2410 Research Article Received: 22 January 2015 Revised: 29 June 2015 Accepted article published: 29 July 2015 Published online in Wiley Online Library: 27 August 2015 (wileyonlinelibrary.com) DOI 10.1002/jsfa.7357 Characterization of curdlan produced by Agrobacterium sp. IFO 13140 cells immobilized in a loofa sponge matrix, and application of this biopolymer in the development of functional yogurt Camila Ortiz Martinez, a Suelen Pereira Ruiz, a Vanderson Carvalho Fenelon, a Gutierrez Rodrigues de Morais, b Mauro Luciano Baesso b,c and Graciette Matioli a,d* Abstract BACKGROUND: Agrobacterium sp. IFO 13140 cells were immobilized on a loofa sponge and used to produce curdlan over five successive cycles. The interaction between microbial cells and the loofa sponge as well as the produced curdlan were characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectrometry. The purity of the curdlan was also evaluated. The storage stability of the immobilized cells was assessed and the produced curdlan was used in a functional yogurt formulation. RESULTS: The average curdlan production by immobilized cells was 17.84 g L -1 . The presence of the microorganism in the sponge was confirmed and did not cause alterations in the matrix, and the chemical structure of the curdlan was the same as that of commercial curdlan. The purity of both was similar. The immobilized cells remained active after 300 days of storage at -18 ∘ C. The use of the produced curdlan in a functional yogurt resulted in a product with lower syneresis. CONCLUSION: A large number of cells physically adhered to the surface of loofa sponge fibers, and its use as an immobilization matrix to produce curdlan was effective. The use of the produced curdlan in yogurt allowed the development of a more stable product. © 2015 Society of Chemical Industry Keywords: Agrobacterium sp; curdlan; loofa sponge; immobilization; FTIR-ATR; yogurt INTRODUCTION The microbial synthesis of polysaccharides has emerged as an important source of new biopolymers for industrial applications. Notable among these is curdlan, a hydrocolloid with unique gelling characteristics. Curdlan is an exopolysaccharide exclusively composed of glucose units connected by  -(1,3) bonds and is com- mercially produced from Agrobacterium species. 1 It can form a thermo-reversible gel by heating its aqueous suspension at 55 ∘ C and subsequent cooling. It can also form a thermo-irreversible gel by heating at 80 ∘ C followed by cooling. Furthermore, gels with different strengths can be formed by varying the time and tem- perature of heating and the concentration of curdlan. 2 The versatility of curdlan associated with health benefits is a valuable tool for the development of new products. The particular properties of curdlan assist the needs of the food industry, where it is used as a gelling agent and stabilizer to improve the viscosity, stability and texture of food. In most foods, it is used in the form of a thermo-irreversible gel, and it is stable during autoclaving, frying and freeze/thaw cycles. It can be used to mimic fat, meat and seafood and has numerous applications in vegetarian food. 3 Curdlan is considered as a dietary fiber because it is not digested by enzymes in the gastrointestinal tract. 4 It has been hypothesized that  -(1,3)-gluco-oligosaccharides obtained from curdlan may ∗ Correspondence to: Graciette Matioli, Postgraduate Program in Food Science, State University of Maringá (UEM), Av. Colombo, 5790, CEP 87020–900 Mar- ingá, PR, Brazil. E-mail: gmatioli@uem.br a Postgraduate Program in Food Science, State University of Maringá (UEM), Av. Colombo, 5790, CEP 87020-900 Maringá, PR, Brazil b Postgraduate Program in Physics, State University of Maringá (UEM), Av. Colombo, 5790, CEP 87020-900 Maringá, PR, Brazil c Physics Department, State University of Maringá (UEM), Av. Colombo, 5790, CEP 87020-900 Maringá, PR, Brazil d Pharmacy Department, State University of Maringá (UEM), Av. Colombo, 5790, CEP 87020-900 Maringá, PR, Brazil J Sci Food Agric 2016; 96: 2410–2417 www.soci.org © 2015 Society of Chemical Industry