The effects of water and glass transition on the hydrolysis of sucrose by invertase in noncrystalline carbohydrate systems were investigated. Maltodextrin/sucrose (2:1) and maltodextrin/lactose/sucrose (1:1:1) were dissolved in distilled water. Invertase (10 mg/17.2 g) was added. Amorphous samples were produced by freeze-drying the solutions. Sorption isotherms were determined gravimetrically at 24 degrees C over the 0.113-0.763 aw, and over 0.239-0.764 aw, the glass transition, Tg was determined using differential scanning calorimetry (DSC). DSC and water sorption results suggested that samples remained noncrystalline. Sucrose inversion was analysed by monitoring glucose content during storage. Sucrose hydrolysis occurred at significant rates at 0.662 and 0.764 aw. The rate increase was not related to the apparent glass transition of the systems.

A synbiotic product of combined Lactobacillus plantarum TISTR 875 with water extracts and crude fibers from corn, mungbean, and soybean was formulated to investigate the survival of L. plantarum during freeze-drying and storage. The impacts of those water extracts and crude fibers on probiotic survival were determined in both a cultural medium and a freeze-drying medium. L. plantarum cultivated in de Man, Rogosa, and Sharpe (MRS) broth containing 2 % of water extract from soybean with 2 % mungbean fiber showed only 0.11 log CFU/ml cell reduction. The survival of L. plantarum harvested at the late log phase, mid stationary, phase and late stationary phase did not show statistical significance (P > 0.05), whereas an initial pH of 6.5 and growth temperature of 37 °C showed greater impact (P < 0.05). The addition of corn extract to the freeze-drying medium as a cryoprotectant had a similar effect on L. plantarum survival as sucrose, but it was better (P < 0.05) than fructo-oligosaccharide and exopolysaccharides from Weissella cibaria A2, soybean extract, mungbean extract, soybean, corn, and mungbean fibers. A protective coating of corn extract was revealed and observed using scanning electron microscopy. The freeze-dried L. plantarum, cultivated in MRS broth containing soybean extract and mungbean fiber with corn extract as a cryoprotectant, retained high viability of 7.21 and 6.88 log CFU/ml after 8-week storage in a vacuum-packed aluminum foil-laminated polyethylene sachet and a nitrogen-flushed glass vial, respectively. ©Springer Science+Business Media New York 2012.

Steam injection heating systems for food and agricultural products are subject to condensation-induced water hammer (CWH), which may cause significant damage to equipment and pose a threat to operators. A method is suggested for process design and operation of a steam injection heater that reduces occurrence of CWH. The method is based on a correlation between the thermodynamic ratio of the product and the Peclet number. A laboratory steam injection heater was instrumented to determine the relationship between CWH, the thermodynamic ratio, and the Peclet number. The thermodynamic ratio for water and various concentrations (55 to 67.5 brix) of sucrose solution was recorded under process conditions at the onset of CWH during steam injection heating. Good correlation was observed between the Peclet number and threshold thermodynamic ratio. A linear equation was found (with r 2 = 0.79) that gives the predicted minimum thermodynamic ratio for system operation without CWH.

Low-moisture biopolymer-based systems are commonly encountered in food. Obviously, understanding the physical basis of their quality [texture, or performance over time or as a function of their composition (water or other added solutes)] is of primary importance. A polymer science approach using physical chemistry concepts based on physical state, phase transitions and molecular mobility can be applied to investigate the performances of food in particular versus moisture. Based on the example of starch-based samples and their texture property changes versus composition, the role of water and sucrose is considered through different aspects. The relations existing between the observed changes and physical state are investigated. While the motions associated with the glass transition were observed at high temperature, secondary relaxations are observed below Tg (at T β): T β decreased with water content and increased with increasing sucrose content. These local motions are suggested to contribute to the observed texture modifications versus water. Moreover, the stability of the glassy state was investigated by differential scanning calorimetry through the study of enthalpy relaxation (physical ageing). The amplitude of enthalpy relaxation decreased with both increasing sucrose and water content. All in all, this study strengthened the hypotheses that sub-Tg mobility could contribute to texture instability versus moisture or sugar content.

Seven food-deprived rats were observed on a progressive-ratio 5 schedule of food reinforcement under baseline conditions and during concurrent access to tap water, a 1 % sucrose solution, or a 5 % sucrose solution. Subjects responded for the alternative reinforcer primarily during the preratio pause. Responding for the alternative reinforcer caused a local increase in pause durations in all conditions, however, the mean pause duration for the session increased only when the 5 % sucrose solution was available. Otherwise, the increase in pause durations that accompanied responding for the alternative reinforcer was offset by reducing pausing at other times. Access to the 5 % sucrose solution changed the relation of ratio size to pause duration in several subjects in that the longest pause durations occurred before the end of the session rather than when the highest ratios were in effect. Breakpoints were largely unaffected by alternative reinforcement.

Food gels prepared from the water extract of fish scales (WEFS) are described in this study. The effects of WEFS, sucrose, and NaCl concentration on gel formation and stability, gel texture, and gel sensory attributes were evaluated. The results indicated that an increase in WEFS concentration led to increases in the formation rate, stability, and texture of the gel. Addition of a moderate amount of sucrose (2%–3%, w/v) and NaCl (0.4%–0.6%, w/v) improved the stability, gumminess, chewiness, and cohesiveness of the gel. However, the addition of an excessive amount of sucrose (>4%, w/v) and NaCl (>0.8%, w/v) decreased the stability, gel strength, adhesiveness, and springiness of the gel. The sensory attributes of fish scales (FS) gels were mainly affected by WEFS concentration. On the basis of combined textural analysis and sensory evaluation, the FS gels formed with 4% WEFS, 3% sucrose, or 0.4% NaCl was proposed in this study. The gel microstructure and water distribution obviously showed an apparent variation, together with a change in the structure of FS gels. Competing hydrophilic forces and electrostatic interactions varied with sucrose and NaCl concentration, altering the structure and water distribution of FS gels.