Preservation of Strawberries Using Guava Leaves Extract

Abstract

Background: A lot of health hazards have been associated with artificial preservatives including: hyperactivity in children, breathing problems such as asthma and bronchitis, weakening of heart tissues, obesity since some contain fatty acids especially in processed foods and gastrointestinal disorders. Sulfite is a common preservative in fruits and was found to have the following side effects: headaches, allergies, palpitations and cancer. Another down side of artificial preservative is that a lot of time is used in developing and acquiring it thus making it expensive. There is therefore need for a natural preservative. Objectives: This study was conducted to develop a natural preservative from guava leaves extract that would help increase the shelf-life of strawberries. Methods: The study was conducted in the food microbiology laboratory, Department of Food Science, Nutrition and Technology, University of Nairobi, Kenya. Crude extract was obtained by crushing dry guava leaves into 100 g powder and adding 600 ml of boiled water. The mixture was allowed to stand for 1 hr to allow extraction. The extract was then filtered and used to determine its inhibition against fungi. The extract was also serially diluted to obtain 5 different concentrations which were used to determine their effectiveness in increasing the shelf life of the strawberries. The results were recorded and discussed. Results: The plates with the highest concentration of guava leaves extract had the lowest number of microbial colonies while the one with the lowest concentration on had the highest number of microbial colonies. The control samples had by far a higher number of microbial colonies than all the different concentrations of the extract. Conclusion: The crude extracts of guava leaves showed inhibition against fungi and increased the shelf life of strawberries. Further studies need to be conducted in order to obtain a purified preservative from the extract.