The effect of garlic and ginger phytogenics on the shelf life and microbial contents of homemade soursop (Annona muricata L) fruit juice

Abstract

The preservative effects of garlic and ginger was compared with that of sodium benzoate in assessing the shelf quality of locally prepared soursop juice. The soursop juice without treatment (T₁) was used as the control while others in four replicates were separately treated with 50 mg/ml garlic (T₂), 50 mg/ml ginger (T₃), mixture garlic and ginger in equal proportion of 50 mg/ml each (T₄) and 10 mg/ml (T₅) sodium benzoate respectively. The microbial counts ranged from 3.0×10⁴-1.27×10⁶ cfu/ml juices with the untreated recording the highest concentration of contamination compared with the treated juices of which sodium benzoate had the least microbial contamination. The microorganisms consistent in all the treatments were Bacillus sp., Staphylococcus sp., Acetobacter sp., Klebsiella sp., Saccharomyces cerevisiae and Candida tropicalis while the distribution of Streptococcus sp., Klebsiella and Penicillium sp., and Proteus sp were sporadic. Marginal decreases in pH values were observed in the stored soursop juices across treatments. The results obtained showed that the treatment of freshly prepared soursop juices with sodium benzoate, and a mixture of garlic and ginger improved storage span and reduced health risks of infection and/or intoxication from their consumption.

Keywords: Shelf life, soursop juice, phytogenics, preservatives, microbial load.