Three dietary fiber (DF) powders; soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and total dietary fiber (TDF) were prepared from cocoa bean shells (CBS) by enzymatic treatment. These DFs were evaluated for their effects on glucose adsorption, glucose diffusion, starch hydrolysis, cholesterol binding, sodium cholate binding and oil binding capacities using in vitro model systems by simulating gastric intestinal conditions. The results showed that SDF generally exhibited significantly (p < 0.05) higher glucose adsorption capacity (GAC), α-amylase inhibition activity, cholesterol and sodium cholate binding capacity, but less significant (>0.05) glucose dialysis retardation index (GDRI) and oil binding capacity, when compared with IDF and TDF which both showed similar effects. Moreover, it was discovered that the three CBS dietary fiber powders contained intrinsic antioxidants (phenolic compounds). The study suggested that CBS could be an alternative cheap source of DF with additional benefits. Thus, CBS fibers could be incorporated as low calorie bulk ingredients in high-fiber diet to reduce calorie and cholesterol levels and control blood glucose level.

Pretreatments of fruits before drying have been proposed as alternative way to improve the quality of dried fruits and reduce drying time. In the present study, the effects of different pretreatments (ultrasound and microwave) on apple cubes prior to spouted bed drying were investigated. Ultrasound pretreatment resulted in a great loss of sugars (25.7% for 15 min) compared to microwave pretreatment, where little rise in sugar content was observed (1.6% at 300 W). Ultrasound pretreatment improved the drying rate more than microwave pretreatment. Nevertheless, microwave-pretreated dried apples were harder and had lower water activity than ultrasound-pretreated ones. Low-frequency nuclear magnetic resonance (LF-NMR) analysis was used to study the water state and revealed that all pretreatments promoted redistribution of water among apple cell compartments and showed that most of the water lost was from the vacuoles. If dried low-calorie fruits are required then ultrasound pretreatment would be preferred.

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