A Three-Cascaded-Enzymes Biosensor to Determine Lactose Concentration in Raw Milk

Abstract

The increasing demand for on-line measurement of milk composition directs science and industry to search for practical solutions, and biosensors may be a possibility. The specific objective of this work was to develop an electrochemical biosensor to determine lactose concentration in fresh raw milk. The sensor is based on serial reactions of three enzymes--beta-galactosidase, glucose oxidase, and horseradish peroxidase--immobilized on a glassy carbon electrode. The sequential enzymatic reactions increase the selectivity and sensitivity of the sensor. The sensor requires dilution of the raw milk and the addition of 5-aminosalicylic acid. Lactose concentrations in raw milk measured by the sensor were in good agreement with those measured by a reference laboratory using infrared technology. The results were obtained in milk samples that varied in fat and protein composition. From the results, we conclude that an electrochemical biosensor for determination of lactose concentration in fresh raw milk can be developed, and that the biosensor presented in this study maintained the qualities required for further development into an online sensor in the milking parlor.

Biosensor and its Application in Food and Dairy Industry: A Review

“…Fall in oxygen consumption is detected by the electrode. Oxygen consumed is proportional to the ascorbic acid content of the sample (Eshkenazi et al, 2000).…”

“…(Eshkenazi et al, 2000) developed a multi-enzymatic amperometric biosensor for lactose in fresh raw milk. The characteristics of the biosensor (easy operation, rapid response, long stability suggested that this method could be used as an economical, on-line lactose measurement technique in the milking parlour.…”

Optical Fiber Sensors for Chemical and Biological Measurements

“…Modern dairy farms include several control and automation systems, which are able to provide interesting data for farm management and to improve the economical results of exploitation [44]. NIR spectrometry has been used to estimate milk composition, but previous works are referred to dry milk, homogenised milk, high cost spectrometry equipment [43], or requires sampling and previous treatment of milk samples [16,49], avoiding a cow-side final implementation.…”

Spectrophotometric quantification of lactose in solution with a peroxidase-based enzymatic cascade reaction system

“…1 amount of enzymes and OPD used) can be scaled down by a factor of three at least. When compared to electrochemical biosensors that use the same set of enzymes but in an immobilized state, the spectrophotometric assay with free enzymes certainly has several disadvantages, particularly if the response time and the detection limit are considered [17][18][19][20]. Furthermore, an optimal biosensor allows the immobilized enzymes to be used for a large number of samples, while each analysis is performed with new enzyme solutions in the spectrophotometric assay.…”