Factors contributing to the rheology of tomato puree
Abson, Rachael (2013) Factors contributing to the rheology of tomato puree. PhD thesis, University of Nottingham.
Tomato (Solanum Iycopersicum) puree is created by homogenising the flesh of tomato fruits. The viscosity of this material and the fibrous content is of commercial interest. Tomato puree consists of suspended particles (consisting of whole cells, broken cells and cellular fragments) in an aqueous serum. The contribution of the non-soluble and soluble material to tomato puree rheology was studied with reference to the varying composition of solids and firmness of tomato fruit at four stages of ripeness; mature green, breaker, pink and red ripe. When purees from the red ripe and the breaker fruit with initial total solids contents of approximately 5.5% were diluted to a range of total solids content (between 5 and 1%), both samples decreased in viscosity with total solids. To observe the effect of the serum on tomato puree viscosity, the pellet fraction containing the particles was spun out of the tomato purees by centrifugation so that the particle fraction and the serum could be assessed separately. On further investigation, the viscosity of puree was shown to be affected only to a small degree by the viscosity of the serum. The fact that stirred viscosity was independent of whether the suspension medium constituted of sucrose solution or serum phase showed that little contribution to the viscosity is coming from the soluble hydrocolloids in the tomato sera.
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