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The adsorption and desorption equilibrium moisture contents (EMC) were determined for Estameran date fruit using saturated salt solution method at 40, 50, 60 and 70°C over the range of relative humidity from 0.05 to 0.85. Equilibrium moisture content decreased with increasing the temperature from 40 to 50°C, at water activities (aw) below 0.3, while for higher water activities, crossing phenomena of the isotherm curves was detected as the temperature increased. Furthermore, equilibrium moisture content increased due to the dissolution of crystalline sugars at higher temperatures and moisture contents. The same phenomenon took place at water activity equal to 0.05 at 60 and 70°C temperatures. GAB, modified Halsey, modified Chung-Pfost, modified Oswin, modified smith and modified Henderson models were used to fit the experimental data. The GAB model was found to be the most suitable for describing the adsorption and desorption curves. The monolayer moisture content (Mm) values at different temperatures were calculated using the GAB equation. Results showed that Mm decreased with increasing temperature. The isosteric heats of desorption and adsorption of water were determined from the equilibrium data at different temperatures by Clausius-Clapyron equation. The isosteric heats of desorption and adsorption decreased with increasing water activity.

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In this study, physicochemical properties, sensory characteristics and shelf life of muffin prepared by substitution of egg white with different levels of whey protein concentrate (WPC) were evaluated. WPC at three levels – 25, 50 and 75 %– was considered as variable treatment. Physicochemical properties including butter pH, butter consistency, cake pH, weight loss, density, moisture, shelf life properties including water activity () and hardness after 1, 2 and 10 days storage and sensory properties including crust color, taste, texture and total acceptance were measured and the result were analyzed. Data analysis showed that WPC substitution levels affected all of properties.  In comparison with control butter pH, cake pH, moisture, density,   and hardness after 1, 2 and 10 days storage decreased whereas consistency and weight loss increased with increase of substitution level. Also WPC substitution levels affected all of sensory properties. Color score increased with 25 and 50 % WPC but decreased with 75% WPC. Texture, taste and total acceptance scores decreased with increase of substitution. No significant difference of taste and total acceptance scores with control up to 50 % replacement level was noticed; however it became significant at 75% replacement level.  

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In this research, different amounts of gum tragacanth (0.5%, 1%, 1.5% and 2% w/w) was added to wheat flour and its effects on bread quality parameters including moisture, specific volume, crumb firmness, color, water activity and bread staling during storage was evaluated. The results suggested that addition of gum tragacanth increased moisture but decreased crumb firmness, loaf volume and specific volume in all samples with reference to the control sample. Measurement of crust and crumb color showed that addition of gum tragacanth at all concentrations significantly decreased lightness of crust and crumb but increased red- and yellowness of both crust and crumb (p  

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Bakery products, like many processed foods, are subjected to the physical, chemical and microbiological spoilage. Mold growth is a problem that limits the shelf life of high and intermediate- moisture bakery products .Water activity is a physical property that has a direct implication for microbiological safety of food. Foods with lower water activities are quite shelf life since they contain small a mount of water available for microorganisms to use for growth. In this research, effects of polyols (Glycerin, Sorbitol, Propylene glycol), invert and glucose syrup on the quality of batter and cake were evaluated. Polyols, invert and glucose syrup at five levels (1, 2, 3, 4 and 5%) were considered as variable treatments. The results showed that, cakes containing with propylene glycol had higher specific volume of batter, less height of cake and higher moisture of cake (P<0.05). Propylene glycol and glycerol were significant different in decreasing water activity other than sorbitol, invert and glucose syrup (P<0.05). Cakes containing propylene glycol and glycerol were more than sorbitol shelf life, invert and glucose syrup. Samples of cakes containing invert had the lowest pH (P<0.05). Thus, the polyols can be used to increase the quality and shelf life of cake.

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Water desorption isotherms of raw and osmotically dehydrated (at 25ºC, for 2 hours, with 10 and 26% NaCl solutions) garlic slices at different temperatures (25, 40, 55, and 70ºC) were experimentally determined over a range of water activity of 0.05–0.90 using a static gravimetric method. Desorption isotherms can be classified as Type III. The water desorption isotherms of raw garlic clearly showed the influence of temperature i.e. increasing water activity at a fixed moisture content with increasing temperature; whereas for the osmotically dehydrated garlic the effect of the temperature was less important. The increase of NaCl content in osmotically dehydrated garlic led to a decrease in water activity at the same moisture content, and this effect was more accentuated at high temperatures. Equilibrium moisture content data at each temperature were satisfactorily fitted with Henderson model and a six-parameters equation based on Henderson model was obtained in order to correlate simultaneously moisture content with water activity, temperature, and osmotic solution concentration. A prediction model based on concentration and physical state of garlic compounds was successfully used to reproduce the experimental data.

