Effects of Processing Techniques on Stability of Sesame Paste

In this paper, the key processes and core indexes that affect the storage stability of sesame paste are investigated, the key technological conditions were compared, such as the making process (roasting temperature and time), different treatment methods of raw materials (peeling and unpeeling), grinding paste number. The storage stability indexes such as centrifugal oil extraction rate, sedimentation oil extraction rate and physicochemical properties such as particle size and specific surface area were measured.Through the analysis and induction of the changes of each index under different technological conditions and the correlation analysis, the correlation between processing technology and storage stability was clarified. The results showed that the roasting time of sesame had a significant effect on the oil evolution rate of the paste sedimentation, and the oil evolution rate showed a decreasing trend at first and then tended to be stable with the extension of roasting time. Baking temperature had no significant effect on the sedimentation rate of sesame paste, but the temperature should not exceed 230 ℃, otherwise the product will have a burnt taste. The correlation coefficients between the centrifugal oil extraction rate and the sedimentation rate on 30, 60 and 90 days were 0.966, 0.955 and 0.967 respectively, showing a very significant positive correlation. The centrifugal oil extraction rate was also significantly positively correlated with the median diameter(D50) and average particle size(Dav) of sesame paste, and the correlation coefficient were 0.952 and 0.913. However, the centrifugal oil extraction rate was negatively correlated with specific surface area S/V, and the correlation coefficient was −0.930. The centrifugal oil extraction rate could be used as the evaluation index of the storage stability of sesame paste. The centrifugal oil extraction rate was used as the evaluation index to compare the centrifugal oil extraction rate of peeled and unpeeled sesame into sesame paste. It was found that the existence of sesame peel could improve the paste viscosity and facilitate stable storage and reduce the centrifugal oil extraction rate. Compared with the number of times of grinding, the centrifugal oil extraction rate was 3.34% under the conditions of 220 ℃ baking temperature, 20 min baking time and 3 times of grinding. The centrifugal oil extraction rate was the lowest and the stability was the best under this condition.