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Title: Trans fatty acid content in used vegetable cooking oil and food safety hygiene practices of informal food vendors in Warwick Triangle, Durban
Authors: Rubushe, Mthokozisi 
Keywords: Trans fatty acids;Vegetable oils;Food safety;Hygiene practices;Food vendors
Issue Date: May-2023
Aim: The aim of the study was to determine the food safety and hygiene practices and the
safety levels of cooking oil used, by the informal food vendors in the Warwick Triangle Avenue
(WTA) to prepare meals to sell to consumers by determining the trans-fatty acid content of the
cooking oil used.
Objectives: The specific objective of the study is to investigate the oil safety, hygiene practices
and food safety knowledge of informal food vendors at the WTA in eThekwini.
Methods: A total number of 40 informal food vending outlets, scattered in the WTA,
participated in the study. Fried food prepared by vendors in the WTA were either deep-fried or
shallow-fried. Therefor the vendors were divided into two groups: 20 deep-frying and 20
shallow-frying groups. This study was descriptive with an analytical component. The data
collection exercise was quantitative, using a socio-demographic questionnaire and a food
handler’s questionnaire. A detailed observation sheet and a sheet for recording the results of
3MTM oil quality test strips were also used. Used cooking oil samples were collected in small
glass bottles for lab analysis. Data was captured in Excel and analyzed using a statistical
package for social science (SPSS) version 24 for descriptive statistics.
Summary of Findings: Adequate cooking spaces was not present in 70.0% (n=14) of DF
vendors and 65.0% (n=13) of SF vendors. Sixty-five percent (n=13) DF and 80.0% (n=16) of
the SF vendors did not have access to safe water for food preparation. Most of the DF vendors
(40.0%; n=8) kept food for less than 15 minutes and 30.0% (n=6) kept the food for more than
45 minutes. A small number of vendors (10.0%; n=2) kept the food from 30 to 45 minutes,
while 20.0% (n=4) kept the food from 15 to 30 minutes. Most of the SF vendors (30.0%; n=6)
kept food for more than 45 minutes and 25.0% (n=5) kept the food for less than 15 minutes,
and 25.0% (n=5) kept the food between 15 – 30 minutes. A small number of vendors (20.0%;
n=4) kept the food for 30 to 45 minutes. Cleaning or removal of rubbish by DF vendors took
place once a day in 45.0% (n=9) of the cases, and twice a day in 6.0% (n=30) for the rest of the
cases. Cleaning or removal of rubbish took place once a day in 5% (n=1) SF of the vending
sites. Only 50.0% (n=10) of DF vendors and 30.0% (n=6) of SF vendors had rubbish bins with
tightly fitting lids. Only 10.0% (n=2) of the DF vendors indicated that they clean their utensils
during food preparation compared to 25.0% (n=5) of the SF vendors. The researcher's
observation reveals that correct cleaning chemicals were not available in all the SF and DF
vending sites (100.0%) such as detergent for clothes and sanitizers and dishwashing liquid. All
the DF and SF vending sites were not sanitized during food preparation, and 65.0% (n=13) of the areas were not cleaned during food preparation. Forty-five percent (n=9) of the DF vendors
changed oil daily, while 30.0% (n=6) changed the oil frequently, with 15.0% (n=3) changing
the oil weekly and 10.0% (n=2) changing it seldom. Forty-five percent (n=9) of the DF
vendors’ cooking oil was suitable for cooking, 20.0% (n=4) was probably suitable and 20.0%
(n=4) was probably not safe depending on the quality of food and 15.0% (n=3) was not safe
and had to be discarded.
Gas chromatography further revealed that a value of 4.62% for methyl palmate (sample A1)
was obtained implying an increase in viscosity, acid value as well as the saturation process.
The highest saturation point was observed for samples A11 and A12. This effect implies an
increase from C17: 1 (monosaturated) fatty acid to C17: 2 (diunsaturated) fatty acid chains.
Additionally, the results obtained indicate that fats and oils experience different degrees of
proportionality in saturation during frying or cooking use, with the magnitude of these changes
varying from sample to sample.
It was observed that most of the DF food handlers did not wash their hands before serving
(90.0%; n=18), as 50.0% (n=10) of the DF vending sites did not have water available for food
handlers to wash their hands.
Conclusion: It was observed that there was no evidence of monitoring of policies and
procedures for all SF vending sites (100.0%; n=20) and for the majority (95.0%; n=19) of the
DF sites. A high degree of composition is observed in the used frying oil samples. The results
indicate high consistency (or repeatability) of used cooking or frying oil from the sampling
points of WTA.
Dissertation submitted in fulfilment of the requirements of the Master of Applied Science in Food and Nutrition in the Department of Food and Nutrition: Consumer Sciences in the Faculty of Applied Sciences at the Durban University of Technology, 2023.
Appears in Collections:Theses and dissertations (Applied Sciences)

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