Lactic acid and pH as indicators of spoilage for vacuum-packed cooked ring sausages

H. Korkeala, Timo Alanko, P. Mäkelä, S. Lindroth

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26 Citations (Scopus)


Lactic acid production and pH changes of 206 vacuum-packed cooked ring sausages stored at 2, 4 and 12°C from 21 different production runs were monitored as a function of time and of microbial growth. The total lactic acid concentrations and pH values were first at a constant level, starting to increase sharply after the lactobacilli count reached about 5 × 107 or 6 × 107 cfu/g, respectively. The lactic acid and pH changes as a function of the lactobacilli count were similar at 4 and 12° C. The sharp increase at high lactobacilli counts was observed in both L-lactic acid and D-lactic acid. The variation was lesser and the increase greater in D-lactic acid formation than in L-lactic acid. Above a level of 3–4 mg lactic acid/g most of the samples were deemed unfit. The pH started to decrease from a level of approx. 6.3; below 5.8–5.9 the samples were deemed unfit. The lowest pH value observed was 4.58. Both a high lactic acid content and a low pH indicated that the sausage was spoiled. These changes, however, took place at later stages of storage, and do not give information about the early phase of spoilage.
Original languageEnglish
Pages (from-to)245-253
JournalInternational Journal of Food Microbiology
Issue number3-4
Publication statusPublished - 1990
MoE publication typeA1 Journal article-refereed


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