Effects of regio-selectively carboxylated polysaccharides on the release of volatile compounds in hydrocolloid model systems

Abstract

The release of thirteen volatile aroma compounds in hydrocolloid model systems containing original and regio-selectively carboxylated polysaccharides (cellulose, ß-glucan, and chitin) was analyzed using a static headspace autosampler and a gas chromatograph. The thirteen volatile compounds studied were esters (ethyl acetate, methyl propionate, ethyl propionate, ethyl butyrate, butyl propionate, ethyl caproate, ethyl caprylate, and ethyl nonanoate), alcohols (2-propanol and 3-methyl-1-butanol), ketone (2,3-butanedione), and aldehydes (trans-2-hexenal and cis-4-decenal). The release of ester compounds increased from ethyl acetate to ethyl butyrate, but then decreased from butyl propionate to ethyl nonanoate, as the carbon number of the compound increased. This result showed that hydrophobicity (Log P) of volatile compounds had a considerable effect on the release of volatile compounds from hydrocolloid system to headspace. But the release of ethyl esters decreased gradually from butyl propionate to ethyl nonanoate. This result also showed that other factors including molecular weight, boiling point, solubility of volatile compounds, viscosity of hydrocolloid system, and interaction between volatile compounds and polysaccharides than hydrophobicity (Log P) affected the release of volatile compounds. Comparing with the release of other volatile compounds, the release of 2-propanol, 3-methyl-1-butanol, and 2,3-butanedione was remarkably reduced. The hydrogen bonding between these three compounds and water molecule within hydrocolloid system or hydroxyl groups in polysaccharides might be responsible for the reduction of their volatility. The release of volatile compounds was easier in water system than in hydrocolloid system containing polysaccharide. This implied that the interaction between polysaccharides (cellulose, chitin, and ß-glucan) and volatile compounds inhibited the release of volatile compounds. The viscosity of hydrocolloid system at three different concentrations (0.1%, 0.5%, and 1.0%) was measured by rheometer. There were no significant differences in viscosity and the release of volatile compounds as the concentration of polysaccharide (cellulose, chitin, and ß-glucan) increased. However, as the concentration of polysaccharide increased, the release of volatile compounds decreased slightly although viscosity did not change. This verified that the interaction between volatile compounds and polysaccharides existed in hydrocolloid model system. This study did not show a significant difference in the effect of pH and water activity on the release of volatile compounds.;선택적으로 카르복실화된 불용성 다당류 (cellulose, β-glucan, chitin)가 포함된 Hydrocolloid 모델시스템에서 13가지 휘발성 향기성분의 방출정도를 static headspace autosampler와 가스 크로마토그래프를 이용하여 분석하였다. 본 연구에 사용된 13가지 향기화합물은 esters (ethyl acetate, methyl propionate, ethyl propionate, ethyl butyrate, butyl propionate, ethyl caproate, ethyl caprylate, ethyl nonanoate), alcohols (2-propanol, 3-methyl-1-butanol), ketone (2,3-butanedione), aldehydes (trans-2-hexenal, cis-4-decenal)계열 화합물들 이었다. Ester계열 화합물들의 방출정도는 분자내 탄소수에 비례하여 기상으로의 방출이 ethyl butyrate까지는 증가하다가 butyl propionate에서부터 다시 낮아지는 경향을 보였다. 이러한 결과들은 향기화합물의 hydrophobicity (LogP)가 hydrocolloid 시스템에서 향기성분의 기상으로의 방출에 큰 영향을 준다는 것을 의미하였다. 즉, ethyl acetate에서 ethyl butyrate까지는 hydrophbicity가 증가함으로 인해, 극성의 Hydrocolloid system에서 방출이 증가한 것으로 보이며, butyl propionate에서 ethyl nonanoate까지는 화합물의 hydrophobicity보다는 분자량의 증가로 인한 휘발성 감소때문으로 여겨진다. 또한 이러한 결과는 향기화합물의 방출에는 hydrophobicity (LogP) 외에 향기화합물의 분자량, 끓는점, 용해도 및 hydrocolloid 시스템의 점도, 향기화합물과 다당류간의 상호작용 등의 다른 요인들이 영향을 미칠 수 있음을 보여주는 것이었다. 2-propanol, 3-methyl-1-butanol, 2,3-butanedion은 다른 화합물들과 비교해 볼 때, 화합물들의 방출정도가 현저하게 적었는데, 이는 Hydrocolloid system 내부의 물 분자 및 다당류의 hydroxyl group과의 수소결합으로 인한 휘발성 감소에서 기인하는 것으로 보여진다.다당류가 포함되지 않은 용액에서보다 다당류가 포함된 Hydrocolloid system에서 향기화합물의 전체적인 방출정도가 적었다. 이는 cellulose, chitin, β-glucan 과 향기성분 간에 상호작용이 존재하여 향기화합물의 방출을 방해하기 때문으로 여겨진다. cellulose, chitin, β-glucan의 농도를 달리하여 hydrocolloid system의 점도를 측정한 결과, 점도와 향기화합물의 방출정도에 있어서는 시료간에 통계적으로 유의적인 차이를 보여주지 않았다. 그러나 다당류의 농도를 증가시킬수록 점도가 증가하지는 않았으나 향기화합물의 방출은 약간의 감소를 보여줌을 볼 수 있었다. 이를 통해 향기화합물과 cellulose, chitin, β-glucan 간의 상호작용을 재확인 할 수 있었다. 향기화합물의 방출에 대한 hydrocolloid system의 pH와 수분활성도의 영향은 이 실험을 통해서는 통계적으로 유의적인 차이가 보여지지 않았다.