The effects of preservatives on tomato (Lycopersicon esculentum mill.) paste at varying environmental conditions

Abstract

Studies were carried out on United Trading Company (UTC variety) tomato paste production to determine the effects of different preservatives on the shelf-life stability of the tomato paste produced aseptically in the laboratory. The experimental tomato fruits were purchased from two local markets in Jos North during the peak of harvest in October 2014. Among the experimental tomato fruits purchased, 6 were spoiled and 44 were looking healthy. The 6 spoiled fruits were used for the isolation of fungi species causing rot in the fruits using standard mycological methods. The 44 healthy tomato fruits used for the production of the paste were weighed, washed with tap water, boiled for 20 minutes (100°C). The epicarp of the boiled tomatoes was peeled and the peeled tomatoes were blended and boiled (to evaporate the water to minimal level) for 1 hour to make a paste. The paste was then cooled for 4 hours on a table. After cooling, 10g of the paste was weighed each in bijou bottles which were 48 in number. Each 10g of the paste weighed was given different treatment using T1 (0.01g salt concentration), T2 (0.02g salt concentration), T3(0.03g salt concentration), T4 (0.02g sodium benzoate), T5 (candle wax used in sealing the bottles) and finally T6 (10g of the paste without any preservative to serve as control). The experimental bottles were divided into 2 sets with each set containing 24 bottles. One set was kept in the refrigerator (4°C) while the other set was kept at an ambient temperature of 25°C±1°C. The experimental pastes (treated and untreated) were evaluated for mycological quality at 1-month interval for 4 months. For every interval, 6 bottles of the paste carrying all treatments and control in each environmental condition were evaluated for mycological quality. After every evaluation, the contents of the paste were discarded. Fungi species isolated in the spoiled/untreated tomato paste include Aspergillus niger, Schizosacchomyces pombe, Brettanomyces intermidius and Fusarium sp. Treated tomato paste using candle wax and 0.03g salt concentration produced the best results under both environmental conditions