Enhancement of Eco-Friendly Ultrasound Process on the Microbiological Quality of Stevia, Mint and Lemon Extracts Stored At Refrigerator Temperature for Four Weeks

Document Type : Original Article


1 Food Toxicology and Contaminants Department, National Research Centre.

2 Food Technology Department National Research Centre

3 Food technology Dep

4 Food technology department National research centre

5 Food Technology department National Research Centre

6 Department of Food Toxins and Contaminants, National Research Centre, Dokki, Cairo, Egypt. P.O. Box: 12622, Dokki, Cairo, Egypt.

7 Department of food technology, National Research Centre.


Now, Ultrasound technology is one of the developed arising technologies to minimize processing, maximize quality and ensure the safety of food products. In recent times, it has been used as a volition processing option to conventional thermal approaches.

This study aimed to evaluate the possible effect of the ultrasound process on the microbiological quality of stevia, mint, and lemon extracts stored at refrigerator temperature for four weeks, trying to extend the shelf life of some natural extracts.

The aim of this study was to evaluate the ultrasonic process on the microbiological quality of Stevia, Mint and Lemon extracts. Stevia, mint and lemon extracts were stored under refrigerator temperature for four weeks and samples were taken from the stored extracts at the time periods of zero, two, and four weeks in order to determine the aerobic mesophilic bacteria, total coliforms count, and mold & yeast counts in the samples taken.Microbiological tests for the enumeration of yeasts and molds, total aerobic mesophilic bacteria and coliforms, were carried out in samples obtained from stevia leaf powder. Results indicated that The the load of aerobic mesophilic bacteria, molds, and yeast; were in the allowable limits according to the standard specifications for the ultrasonicated stevia syrup. Total coli forms were found to be absent in all samples during storage period for 4 weeks under cooling conditions. In conclusion the use of ultrasound technology in this study had an effective effect in reducing the microbial load of all extracts under study, and this encourage its use as one of the important means of food preservation - in addition to that it is non-toxic, environmentally friendly and an emerging green technology because it saves a lot of energy and increases production.


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