Improved Production of Cyclodextrins by Alkalophilic Bacilli Immobilized on Synthetic or Loofa Sponges

This study aimed to improve the production of β-cyclodextrin (β-CD) by microbial cells immobilized on synthetic or loofa sponges both with and without the use of alginate or chitosan. The most suitable matrix for the immobilization of Bacillus firmus strain 7B was synthetic sponge and for Bacillus sphaericus strain 41 was loofa sponge. After 330 days of storage, the β-CD production by Bacillus firmus and Bacillus sphaericus remained at around 41% and 49%, respectively, of initial levels. After 24 days of immobilization on loofa sponge, Bacillus sphaericus strain 41 achieved an improved operational stability, reaching 86.6 mM β-CD after 20 days of production, compared to only 32.8 mM of β-CD produced by free Bacillus sphaericus strain 41 cells. The expected increase in β-CD production by immobilized cells of Bacillus firmus strain 7B on synthetic sponge for 4 days was not statistically different to that for cells immobilized for 24 days. The application of this process on an industrial scale using loofa sponge, an inexpensive and renewable matrix, will allow the stable production of β-CD

Description of recovery method used for curdlan produced by Agrobacterium sp. IFO 13140 and its relation to the morphology and physicochemical and technological properties of the polysaccharide.

Curdlan is a linear polysaccharide considered a dietary fiber and with gelation properties. This study evaluated the structure, morphology and the physicochemical and technological properties of curdlan produced by Agrobacterium sp. IFO 13140 recovered by pre-gelation and precipitation methods. Commercial curdlan submitted or otherwise to the pre-gelation process was also evaluated. The data obtained from structural analysis revealed a similarity between the curdlan produced by Agrobacterium sp. IFO 13140 (recovered by both methods) and the commercial curdlans. The results showed that the curdlans evaluated differed significantly in terms of dispersibility and gelation, and only the pre-gelled ones had significant potential for food application, because this method influence on the size of the particles and in the presence of NaCl. In terms of technological properties, the curdlan produced by Agrobacterium sp. IFO 13140 (pre-gelation method) had a greater water and oil holding capacity (64% and 98% greater, respectively) and a greater thickening capacity than the pre-gelled commercial curdlan. The pre-gelled commercial curdlan displayed a greater gelling capacity at 95°C than the others. When applied to food, only the pre-gelled curdlans improved the texture parameters of yogurts and reduced syneresis. The curdlan gels, which are rigid and stable in structure, demonstrated potential for improving the texture of food products, with potential industrial use

Scanning electron microscopy of: commercial curdlan—(A) 40x and (B) 1000x magnification; pre-gelled commercial curdlan—(C) 40x and (D) 1000x magnification; curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (pre-gelation method)—(E) 40x and (F) 1000x magnification; curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (precipitation method)—(G) 40x and (H) 1000x magnification.

<p>Scanning electron microscopy of: commercial curdlan—(A) 40x and (B) 1000x magnification; pre-gelled commercial curdlan—(C) 40x and (D) 1000x magnification; curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (pre-gelation method)—(E) 40x and (F) 1000x magnification; curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (precipitation method)—(G) 40x and (H) 1000x magnification.</p

Flow curves of yogurt samples without heat treatment (A) with heat treatment (B); viscosity curves of yogurt samples without heat treatment (C) and with heat treatment (D).

<p>Yogurt without curdlan (–), with commercial curdlan (Δ), with pre-gelled commercial curdlan (○) and with curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (pre-gelation method) (■). The direction of the gray arrows indicates the ascendant and descendant curves.</p

FT-Raman spectra of: (A) commercial curdlan, (B) pre-gelled commercial curdlan, (C) curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (pre-gellation method), (D) curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (precipitation method).

<p>The dotted lines show the characteristic peaks of the samples.</p

Carbohydrate, moisture and sodium content (%) of different samples of curdlan.

<p>Values indicate mean ± standard-deviation.</p

Water Holding Capacity (WHC), Oil Holding Capacity (OHC) and Water Solubility Index (WSI) (g g^-1) of the commercial, pre-gelled commercial curdlans and those produced by <i>Agrobacterium</i> sp. IFO 13140 (pre-gelation method).

<p>Values indicate mean ± standard-deviation.</p

Temperature dependency of: (A) apparent viscosity and (B) G' (continuous line) and G" (dotted line) modulus of the aqueous dispersions of curdlan.

<p>Pre-gelled commercial curdlan (empty symbol) and curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 recovered by the pre-gelation method (full symbol) at (■) 20, (●) 40 and (▲) 80 g L^-1.</p

Strength (×10⁻³ N) of pre-gelled commercial curdlan and the curdlan produced by <i>Agrobacterium</i> sp. IFO 13140 (pre-gelation method) samples after undergoing different heat treatments.

<p>Values indicate mean ± standard-deviation.</p