Hepatitis A virus of Picomaviridae virus family cause polio, enteric cytopathogenic human orphans (ECHO) and Coxsackie viruses, which are also known as causative factors of foodborne viral infections (Fries, 1994). An upcoming viral pathogen is the Norwalk and Norwalk-like viral agent that has stimulated eruptions of gastroenteritis called Norwalk virus illness. Foods concerned have been raw vegetables, salads, raw shellfish and polluted water (WHO, 1976, Anon, 1986). The viral existence in raw seafood is sketched indirectly by the conclusion of fecal coliforms, but it has been established that this is not an capable tool for the counting of these viruses (Atmar et al., 1993).
Identification, assessment and management of food-related microbiological hazards
Verocytotoxin of Escherichia coli O157 in minced beef and dairy food products in Italy
Verocytotoxin (VT)-generating Escherichia coli (VTEC) are an eminent supply of severe disease in humans. VTEC may correlate to several serotypes, but strains of serotype O157:H7 are generally linked with haemorrhagic colitis and haemolytic uraemic syndrome (HUS) (Griffin and Tauxe, 1991). The GIT----gastrointestinal tract------ of ruminants, especially in cattle, represents the natural reservoir of VTEC pathogen. The infection can be taking place via transmission of this bacterial pathogen from animals to human beings by dissimilar routes, such as direct contact and contact with water and contamination of soil with ruminant manure -------Tozzi et al., 2001). On the other hand, E. coli O157 is regareded to be a typical foodborne pathogen (Armstrong et al., 1996) and lots of epidemiologic and microbiologic observations on large epidemic outbreaks have concerned the utilization of undercooked minced beef or raw milk (Coia, 1998).
Sensitive and specific analytical procedures have been discovered to identify E. coli O157 in different kinds of foods (Baylis et al., 2001). The immune magnetic separation (IMS) enrichment technique, particularly, has significantly improved the facility to isolate the organism and has been used in numerous surveys. VTEC infections are comparatively infrequent in Italy. Outbreaks have been seldom reported and the approximate annual occurrence of HUS in children aged 0-12 years is about 0.3100,000 residents (Tozzi et al., 2003). This calculation is about two or three times minor than those reported in the UK or in other European countries (Caprioli and Tozzi, 1998).
Even though this apparently little incidence, VTEC O157 has been isolated at diverse rates from the content of cattle intestines at slaughter, in particular at some stage in the warm season and on cattle farms (Conedera et al., 2001). Additionally contamination by this bacteria has been reported on cattle carcasses at slaughter (Bonardi et al., 2001), minced beef (Colombo et al., 1998), and unpasteurized cow and sheep (Rubini et al., 1999) milk.
Because only restricted studies were formerly conducted on foodstuffs in Italy, the target of this survey was to assess the incidence of VTEC O157 contamination in minced beef and in diverse types of dairy products (DP) gathered in different regions of Italy using the extremely sensitive IMS technique, thereby giving national data on the occurrence of this pathogen in food.
Antimicrobial resistance of Listeria monocytogenes isolated from dairy food products
The significance of dairy-based food as a factor for the virus disease transmission has been recognized; particularly in countries where hygienic standards are not strictly followed (Meyer-Broseta et al., 2003). Contaminated milk and milk products may can act as a harbour for different microorganisms which are accountable for several food-borne issues (Danielsson-Tham et al., 2004; MacDonald et al., 2005; Oliver et al., 2005). Listeria is well thought-out to be one of the main significant causes of food-borne diseases.
