Optimization of the production of a self-stable powder from date fruit variety ‘Shahani’

The objective of this study was to prepare a self-stable powder from date paste. The concept of glass transition temperature (Tg) was used to predict the stability of powder at room temperature. The effect of maltodextrin (MD) as a drying additive in the range of 28 - 55%, tricalcium phosphate (TCP) as an anti-caking agent and glycerol monostearate (GMS) as a flowability agent in the range of 0.3 - 3% on some physico-chemical and thermal properties of the date powder was studied, using response surface methodology (RSM). Proposed mathematical models were successfully capable to fit the experimental results for different physico-chemical properties of the powder such as moisture content, bulk density, solubility, Tg, hygroscopicity and color index (L*, a*) with high R2 values (R2 > 0.9). The optimal combination of additives was determined as 35% MD, 3% TCP and 3% GMS with the overall desirability of 82.3%

Stability of proteins in the glassy state

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Effect of Ultrasound on Physicochemical Properties of Wheat Starch

Application of ultrasound process is growing in food industry for different purposes including homogenization, extraction, blanching and removal of microorganisms, etc. On the other hand, starch is a natural polymer which exists in many foods or added into the food as an additive. Therefore, determination of the effects of ultrasound on starch characteristics can be useful in interpretation of the properties of starch-containing products. The main aim of this study was to determine the physicochemical changes of wheat starch treated by ultrasound waves. Therefore, an ultrasound probe device was used which ran at 20 kHz, 100 W and 22°C. Starch suspension in distilled water (30% w/w) was prepared and treated with ultrasound for 5, 10, 15 and 20 min. The results showed that increases in processing duration led to increases in water solubility of starch, water absorption and gel clarity (as determined by spectrophotometry). Starch intrinsic viscosity as measured using an Ostwald U-tube showed lower intrinsic viscosity with increases in ultrasound time. Gel strength of the samples as determined using a texture analyzer was reduced by longer processing time. The scanning electron microscopy revealed that increasing the duration time of the ultrasound treatment could produce some cracks and spots on the surface of the granules. In total, it was concluded that the ultrasound treatment resulted in some changes from the starch granular scale to molecular levels. Some of the starch molecules were degraded upon ultrasound processing. Such changes may be observed for the starch-containing foods treated with ultrasound and they are enhanced with increases in ultrasound time intervals

Effect of moisture content on textural attributes of dried figs

A b s t r a c t. Due to their soft texture consumers prefer moist figs, which has motivated fig processors to increase the production of this product. However, as water enhances the browning reaction rate, moisture content optimisation of moist figs is very im-portant. Processed figs must have suitable texture softness with browning kept to a minimum. The purpose of this study was to exa-mine the effect of moisture content on the textural attributes of dried figs. Hardness, compression energy, gradient, gumminess and chewiness of fig samples decreased with moisture content expo-nentially, whereas the trend of springiness and cohesiveness with change of moisture content was nearly constant. Moreover, in the texture profile analysis plot of rehydrated figs, the presence of nega-tive area is an indication of adhesiveness which was zero in control dried figs. The results of the texture profile analysis tests proved the existence of a critical moisture content of about 18.4%, above which no significant effect of moisture content on textural parame-ters was found. The glass-rubber transition results from differen-tial scanning calorimeter may explain the different texture profile analysis attributes of dried figs compared with rehydrated figs. K e y w o r d s: moisture content, texture profile analysis, dried fig, glass transitio