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Sterility Testing for Milk and Beverages.
Milk and beverages are often heat treated to extend their shelf life. UHT products have a shelf life of 6 to 12 months and extended shelf life products 4-7 weeks. The normal protocol for UHT products are incubated at 37°C for aerobics and 55°C for thermophillics for 5 days with an additional 2 days for bacterial enumeration. Extended shelf life products have a shelf life of 42 days. Normal protocol requires 10 days of incubation at 20°C plus 2 days of enumeration leaving 30 days to sell the products. Promicol can perform the sterility testing in 2 days. Promicol measures the ATP from bacteria that has multiplied in the pack if the pack is compromised. Free ATP that is present in the milk is first removed by the addition of enzyme proase. Then Promex is added to release the ATP from the bacterial cells. Finally Prolux is added to create a bioluminescence that is measured with a sensitive photocell. This light measurement is then correlated with the presence of bacteria. There is no sample preparation. Simply mix and pipette the sample to a microtitre plate and insert into the Promilite M4 reader and walk away. Results are available in 20 mins for 96 samples.
Rapid Bacterial Enumeration- MOCON Greenlight
Enumeraion of bacterial loads and yeast and molds are important for a food production facility. Normal enumeration on agar plate takes 24 to 48 hours. The Mocon green light is a revolutionary method of measuring bacterial load using oxygen sensing. Testing is simple. Simply place your swab or food sample into a vial and insert it into the Mocon AP check. During testing the Mocon Green light internal incubator maintains the temperature needed for bacterial growth and at the same time measures the oxygen consumption. This instrument uses light to excite a platinium porphyrin sensor at the bottom of the vial and detects the fluorescent signal emitted. This signal is proportional to the oxygen content. As aerobic bacteria grows it respirates and consume oxygen. The oxygen consumed is correlated to the amount of bacteria growing in the vial by a software. From the growth characteristics the initial bacterial load is predicted. Results are available for 10 cfu in 16 hours and 106 CFU in 5 hours. Typical sensitivity is less than 15 CFU.
Test for Lactose
Lactose is a disaccharide that is found in milk and it is a compound of galactose and glucose. There are about 4-5% of lactose in milk. In the stomach lactase hydrolyses the lactose for digestion and the lack of this enzyme causes lactose intolerance. The amount of lactose is one of the parameters defining the quality of milk and in many countries it enters into the payment scheme. This method follows the ISO 26462/IDF 214 method for the enzymatic determination of the lactose content of milk and reconstituted milk by measurement of the difference in pH. This method is a valid alternative to the HPLC method of lactose determination.
Test for L-lactic Acid
Lactic acid is produced by the fermentation of lactose by bacteria. Its concentration depends on the number of microbes in the milk and as such it is a good indicator of the freshness of the milk. Heat treatment like UHT destroys the bacteria in the milk but not the L-lactic acid and measurement of this parameter can tell the history of the milk product. This test can be done on other milk products like milk powder, whey after reconstitution in water. This method is used with the EC CL10 automated analyser which uses a differential pH technology to overcome the problems of Classical UV methods. With this enzymatic method accurate results with operative simplicity is achieved.
Test for Titratable Acidity
This is a test usually done in milk production to indicate the freshness of the milk. Bacteria in milk produces acid that can be measured even after heat treatment like pasteurization and UHT. Acidity is usually measured by acid base titration at a pH of 8.4 where the phenolphthalein indicator turns from colorless to pink. This color transition is difficult to see due to the masking effect of the milk solids. This problem is overcome with this differential pH technology of the EC CL 10 Plus analyser which uses an enzymatic method related to changes in pH.
Test for Citric Acid in Juice and Milk.
Citric acid is present in milk at a level 0f 0.1-0.2%. Citric acid gradually decreases with aging in particular if the milk is soured. However it is not a product of fermentation but consumed during fermentation. Citric is commonly measured in juices as it is an organic acid that exist in all fruits especially citrus fruits used to make juices. Fruit juices vary in citric acid content depending on the type of fruit and the use of citric acid additives.
Citric acid in milk and fruit juices can be measured using the EC CL 10 plus. This technology uses a differential pH measurement combined with an enzymatic method to measure the amount of citric acid. This result is improved accuracy and simplicity of measurement.
Test for Urea in Milk
Urea in milk is measured in milk to define its quality and is a crucial parameter that enters into the payment scheme in many countries. It is a method for determining dilution of milk with water. Urea content in normal milk is 24-33mg/100ml. The traditional method of determining the urea content of milk is tedious with labour intensive sample preparation. This measurement in traditional method is difficult due to interference from ammonium found in milk. However the differential pH technology used together with the EC CL10 Plus analyser precisely targets the urea in a simple procedure. This enzymatic procedure eliminates any potential interference from ammonium. Results are available in less than 1 minute.
FREQUENTLY ASKED QUESTIONS
How many samples can the promicol do in one hour.
Can promicol quantify the number of bacteria in the sample
Promicol measures the amount of ATP in bacteria. This amount of Atp depends somewhat on the species of bacteria or whether it is a mold and yeast. As such promicol can typically tell roughly the level of bacteria to log levels but measurement is imprecise.
What is the limit of detection of the number of bacteria.
Usually this is limited to 103 bacteria.
Can promicol be used for chocolate drinks?
Ans: Promicol has a special protocol for chocolate milk and as such can be used.
Is the mocon greenlight sensor consumed with the reaction?
No the sensor is an oxygen sensitive electrode that gives off fluorescence when in contact with oxygen.
Can mocon be used with opaque products?
Mocon can be used with non-transparent product as the fluorescence is measured not on the product side.
Do you need to do serial dilutions with mocon method?
No dilutions is needed. High concentrations of bacteria gives results in shorter time whilst low counts need a longer time.
what is the limit of detection of the mocon method
For more information on the above tests contact the friendly Arasains sales staff or fill in the enquiry form.
For more questions ask Dr Lee
Caution : not all question can or will be answered