Microbiological analysis is an of import technique to guarantee the quality and safety of the nutrient merchandises for ingestion. Conventional microbiological methods are normally used for the designation and numbering of harmful micro-organisms in nutrient merchandises. However, these methods are clip devouring and boring ( Vasavada, 1993 ) . Furthermore, these methods can non be used during the processing system of nutrient merchandises ( Bell et al. , 1994, Damez and Clerjon, 2008 ) .
In modern nutrient processing industries, rapid microbiological techniques are going an of import tool over conventional methods because rapid techniques provide consequences more rapidly than conventional methods as it require less clip for the readying and processing of samples and reading of the consequences. In add-on, the usage of rapid microbiological techniques increases the entire figure of samples which can be analysed per twenty-four hours which is boring work to execute by conventional microbiological analysis ( Vasavada, 1993 ) .
Rapid microbiological methods are automated or semi automated methods such as electric resistance measuring, conductance analysis, bioluminescence, colorimetric analysis, enzyme-linked immunosorbent check ( ELISA ) , flow cytometry, reflectometry, radiometry etc. which are now a yearss normally used for the rapid sensing of micro-organisms during the processing system of nutrient merchandises ( White, 1993, Vasavada, 1993 ) .
Impedance measuring is an of import transduction technique used in microbiological analysis of nutrient merchandises ( Madrid et al. , 1999 ) . When micro being grow in the civilization medium, so its growing and metabolic activity transforms proteins, saccharides and fats into smaller, extremely charged terminal merchandises such as aminic acids, lactate, acetate etc ( Vasavada, 1993 ) .
Furthermore, the metabolic activity causes alterations in the chemical composing of civilization media such as ionic content. The alteration in ionic content of civilization medium further changes the conduction of civilization stock which can be monitored by the usage of electrodes on an alternating current fluxing through the medium and therefore electric resistance can be measured ( Swaminathan and Feng, 1994 ) .
The mensural electric resistance determines the microbic content in the medium ( Madrid et al. , 1999 ) . Impedancimetry is besides used for the sensing of aerophilic mesophiles, fecal and entire coliforms ( Orsi et al. , 1997 ) . Bactometer and Malthus system instruments are used to mensurate the electric resistance and conductance alterations in the medium ( Vasavada, 1993 ) .
Impedancimetry technique has been approved by AOAC ( Association of Official Analytical Chemists ) for its usage in the nutrient borne pathogens such as Staphylococcus aureus, Clostridium Botulinum, Listeria monocytogenes, Yersinia enterocolitica and Campylobacter. It has besides been by experimentation observed that electric resistance technique can be used for the measuring of microbic contaminations in juices and drinks ( Vanne et al. , 1996 ) .Furthermore, impedancimetry can be used as a powerful tool for the monitoring of assorted beings such as entire aerophilic mesophiles, fecal and coliform in dairy and ready to utilize veggies ( Orsi et al. , 1997 ) .
Impedancimetry technique can be used for the quality indicant of meat as a non destructive method. As meat is electrically anisotropic and its electrical belongingss depends on the way of the electrical field in the sample. It has been studied that the electrical belongingss can be measured by puting the electrodes in three different waies in meat. Furthermore, the electric resistance value of musculus reduces quickly during the pre-rigor phase in porc and beef and is an index of ageing of meat ( Lepetit et al. , 2002 ) .
It has been studied and observed that impedancimetry techniques can be used as a rapid method in the milk processing works for mensurating the sum, mesophilic and psychrotropic counts in natural milk ( R and M. K, 1983 ) .
ATP- bioluminescence is another rapid method for gauging the populations of micro-organisms in nutrient sample every bit good as on the clean surfaces, utensils ( T. R, 1985 ) and procedure equipments ( Vanne et al. , 1996 ) . Furthermore, it is besides helpful in keeping hygiene in nutrient processing works ( de Boer and Beumer, 1999 ) .
ATP – bioluminescence is a rapid method which measures the figure of bacteriums nowadayss in the sample by mensurating the visible radiation produced by the stoichiometric transition of ATP into photons of visible radiation ( Griffiths, 1993 ) . Microbial and nutrient ingredients cell contains adenosine-5-triphosphate ( ATP ) which is calculated by utilizing the luciferin- luciferace enzyme composite found in the tail of firefly Photinus pyrali ( Figure 1 ) ( de Boer and Beumer, 1999 ) .
Figure 1: Representation of the fire beetle luciferase reaction ( Griffiths, 1993 )
The entire light end product of the sample is straight relative to the sum of ATP present and can be measured by luminometer ( de Boer and Beumer, 1999 ) . It has been observed that ATP bioluminescence method can be used to observe every bit few as 1 x 104 cfu/ml of bacteriums in nutrient within 5 to 10 min ( Griffiths, 1993 ) .
ATP bioluminescence technique can be applied in dairy industry to measure the hygiene of nutrient contact surface in assorted state of affairss ( Vilar et al. , 2008 ) . Furthermore, it has been claimed that ATP-bioluminescence technique can be used to observe the bacteriums in milk up to the concentration of 1 ten 104 within 5 to 10 proceedingss. This rapid analysis of bacteriums in milk makes the technique utile as a rejection parametric quantity for the entrance milk in milk processing industry. However, it has besides been claimed that the technique can mensurate 24 samples within 1-2 hours without culturing ( Griffiths, 1993 ) .
ATP – bioluminescence technique can besides be used in microbic analysis of nutrient such as porc and beef carcases ( Vilar et al. , 2008 ) .Furthermore, the technique can be used as an index of bacterial activity and can besides be used to observe the presence of antibiotic residue than the methods based on acerb production in milk ( J et al. , 1993 ) .
