Thermobactebiology of Some Ghanaian Canned Foods
Date
1976-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Ghana
Abstract
The microbiological content and the thermal processes in use for s ix locally canned vegetables, Bambara
Beans in sauce , Garden eggs in Brine, Okro in brine ,
Whole Tomato in tomato juice and Pepper puree were studied
to establish causes of spoilage in the canned products, .
Preliminary can examination and microbiological
analysis of the canned product s showed that both leakage
and under processing occur red widely in the products.
Leakage occurred chiefly as a result of improper double
seaming operation^. It was shown that the seaming process**
es in use at the factories tended to produce cans with loose
double seams ( i . e 0 large Free Space and small % Over laps ), ,
Side seam defects (due mainly to inadequate sold er in g ) were
also considered significant as a cause of leakage, A procedure for predicting when leakage was likely
to occur in the product s was evolved based on Free Space
measurements ; and it was considered that Free Space
measurement s could be used in the factories to prevent
the occurrence of leakage, Heat processes in use at the Factories were evaluated
and compared with recognized process in g standards for
low acid food s . It was found that the heating processes
in use were not adequate to prevent a residual population
of thermophilic spores occurring in the end product s and
al so to prevent the occurrence of Clostridium botul inium
spores in the products, White this was shown to contribute to the high incidence
of spoilage due to underprocessing the products
were al so a potential health hazard to consumers .
Some of the thermophilic spores isolated from the
product s included Baci l lus polymyxa. Bacillus s tearo -
th erm ophi lus and Clostridium therm osaccharolyticum .
The isolation of relatively low heat resistant spores
of Bacilluscereus and Clostridium histolyticum from the product s suggested a likely occurrence of high p reprocessing
bacterial contamination. Investigation conducted on
the raw vegetable product s prior to heat processing showed
that delays which occur red between the cleaning of the vegetables and the heating process could result in a 10 - 100
fold increase of the initial bacterial load in the raw vegetables . While this could lead to pr e -processing spoilage , a
residua l spore population could also remain in the end product
after the heat processing.
Based on the results obtained from the microbiological analysis and heat process evaluation new heating
processes were defined f o r use in the factories to prevent
the occurrence of underprocessing .
Further work is however needed on the relative
heat resistance of thermophilic spores isolated from
tropical products. This information could be used to
define minimum processing standards for tropical based
products .
Description
Thesis(MSc)-University of Ghana,, 1976