L. monocytogenes, a ubiquitous microorganism, is competent to cause severe Listeriosis infections in human beings (encephalitis, meningitis and septicaemia mainly in immune compromised individuals) and animals (mastitis, diarrhea and gastroenteritis) (2002; McLauchlin et al., 2004; Aygun and Pehlivanlar, 2006). L. monocytogenes has been implicated in various outbreaks and sporadic cases of disease primarily linked with the utilization of pasteurized milk, cheeses prepared from unpasteurized milk and other dairy based commodities that provide a good medium for the development and endurance of many pathogenic organisms in different countries (Kells and Gilmour, 2004; Manfreda et al., 2005). Generally, Listeria species existence in food is a signal of microbial contamination (Gilot and Content, 2002). The detection of Listeria using biochemical tests is hard, time-consuming and an inexact procedure. Due to this reason and for superior precision, PCR was used, depending on DNA/RNA composition of the organism rather than the phenotypic expression that may differ in accordance with development circumstances (Cocolin et al., 2002). The gene encoding for the invasive-associated protein (iap) is general to all Listeria species. The gene portions at the 3â€²and 5â€² ends are conserved for all Listeria species while the fundamental portions are species-specific. This feature makes the gene a perfect device for PCR to distinguish Listeria isolates and to be proficient to categorize them into dissimilar species (Gilot and Content, 2002). The iap gene, which encodes for the main extracellular protein p60, is an vital murein hydrolase essential for septum division in cell allotment (in a late step). Moreover, p60 provides to the adherence/attachment of Listeria to definite eukaryotic cells (Bubert et al., 1999). The extreme use of antimicrobials has led to the development of antimicrobial-resistant bacteria. Antimicrobials used as promoters for growth in animal feed have compacted the effects of infectious illness (for example, diarrhea, skin and organ abscesses and mastitis) but led to the distribution of antimicrobial-resistant L. Monocytogenes into the environment (Jansen et al., 2003). Identification of antimicrobial resistance of L.monocytogenes in humans and animals is of greatest significance in order to (a) distinguish alterations in the resistance patterns to generally used antimicrobials, (b) implement pro-active measures to manage the use of antimicrobial agents and (c) avoid the multiplication of multi-drug resistant strains which can have a lot of undesired effects (Harakeh et al., 2005). Antimicrobial resistance of L. monocytogenes may be coupled with the occurrence of a plasmid or resolute by genes that are exchanged by conjugation process. Also, mutational incidents in chromosomal genes can take part in a major role in developing resistance to Listeria species (Poros-Gluchowska and Markiewicz, 2003).
In Lebanon, the Bekaa Valley based dairy food products are utilized by many on a daily basis. In view of the marked significance of Listeria as food-borne pathogens, a study conducted in that region helped to assess the antimicrobial resistance of PCR-performed and prooved L. monocytogenes organisms isolated from dairy food products which are utilizeded raw in Lebanon. The foods incorporated in this study were: Baladi cheese (Lebanese cheese balls), Shankleesh (a mold ripened cheese) and Kishk (a dried fermented milk-wheat mixture), which are mostly produced in the Bekaa Valley (Saleh et al., 2009).
Carnobacterium maltaromaticum: Identification, isolation tools, ecology and technological aspects in dairy products
Strains from Carnobacterium maltaromaticum are facultative anaerobic, catalasenegative, Gram positive rod shaped LAB which creates L (þ)-lactic acid from glucose (Collins etal., 1987). Their presence at various levels in food including fish, meat and dairy products has resulted in an increased number of scientific investigations to study their ecology, role and effect on these food products. For decades, the emphasis has been on product developments in the dairy industry with respect to organoleptic properties and/or health protection such as the control of food borne pathogens. As discussed in this review, the major potential role of C. maltar- omaticum might be as a ripening flora by producing flavouring compounds and as a bio preservative flora, by inhibiting the growth of food borne pathogens.
Carnobacterium species constitute a genus of Lactic Acid Bacteria (LAB) present in different ecological niches. The aim of this article is to summarize the knowledge about Carnobacterium maltaromaticum species at different microbiological levels such as taxonomy, isolation and identification, ecology, technological aspects and safety in dairy products. Works published during the last decade concerning C. maltaromaticum have shown that this non-starter LAB (NSLAB)could present major interests in dairy product technology. Four reasons can be mentioned: i) it can grow in milk during the ripening period with noncompetition with starter LAB, ii) this species synthesizes different flavouring compounds e.g., 3-methylbutanal, iii) it can inhibit the growth of food borne pathogens as Listeria monocytogenes due to its ability to produce bacteriocins, iv) it has never been reported to be involved in human diseases as no cases of human infection have been directly linked to the consumption of dairy products containing this species.
Serotypes and virulence genes of Shiga toxin-producing Escherichia coli identified from ovine and caprine milk and other dairy products in Spain
The target of a research conducted in Spain was to determinate the occurrence, serotypes and virulence genes of Shiga toxin-generating Escherichia coli (STEC) strains isolated from diverse dairy products (DP) with the intention of determining whether DP signify a possible source of STEC pathogenic for humans. A total of 502 DP Samples were collected from 64 dissimilar ovine and caprine flocks and 6 dairy plants in which unpasteurised milk collected fresh cheese curds included. Samples were examined for STEC using PCR methods. A total of 9 STEC strains were identified in this research. PCR showed that the strains carried stx1 genes, stx2 genes and some contained both stx1 and stx2. Only O157:H7 serotype exhibited virulence factors. The strain O157:H7 identified possessed intimin type g1. This research confirms that DP is a significant pool of STEC pathogenic for humans.
