Sensory and microbial quality of milk processed for extended shelf life by direct steam injection

M. R. Blake, Bart C Weimer, D. J. Mcmahon, P. A. Savello

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Heat treatments of milk between 100 and 145°C produce a new type of product with a shelf life of 15 to 30 days at 7°C, which is termed extended shelf life (ESL) milk. Little information is available on the safety and sensory qualities of this product. Extended shelf life milk is being processed commercially to expand the distribution area of fluid milk products. After arrival at market, this product still has the shelf life of a pasteurized product. In this study milk was processed by direct steam injection at temperatures between 100 and 1400°C for 4 or 12 s. Holding time did not significantly affect the sensory quality of the milk. A trained taste panel found cooked flavor and other off flavors varied significantly with increasing processing temperature and storage time. There were no significant differences noted in cooked or off flavors between 132 and 1400°C. Psychrotrophic Bacillus species were isolated from milk processed at and below 132°C, while no organisms were isolated from milk processed at temperatures at or above 134°C. Consumer preference panels indi-cated consumers preferred milk processed at 134°C for 4 s to ultra-high-temperature (UHT) processed milk, although there was a slight preference for high-temperature short-time processed (HTST) milk compared to milk processed at 134°C for 4 s. Higher temperatures had a less destructive effect on lipase activity, while storage time did not significantly affect lipase activity.

Original languageEnglish (US)
Pages (from-to)1007-1013
Number of pages7
JournalJournal of Food Protection
Volume58
Issue number9
StatePublished - Sep 1995
Externally publishedYes

Keywords

  • Bacillus
  • ESL milk
  • Milk processing
  • Milk quality

ASJC Scopus subject areas

  • Food Science
  • Microbiology
  • Biotechnology
  • Applied Microbiology and Biotechnology

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