The conventional methods in microbiology involve the analysis of bacteriums, barms or molds by the usage of plating, proving biochemically or microscopy. But with advancement of clip, new methods in nutrient processing, accelerating gait of the nutrient trade and consumer demand for safer nutrient merchandises caused an ultimate displacement towards methods which were more accurate and faster which eventually led to the development of Rapid Microbiological Methods ( Baumgartner, 1995 ) . The mechanization and development of rapid methods in the field of microbiology has proved it to be a really dynamic country which makes usage of immunological, biochemical, biophysical and microbiological methods to ease early sensing of micro-organisms, the by-products produced by them and their numbering, word picture in clinical, nutrient, industrial and environmental samples ( Fung, 1992 ) . In the past 20 old ages the field of rapid microbiological methods has advanced to great degrees so much so that velocity, easiness of usage of operation and repeatability can be achieved in a really accurate and easy manner through mechanization. In present clip there are many companies which specialize in the industry and production of instruments to supply aid in rapid methods of sensing ( Robinson, 1995 ) . A rapid microbiological method to be of any important value must be proven to hold defined parametric quantities or properties of truth, preciseness, specificity, sensitiveness, selectivity and must be applicable in a assortment of research lab applications, this is one of the rule ways to place the viability of a method ( Archer, 1996 ) .
RAPID MICROBIOLOGICAL METHODS
Rapid methods have become an inseparable portion of the nutrient industry as the trade conventions convened over the old ages have passed a declaration that the quality of meat, its freshness and hygiene has to be determined by rapid methods which reduces the clip of proving by considerable sums ( B & A ; uuml ; lte and Reuter, 1984 ) .
The bioluminescence technique used for the finding of adenosine tri-phosphate is a really dependable method to gauge life cell, for case meat and meat merchandises. This method is based on the luciferin-luciferase system ( B & A ; uuml ; lte and Reuter, 1984 ) . Luciferin is found in luminescent organasims like fire beetles. Any technique or method using the luciferin-luciferase system is based on the measuring of visible radiation produced during the oxidization of luciferin in the presence of adenosine tri-phosphate and Mg ( John, 1970 ) . This method is typically used for proving meat and meat merchandises which involves the usage of samples from the surface of the meat merchandise. In instance of big meat atoms and any signifier of debris centrifugation method is employed to divide them from the sample. The luciferin-luciferase system is so used to mensurate the microbic ATP ( B & A ; uuml ; lte and Reuter, 1984 ) .
Direct EPIFLUORESCENT FILTER TECHNIQUE ( DEFT )
The direct epifluorescent filter technique more normally known as DEFT is used to find the microbic quality of milk and other sorts of nutrient merchandises. The most positive facet about this method which acts in its favor is that the structural features of microorganisms can be determined. The rule of this method is based on a bunch count in the milk sample which gives a closer consequence to plate counts which is used to mensurate the sum of bacteriums present ( Ubaldina and Kroll, 1985 ) . This technique makes usage of membrane fluorescence and epifluorescence microscopy and takes less than 20 five proceedingss to finish and is really accurate with milk incorporating 5 ten 103 to 5 tens 108 bacteriums per milliliter. Bacteria nowadays on the DEFT slides can be counted by usage of telecasting image analysis ( Pettipher and Rodrigues, 1982 ) .
The Coulter rule was developed in 1950 ‘s by Wallace H. Coulter who was subsequently helped by his brother Joseph R. Coulter, Jr. during his research. It was a really consecutive frontward method of go throughing cells through a sensing aperture. This technique laid a really strong base for the usage of automated cell numbering techniques and the instruments used for it in industries ( Graham, 2003 ) . Initially during the research on this method Wallace H. Coulter was working to achieve a light way of really little dimensions for better atom dimensions, nevertheless this required an internal aperture but the optical maser had non yet been invented so alternatively Coulter made usage of pulsations which terminated in an electrical way of little dimensions. This led to the detection of atom volume. This method can be employed for atom numeration of all finely divided particulate affair for case blood cells. The basic rule of this method is based on the ordinance of the electric resistance of electrical current way of little dimensions by the usage of D.C and an alternating field. The biological cells have really thin membranes therefore, when a high electrical frequence is applied and if the applied aperture current is besides of the same frequence the current flows through the cells and the coincident D.C produces a response with regard to the volume of the atom. The electrical feeling zone more normally known as aperture electric resistance technique can be combined with other feeling agencies such as light spread, polarisation and fluorescence to accurately sort the atoms or cells ( Morgan, 1996 ) .
Reflectometry is a method which measures the intervention forms of reflected moving ridges in comparing with mention contemplations to place the contemplation features of the sample. This method is largely employed to prove meat samples. The first phase in this procedure is to put up the instruments to mensurate coefficient of reflection of beef samples. The following phase involves the cooking the meat based on the parametric quantities used in the shear force testing of meat, this is used as the mention sample. The last measure is to compare the measurings obtained by the reflectometry system with that of the mention sample ( Schlutz, 2008 ) . It can besides be used to prove dirt samples and other solute concentrations ( Persson and Berndtsson, 1998 ) . For mensurating wet content in porous stuffs clip sphere reflectometry method is employed ( Cern & A ; yacute ; , 2009 ) .