Shiga toxin-producing Escherichia coli (STEC), also named verotoxin-producing E. coli, is the most vital recently emerged group of food-borne pathogens, specially the serotype O157:H7 (Paton and Paton, 1998). STEC intricate two potent phage-encoded cytotoxins named Shiga toxins (Stx1 and Stx2) or verotoxins (VT1 and VT2). A number of serotypes belonging to STEC can result severe diseases in human beings, together with hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS), and thrombocytopenic purpura (TP), which may establish fatal in immune compromised patients (Banatvala et al., 2001). It is now usually approved that the key portion of the histo pathological lesions connected with both HC and HUS is a result of the contact of Stx with endothelial cells. In addition to toxin production, an additional virulence-associated factor articulated by STEC is a protein named intimin, which is accountable for the close connection of STEC to intestinal epithelial cells, leading attaching lesions in the intestinal mucosa. Intimin is programmed by the chromosomal gene are, which is separation of a pathogenicity island named the locus for enterocyte effacement (LEE) (Donnenberg et al., 1997). A factor that may also influence virulence of STEC is the entero haemolysin (Ehly), also called entero haemorrhagic E. coli haemolysin (EHEC HlyA), which is encoded by ehxA gene (Schmidt et al., 1995). Ruminants like cattle, sheep and goats, can carry STEC and O157:H7 in their faeces, they are considered as reservoirs of these pathogens (Beutin et al., 1993; Blanco et al., 2001). Recently, it has been established that in Spain a half of the investigated animals especially sheep feces carry these bacteria (Blanco et al., 2003; Rey et al., 2003). Transmission takes places during utilization of undercooked meat, unpasteurized dairy food products and vegetables, or water spoiled by faeces of carriers. In addition, person-to-person transmission has also been acknowledged.
Comparatively little information is obtainable about the occurrence of isolation of STEC from ill persons in Spain since most laboratories do not regularly culture for this organism (Blanco et al., 2004). Given the importance of ovine and caprine livestock in our country, and the fact that several milk products from such species are not treated with any prior bacteriological sterilisation procedures, the aim of the present research was to examine the status of STEC O157:H7 and STEC non- O157 in ovine and caprine milk and other dairy products in order to determinate the possible risk that the expenditure of these products can have from the standpoint of public health and hygiene.
Evaluation of enrichment procedures for recovering
Listeria monocytogenes from dairy products
Outbreaks of human Listeriosis which is a food-associated illness (Schlech et al., 1983) have encouraged current efforts towards developing efficient methods for recovery of Listeria monocytogenes from foods. For several years, L. monocytogenes was considered as mainly a zoonotic pathogen, and laboratory detection of this pathogen from infected tissues depended upon the capability of the organism to endure and develop at low temperatures (Gray et al., 1948). This approach entails long-term incubation periods, up to a number of weeks, and is evidently not appropriate for epidemiological observations of outbreaks, or for the routine monitoring of food products.
To cut down the time for isolation of L. monocytogenes from foods numerous selective enrichment procedures, each using dissimilar media preparations and plating technics, have been discovered. The U.S. Centers for Disease Control has established a two-stage enrichment protocol for dairy food products which includes preliminary non-selective cold enrichment incubation and it is succeeded by a 24 hour secondary selective enrichment at 37Â°C. Doyle and Schoeni (1986) have given an enrichment technique using a selective broth incubated for 24 h below aerobic conditions suitable for microorganisms. At the same time as these procedures have been reported to have same efficiency in improving low numbers of L. monocytogenes inoculated straight into raw milk, only some experiments have been performed to evaluate the efficiency of such procedures to recover the pathogen from contaminated product (McClain and Lee, 1988).
