Sugar beer pectin is a food ingredient with specific functional properties.
It may form gels by an oxidative cross-linking of ferulic acid. In the pre
sent study, the gel forming properties of three oxidative enzymes were exam
ined in different food relevant conditions. The enzymes chosen were two lac
cases and one peroxidase. The textural properties of the produced gels were
measured on a texture analyser. The influence of sugar, salt and protein w
ere analysed. Finally, the enzymatic gelation was studied in three food pro
ducts with added sugar beet pectin. These were black currant juice, milk an
d chopped heat-treated meat emulsion.
The addition of salt resulted in softer, less stiff and chewy, and less adh
esive gels. Generally speaking, sugar addition increased the hardness but a
t high concentration the gels were very brittle. However, Young's modulus w
as lower in gels containing sugar than in standard gels. Protein reduced th
e hardness, stiffness and chewiness of the gels whereas there were some var
iation in the effect of protein on the adhesiveness of the gels. Sugar beet
pectin in black currant juice formed a gel and a gelation also took place
in milk. In luncheon meat a cohesive gel was formed which bound the meat pi
eces together thereby making the product sliceable. However, in two of the
food products some unwanted side effects were observed. The enzymes did not
only catalyse the cross-linking, but also oxidised the anthocyanins in the
black currant juice and short chained fatty acids in milk. This caused a d
iscoloration of the juice and the development of a strong off-flavour in th
e milk. In luncheon meat no unwanted side effects are found. (C) 2000 Elsev
ier Science Ltd. All rights reserved.