Comparison of the stability between branched-chain amino acid (BCAA)-coated liposome and double emulsion

분지쇄아미노산(BCAA)이 포집된 더블에멀션과 리포좀의 안정성 비교

Abstract

This study was conducted to compare the stability between branched-chain amino acid (BCAA)-encapsulated liposome and double emulsion (DE). Liposome was produced by high-speed homogenization and ultrasonication whereas DE was prepared by homogenizing with surfactants. All samples were fixed at pH 4 and 7 and stored at 4, 25, and $40^{\circ}C$ for 5 days. Encapsulation efficiency and cumulative release rate were measured under $4^{\circ}C$ and at $25^{\circ}C$. The results showed that the size of BCAA-coated liposome was greater at pH 7 than at pH 4. The zeta-potential value of BCAA-coated liposome was greater at pH 4 than at pH 7. It was supposed that the negatively charged liposomes attracted the positively charged BCAAs at pH 4 resulting in the formation of the vesicle with smaller size. Particle size of DE was smaller than $100{\mu}m$. Encapsulation efficiencies of BCAA in DE or liposome were over 97%, approximately, and the cumulative release rates of them were below 30% for 5 days.

본 연구에서는 식품에 적용할 수 있는 코팅방법인 리포좀과 더블에멀션의 안정성을 연구하기 위해 기능성 아미노산인 BCAA를 함유한 리포좀과 더블에멀션을 제조하였다. 리포좀의 입자크기는 pH 7보다 pH 4에서 더 작게 나타났는데, 이는 양쪽성 이온인 BCAA가 pH 4에서는 양전하를, pH 7에서는 음전하를 띠기때문에 음전하인 레시틴과의 상호작용을 하여 그 크기에 차이가 있는 것으로 판단된다. 제타전위의 절댓값은 pH 7보다 pH 4에서 더 크게 나타나 pH 4에서 리포좀의 분산안정성이 더 높은 것으로 나타났다. 더블에멀션은 초기 입자의 크기가 $100{\mu}m$ 이내, 제타전위는 모두 절댓값이 30 mV 이상이었으나, 시간이 경과함에 따라 그 크기가 커지고, 제타전위의 절댓값은 감소하는 경향을 보였다. 리포좀과 더블에멀션의 BCAA 포집율은 모두 97% 이상이었고, 누적 방출율은 리포좀에서 더 크게 나타났으나 5일간 누적방출율은 30% 미만으로 나타났다. 따라서 리포좀과 더블에멀션은 높은 효율로 특정 기능성 물질을 안정적으로 포집한다는 특징을 가지며, 추후 계속적인 연구를 통해 이를 식품 산업에 적용할 수 있을 것으로 기대된다.

Fig. 1. Changes in particle size of BCAA-coated liposome depending on the storage temperatures at 4℃ (A), 25℃ (B) and 40℃ (C).

Fig. 2. Zeta-potential of BCAAs depending on pH values.

Fig. 3. Changes in particle size of BCAA-coated double emulsion depending on the storage temperatures at 4℃ (A), 25℃ (B) and 40℃ (C).

Fig. 4. Zeta-potential value of BCAA-coated liposome on storage conditions at 4℃ (A), 25℃ (B) and 40℃ (C).

Fig. 5. Zeta-potential value of BCAA-coated double emulsion on storage conditions at 4℃ (A), 25℃ (B) and 40℃ (C).

Fig. 6. Encapsulation efficiency of liposome and double emulsion containing BCAA.

Fig. 7. Cumulative release rate of liposome containing BCAA adjusted to pH 4 (A) and adjusted to pH 7 (B).

Fig. 8. Cumulative release rate of double emulsion containing BCAA adjusted to pH 4 (A) and adjusted to pH 7 (B)