논문 상세보기
pp.7-13
본 연구에서는 rheometer를 이용하여 식용유 함량을 75, 80, 85%로 달리하여 제조한 3종류의 마요네즈의 정상유동특성과, 진폭을 작게 한 전단변형하에서의 동적유동특성을 광범위한 전단속도와 frequency 영역에서 측정하였다. 이들 결과로부터 정상유동특성의 전단속도 의존성 및 동적점탄성의 frequency 의존성을 조사하였다. 마요네즈는 항복응력과 shear-thinning 및 thixotropy성을 지니고 있었으며 이들 성질은 식용유 함량이 증가할수록 강화되었다. 점탄성의 측정결과 광범위한 frequency 영역에서 G'값은 G"값보다 매우 크게 나타났으며 G'과 G"의 frequency 의존성을 나타내는 척도인 n'과 n"은 각각 0.10, 0.20이었으며 G"이 G'보다 frequency 의존성이 더 큰 것으로 나타났다. 한편 75, 80, 85% 마요네즈의 부피평균직경은 각각 3.89 μm, 3.04 μm, 3.15 μm로 식용유 함량이 75%인 경우가 가장 크게 나타났다.
The steady shear flow and the small-amplitude dynamic viscoelastic properties of mayonnaises with different oil contents (75-85%) have been studied over a wide range of shear rates and angular frequencies by using a cone-plate rheometer. Yield stress was determined by Casson model. The fluid consistency coefficient (K) and flow behavior index (n) were determined by Herschel-Bulkley model. The volume-weighted average diameters of oil droplets for mayonnaises with 75, 80 and 85% oil contents were 3.89, 3.04 and 3.15 μm, respectively. All of the mayonnaises had yield stress, shear-thinning behavior and thixotropy. These properties were fortified as the oil content in the mayonnaise increased. The magnitude of storage modulus and complex viscosity increased with the increase of oil contents. Over a wide range of angular frequencies, the value of storage modulus (G') for mayonnaise was much higher than that of loss modulus (G"). Both G' and G" increased with increasing angular frequency but they had slight dependency on angular frequency. Parameters, n' and n" were 0.10 and 0.20, respectively, meaning that frequency dependency of G' was smaller than that of G". The mayonnaise with higher oil content had more pronounced gel-like characteristics than that with lower oil content.