Impedance microbiology is an old survey ; it was foremost presented by Stewart in July 1898 in The Journal of Experimental medical specialty. In this Stewart measured the electrical response curves following the rot of blood and serum which was similar to the curves obtained from the electric resistance systems in usage soon. The lone major difference was that Stewart was mensurating electric resistance alterations in surplus of 30 yearss whereas electric resistance now is a rapid microbiological method holding varied applications ( Silley and Forsythe, 1996 ) . Electric resistance measurings are based on the electrical alterations in little sums of solid or liquid media due to the growing and physiological activity of micro-organisms. During the procedure of measuring the chief parametric quantity provided is impedance sensing clip, this value is produced on sufficient production of microbic metabolites. This factor depends on initial concentration, the slowdown stage and the coevals clip of the turning beings ( Kleiss et al. , 1995 ) .
There are two chief techniques for mensurating in electric resistance microbiology, a direct method and an indirect method. In the direct method the electrodes are immersed in the same cell the inoculant is present in and the alterations in electric resistance consequence from alterations taking topographic point in the majority electrolyte which are produced by the metabolic activity of microorganism. The indirect method is employed when the salt concentration in the civilization stock is really high. In this method the microbic metamorphosis is measured by maintaining path of the C di-oxide produced in a chamber with electrodes and KOH ( Felice et al. , 1999 ) .
The technique of electric resistance measuring can be utilized to a great extent in the nutrient industry. The technique of entire feasible counts can be used to prove frozen veggies, grain merchandises, UHT low acid nutrients, confectionery, fish and meat merchandises ( Silley and Forsythe, 1996 ) .
In the milk industry electric resistance is used to supervise the growing of lactic acid bacteriums and other nutrient poisoning doing beings. The lactic acid bacterium content is monitored within the starter civilization by mensurating the electric resistance alterations caused due to the metamorphosis of the bacteriums within the sample. Any instability caused in this is usually attributed to bacteriophages which can be detected by utilizing a sensitive check ( Silley and Forsythe, 1996 ) .
The technique of electric resistance measuring is used to a great extent to prove for salmonella within nutrient samples. This has resulted in electric resistance microbiology being a recognized method for showing of carnal provenders. For the usage of electric resistance in the sensing of salmonella species within the sample, it is subjected to anaerobic conditions by supplying a big volume with little surface country. The usage of this status reduces the clip for sensing. The electric resistance method for sensing of salmonella species was accepted by the association of analytical communities after 17 collaborative lab tests were performed ( Silley and Forsythe, 1996 ) .
In the twelvemonth 1989, Phillips and Griffith reported that the Listeria species could be detected by electric resistance by doing usage of a somewhat changed medium incorporating acriflavine, Fortaz, nalidixic acid and aesculin. The electric resistance curve generated can be used to place between Listeria and non-listeria species ( Silley and Forsythe, 1996 ) .
The indirect electric resistance method is utilized to observe coliforms and e. coli within samples. The rule was based on the fact that coliforms could ferment lactose which changed the broth coloring material from ruddy to yellow and in instance of vitamin E coli it was its belongings to split the substrate methylumbelliferyl-?-D-glucuronide to give fluorescent methylumbelliferone ( Silley and Forsythe, 1996 ) .
The really first calorimetric measuring with regard to nutrient was done by Dubrunfaut, but he studied the energy and heat balance of a agitation VAT as he did non hold the modern calorimeters used today ( Wads & A ; ouml ; and G & A ; oacute ; mez Galindo, 2009 ) .
The procedure of microcalorimetry is based on mensurating a little amout of heat generated during biological procedures. The chief map of a microcalorimeter involves the measuring of heat formed during a thermodynamic procedure and can find exact values of heat content alterations or alteration in internal energy. It has great applications in the nutrient industry due to its truth, non-destructivity and high sum of sensitiveness. It can be utilized to explicate the forces stabilising the constructions of biological molecules ( Coimbra, 2009 ) .
Microcalorimetry is of the isothermal titration and differential scanning type ( Coimbra, 2009 ) .Isothermal titration calorimetry is used to place interaction between molecules like proteins, polyoses, DNA, lipoids. It can besides be utilized to mensurate the alterations in heat within colloidal systems ( Chanamai and McClements, 2001 ) . Differential scanning microcalorimetry is used to mensurate heat alterations in a sample under conditions in which the rise or autumn in temperature is controlled ( Coimbra, 2009 ) . Differential scanning microcalorimetry can besides be used to analyze alterations in proteins as a map of temperature. When proteins are denatured by the usage of thermic energy it leads to the break of assorted chemical forces and the alterations which result from this are reflected on a differential scanning microcalorimetry thermogram ( Li-Chan and Ma, 2002 ) .
Differential scanning microcalorimetry is used more widely in the nutrient industry as it is most adaptable in a varied scope of applications and gives a better apprehension of the nutrient components like oil and fats. Microcalorimetry is largely used to prove vegetable oil and deep fried or microwaved samples by comparing the differential scanning microcalorimetry features with that of the entire polar compounds, viscousness and colour alterations ( Li-Chan and Ma, 2002 ) .
Rapid microbiological methods have become an built-in portion of the industry particularly the nutrient industry as these methods can give accurate consequences in a really short period of clip as compared to conventional microbiological techniques. This saves the industry a batch of clip, money and it gives the consumers a satisfaction of the merchandise being safe as it has been tested by a dependable technique. The consequences obtained from these methods can be employed to keep better criterions of production and hygiene when fabricating a nutrient merchandise.