Determination of freezing point standard for UHT milk

Autores

  • Vanerli Beloti Universidade Estadual de Londrina
  • Edson Antonio Rios Universidade Estadual de Londrina
  • Márcia Rocha Silva Universidade Estadual de Londrina
  • Ronaldo Tamanini Universidade Estadual de Londrina
  • Alberto Koji Yamada Universidade Estadual de Londrina
  • Livia Cavaletti Correa da Silva Universidade Estadual de Londrina

DOI:

https://doi.org/10.5433/1679-0359.2015v36n5p3181

Palavras-chave:

Cryoscopy index, Freezing point, Milk, Stabilizing agents, Quality, UHT.

Resumo

The extended shelf life and undemanding storage requirements of UHT (ultra high temperature) milk make it the most consumed fluid milk in Brazil. The thermal treatment to which UHT milk is subjected alters casein micellar structure, leading to protein sedimentation and age gelation. Therefore, the current legislation allows the addition of up to 0.1% stabilizing salts (sodium citrate and/or sodium phosphates) in milk. The adding of stabilizing salts hinders the possibility of inclusion of freezing point and density as quality parameters of UHT milk. Evaluation of freezing point is the main test to detect adulteration of milk with water; however, addition of stabilizers alters its results. This study aimed to measure the alterations in freezing point and density caused by stabilizers in samples of pasteurized milk added with sodium citrate or sodium phosphates, in order to propose standards for freezing point and density for UHT milk. For this purpose, 16 aliquots of milk were prepared in nine repetitions with different concentrations (0%, 0.001%, 0.01%, 0.05%, 0.075%, 0.1%, 0.125%, and 0.15%) of sodium citrate or a commercial mix of sodium mono-, di- and triphosphate. The density and freezing point of all aliquots were tested. As expected, addition of stabilizers lowered the freezing point of milk. Addition of 0.1% citrate and commercial mix promoted an average reduction of –0.021°H (± 0.001) and –0.017°H (± 0.002) in freezing point, respectively. However, no significant change in the density of milk was observed. Given that UHT milk industry usually adds the maximum limit of 0.1% of stabilizers in order to obtain proper effect, the interval from –0.572°H to –0.545°H can be suggested as the standard for freezing point to UHT milk. However, as the addition of stabilizers caused no significant change in the density of UHT milk, the density parameter of raw and pasteurized milk in the range from 1.028 g.mL-1 to 1.034 g.mL-1 could be applied to UHT milk.

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Biografia do Autor

Vanerli Beloti, Universidade Estadual de Londrina

Profª Drª, Deptº de Medicina Veterinária. Preventiva, Universidade Estadual de Londrina, UEL, Londrina, PR, Brasil.

Edson Antonio Rios, Universidade Estadual de Londrina

Discente do Curso de Pós-Graduação em Ciência Animal, UEL, Londrina, PR, Brasil.

Márcia Rocha Silva, Universidade Estadual de Londrina

Discente do Curso de Residência em Inspeção de Leite e Derivados, UEL, Londrina, PR, Brasil.

Ronaldo Tamanini, Universidade Estadual de Londrina

Médico Veterinário, Dr., UEL, Londrina, PR, Brasil.

Alberto Koji Yamada, Universidade Estadual de Londrina

Discente do Curso de Pós-Graduação em Ciência Animal, UEL, Londrina, PR, Brasil.

Livia Cavaletti Correa da Silva, Universidade Estadual de Londrina

Discentes do Curso de Pós-Graduação em Ciência Animal, UEL, Londrina, PR, Brasil.

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Publicado

2015-10-21

Como Citar

Beloti, V., Rios, E. A., Silva, M. R., Tamanini, R., Yamada, A. K., & Silva, L. C. C. da. (2015). Determination of freezing point standard for UHT milk. Semina: Ciências Agrárias, 36(5), 3181–3188. https://doi.org/10.5433/1679-0359.2015v36n5p3181

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