ABSTRACT

The microbial quality of pasteurized soursop juice locally produced and the effect of acidification and chemical preservative on the juice were investigated. Soursop fruits were obtained from Umuahia market and analyzed according to standard methods. Microbiological and storage stability of the juice were evaluated following pasteurization at 60°C for 1hr, acidification with lime (2m1) and addition of 0.05% sodium benzoate (NaB). Microbial load increased in the control sample (without treatments), from 4.3x10⁶ cfu ml to 14.6x10⁶cfu ml^-1. Pasteurized soursop juice recorded a decrease in microbial load from 2.2x10³cfu ml^-1 to 4.2x10' cfu ml^-1. Juice treated with sodium benzoate also recorded a marked decrease in microbial load from 1.2x106cfu ml^-1 to 2.3x105cfu ml^-1 as well as acidified soursop juice which decreased from 2.3x10⁶cfu ml to 4.8x10³cfu Pasteurized soursop juice recorded an increase in pH from 4.89 to 4.98 and a decrease in titrable acidity from 23.25 to 21.92. Soursop juice treated with sodium benzoate recorded an increase in pH from 5.94 to 6.23 and a decrease in titrable acidity from 23.62 to 18.10. Acidified soursop juice recorded a decrease in pT-1 from 4.03 to 3.95 and an increased but steady titrable acidity of 37.50. The results of the ANOVA showed significant differences (p<0.05) in the parameters tested. The study revealed that the synergistic effect of pasteurization, acidification and treatment with sodium benzoate can be used to extend the shelf-life of soursop juice for up to two weeks.