Determination of Lactose Concentration in Milk Serum by Refractometry and Polarimetry

Rodica Căpriță

Abstract


The research had in view to evaluate and compare two instrumental techniques used for the determination of milk lactose. Refractometric and polarimetric measurements were carried out on milk serum obtained after precipitation of casein by two different methods: by acidification of milk to its isoelectric point (E1), and by using copper sulphate and potassium ferrocyanide (E2). The average lactose content measured by refractometry was 5.469±0.256g% for method E1 and 5.852±0.218g% for method E2. The obtained average lactose values measured by polarimetry were higher both for E1 (5.613±0.253g%) and E2 (5.910±0.224g%) methods, due to the interference with other optically active components. The experimental data revealed a high correlation between the results obtained by refractometry and polarimetry (r = 0.8712) when casein precipitation was performed by potentiometric titration until pH = 4.6, at 25°C with 2N acetic acid (method E1).


Keywords


lactose, milk, refractometry, polarimetry

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References


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LUCRARI STIINTIFICE ZOOTEHNIE SI BIOTEHNOLOGII (SCIENTIFIC PAPERS ANIMAL SCIENCE AND BIOTECHNOLOGIES)

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ISSN-L  1841 - 9364
(former ISSN 1221-5287, E-ISSN 1841-9364)

PUBLISHER: AGROPRINT Timisoara, Romania
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Banat´s University of Agricultural Sciences and Veterinary Medicine "King Michael I of Romania" from Timisoara
Bioengineering Faculty of Animal Resources
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