Occurrence of Yersinia enterocolitica in milk and dairy products in Morocco
Yersinia enterocolitica is a ubiquitous Gram-negative bacterium potentially pathogenic for man and has been associated with human gastro-intestinal infections (Amsterdam et al., 1984). Y. enterocolitica can multiply rapidly at normal refrigeration temperature (Stern et al., 1980). This microorganism has been isolated in different countries particularly from raw milk (Christensen) and pasteurized milk (Walker and Gilmour, 1986). The occurrence of Y. enterocolitica in derived dairy products was rarely reported. A previous investigation (Hamama and El Mouktafi, 1990) conducted on the incidence of Y. enterocolitica in raw milk produced in Morocco, indicated the presence of this organism in 40.4% of the samples. The purpose of the present study was to ascertain whether Y. enterocolitica could be isolated from Moroccan dairy products made from either raw or pasteurized milk and obtained from both traditional dairies and modern dairy plants.
Food Safety Interventions for Dairy Production
It is well observed that foodborne diseases cause major economic losses. In the United States alone, the foodborne diseases responsibe for millions of diseases, high hospitalizations and deaths each year (Mead et al., 1999). several agents accountable for food originated diseases have only recently been identified. Well-publicized food borne illness outbreaks have produced widespread consumer consciousness of potential intimidation to human health from food. Modern communication systems have improved consumer awareness of outbreaks that take place around the world and have declined the sense of safety connected with distance. Geographical restrictions to the spread of ailment have been condensed by the globalization of food systems and by the regular transportation and other factors. Consumer self-assurance in available food handling and processing systems has been cut down by the appearance of transmissible spongiform encephalopathies related with animal products (Boor and Brown 2001). The potential for further animal or human disease causing pathogens to endure existing food processing methods (for instance pasteurization) is an area of ongoing research (Grant et al., 2002). The dairy industries have been enormously flourishing in processing safe and nutritious food items. Milk is an enriched food and it is very suitable for development of pathogenic organisms. Utilization of raw milk is considered as a risk factor for foodborne illness, but pasteurization has been shown as a highly effective method in ensuring the safety of dairy food products (Headrick et al., 1998). Milk and other milk products such as ice cream, and cheese have been noted as the medium for less than 1.35% of all food originated illness outbreaks reported by the Centres' for Disease Control (Bean et al., 1996). In the case of pasteurized dairy products, errors in the pasteurization procedures or the incorporation of non pasteurized eggs have regularly been recognized as the route of spoilage (Ryan and Nickels, 1987). Errors that take place during pasteurization, expenditure of raw milk products, contamination and spoilage of milk food products by heat-resistant pathogens, milk adulteration with chemicals, and foodborne disease transmission by dairy cows are measured as potential harm to human health associated to the dairy industry. A supplementary concern is transmission of zoonotic pathogens -----animal originated pathogens-------- to farm workers and visitors. The antibiotics and its use in animal agriculture in the growth of antimicrobial resistance is divisive and gradually scrutinized (Khan et al., 2000; White et al., 2001). The dairy food products safety can be improved by implementation of a number of management practices.
Consumers are more and more anxious about the safety of their food and unsure about food production procedures. Potential hazards to human health associated with dairy products and dairy farming industry consist of pasteurization faults, utilization of raw milk food products, contamination of milk and milk products by developing heat-resistant pathogenic organisms, emergence of antimicrobial resistant zoonotic pathogens, milk adulteration practices with hazardous chemicals, transmission of pathogens to humans during animal contact, and foodborne illness correlated to cull dairy cows. Microbial contamination of milk and its possible routes must be controlled or regulated by adoption of different hygienic practices that can be simply evaluated. Uniform adoption of milking practices has been shown that its efficacy in the reduction of microbial contamination of milk and milk products. Salmonellosis or listeriosis diagnosis on a dairy farm should be taken in an account as a warning that other severely infected animals may be present in the farm. Coliform counts should be regularly performed and its count in milk tank is considered as an indicator of faecal contamination. Dairy farmers should take attention on their market cattle leaving their farms. The inapt or prophylactic use of antimicrobial drugs must be reduced to make sure that antimicrobial resistance does not build up in animal pathogens.
