Improvement of Spread-Ability of Peanut Butter Stabilized by Monoglyceride

In this work, the ''sijibao'' peanut butter stabilized by the hydrogenated vegetable oil, a peanut butter with spread-ability widely recognized by consumers, was used as the reference. Then sensory evaluation about spread-ability, rheological properties, texture parameters, solid fat content and microstructure of the peanut butters stabilized by monoglyceride and peanut oil were analyzed to clarify whether the addition of peanut butter could improve the spread-ability of peanut butter stabilized by monoglyceride and the corresponding mechanism. Results indicated that the sensory scores of monoglyceride-stabilized peanut butter on spread-ability were significantly lower than those of peanut butter with hydrogenated vegetable oil. However, 2.0% peanut oil was added to monoglyceride-stabilized peanut butter and its sensory score was close to that of peanut butter with hydrogenated vegetable oil, indicating good spread-ability. The steady-state shear curve showed that the addition of peanut oil reduced the apparent viscosity of monoglyceride-stabilized peanut butter. Meanwhile the yield stress at 25 ℃ decreased from 201.79 to 103.70 Pa, and the reduction percentage of viscosity at 32~42 ℃ decreased from 62.7% to 53.2%. Furthermore, the addition of peanut oil caused the reduction on firmness of monoglyceride-stabilized peanut butter from 376.19 g to 289.42 g and the consistency from 2050.24 g to 1607.23 g. The solid fat content decreased to less than 8.0%. These results indicated that the physicochemical properties of monoglyceride-stabilized peanut butter after adding peanut oil were very close to those of hydrogenated vegetable oil-stabilized peanut butter, which might be the reason for the improvement of its spread-ability. Additionally, microstructure showed that the addition of peanut oil significantly improved the large and dense crystalline agglomerates of peanut butter stabilized by the monoglyceride and thereby the uniform distribution system formed. In summary, the addition of peanut oil effectively on the one hand improved the physicochemical characteristics of monoglyceride-stabilized peanut butter, on the other hand increased its uniformity, which produced the improvement of spread-ability.