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Noughl (sugar coated almond or walnut) is a traditional confectionary sugar-based product which is also produced by addition of spices and dried damask rose in recent years. In spite of its popularity, noughl suffers from dehydration in a short time after being exited from the package. Thereupon, the aim of the present study was to investigate the additives' impact (cinnamon, damask rose and saffron) on physico-mechanical properties (moisture content, texture, surface area, color and a_w) of noughls and also the trend of moisture loss during storage. The results indicated that the most moisture loss took place at the first 3 days after opening the package. Based on the rheological tests, the highest and the lowest breakage energy belonged to damask rose (35.48 N.mm) and cinnamon (9.1 N.mm) noughls, respectively. Besides, it was found that storing for 14 days led to increase of vanilla noughl firmness for more than three times. Moreover, mean value of water activity of noughls was lower than 0.56. Comparison of mean value of the color total difference (ΔE*) at 0 and 21^st days declared that cinnamon and vanilla noughls had the highest and the lowest color alteration, respectively. According to image processing analyses, suitable indicators to show color changes during time were a* and L* channels for cinnamon and damask rose noughls and b* and L* channels for saffron and vanilla noughls.

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In recent years, infrared radiation (IR) has been considered as one of the suitable methods for drying and decontamination of different spices. However, the low penetration depth of the IR limits its use for food processing in the industry. Due to the importance of Carum carvi as a spice with medical properties, this research aimed to determine the effect of the sample’s structure (powder and seeds), water activity (0.24, 0.56 and 0.89) and the power of IR emitter (222 to 960W) on the penetration depth of the IR into Carum carvi For this propose, the heat fluxes received by copper black body that placed under samples with different thickness was measured. Afterward, the penetration depth was calculated through a mathematical model. The results indicated while aw of the sample, the IR power, and their interaction had a significant effect on the penetration depth of the IR, the structural properties of the sample had no significant effect on it. Increasing the infrared power to 601W enhanced the penetration depth in all of the samples. The highest penetration depth into the powder and the seeds of Carum carvi with aw 0.24 was achieved at the IR power of 601W, and was recorded 4.07±0.27 and 3.85±0.23mm while the samples with aw 0.89 were shown the highest penetration depth when they were irradiated by IR power of 845W) 4.12±0.18 and 4.09±0.13mm). According to the results, determining of IR penetration depth in the spice can be used to determine of their optimal thickness during the infrared food process.

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The aim of this study was to investigate the feasibility of producing a pastilles based on dates puree and concentrated whey and optimizing its formulation. In order to optimize the production conditions of pastilles based dates and concentrated whey,response- surface methodology was used.In this study,the conditions of production of pastilles product(concentration of xanthan gum (0.1-0.5%)and agar(0.3-0.9%) as well as concentration of whey(5-15%)were optimized to achieve maximum protein and total acceptability and total color index.According to the results of the statistical analysis of the data,a linear model for moisture, water activity, pH and total color index and a quadratic model for total acceptability were selected.The results showed that the concentration of whey had a significant effect on all responses.Increased concentration of whey had a positive effect on moisture of the samples and had a reverse effect on water activity,pH and total color index.The overall acceptability index did not show a steady trend,with a 10% increase in concentrated whey increasing and then decreasing.As the xanthan gum and agar gum content increased, the moisture content of the samples increased,but water activity decreased.The overall acceptability index also showed the highest value in average percentages for the two gums(as was the case for whey).The optimum operating conditions obtained for the jelly production process included xanthan gum concentration of 0.36% (w / w),agar gum concentration of 0.46% (w / w) and concentrated whey 13.92% (w / w).The predicted responses under these conditions were 36.62% moisture content, 0.66% water activity, 3.25 pH, 1.17 protein content,overall acceptability score of 6.56 and total color index of 45.94%.After the evaluation,it was found that the actual results were very close to the model estimates,indicating accurate model prediction. 

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The impact of a_w (0.65-0.9), temperature (15-30°C) and their interaction on the germination and radius growth of Aspergillus fumigatus isolated from cake was surveyed on Yeast Extract Glucose Chloramphenicol Agar (YGC-Agar) during 60 days as well as the capabilities of Gompertz and Logistic models for fitting data were explored. Rising a_w (from 0.65 to 0.9) and temperature (from 15 to 25°C) caused significant enhancing of germination and growth rate of A. fumigatus (P < 0.05). However, in constant a_ws, further increasing of temperature (up to 30°C) led to meaningful decreasing of these parameters (P < 0.05). A. fumigatus did not germinate at a_w 0.65. In addition, germination was observed at a_w 0.7 and 0.75 only when the temperature was 15 and 25°C while the mycelium growth was not occurred at these conditions. Although the germination rate was relatively high at a_w 0.8, the mycelium growth was very limited. The most amount of germination and radius growth was for a_w 0.85 -0.9 and temperature 15-25°C (P < 0.05). Consequently, the optimum growth of A. fumigatus was seen at a_w 0.9 and temperature 25°C and the best shelf life of cake proved at a_w < 0.7. Furthermore, fitting the growth curves demonstrated the more accuracy of Logistic model rather than Gomperts model.