Heat stability of milk: interrelationship between assay temperature, pH and agitation
| Autor: | Douglas B. Hyslop, Patrick F. Fox |
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| Rok vydání: | 1981 |
| Předmět: | |
| Zdroj: | Journal of Dairy Research. 48:123-129 |
| ISSN: | 1469-7629 0022-0299 |
| DOI: | 10.1017/s0022029900021531 |
| Popis: | SummaryAs determined by the standard subjective assay procedure, the minimum in the heat stability–pH curve of milk persisted down to at least 116 °C. However when samples were not agitated during heating the minimum became progressively less pronounced as the assay temperature was lowered and it disappeared at approximately 116 °C. Activation energies (Ea) for unagitated samples were approximately 30 Kcal/mole at pH 6·87 (maximum) and at pH 7·18, throughout the temperature range 116–145 °C and for the pH 6·95 (minimum) sample at 116–125 °C; however Eα for the pH 6.95 sample increased to approximately 100 Kcal/mole in the range 127–135 °C suggesting that some highly temperature-dependent reaction had occurred and caused premature coagulation at certain pH values, i.e. to a heat stability minimum. The stability of concentrated milk (20% total solids) was very low at pH values above 6·9, regardless of whether the samples were agitated or not during heating and the maximum/minimum in the heat stability–pH curve persisted down to at least 90 °C in both agitated and quiescent samples. |
| Databáze: | OpenAIRE |
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