Abstract
The purpose of this study was to investigate the effect of chitosan on the shelf-life and quality of Paeksulkis(Korea rice cake). Paeksulgis containing 0-0.5% chitosan were stored at 5$^{\circ}C$ for 4 week and 2$0^{\circ}C$ for 1 week to test the effect of extenting shelf-life of Paeksulgis by chitosan. The pH of Paeksulkis was 5.65 without chitosan and pH of those were about 7.0(6.94-7.01) with 0.05-0.5% level of chitosan. Moisture content of Paekrukis wish or without chitosan was 38-40%. In Hunter’s color values of Paeksulkis of control, the lightness (L) was 84.28, redness(a) was -1.56 and yellowness(b) was 7.68. The lightness (L), redness(a) and yellowness(b) of Paeksulkis were increased by the increasing concentration of chitosan. In mechanical characteristics, cohesiveness concentration of Paeksulkis were the highest in control while obtained the highest score in color, after swallowing and overall quality (p<0.05). The score of flavor and consistency of Paeksulkis with different levels of chitosan wre not significant while the score of moisture in Paeksulkis with 0.05-0.5% level of chitosan was significantly higher than control (p<0.05). The score of flavor and consistency of Paeksulkis with different levels of chitosan were not significant while the score of moisture in Paeksulkis with 0.05-0.5% level of chitosan was significantly higher than control (p<0.05). Total bacterial counts (TBC) of Paeksulgis immediately before storage were 4.2$\times$10$^2$CFU/g in control and those containing 0.3-0.5% of chitosan were 0.5-1.0 log cycle lower than control. TBC of Paelsulgis containing chitosan was lower than increased for 2 weeks, reached at 1.8$\times$10$^{5}$ CFU/g and decreased for 2 weeks, reached at 1.8$\times$10$^4$CFU/g during storage at 5$^{\circ}C$. TBC of Paeksulkis with more than 0.3% of chitosan were 1.9 log cycles lower than that of control during storage at 5$^{\circ}C$. TBC of Paeksulkis with more than 0.3% of chitosan were 1.9 log cycles lower than that of control during storage at 5$^{\circ}C$ for 4 weeks. TBC of Paeksulgis increased to 10$^{8}$ CFU/g in control and 10$^{6}$-10$^{7}$ CFU/g in more than 0.3% chitosan during storage at 20$^{\circ}C$ for 1 week. The shelf-life of Paeksulkis was increased with increasing concentration of chitosan both temperature at 5$^{\circ}C$ and 20$^{\circ}C$.
키토산을 각각 0% (Co), 0.05%(A), 0.1%(B), 0.3%(C), 0.5%(D)의 비융로 침가하여 백설기를 제조하여 키토산 첨가에 따른 백설기의 품질특성과 저장성을 조사하였다. 백설기의 품질특성은 pH, 수분함량, 색상, 기계적 texture를 측정하고 관능검사를 행하였으며 백설기의 저장성은 $5^{\circ}C 와 25^{\circ}C$. 에서 저장중 생균수의 변화를 조사하였다. 키토산을 첨가하지 않은 대조구의 pH는 5.65로 산성 올 나따낸 편이나 키토산 첨가군은 모두 pH 7청도로 높은 편이었으며 수분함량은 38-40%로서 시료간에 차이를 나타내지 않았다. 백셜기의 색상은 대조군의 명도 (L치)가 84.28, 적색도(a치)가 -1.56, 황색도(b치)가 7.68 이었으며 키토산의 증가에 따라 명도, 적색도, 황색도 모두 증가하는 경향이었고 $\Delta$E(색채)는 대조군에 비해 모든 군에서 차이를 나타내었으나 유의차는 볼 수 없었다. Texture 측정결과, 응집성(Cohesiveness)과 탄성 (Springness)은 대조군이 가장 높았으며 검성과 부서짐성 은 대조군에 비해 키토산의 챔가 함량이 중가할 수록 중가하는 경향을 나다내였다 관능검사결과, 대조군이 색상, 삼킨후의 느낌, 총합팽가에서 유의적으로 높았으며 향파 부드러운 정도는 유의적 차이가 없었고 촉촉한 정도는 키토산 첨가군이 대조군에 비하여 유의적으로 높은 접수를 얻었다(p<0.05). 떡의 저장직전의 생균.수는 대조구에서 $4.2\times102$C CFU/g이었으며 키토산 을 0.05 -0.1 % 첨가한 경우에는 대쪼구와 큰 차이가 없었으나 0.3-0.5% 첨가한 ;경우에 는 대조구보다 0.5 -1.0 log cycle 낯은 생균수 이었다 $5^{\circ}C$에서 4주일간 저장했윷 때 대조구는 저장 2주일까지 생균수의 증가를 냐타니}어 $8.1\times105$CFU/g에 도달한 후 $1.8\times104$CFU/g 으로 감소하였으며 키토산 첨가구는 0.3% 이상외 키토산 침가구는 대조구보다 1.9 log cycle 이상 낮은 생률수를 유치하였다 백성기를 20t에 l주일간 저장했을 때 대조구의 생균수는 108 많D/g 이상에 도짤하였으나 0.3%의 키토산 첨가구는 106_107 앉D/g에 도짤하였다 키토산 첨가 백설기의 Shelf~life는 $5^{\circ}C$와 $20^{\circ}C$에서 모두 대조구에 비하여 연장되는 효과를 나타내었다.
