Enzymatic gelation of sugar beet pectin in food products

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 present study, the gel forming properties of three oxidative enzymes were examined in different food relevant conditions. The enzymes chosen were two laccases and one peroxidase. The textural properties of the produced gels were measured on a texture analyser. The influence of sugar, salt and protein were analysed. Finally, the enzymatic gelation was studied in three food products with added sugar beet pectin. These were black currant juice, milk and chopped heat-treated meat emulsion. The addition of salt resulted in softer, less stiff and chewy, and less adhesive gels. Generally speaking, sugar addition increased the hardness but at high concentration the gels were very brittle. However, Young's modulus was lower in gels containing sugar than in standard gels. Protein reduced the hardness, stiffness and chewiness of the gels whereas there were some variation 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 pieces 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 discoloration of the juice and the development of a strong off-flavour in the milk. In luncheon meat no unwanted side effects are found. (C) 2000 Elsevier Science Ltd. All rights reserved.