ABSTRACT

This study adopted survey and experimental design which aimed at assessing the shelf life attribute of cakes produced with five different preservatives for longevity in household and commercial production. Preservative such as rum, spirit, lime juice, Sorbic acid, rum and spirit,and dry gin were used to prepare different cakes which were preserved under room temperature and were labeled sample A,B,C,D,E,F. Microbial analysis was carried out: the culture media used was a general purpose medium, potato dextrose alga, a differential culture mediumforfungi only, Manrogosa and Sharpe alga, macconkey algafor coliforms, mannitol salt alga for detection of staphylococcus aureus and salmonella shigella alga. The inoculation method used was spread plate technique of inoculation. Incubation was done inverted in a thermostatically controlled incubator set at 37° C and 42°C respectively for 72 hours and this was monitored on three days intervalfor one month. The morphological characteristics ofall the organism under view were done using a microscope focused at a low power ofx4 and xlO, then at higher power of x40, xlOO and oil immersion magnification. The results of the microbial analysis done at 10'6 dilution factor from day zero to day fifteen shows that there was no significant growth of microbial colony on the six cake samples on day 0 and day 3. Mild microbial growth began to occur on the 6lh day ofstorage alongside Lactobacillus spp. Sample A from the beginning showed the highest resistivity to microbial attack. This sample kept microbial presence on check at 9cfu/g offungifrom day 6 to day 15. Sample A wasfollowed closely by sample E. The total microbial load, which is the total number ofbothfungi and bacteria present on the sample, corresponds to 1.30xl07cfu/g of cake; which 13,000,000 colonies of microbes grew on the cake after the 15days. In conclusion, among the best performing preservatives were that used for sample A which was rum with 30ml rum on 600g of cake. Another proven preservative for cake making was combination ofrum and spirit usedfor sample E at the same level of addition of 30ml. The microorganisms identified Lactobacillus lactis as the only bacteria spoiler agent, while other spoiler agents are yeast and molds such as Sacharomyces lactis, Sacharomyces uvarum, Botrytis spp, Sporendonema sebi, Stachabotrys spp, Rhizopus nigricans, Mucor spp. On recommendation, the quantity of such preservatives of rum or combination ofrum and spirit should be increased triple fold in every 600g of cake batterfor maximum antimicrobial activity during keeping time. Studies should be carried out on incorporation ofvery active antifungal agent into the cake before baking. It is also important to recommend that the combination ofmore than three different preservatives be used in checking the attack ofmicrobes on cake. Cake should be stored at temperatures above 45°C in hot shelves as nofungal can thrive luxuriantly at such elevated temperature.