• 한국식품과학회지
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• 제53권5호
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• pp.553-560
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• 2021

본 연구에서는 저온진공조건에서 추출 시간과 농도에 따른 녹차 열수추출조건을 최적화한 후 HP-20 column으로 caffeine을 제거한 녹차 추출물을 이용해 theanine 함유 기능성 젤리를 제조하였다. 또한, theanine 함유 젤리의 품질 특성, 제형안정성 및 항산화 효과, AChE 억제능을 조사하였다. 최적추출조건은 8% 녹차 분말을 2시간 추출하여 theanine 0.95 mg/mL, GABA 0.28 mg/mL, caffeine 1.45 mg/mL 추출액을 HP-20 column을 이용해 80% 에탄올로 카페인을 제거하였다. 3종의 겔화제와 농도별로 4종의 theanine 추출물 S1-S4(10-50%)을 제조해 품질 특성을 조사한 결과, 젤리에 theanine 추출물이 많을수록 L값과 b값이 증가하였다. 젤리의 물리적 특성을 조사한 결과, 3가지 겔화제 중 타마린드검, 잔탄검, 로거스트콩검(2:3:5=w/w/w)을 조합한 겔화제 III이 경도와 점착성이 낮고 탄력성이 높아 조직감이 가장 뛰어났다. 제형안정성 조사 시, 35%가 첨가된 S3가 이수율 25.88%과 붕괴율 1.31%로 우수한 제형안정성을 나타냈다. 또한 theanine 함유 젤리는 95℃, 30분간 가열조건에도 theanine과 GABA 성분이 파괴되지 않고 대부분 잔존하는 것을 TLC와 LC-MS 분석을 통해 확인했다. Theanine 추출물의 농도가 높을수록 DPPH radical 소거능은 증가하며, S4(50%)는 0.075 mg/mL ascorbic acid 수준과 유사한 항산화력을 나타냈다. AChE 저해 효과는 S3(35%)가 가장 높았으며 이는 donepezil 2.5 μM과 동일한 수준의 AChE 저해 활성을 나타냈다. 따라서 본 연구는 녹차 추출물에서 caffeine을 제거한 theanine 추출물로 기능성 젤리를 제조하였으며 품질 특성을 조사하였다.

• Advances in nano research
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• 제16권6호
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• pp.565-577
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• 2024

Vibration investigation of fluid-filled functionally graded cylindrical shells with ring supports is studied here. Shell motion equations are framed first order shell theory due to Sander. These equations are partial differential equations which are usually solved by approximate technique. Robust and efficient techniques are favored to get precise results. Employment of the Rayleigh-Ritz procedure gives birth to the shell frequency equation. Use of acoustic wave equation is done to incorporate the sound pressure produced in a fluid. Hankel's functions of second kind designate the fluid influence. Mathematically the integral form of the Langrange energy functional is converted into a set of three partial differential equations. A cylindrical shell is immersed in a fluid which is a non-viscous one. These shells are stiffened by rings in the tangential direction. For isotropic materials, the physical properties are same everywhere where the laminated and functionally graded materials, they vary from point to point. Here the shell material has been taken as functionally graded material. After these, ring supports are located at various positions along the axial direction round the shell circumferential direction. The influence of the ring supports is investigated at various positions. Effect of ring supports with empty and fluid-filled shell is presented using the Rayleigh - Ritz method with simply supported condition. The frequency behavior is investigated with empty and fluid-filled cylindrical shell with ring supports versus circumferential wave number and axial wave number. Also the variations have been plotted against the locations of ring supports for length-to-radius and height-to-radius ratio. Moreover, frequency pattern is found for the various position of ring supports for empty and fluid-filled cylindrical shell. The frequency first increases and gain maximum value in the midway of the shell length and then lowers down. It is found that due to inducting the fluid term frequency result down than that of empty cylinder. It is also exhibited that the effect of frequencies is investigated by varying the surfaces with stainless steel and nickel as a constituent material. To generate the fundamental natural frequencies and for better accuracy and effectiveness, the computer software MATLAB is used.