Soymilk Preservation Using Extracts Of Cloves (Syzygium Aromaticum Myrtaceae) And Guinea-Pepper (Xylopia Aethiopica Annonaceae).

Abstract

The significance of preservatives in food preparations lies in their ability to inhibit or retard the growth of microorganisms which in turn reduces their deteriorative effects on food. The preservative effects of varying concentrations (1%, 3%, 5% v/v) of extracts of cloves (Syzygium aromaticum myrtaceae), guineapepper (Xylopia aethiopica annonaceae) and a combination of the two extracts on soymilk were studied in both shelfed and refrigerated samples. The pH, protein and fat contents, and microbial load were used as parameters for determining the stability of the milk. The pH values for clove extract-treated soymilk samples on shelf showed increased level of acidity (5.16±0.13) compared to treated-refrigerated samples (6.62±0.03), while the protein contents decreased more with storage time and these were concentration dependent. The fat contents of the treated samples especially those treated with a combination of extracts were significantly higher (P<0.05) than the untreated soymilk samples. Reduction in total microbial count was more pronounced in samples treated with clove extract (1.92 x 105) than those treated with guinea pepper extract (2.70 x 105) and the controls. The cloves-guinea pepper extract combination demonstrated the best preservative effect than the single extracts in terms of nutrient content but the antimicrobial activity of the clove extract at 3% was significantly higher (P<0.05) than those of guinea-pepper and the combination. The use of cloves as a preservative increased shelf life of soymilk by 2 on shelf and 8 days in the refrigerator, guinea pepper extended shelf life by 1 day on shelf and 6 days in refrigerator while combination of the extracts maintained a longer shelf life of 12 days in the refrigerator and 2 days on the shelf. The result of the study shows that a combination of the extracts is a better preservative of soymilk than the single extracts.