Bio-preservation of fresh tomatoes (solanum lycopersicum l.) with zingiber officinale (ginger), psidium guajava (guava), and allium cepa (onion) plant extracts

Abstract

Tomatoes are members of the Solanaceae family, and are one of the world’s most important vegetables because they form a major component of the daily meal of almost everyone around the world. One of the major challenges of tomatoes is perishability, which greatly reduces their shelf life. So many plants have been studied and proven to contain phytochemicals such as phenols, glycosides, tannins, etc. which have capacity to kill microorganisms, some of which are the cause of post-harvest rotting of tomatoes. This research employs three active plants (Zingiber officina -Ginger, Allium cepa -Onion, and Psidium guajava -Guava), crude extracts of which are tested on their capacity to extend the shelf life of tomatoes in light of developing a bio-preservative. The guava leaves were obtained from the compound of the School of Biosciences Makerere University, while the ginger rhizome and the onion bulbs were bought from Nakawa market, Kampala. The plant extracts were extracted from the labs at the School of Biosciences, College of Natural Sciences of Makerere University, where the entire experiment was also conducted. The tomatoes were regularly sprayed with the plant extracts twice a day, at ten hour intervals, and left to stand on the table at room temperature, until 80% of the tomatoes in the control, where tomatoes were only sprayed with tap water got rotten. This marked the start of shelf-life extension period for the tomatoes that were sprayed with the crude plant extracts. The cumulative number of tomatoes that got rotten in every treatment was recorded per week. Results showed that all the three plant extracts significantly extend shelf life of the tomatoes, by at least ten more days compared to the control which was treated with tap water. Guava leaf extract was the best (twenty-one more days), followed by ginger rhizome extract (twelve more days), and onion bulb extract had the least impact on the extension of tomato shelf life (ten more days). Therefore, crude guava, ginger, and onion extracts can potentially be used by farmers, and traders who stock tomatoes to preserve their tomatoes for at least three weeks as cheap, and healthy bio-preservative.