SCOPE OF DAIRY FOOD SAFETY ISSUES
Healthy dairy livestock are regarded as a pool for numerous important food borne human disease pathogens. Nontyphoidal Salmonella spp., and Campylobacter jejuni are well thought-out as a significant threats to food safety for the reason that of the enormous number of diseases they result. Listeria monocytogenes and Escherichia coli O157:H7 are predominant pathogens due to the severity of symptoms related with infection and the number of deaths that happen in contagious people. These bacterial pathogens are shed in cattle feces and can contaminate farm premises together with unpasteurized bulk tank milk. In some cases, colonization of the pathogens in the udder can also donate to spoilage of bulk milk provisions. Salmonella spp., are an occasional source of mastitis in dairy cows but some species of Salmonella have been renowned to colonize udder regions and shed at levels of up to 1500-2000 organism/ml (Tauxe, 1997). Listeria monocytogenes has been notified to cause mastitis and can be drop in milk. For example, a research that observed >500 isolates of milk gained from coliform mastitis cases was not capable to isolate O157:H7 from any of the samples they tested and E. Coli O157:H7 has not been documented as a cause of mastitis disease in cows (Cullor, 1997). C. jejuni can be existing in milk, but fecal contamination of milk could be the way of exposure. Pasteurization of milk is very efficient when regulatory standards for bacterial populations in unprocessed milk are met, in killing all of these bacterial pathogens.
There are different primary routes of possible exposure of humans to these pathogens and other dangerous hazards to human safety connected with the dairy industry: 1) intake of contaminated raw milk, 2) contact with fecal contaminated beef, and infected animals. Consumption of raw milk is a high-risk factor that is recorded by a small quantity (<5%) of the overall US population but can be a considerable risk factor for definite subpopulations (Yang et al., 1998). Use of raw milk and its products occurs normally in dairy farm workers (Reed and Grivetti, 2000).
Fecal contamination of dairy cattle carcasses and consumption of not properly cooked hamburger is a source of E. coli O157:H7 exposure and numerous other pathogens, and some of the most lethal disease outbreaks have been coupled with such type of exposure. zoonotic diseases can be originated by the direct or indirect contact with infected animals. Farm environment, living in an area in nearness to farm animals, and living habitatnear by manure have all been recognized as important risk factors for E. coli O157:H7 (O'Brien et al., 2001; Valcour et al., 2002). The general feature of these potential exposure routes are the occurrence of fecal contamination, and it is instinctive that the decrease of fecal contamination of food should be a main purpose of food safety programs.
POTENTIAL CONTROL POINTS FOR DAIRY FOOD SAFETY
There is sufficient proof that milk contamination by microbes can be inhibited by the use of identical best administration practices. Mastitis control programs aiming on hygienic yield of milk have been extensively adopted for at least few years. Farmers have gained incredible success in dropping the occurrence of infectious mastitis by adopting the five basic principles of mastitis disease control: postmilking teat disinfection process, dry cow antibiotic treatment, suitable management of clinical cases, culling of severely affected cows, and milking machine maintenances. Infectious bacteria like Staphylococcus aureus and Streptococcus agalactia, are now accountable for a lesser amount of one-third of all mastitis cases in contrast with >70% of all cases nearly two decades ago (Hillerton et al., 1995).
Although many factors of the five-point mastitis regulations plan have been broadly adopted, many other best control strategies are not extensively used. Regular recording of disease and its treatments, operating procedures, usual observations that involve frequent diagnostic tests and involvement in quality control systems have not been broadly adopted in the dairy industries (Wilson et al., 1998; Ruegg, 2001).
HACCP - Hazard analysis critical control point
Hazard analysis critical control point (HACCP) programs have been graded as the solution for dairy food safety assurance (Reneau et al., 1998). HACCP programs need decisive reviews of management processes which exists, the organization of restrictions via recognition of critical control points, the use of regular observation trials, successful record maintenance, and records of standard processes etc. The technology and other related procedures to perform on-farm HACCP programs is somewhat restricted by high expensive available testing methods (Gardner, 1997). Alternative approaches such as "Hurdle Technology" aroused and became very relevant due to these restrictions have led some to avoid farm-level HACCP programs (Heggum, 2001).
Hurdle technology is an application of a grouping of particular "hurdles" to microbiological development joint with processing steps that sustain and progress the microbial stability and food qualities (Leistner, 2000; Heggum, 2001). Hurdles frequently used in food processing are focussed at microbial growth restriction in food products and consist of process such as chilling, variation in pH, the use of microorganisms and changes in water content (Leistner, 2000). The production of a hostile environment that is favourable for the growth of microorganisms is the basic concept of hurdle technology. But farm based hurdle technology concept may be consists of best management practices to exclude the bacteria from raw milk supplies. For instance, in the United States the production of milk is governed by a primary regulatory document which implicit the use of ''hurdles'' to microbial growth. The Pasteurized Milk Ordinance emphasises production standards and milk processing, its handling and transportation etc (Anonymous, 1999).
