To investigate the functional activity of different citrus fruit peels, antioxidant compounds in 70% ethanol extracts of mandarin, lemon, orange, and grapefruit peel powders were identified, and antioxidant and antibacterial activities were quantitated. Mandarin peel contained the highest content of total phenolic compounds and total flavonoid substances (21.46±0.12 mg GAE/g and 11.57±0.05 mg RE/g, respectively). The total phenolic compound content of the three other citrus fruits was 14.16±0.18-18.44±0.07, and their total flavonoid content was 5.51±0.10-7.46±0.09 mg RE/g. DPPH radical scavenging activity was the highest in lemon peel (87.64±0.21%), and mandarin peel displayed the best antioxidant activity with respective ABTS radical scavenging activity and FRAP measurements of 43.20±0.61% and 78.82±1.06 mM TE/g. Grapefruit peel antimicrobial activity increased with treatment time, and was the most potent among the four tested citrus species, inhibiting Staphylococcus aureus by about 4.05 log cycle. These findings demonstrate that mandarin and grapefruit peel can be used to prevent oxidation, improve food storage capabilities, and potentially preserve food quality.

ABSTRACT
Materials and Methods
    재료
    감귤류 과피의 건조
    일반성분
    감귤류의 과피 추출물 제조
    총 페놀화합물 함량
    총 플라보노이드 함량
    1,1-Diphenyl-2-picry-2-hydrazyl (DPPH) 라디칼 소거능
    2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS)라디칼 소거능
    Ferric reducing power (FRAP) 측정
    식중독 세균 및 억제 활성
    통계처리
Results and Discussion
    감귤류 과피의 건조 시간 선정
    일반성분
    총 페놀화합물 함량
    총 플라보노이드 함량
    DPPH 라디칼 소거능
    ABTS 라디칼 소거능
    FRAP assay
    식중독 세균 억제 활성
국문요약
Conflict of Interests
ORCID
References

• 최현정(전라북도보건환경연구원 식품분석과) | Hyeonjeong Choi (Division of Food Analysis, Jeollabukdo Institute of Health & Environment Research, Imsil, Korea)
• 김용석(전북대학교 식품공학과) | Yong-Suk Kim (Department of Food Science and Technology, Jeonbuk National University, Jeonju, Korea) Corresponding author