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Evaluation of properties of soymilk added with dragon fruit and eggplant peels extracts

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Soymilk as one of soybean-processed products has become more and more consumed in Indonesia since the beginning of 1990. However, soymilk is known to have very short shelf life due to its high protein content leading to microbial contamination. This study aimed to utilize peel waste from natural plant sources, i.e. eggplant (Solanum melongena L.) and dragon fruit (Hylocereus polyrhizus) to prolong the shelf life of fresh soymilk by inhibiting the microbial growth. The microbiological analysis showed that a notably higher inhibitory effect of dragon fruit peel extract was achieved when the treated soymilk was stored at 4┬║C. Modified samples exhibited lower number of colonies even after 6 days. Interestingly, antimicrobial activity of eggplant peel extract in cold soymilk could be observed only on day 3 until day 9. Hence, it is assumed that chlorogenic acid, as primary antimicrobial agent in eggplant peel, needed certain interval of time to activate its inhibitory activity against microorganism. From this study, it can be concluded that both peel extracts could not prolong the shelf life of soymilk when stored at ambient temperature. Generally, all soymilk samples added with peel extracts fulfilled the required SNI standard in terms of pH value, protein content, and total solid content. Sensory evaluation proved that soymilk treated with dragon fruit peel extract were favored over that with eggplant extract. Overall, samples with dragon fruit peel extract attained comparable acceptance level as plain soymilk. In conclusion, the research indicated a potential application of usual household waste, namely dragon fruit and eggplant peels, as antimicrobial agents for protein-rich beverage. To the best of author's knowledge, this is the first study where the usage of eggplant and dragon fruit peel extracts in soymilk has been investigated.rnrnNOTE: CD error

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B01265

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Series Title

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Call Number

1265

Publisher

: Swiss German University., 2012

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Language

English

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Classification

NONE

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Subject(s)

FT

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