ATP – bioluminescence technique has a possible to be utilised as a tool for quality control of fruit juices. It has been analysed that the technique can be used during the processing operation at ambient status for the measuring of active population of barm and bacteriums in fruit juices ( T. R, 1985 ) .
Flow cytometry method
Flow cytometry is another rapid technique which is used to mensurate the microbic populations and can be used for both qualitative and quantitative analysis of nutrient ( Comas-Riu and Rius, 2009, Gunasekera et al. , 2000 ) .It is highly sensitive method and avoids the demand for culturing processs ( Gunasekera et al. , 2000 ) .
Flow cytometric technique measures the microbic population of the sample by utilizing the rule of light dispersing and emanation of fluorochrome molecules. A flow cytometer consists of several systems such as light beginning ( laser visible radiation ) ; series of lenses ; optical filters and light sensors ( photodiodes or photomultipliers ) .In its operation, the sample is injected into the Centre of the sheath flow, coercing the cell to go through across the focused visible radiation and the system detects the microbic population by mensurating the signal produced by light sensors ( Figure 2 ) . It has been observed that the system can observe up to 100,000 cells ( Comas-Riu and Rius, 2009 ) .
Figure 2: Diagram of flow cytometry technique ( Comas-Riu and Rius, 2009 ) .
Flow cytometry technique can be applied in dairy industry for the measuring of entire bacterial Numberss. It has been observed that the sensitiveness of the flow cytometry method is less than 104 entire bacteria/ml of natural milk. Furthermore, the method takes 30 seconds aa‚¬ ” 2 proceedingss for the measuring depending upon the figure of bacteriums present in the natural milk ( Gunasekera et al. , 2000 ) .
Flow cytometry technique can be used as an index for the microbiological quality of milk ( Comas-Riu and Rius, 2009 ) . Furthermore, the technique has besides been used for the sensing of listeria monocytogenes in natural milk and salmonella spp. in processed milk ( Gunasekera et al. , 2000 ) .
In add-on of that, it has been besides found that the flow cytometry technique is appropriate for the monitoring of the growing of bacteriums in refrigerated natural milk, homogenized milk and flavoured milk during the shelf storage period ( Gunasekera et al. , 2000 ) .
Enzyme linked immuno-sorbent check ( ELISA )
Enzyme linked immuno-sorbent check is another rapid method for the analysis of mycotoxins in nutrient merchandises and has been used since a decennary for the analysis of toxins. The technique works on the footing of interaction between antibody and antigen ( Asensio et al. , 2008 ) . In its operation, the mycotoxin is foremost extracted from the land sample with the aid of dissolver followed by the commixture of a part of the sample infusion and a conjugate of an enzyme coupled mycotoxin and so is added to the antibody-coated micro-titer Wellss.
Further any mycotoxin nowadays in the sample infusion or control criterions is legitimated to vie for the antibody adhering sites with the enzyme-conjugated mycotoxin. After rinsing the micro titre Wellss, add-on of an enzyme substrate is done and the add-on consequences in the development of bluish coloring material. The color strength is reciprocally relative to the concentration of mycotoxin in criterion or sample.
Furthermore, a solution is so added to halt the enzyme reaction and the strength of the solution coloring material in the microtiter wells is measured optically utilizing an ELISA reader
with an optical density filter degree of 450 nanometers. The optical densenesss ( OD ) of the samples are so compared with theoptical densenesss of the criterions followed by the finding of interpretive consequence ( Zheng et al. , 2006 ) .
ELISA is used in the finding of genuineness of nutrient such as meat, fish, milk merchandises, fruit juices etc from debasement ( Asensio et al. , 2008 ) . Furthermore, ELISA is besides loosely used as an effectual showing tool in regulative, residuary and industrial research labs ( M. Vass et al. , 2008 ) as it is the rapid technique for observing the concealed allergens in nutrient ( Poms et al. , 2004 ) .
Radiometric technique is another rapid method for the analysis of microbic concentration in nutrient merchandises. Radiometry techniques plants on the measuring of CO2 produced by micro-organisms by the transition of 14C-labeled substrates and the measuring of CO2 is done by the instrument named as Bactec ( W. S et al. , 1977, Durwood B et al. , 1978 ) .
Radiometric Technique is a showing method for finding whether the nutrient is safe to devour or non within few hours as compared to the conventional methods such as standard home base count which takes 24 -48 for the analysis ( W. S et al. , 1977 ) .
It has been by experimentation observed that radiometric technique is every bit effectual to plate count technique for the measuring of micro-organism and can be used in the microbiological analysis of cooked and frozen nutrients ( Durwood B et al. , 1978 ) .
Coefficient of reflection colorimetric analysis
It is a rapid microbiological technique for the sensing and numbering of bugs such as coliform, barm and cast. The technique works on the rule that the growing and metamorphosis of micro beings in the sample changes the dye pigmentation, which can be measured straight by coefficient of reflection colorimetric analysis ( Vasavada, 1993, Gunasekera et al. , 2000 ) .
It has been by experimentation observed that coefficient of reflection colorimetric analysis can be used as a method to moniter the microbic growing and lipase activity in milk and dairy merchandises ( M. R. BLAKE et al. , 1996 ) .
Rapid microbiological methods such as electric resistance measuring, ATP-bioluminescence, colorimetric analysis are going an of import tool for the rapid analysis of microbic population and enzymatic growing during the processing of nutrient merchandises such as milk, dairy merchandises, ready to eat veggies, fish, beef, porc etc as these techniques provides accurate consequences within short clip than conventional microbiological techniques and can be utile for keeping the hygiene and safety for the production of nutrient merchandises for ingestion.