Alberto Koji Yamada

A Low-Cost NIR Digital Photometer Based on InGaAs Sensors for the Detection of Milk Adulterations With Water

The adulteration of milk with water is a very common problem, which reduces its nutritional value and industrial yield, and can also represent a major risk of contamination. The standard method for detecting this kind of fraud is the cryoscopy, which fails when the adulteration is done along with other substances. Therefore, there is a need for new and more robust techniques for this purpose. With this goal, we propose a prototype of a digital photometer to quantify water added to milk. This is a microcontrolled, portable device, which uses three LEDs with emission in the near-infrared (IR) region and was developed without the use of lenses, filters, or moving parts. This equipment measures the transmittance of IR radiation through milk samples to assess the addition of water. In this paper, we present the results of experiments that were conducted with diluted milk samples containing 0%-25% of added water, using the proposed equipment and the standard method of cryoscopy. In the measurements of the percentage of added water, the mean absolute error was <;1%. In terms of repeatability, in two sets of ten measurements, we obtained absolute deviations from the average corresponding to less than 0.7% of added water. Results show that the prototype response is similar to the one of a commercial cryoscope but faster.

ESTABILIDADE TÉRMICA DA CASEÍNA E ESTABILIDADE AO ÁLCOOL 68, 72, 75 E 78%, EM LEITE BOVINO

Milk heat stability, evaluated through alcohol or alizarol test, is affected by several factors, the main one is milk acidificat ion. However, enzymatic hydrolysis, high somatic cells counts (SCC), excess of calcium ions and ethanol addit ion also af fect its stability to alcohol , reducing its correl ation with heat stability. The objective of this work was to determine the occurrence of instable non acid milk (LINA) in Sapopema-PR, evaluate heat stability of LINA and its relation with SCC and total bacteria count (TBC) and also evaluate the interference of alcohol concentration, used to perform alcohol test, on milk stability. A total of 85 samples were submit to alcohol test at 68, 72, 75 e 78%, determination of Dornic acidity, boiling test , SCC and TBC. High occurrence of LINA was observed. The highest frequency of LINA 65,88% occurred at alcohol concentration of 78% v/v and the lowest 15,29% at 68% v/v. With one exception, LINA samples were stable to boiling test, showing that its rejection by industry that produces pasteurized milk and dairy products would be unnecessary. The means obtained to SCC and TBC were elevated in both LINA samples and instable samples with acquired acidity.