Effect of pH on fecal recovery of energy derived from volatile fatty acids

C. Lawrence Kien, Edward A. Liechty

Research output: Contribution to journalArticle

7 Scopus citations


We assessed the effect of pH on volatilization of short-chain fatty acids during lyophilization. Acetic, propionic, valeric, and butyric acids were added to a fecal homogenate in amounts sufficient to raise the energy density by 18-27%. Fecal homogenate samples were either acidified (pH 2.8-3.2). alkalinized (pH 7.9-8.7), or left unchanged (4.0-4.8) prior to lyophilization and subsequent bomb calorimetry. Alkalinizing the fecal samples prevented the 20% loss of energy derived from each of these volatile fatty acids observed in samples either acidified or without pH adjustment. These data suggest that in energy balance studies involving subjects with active colonic fermentation, fecal samples should be alkalinized prior to lyophilization and bomb calorimetry.

Original languageEnglish (US)
Pages (from-to)923-925
Number of pages3
JournalJournal of pediatric gastroenterology and nutrition
Issue number6
StatePublished - Jan 1 1987


  • Bomb calorimetry
  • Loss during lyophilization
  • Volatile fatty acids

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Gastroenterology

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