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To investigate whether in situ pectin engineering would be a helpful tool in tailoring the consistency and
syneresis of vegetable purées, carrot was selected as a plant tissue in which the textural properties are
largely influenced by pectin methylesterase-induced pectin changes. The effect of low-temperature
and high-temperature blanching, as well as the effect of two types of mechanical disruption, blending
and high-pressure homogenisation, on the flow properties of carrot purée was explored. The influence
of these different purée preparation steps on pectin was examined via physicochemical analysis of
fractionated walls and isolated polymers, and via anti-pectin antibodies entailing in situ and ex situ
analyses. Purée prepared by blending non-pretreated carrots showed a rather high consistency and
pronounced syneresis. Treatments that solubilise pectin, such as high-pressure homogenisation and, in
particular, high-temperature blanching, limited syneresis phenomena. In contrast, when the intercellular
adhesion in carrot tissue was strengthened via low-temperature blanching, the degree of syneresis
increased. High-pressure homogenisation was useful to reduce the carrot tissue particle size and,
consequently, resulted in a lower consistency carrot purée. Low-temperature blanching on the other
hand increased the consistency of carrot purée as the higher level of intercellular adhesion presumably
led to an increased resistance to particle disintegration upon blending or high-pressure homogenisation |
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