Determination of Minimum Food Preservative Combination Levels for Fruit Juices
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Date
2013
Journal Title
Journal ISSN
Volume Title
Publisher
Uva Wellassa University of Sri Lanka
Abstract
Higher levels of food additives than the maximum permitted levels are used by the food
manufactures. According to Sri Lankan Food Act, These permitted levels of food additives are
higher than the international standards (reference). Especially, in fruit juice manufacturing high
levels of food preservatives are used. Different studies have shown that higher levels of food
preservatives may cause health hazard such as gastric irritation, allergic conditions, asthma
conditions and long term consumption may lead to cancers and genetic disorders in babies
(Freedman, 1980). Developed countries are more concerned about the residual effect of food
additives. Due to the fact that the residual level of food preservatives of Sri Lankan products is
higher than the international standard, those products are failed at the export market. This study
was conducted to find out the minimum levels of preservative combinations that minimize the
risk to human health with respect to fruit juice preservation.
Methodology
The study was carried out at Microbiological Division of the Research and Development
Department, Expolanka (Pvt) Limited. Two experiments were conducted during this study.
Experiment I was conducted to evaluate the minimum inhibitory concentrations of food
preservatives for selected microorganisms. Series of different concentrations of Sodium
metabisulphite, Potassium sorbate and Potassium benzoate solutions were produced and pH was
adjusted to 3.3. All the prepared preservative solutions were filter sterilized. Disk diffusion
method was used to investigate the minimum inhibitory concentration of above preservatives
and
Saccharomyces spp. Minimum inhibitory concentrations of three preservatives were defined for
the tested microorganisms.
In second Experiment, the effectiveness of these minimum inhibitory concentrations of
preservatives in preservation of fruit juices was determined. Mango, wood apple, mix fruit, lime
and guava juices were used to meet the fruit juice specification given in the food act and SLSI
guideline. Two preservative combinations were used by combining minimum inhibitory
concentrations of preservatives. Sodium metabisulphite (SMS) with potassium sorbate (PS) and
Sodium metabisulphite with potassium benzoate (PB) were combined and these combinations
were assigned to all the fruit juice samples.
Combination 01: Sodium metabisulphite 25 ppm + Potassium Sorbate 150 ppm
Combination 02: Sodium metabisulphite 25 ppm + Potassium Benzoate 60 ppm
All the samples were incubated at 25 C for 14 days as per the food act. Total plate count and
yeast and mould (Y/M) were enumerated using the standard method as described by the Sri
Lanka Standard Institution (SLS 516 part 2). The data obtained in the present study was
statistically analyzed with analysis of variance (ANOVA) using Minitab 16 statistical package.
Pair wise comparisons were done by tukey at 5% significance level.
Description
Keywords
Agriculture, Fruit Cultivation, Export Agriculture, Beverage, Food Preservative