Application of osmometry in quality analysis of milk
The aim of this study was to evaluate osmometry as a tool in quality analysis of milk. The osmolality of raw milk, sterilized milk, skimmed UHT (ultra-high temperature treated) milk, pasteurized milk, standardized UHT milk and fermented milk (Lactococcus lactis culture) was determined by freezing po...
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2016
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| author | Musara, Colin Pote, William |
| author_facet | Musara, Colin Pote, William |
| author_sort | Musara, Colin |
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| description | The aim of this study was to evaluate osmometry as a tool in quality analysis of milk. The osmolality of raw milk, sterilized milk, skimmed UHT (ultra-high temperature treated) milk, pasteurized milk, standardized UHT milk and fermented milk (Lactococcus lactis culture) was determined by freezing point osmometry. The relationship between osmolality and pH of fermented milk was further investigated during spontaneous fermentation of UHT milk at 37°C for 48 h. Average osmolality values (mean ± SD) were raw milk 290.2±7.98, sterilized milk-290.2±5.84, skimmed UHT milk-290.8±3.31, pasteurized milk-283.6±2.28, standardized UHT milk-281±4.59 and fermented milk-466.0±17.30 mOsmoles kg−1. For fresh milk samples, 88 % showed normal osmolality, 8 % were hypo-osmotic and 4 % hyper-osmotic.
Fermentation studies revealed a high negative correlation between osmolality and pH, with a correlation coefficient of −97.49 %. Hypo-osmotic milk shows mixing of milk with water along the production chain. Hyper-osmotic milk indicates fermentation of milk at high ambient temperatures or with prolonged storage. It may also reveal adulteration of fresh milk with a soluble substance. Osmolality was highest for fermented milk owing to production of lactic acid during fermentation. This was confirmed by the high negative correlation between osmolality and pH of milk in fermentation studies. Hence the osmolality of fermented milks may be used as an index of the extent of fermentation. |
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| id | ir-11408-1674 |
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| publishDate | 2016 |
| publisher | Springer |
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| spelling | ir-11408-16742022-06-27T13:49:06Z Application of osmometry in quality analysis of milk Musara, Colin Pote, William Milk, Osmolality, Quality analysis, Adulteration, Fermentation The aim of this study was to evaluate osmometry as a tool in quality analysis of milk. The osmolality of raw milk, sterilized milk, skimmed UHT (ultra-high temperature treated) milk, pasteurized milk, standardized UHT milk and fermented milk (Lactococcus lactis culture) was determined by freezing point osmometry. The relationship between osmolality and pH of fermented milk was further investigated during spontaneous fermentation of UHT milk at 37°C for 48 h. Average osmolality values (mean ± SD) were raw milk 290.2±7.98, sterilized milk-290.2±5.84, skimmed UHT milk-290.8±3.31, pasteurized milk-283.6±2.28, standardized UHT milk-281±4.59 and fermented milk-466.0±17.30 mOsmoles kg−1. For fresh milk samples, 88 % showed normal osmolality, 8 % were hypo-osmotic and 4 % hyper-osmotic. Fermentation studies revealed a high negative correlation between osmolality and pH, with a correlation coefficient of −97.49 %. Hypo-osmotic milk shows mixing of milk with water along the production chain. Hyper-osmotic milk indicates fermentation of milk at high ambient temperatures or with prolonged storage. It may also reveal adulteration of fresh milk with a soluble substance. Osmolality was highest for fermented milk owing to production of lactic acid during fermentation. This was confirmed by the high negative correlation between osmolality and pH of milk in fermentation studies. Hence the osmolality of fermented milks may be used as an index of the extent of fermentation. 2016-07-12T14:06:39Z 2016-07-12T14:06:39Z 2014-03 Article 0022-1155 http://hdl.handle.net/11408/1674 Journal of Food Science and Technology;Vol. 51, No. 3. p. 606–610 open Springer |
| spellingShingle | Milk, Osmolality, Quality analysis, Adulteration, Fermentation Musara, Colin Pote, William Application of osmometry in quality analysis of milk |
| title | Application of osmometry in quality analysis of milk |
| title_full | Application of osmometry in quality analysis of milk |
| title_fullStr | Application of osmometry in quality analysis of milk |
| title_full_unstemmed | Application of osmometry in quality analysis of milk |
| title_short | Application of osmometry in quality analysis of milk |
| title_sort | application of osmometry in quality analysis of milk |
| topic | Milk, Osmolality, Quality analysis, Adulteration, Fermentation |
| url | http://hdl.handle.net/11408/1674 |
| work_keys_str_mv | AT musaracolin applicationofosmometryinqualityanalysisofmilk AT potewilliam applicationofosmometryinqualityanalysisofmilk |