Kulit ubi jalar ungu (Ipomoea batatas L.) merupakan limbah yang jarang
dimanfaatkan meskipun memiliki kandungan antosianin lebih tinggi dibandingkan
daging umbinya. Antosianin merupakan pigmen alami yang berpotensi digunakan
untuk mengetahui potensi ekstrak kulit ubi jalar ungu sebagai pewarna alami
alternatif kristal violet pada pewarnaan sederhana bakteri Staphylococcus aureus
dan Escherichia coli. Penelitian dilakukan dengan pengamatan secara mikroskopis,
stabilitas terhadap paparan cahaya menggunakan botol bening dan botol gelap, serta
stabilitas pada suhu penyimpanan ruang dan refrigerator selama 7 hari. Kristal
violet digunakan sebagai kontrol. Hasil pengamatan secara mikroskopis dianalisis
menggunakan perangkat lunak ImageJ untuk menentukan

Purple sweet potato peels are a rarely utilized byproduct, even though they contain
higher levels of anthocyanins than the tuber flesh. Anthocyanins are natural
pigments with potential applications as an alternative to crystal violet in simple
bacterial staining. This study aimed to determine the potential of purple sweet
potato peel extract as a natural alternative to crystal violet for the simple staining
of Staphylococcus aureus and Escherichia coli. The study was conducted through
microscopic observation, light stability testing using clear and dark bottles, and
stability testing at room temperature and in the refrigerator for 7 days. Crystal
violet was used as a control. The results of the microscopic observations were
analyzed using ImageJ software to determine the % staining effectiveness, and the
data were statistically analyzed using SPSS. The results showed that purple sweet
potato skin extract was able to stain Staphylococcus aureus and Escherichia coli
effectively and remained stable through the 7th day of observation. ImageJ analysis
indicated staining effectiveness of 97%–108%, which falls within the standard
range for good effectiveness (85%–115%). An independent samples t-test on the
light exposure treatment showed a significance value of 0.034 for Staphylococcus
aureus and 0.944 for Escherichia coli, indicating that light exposure affects the
stability of the dye on Staphylococcus aureus but not on Escherichia coli. In the
storage temperature treatment, significance values <0.05 were observed for both
bacteria, indicating that temperature affects the stability of the extract. Thus, purple
sweet potato peel extract has the potential to be used as an alternative natural dye
in simple bacterial staining and exhibits good stability up to the 7th day of storage.
Keywords:Purple sweet potato peel, anthocyanin, simple staining, Staphylococcus
aureus, Escherichia coli.