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Microbial spoilage of luncheon meat prepared in an impermeable plastic casing
Author(s) -
Bell R.G.,
Gill C.O.
Publication year - 1982
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1982.tb04738.x
Subject(s) - food science , food spoilage , micrococcus , nitrite , lactic acid , syneresis , bacterial growth , bacillus (shape) , hydrolysis , starch , bacteria , chemistry , biology , microbiology and biotechnology , biochemistry , nitrate , genetics , organic chemistry
Freshly cooked luncheon meat in a plastic (PVDC) casing had an aerobic plate count of about 10 2 /g. The flora was composed of approximately equal numbers of Bacillus and Micrococcus spp. Storage at 10°C for 42 d produced little increase in bacterial numbers, or changes in pH value or glucose content at either the surface or core of the luncheon meat. Storage at 25°C allowed Bacillus spp. to proliferate at the surface. The inhibitory effect of salt and nitrite on the growth of heated Bacillus spores at low redox potentials probably accounts for the absence of growth within the product. Growth at the surface was accompanied by a fall in pH (6.8 to 6.2) and an increase in glucose (1.6 to 3.6 mg/g) and L(+)‐lactic acid (1.2 to 2.3 mg/g). By day 14 the Bacillus spp. had been displaced by a Streptococcus sp. (10 7 /g) which remained the dominant organism until the experiment ended on day 28. The pH continued to fall from 5.7 on day 14 to 5.2 on day 28, the L(+)‐lactic acid rose to 6.1 mg/g, but the glucose remained constant at the day 7 level (3.6 mg/g). This indicates that glucose converted to lactic acid was largely replaced by hydrolysis of the starch portion of the luncheon meat mediated by amylases produced by the Bacillus microflora. It appears that growth of the Streptococcus is dependent upon the denitrifying activities of the initial Bacillus flora reducing the concentration of nitrite ion to non‐inhibitory levels.