M.Sc. Dissertation
The purpose of this study was to assess the quality of juices manufactured and sold for
immediate consumption in Dar es Salaam Municipalities, Tanzania. The assessments were
based on identifying the levels of preservatives, hygienic practices in manufacturing
industries and determine microbiological quality of the juices. High Performance Liquid
Chromatographic (HPLC) method was modified and validated for determination of
benzoic and sorbic acids, while direct titration method was used for quantitative estimation
of total sulphur dioxide. Microbial quality was determined by counting viable micro-
organisms using plate count method and coliform determination method. There were a
total of 110 juice samples from five different manufacturers. A total of 22 different types
of juices in replicates of five. Results show that more than 72% of samples tested did not
comply with Tanzanian standards for soft drinks because of the presence of exceeded
levels of allowable preservatives (> 350mg/ml for sorbic and benzoic acids) and only 40%
complied with labelling standard.
Samples which were found to have higher than
specified levels of preservatives did not show any microbial growth. It was observed that
63 % of microbial growth (for total bacterial count) was from those samples without
preservatives. The major micro-organisms found in juices were Alicylobacillus and
Lactobacillus spp.
Therefore it is necessary for the Regulatory board to provide training on the effects of
misuse of preservatives and education on hygienic procedures. It should also conduct
inspections and increase efforts in enforcing laws to the manufactures.