1. Evaluation of The Microbiological quality of two types of salads
prepared at The Libyan air- lines Catering Center in Tripoli, Libya
2Madiand Nuri S.2*,Yahia S. Abugnah1iElham A. Kwild
Libya.Libyan air lines Catering Center, Tripoli Int. Airport, Tripoli,1
Food Science Dept., Faculty of Agriculture, University of Tripoli, Tripoli, Libya.2
Abstract:
The aim of this study was to evaluate the microbiological quality of two types of
salads prepared at airlines catering center near Tripoli International Airport / Libya. The
study lasted for 10 months (January – October,2010) , during this period 231 samples were
collected, (132 for the economy class and 89 samples for business and flight crew class
salad). All samples were subjected to periodical microbiological analysis which included
Total Plate Count (TPC), Total Coliforms (TCF) in addition to detection and enumeration of
some pathogenic bacteria specifically; (Escherichia coli, Staphylococcus aureus, , Salmonella
, Vibrio parahaemolticus, , Bacillus cereas and Listeria).
The results of the study have shown that the initial (TPC) means for the first type of
cfu/g)3cfu/g) using the traditional method and (54.17x103salad ranged from (11.38 x10
cfu/g)2were in the range of (54.07x10using the compact dry method, while the (TCF) counts
cfu/g) using the first and the second method respectively. On the other hand2and ( 14.90 x10
cfu/g)2the initial (TPC) means for the second type of salad were in the range of (64.00x10
cfu/g) using the second method, and the (TCF) counts230 x10using the first method and (81.
cfu/g) using both methods respectively. Even2cfu/g) and (78.60 x103were (15.40 x10
though, there was no significance difference between the two types of salads in respect of
TPC and TCF counts, data indicates a slight significance difference between the methods of
enumeration. The conventional method appears to have a relatively better support for total
microbial growth vs. the compact one. But the latter was relatively better for detection and
isolation of the four types of pathogens under study.
A gradual decline in both (TPC & TCF) counts was noticed throughout the period of
the study and reached their minimum at the end of the last month. Such pattern of decline is
monthsrdand 3nd61.69% reduction in TPC of type 1 salads at the 2equivalent to 14.24% and
vs. 90.77% reduction at the end of the last month of the study using the conventional method
of enumeration. Relatively similar pattern was noticed for type 2 salads.
With respect to the previously mentioned pathogenic bacteria the results have shown that
their presence was different depending on the type of salad and the detection method applied.
For instance, Staphylococcus aureus was most predominant in the economy class salad
representing 17.4% of the samples using the traditional method and 14.4% using the compact
dry method. As for E.coli it was detected in 7.6% and 9.8% of the samples using the
traditional method and the compact dry method respectively. On the other hand, Salmonella
was present in only 3% and 3.8% of the samples using both methods of detection
respectively. In case of the second type of salad the presence of those pathogens was reversed
since E.coli showed highest presence (14.6% , 16.9 %) followed by S. aureus (13.5% ,
11.2%), and the third rank was Salmonella with (6.74%, 6.70%) using the traditional method
and the compact dry method respectively. The least came Vibrio parahaemolticus (4.9%)
which was enumerated using the compact dry method only. As for Bacillus cereas and
Listeria they were not detected in either type of salads.

2. Finally, it is worth mentioning that a noticeable decrease in the overall
microbiological counts (TPC) and (TCF) counts has been recorded after the sixth and the
seventh months of the study which was coincided with the application of the (HACCP)
system for the first time at the catering center.
Key words: Air lines, Economy Class, Business Class, Vegetable salads,Shrimp, Total Plate Counts,
Total Coliforms, Pathogenic Bacteria.
*e.mail: abojnah_y74@yahoo.com