Effects of locust bean gum on the structural and rheological properties of resistant corn starch.

In this study, interactions between resistant corn starch (RS) (5% w/w) and locust bean gum (LBG) (0, 0.125, 0.25, 0.50 and 1.0% w/v) on the viscoelastic, pasting and morphological characteristics of aqueous dispersions were evaluated. Results showed that the storage modulus (G'), loss modulus (G''), and apparent viscosity values of starch/gum (RS/LBG) mixtures were enhanced with the addition of LBG, and the rheograms demonstrated a biphasic behavior. RS/LBG samples were predominantly either solid like (G' > G'') or viscous (G'' > G'), depending on the added concentration level of LBG. Gum addition also caused higher peak viscosity, breakdown and total set back of RS/LBG mixtures. A strong correlation between rheological and structural properties was found. Confocal laser scanning microscopy (CLSM) images confirmed the transition of starch particles from a scattered angular shape to clustered structures cross-linked by dense aggregate junction zones justifying the observed changes in rheological properties.

Heat transfer simulation and retort program adjustment for thermal processing of wheat based Haleem in semi-rigid aluminum containers.

A mixed computational strategy was used to simulate and optimize the thermal processing of Haleem, an ancient eastern food, in semi-rigid aluminum containers. Average temperature values of the experiments showed no significant difference (α = 0.05) in contrast to the predicted temperatures at the same positions. According to the model, the slowest heating zone was located in geometrical center of the container. The container geometrical center F0 was estimated to be 23.8 min. A 19 min processing time interval decrease in holding time of the treatment was estimated to optimize the heating operation since the preferred F0 of some starch or meat based fluid foods is about 4.8-7.5 min.

High pressure impregnation (HPI) of apple cubes: Effect of pressure variables and carrier medium.

High pressure impregnation (HPI) is a novel technique to infuse desired fluids into porous biomaterials. In this study, the effect of 24 different pressure-time combination treatments were studied: come-up time (0 to 6 min), pressurization rate [100, 150, 200, 300 (MPa/min)] and pressure holding times (0-30 min) at 100, 300 & 600 MPa. Experiments were carried out based on HPI of ascorbic acid (AA) as a low viscosity aqueous (1%) Newtonian fluid. AA infusion reached 215 to 250 mg/kg when reaching operating pressure of 200 MPa irrespective to pressurization rate or come-up time. A model for the entire process was developed based on the combination of a first-order kinetics during the come-up time and a linear diffusion process during pressure holding time. In addition, impregnation of 0.5%, 1%, 2%, and 4% chitosan (CH) into apple cubes, as a high viscosity non-Newtonian carrier fluid, showed a quadratic trend for CH uptake. Moreover, HPI pre-treatment with CH prior to freezing demonstrated significant reduction in texture breakdown and drip loss in frozen-thawed apple cubes. Finally, microstructural studies were also carried out, and the microscopic images showed a progression of perpendicular flow paths at the peripheral layers as well as certain cellular rearrangements.

Effect of high-pressure treatment on the structural and rheological properties of resistant corn starch/locust bean gum mixtures.

In this study, effects of a 30min high pressure (HP) treatment (200-600MPa) at room temperature on the rheological, thermal and morphological properties of resistant corn starch (RS) (5% w/w) and locust bean gum (LBG) (0.25, 0.50 and 1.0% w/v) dispersions were evaluated. Results showed that the storage modulus (G'), loss modulus (G''), and apparent viscosity values of starch/gum (RS/LBG) mixtures were enhanced with an increase pressure level, and demonstrated a bi-phasic behavior. HP treated RS/LBG samples were predominantly either solid like (G'>G'') or viscous (G''>G'), depending on the pressure level and LBG concentrations. Differential scanning calorimetry (DSC) analysis of the pressurized mixtures showed a major effect on gelatinization temperatures (To, Tp,), and it was observed that RS/LBG mixtures gelatinized completely at ≥400MPa with a 30min holding time. Confocal laser scanning microscopy (CLSM) images confirmed that at 600MPa, RS/LBG mixtures retained granular structures and their complete disintegration was not observed even at the endpoint of the gelatinization.

Numerical modeling of heat transfer and pasteurizing value during thermal processing of intact egg.

Thermal Pasteurization of Eggs, as a widely used nutritive food, has been simulated. A three-dimensional numerical model, computational fluid dynamics codes of heat transfer equations using heat natural convection, and conduction mechanisms, based on finite element method, was developed to study the effect of air cell size and eggshell thickness. The model, confirmed by comparing experimental and numerical results, was able to predict the temperature profiles, the slowest heating zone, and the required heating time during pasteurization of intact eggs. The results showed that the air cell acted as a heat insulator. Increasing the air cell volume resulted in decreasing of the heat transfer rate, and the increasing the required time of pasteurization (up to 14%). The findings show that the effect on thermal pasteurization of the eggshell thickness was not considerable in comparison to the air cell volume.