ANTIMICROBIAL AND ANTIOXIDANT EFFICACY OF SOME NATURAL PLANTS EXTRACTS

Document Type : original papers

Authors

Food Industries, Fac. of Agric., Menoufia Univ.

Abstract

In this study, antioxidants, and antimicrobials of guava leaves, pomegranate peels, and turmeric powder were extracted by water, ethanol 70% and ethyl acetate. The extracts were characterized through the determination of yield extract, total phenolics, total flavonoids, antioxidant activity, antioxidant stability, phenolic, and flavonoid fractions as well as antimicrobial activity. The solvents which have high antioxidant and antimicrobial effects were selected to improve the shelf-life quality of meatballs during cold storage at 5°C for 16 days and cupcakes during storage at room temperature (25°C) for 28 days. The results showed that the pomegranate peels extracts and water extracts had the highest yield extract, while pomegranate peels extracts and ethyl acetate extracts had the highest total phenols and total flavonoids content. Guava leaves ethanol 70%, pomegranate peels ethanol 70% and turmeric ethyl acetate extracts at concentrations 30 and 40 mg/ ml appeared stronger antioxidant activity than the other extracts evaluated by DPPH method. Turmeric powder ethyl acetate extract (20mg/ ml) had a lower reduction in antioxidant activity after heating, while at concentration 0.5% had the lowest peroxide value of heated oil by Schaal test and had a higher oxidative stability parameter than the other extracts measured by Rancimat. Guava leaves ethanol 70% extract contained abundant phenolic and flavonoid compounds fractioned by HPLC. Turmeric powder ethyl acetate extract (20 mg/ ml) had a higher inhibition zone and lowest minimal inhibition concentration (2.5 mg/ ml) than other studied extracts against all tasted bacteria. Meatball with pomegranate peels ethanol extract had the lowest means of pH value, thiobarbituric acid value, total volatile nitrogen value, total aerobic bacterial count, while meatballs with pomegranate peels ethanol extract and guava leaves ethanol extracts had a lower means of psychrophilic bacterial count, lipolytic bacterial counts, proteolytic bacterial counts, coliform bacterial, and yeast and mold count. Meatball control had a lower means in all sensory properties (except colour) than other meatballs with different plant materials extracts.Cupcake with pomegranate peel ethanol extract had a lower means of acid value, thiobarbituric acid value, and peroxide value, while cupcakes with different plant material extracts had a lower means total bacterial count and coliform bacterial count. Cupcake with pomegranate peel ethanol extract and cupcake with turmeric powder ethyl acetate extract had a lower means yeast and mold count. All sensory properties mean of all cupcake samples were gradually decreased with the increase of storage period. Cupcake control had a lowermeans in all sensory properties than other cupcakes with different plant materials extracts.

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