Citrus sinensis is one of the most abundant citrus species consumed. Orange peels are a waste by-product of the fruit and may potentially contain useful phytonutrients with biological relevance. Fresh and dry peels of sweet orange were subjected to Soxhlet extraction and then concentrated using a rotary evaporator. Total phenolic, flavonoid and tannin content were determined using standard methods. Antimicrobial activities against five (5) bacterial strains (Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli and Salmonella typhimurium) and three (3) fungal strains (Candida albicans, Aspergillus niger and Penicillium notatum) was carried out by observing the zone of inhibition using disc diffusion method. The total phenolic, flavonoid and tannin content was higher in the fresh peel extract compared to the dry peel extract. Antimicrobial activities revealed that the fresh peel extract had better antibacterial activities against all bacterial strains and one fungal strain studied compared to the dry peel extract. Growth of Aspergillus niger and Penicillium notatum were however better inhibited by the dry peel extract than the fresh peel extract. This study investigated the phenolic content and antimicrobial activities of fresh and dry Citrus sinensis peel extracts. The results from the study conclude that the fresh Citrus sinensis peel extract contains more phenolics and possesses better antimicrobial activities against the studied microbial strains compared to the dry peel extract. The findings in this study suggest that drying plant parts before extraction for phytonutrients may lead to loss of active components.

中文翻译：

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新鲜和干燥乙醇提取物柑橘（O.beck）Osbeck（甜橙）果皮的定量植物化学分析和抗菌活性

柑桔是消耗最丰富的柑桔种类之一。橘皮是水果的废副产品，可能含有与生物学相关的有用植物营养素。将新鲜和干燥的甜橙果皮进行索氏提取，然后使用旋转蒸发仪进行浓缩。使用标准方法测定总酚，类黄酮和单宁含量。通过观察该细菌对五（5）个细菌菌株（金黄色葡萄球菌，粪肠球菌，铜绿假单胞菌，大肠杆菌和鼠伤寒沙门氏菌）和三（3）个真菌菌株（白色念珠菌，黑曲霉和黑青霉）的抗菌活性。使用盘扩散法抑制。总酚 新鲜果皮提取物中的类黄酮和单宁含量高于干果皮提取物。抗菌活性表明，与干果皮提取物相比，新鲜果皮提取物对所有细菌菌株和一种真菌菌株均具有更好的抗菌活性。然而，干皮提取物比新鲜皮提取物更好地抑制了黑曲霉和黑青霉的生长。本研究调查了新鲜和干燥柑桔皮提取物的酚含量和抑菌活性。研究结果表明，与干皮提取物相比，新鲜柑橘皮提取物包含更多的酚类，并且对所研究的微生物菌株具有更好的抗菌活性。