PRACTICAL INTERVENTIONS FOR DAIRY FARMS
There are several practical on-farm management methods that can be adopted to improve dairy product food safety. For example, The North American dairy industry presently produces safest and nutritious food products and distributing them in the world.
1. Reduce the contamination of milk. To reduce the growth and transmission of pathogenic microorganisms, relevant hygienic standards emphasize proper hygiene of housing area and milking centers of cows. Regular evaluation of farm hygiene with the aid of scoring systems can be used to inspire farmers. Udder hygiene scoring charts shows cows with dirtier udders have considerably higher occurrence of infection with mastitis causing pathogens (Schreiner and Ruegg, 2002, unpublished).
(Figure 1. Udder hygiene scoring chart (Schriener and Ruegg, 2002).
Reduced of milk contamination by uniform adoption of milking practices
Many farms are presently using high cleaning practices during milking process. For instance, the uses of predipping and forestripping practices have been shown to improve milk safety (Galton et al., 1986). The use of iodine as a disinfection agent in predipping has been shown to decrease plate counts and coliform bacterial counts in raw milk when compared to other practices of premilking udder preparation. The predipping approach is very effective and has shown its efficiency in the overall decline of zoonotic microbial counts in raw milk. For example, Predipping has been revealed to trim down the hazard of Listeria monocytogenes in milk filters (Hassan et al., 2001). It is important that the assessment of milk before connecting milking units. Like predipping, forestripping practice has also been exposed to considerably reduce the risk of contamination by L. monocytogenes (Hassan et al., 2001).
Perform coliform counts.
To recognize bacteria that originate from fecal contamination of milk there should be a regular test carries out based on coliform counts in the raw bulk tank milk. These bacterial populations can spoil milk during poor udder preparation or unhygienic usage of the milking machines. The bacterial counts should be fewer than 100 cfu/ml for milk planned to be pasteurized before utilization. Coliforms can persist in residual films left on milking pipelines or machines. The equipment cleaning process should be investigated if the Coliform counts greater than 1000 cfu/ml, because it indicate the incubation of coliforms in the milk (Boor et al., 1998).
HACCP-based rapid detection methods for microorganisms
HACCP system is fetching progressively more established in food control. Hazard analysis critical control point is a management tool and it is very capable to advance the quality of products and also more safe to improve the efficiency of operations associated with the product manufacturing. The major hazards by microbiological contamination of food productions can be successfully reduced by the adoption of HACCP tools (Campbell-Platt, 1994). A better perceptiveness of the microbiology of the foods and its ingredients is also an crucial part of developing an HACCP concept. When a system has been appropriately conceived, implemented, observed, demonstrated and reviewed then it give a better guarantee of the microbiological status of the food products. This is the concept of a HACCP program. It is far better than that when relying on end-product testing (Jouve, 1994). Traditional microbiological methods are time consuming one and to detect and enumerate foodborne microorganisms for a reliable result it takes more time periods. This is because of, in many cases; the products have already been utilized by the consumers before the testings are finished. Consequently, optional assays based on diverse microbiological methods are frequently being developed (Vasavada, 1993). Commercial methods in food microbiological testing include impedimetry, direct epifluorescence microscopy, ATP bioluminescence, turbidometry, immunological methods and methods based on gene technology are extremely automated therefore they reducing other manual works. DNA or RNA analysis provides rapid results and gives exact information about the micro organisms responsible for the food contamination. Immunological assays can also provide information about the microbial metabolites.
The HACCP system is also capable to control the microbiological threats that may occur in food preparations or handling operations. Also HACCP does not depend post-testing procedures and it is more flexible and can take part in all stages of food production and its distribution within strict control limits (Smith et al., 1990). These peculiarities make HACCP a superior management tool in food industries. According to Notermans et al. (1994), to identify potentially hazardous microorganisms associated with a particular food product, the hazards related with each microorganism and the possibility of their incidence must be assessed. HACCP is a highly efficient strategy that analyses the Critical Control Points (CCPs) at which the possible hazards can be managed. After detection of potentially dangerous microorganisms, their microbial counts in raw food materials are calculated. Following these steps Storage tests and predictive microbiological tests can be performed to obtain information about whole food manufacturing process on the numbers of potentially harmful pathogens. On-line biosensors are recently integrated in HACCP system as a rapid monitoring method to identify microorganisms in food industry (Goldschmidt, 1993).