The moisture contained in conventionally extracted red crab shell samples was lower than than in samples extracted using high pressure. In contrast, ash content increased as the extraction time increased and displayed no significant variation in high pressure extraction. Extraction time was influential, with lower lightness (L-value) being obtained in samples extracted at high pressure as compared to traditional extraction. However, large variation in a- and b-values resulted from traditional extraction. For both traditional and high pressure extraction increases in pH, salinity and saccharide content were noted with increasing extraction time, but these parameters did not vary substantially in red crab shell extracted at high pressure. The mineral content in samples extracted by high pressure was higher than in traditionally extracted samples. The mineral content increased with time, with marginally higher contents of essential amino acids and flavor enhancing amino acids noted following high pressure extraction. The contents of the flavor enhancing amino acids increased from 30?60 min, thereafter decreasing. Assessment of consumer acceptance revealed that, while traditionally manufactured red crab sauce was popular, sauce manufactured using a 60 min high pressure extraction was preferred. Extending the high pressure extraction time to 75 min produced a less sensory acceptable product, due to higher mineral and protein levels.
In order to examine the pre-treatment effect of crab shell on Pb2+ removal by crab shell in aqueous solution, acid and alkali pre-treated crab shell were used. Electron microscopy techniques such as TEM (transmission electron microscopy) and SEM (scanning electron microscopy), and EDX (energy dispersive X-ray) and FTIR (Fourier transform infrared) spectrometry techniques were used to investigate the process of Pb2+ removal by acid and alkali pre-treated crab shell. The Pb2+ removal by acid pre-treated crab shell was much lower than that by untreated crab shell because of the decrease of CaCO3 from the crab shell. However, the Pb2+ removal by alkali pre-treated crab shell increased compared to that by untreated crab shell. The results were confirmed by TEM, SEM, EDX and FTIR.
In order to examine the inhibition effect of other heavy metal ions on the removal of heavy metal ions by crab shell in aqueous solution, 10 heavy metal ions (Cr3+, Cd2+, Ni2+, Zn2+, Hg2+, Cu2+, Mn2+, Fe2+, Fe3+, Pb2+) were used as single heavy metal ions and mixed heavy metal ions, respectively. In single heavy metal ions, Pb2+, Cr3+, Cu2+ were well removed by crab shell, however, Cd2+, Ni2+, Zn2+, Mn2+ were not. The heavy metal removal increased as the increase of covalent index (Xm2r), and the relationship classified heavy metal ions as 2 heavy metal groups (Fe3+, Fe2+, Cu2+, Cr3+, Mn2+, Ni2+, Zn2+ group and Pb2+, Hg2+, Cd2+ group). In mixed heavy heavy metal ions, the removals of Fe2+, Fe3+, Pb2+, Cu2+ as 0.49 mmol/g, regardless of the existence of other heavy metal ions, were similar to the result of single heavy metal ions experiment. The removals of Mn2+, Cd2+, Ni2+ decreased as the existence of other heavy metal ions, however, the removal of Zn2+, Cr3+, Hg2+ increased.
Several effects on Pb2+ removal by crab shell from aqueous solution were investigated. As the increase of initial Pb2+ concentration and decrease of initial crab shell concentration, the time required to reach an equilibrium state and the residual Pb2+ concentration increased. In our experimental ranges, the optimum initial Pb2+ concentration and crab shell concentration were below 103 mg/l and over 0.5 mg/l, respectively. Also, in order to investigate the mechanism of Pb2+ removal by crab shell in aqueous solution, the crab shell was compared with chitosan and chitin on aspects of Pb2+ removal capacity and Pb2+ removal rate. The Pb2+ removal by crab shell was greater than that by chitin and chitosan. The role of chitin was not so great in Pb2+ removal by crab shell. The Pb2+ removal by chitosan was not exactly correlated to the molecular weight of chitosan.
In order to examine the availability and effectiveness of crab shell for the removal of heavy metals in aqueous solution, the crab shell was compared with cation exchange resin (CER), zeolite, granular activated carbon (GAC) and powdered activated carbon (PAC) on aspects of heavy metal removal capacity, rate and efficiency. In the removal of Pb, Cd and Cr, the heavy metal removal capacity of crab shell was higher than those of any other sorbents (CER, zeolite, GAC, PAC), and the order of heavy metal removal capacity was crab shell > CER > zeolite > PAC =~GAC. However, in the removal of Cu, the result of crab shell was slightly lower than that of CER. The initial heavy metal removal rate was affected by the sorts of sorbents and metals. In all heavy metals, the heavy metal removal rate of crab shell was higher than those of any other sorbents. Under the heavy metal concentration of 1.0 mmole/ℓ, the heavy metal removal efficiency of crab shell was maintained as 93∼100 %, which was much higher than those of any other sorbents.
김치의 향미개선 및 게껍질 분말 첨가김치의 부미를 제거하기 위한 향미개선제로서 우골추출물의 첨가효과를 검토하였다 우골추출물은 김치의 숙성중 pH와 산도, 총균수, 젖산균비, Leuconostoc과 Lactobacilli의 수에는 큰 영향을 미치지 못하였으나 산미와 김치냄새를 감소시키고 종합적 맛을 개선시키는 향미 개선제로서의 역할을 하였다. 또 우골추출물(0.03%)을 게껍질분말(1.5%)과 함께 첨가할 경우는 게껍질분말만을 첨가한 경우보다 높은