Dry Calibration Milks for Infrared Milk Analyzers

Abstract

Abstract A study has been carried out to determine the practicality of formulating dry, stable calibration milk powders for calibration of infrared milk analyzers for routine quality control purposes in commercial dairies. The powders are based on dairy Ingredients and are reconstituted to produce calibration milks that cover a wide range of fat, protein, and lactose composition combinations. The butterfat component included emulsifiers to aid in reconstituting the powders and to stabilize resulting emulsions. Reconstitute was carried out on a weight/weight basis using a top-loading balance and mixing with a simple hand-held, electric household mixer. The reconstitutlon procedure produced stable emulsions and was shown to be repeatable to within the accuracy specifications of Infrared instrumentation. The calibration results obtained with the powders relative to reference calibration milks purchased from the Central Milk Testing Laboratory (CMTL) In Guelph, Ontario, were excellent, and generally met AOAC specifications for Instrument calibration. In addition, the reconstituted milks had excellent emulsion stability to prolonged holding at 40°C and produced consistent results when analyzed over a 21-day period, showing no signs of spoilage when preserved with potassium dlchromate and refrigerated when not In use. The powders were deemed adequate for calibration of Infrared milk analyzers used for routine, In-plant, quality control purposes and would be a convenient alternative for CMTL calibration milks shipped by courier.