a. ayoubi

Raisin is one of the most nutritious dried fruits and rich in various vitamins, minerals, fiber and antioxidant compounds (Mehraban et al. 2015). Iran is one of the major producers and exporters of raisin in the world. During storage period, raisin turns hard and sticky due to exudates syrup and moisture loss. It has been shown that application of edible coating could be useful to overcome this problem and extend shelf life of this product (Ghasemzadeh et al. 2008). Waxes and vegetable oils have been used to coat raisin (Debiofort et al. 1998) Ayoubi et al (2015) coated raisin with carnuba wax and glycerol monostearate. Also, Ghasemzadeh et al (2008) used edible coating based on starch and pectin to coat raisin. Sodium alginate is a water-soluble linear polysaccharide derived from alginic acid and has been considered as an edible coating due to its low cost, non-toxicity and biodegradability (Danapal and Associates 2012). In the present study, the effect of edible coating based on sodium alginate to maintain the keeping quality of raisins during storage at 25 °C for 6 months has been investigated.

raisin was produced from Seedless Asgari grape variety with the soda oil method. It was coated with sodium alginate at levels of 1 and 2%. After coating, samples were packaged in Zip-kip polyethylene bags and stored at 25 °C for 180 days. Physicochemical (weight loss, brix, pH, total phenol, color and hardness), microbial (total count) and sensory (color, texture, taste and overall acceptability) properties were determined during storage in the first day and 45, 90, 135 and 180 days after starting the storage. The weight loss was calculated from the difference between raisin weight in 45, 90, 135 and 180 days with the initial weight. Brix was measured by a refractometer (Protable VBR model, Switzerland). The pH value was measured by a digital pH meter (3020, Jenway, UK). In order to determine the total phenolic contents, the Folin–Ciocalteu method (Taga et al. 1984) was employed and measurements were done at 765 nm with a spectrophotometer (UNICO 2802, China). The color measurement was done using a colorimeter (TES-135A, Taiwan). Hardness of raisins was determined in a puncture test using a QTS texture analyzer (CNS Farnelll, Essex, UK) equipped with a needle probe (stainless steel cylinder of 2 mm in diameter with a conical needle bit) and a test speed of 60 mm/ min during the test. Hardness was defined as the maximum force to puncture raisin from the top to a 2mm depth (Rolle et al. 2011). To determine the total count, pour-plating method was used in PCA medium and incubation was performed at 37 °C. The sensory evaluation was performed by 5-point hedonic scale (1 most disliked, 5 most liked) by 10 trained panelists. The sensory evaluation of all treatments was carried out during storage time (in the first day and 45, 90, 135 and 180 days after storing). A factorial test in completely randomized design with 3 replications was utilized in this study. Analysis of variance (ANOVA) was performed by using MSTAT-C software. Duncan's multiple range test was used to compare the means at the 5% significance level and the graphs were plotted by Microsoft Excel software.

The results of analysis of variance showed edible coating significantly affected the weight loss. Sodium alginate coating reduced the raisin weight loss. In addition, storage had significant effect on weight loss. The weight loss was gradually increased during the storage period. The results of analysis of variance indicated significant effect of edible coating and storage time on raisin brix. During the storage time, brix increased, while the rate of this increasing in samples coated with sodium alginate was less than the control. The results also showed the effect of edible coating and storage time on the pH of raisins was not significant. During storage, the total phenolic content of raisins was gradually reduced. The edible coating reduced the intensity of this reduction. At the end of the storage period, the most total phenol content was observed in 2% sodium alginate treatment. The results of the color parameters evaluation showed that during the storage time lightness of raisin decreased. In addition, the effect of edible coating on this color parameter was significant (p<0.01). L of 1% sodium alginate treatment was significantly more than the control at 180 days after storing and this significant difference observed in 2% sodium alginate treatment at 45, 90 and180 days after storing. The effect of edible coating was not significant on redness but this color property significantly increased during storage period. It seems that browning reactions caused this color change. Also evaluation of yellowness results indicated sodium alginate coating had not significant effect on this color parameter. Storage caused significant changes in raisin yellowness (p<0.01). During storage time initially b value increased and then decreased. The most lightness and the lowest value of redness to yellowness ratio represent the best color of raisin. Analysis of variance show redness to yellowness ratio of raisin significantly increased during storage time (p<0.01). The edible coating was significantly effective in reducing rate of this change. After 180 days storage, the highest and lowest a/b value were related to the control (1.07) and 2% sodium alginate treatment (0.69), respectively. Observations showed raisin texture gradually hardened during the storage period (p<0.01). According to the results of study, the edible coating has not significant effect on raisin hardness. The data showed edible coating had no significant effect on total count, but microbial growth significantly decreased during storage (p<0.01). Acidity, water activity, inhibitor compounds such as phenolic compounds and some products of non-enzymatic browning reaction of Millard are some factors that inhibit microbial growth in raisins during storage (Zhao and Hall 2008; Bower et al. 2003). Based on the sensory evaluation results, storage darkened raisin color and reduced the color score. Edible coating was effective in preserving the color so that at the end of storage time the color score of coated samples was significantly more than the control. During storage time taste and texture scores significantly decreased. Although the edible coating had not significant effect on these sensory properties. Storing significantly reduced the overall acceptance score of raisin. At the end of the storage period, the overall acceptance score of coated samples were more than the control; However, according to the results of Duncan's multiple range tests only the difference between the overall acceptance score of the control and 2% sodium alginate treatment was significant at 135 days of storage.

The cake is a very diverse variety of flour products that are popular among people, especially children and adolescents. This product is a sweet with a special soft tissue that flour, oil, sugar and eggs are the main its ingredients (Institute of Standards and Industrial Research of Iran 2006). Despite the benefits of sucrose as a natural sweetener with desirable performance characteristics, due to problems with blood pressure, heart disease, tooth decay, obesity and increased blood glucose and insulin levels, especially for harmful diabetics in addition, due to economic and technological issues, increasing research are under way to replace sugar with other sweeteners. One of the important issues regarding the replacement of sugar in food products is the choice of the type of sweetener to replace and how to preserve the quality of the product during the storage period (Gohari Ardabili et al 2005). Sugar is an essential ingredient in the preparation of various types of cakes, which in addition to the role of sweetening has a great effect on the physical and chemical properties of the product (Specter and Setser 1994). There are many substitutes for sugar for use in baking products. For example, raw honey, maple syrup, molasses, stevia, xylitol, brown rice syrup, sugarcane condensate extract, glucose syrup, brown sugar, dextrose, corn syrup, invert sugar, malt extract and date sugar are the natural substitutes for sugar in the baked goods (Asghar et al 2006, Obiegbuna et al 2013). Considering the nutritional properties and high sugar content, date palms are used as a desirable substitute to sugar in food formulations to increase nutritional value and avoid sucrose complications. One of the products produced from dates is honey or date liquid sugar, which contains compounds such as glucose, fructose, sodium, potassium, calcium and magnesium, and because of the solid particles being separated from the liquid portion of the product, it can be used to prepare the syrup and clear beverages (Kordi et al 2010). Date liquid sugar is concentrate of clear and bleached date syrup that is produced after extraction date juice with removing pectin compound, protein, fiber and its color is brown to yellow. Its properties are similar to honey bee honey, and this product has high functional and nutritional value. In this study, date liquid sugar was used as a replacement for sugar in cake production with the aim of evaluating the physicochemical and sensory properties of the cake. The date liquid sugar used in this work was purchased from Dambaz Company and wheat flour was purchased from Tavakkol factory of Kerman. Other materials including sugar, oil, egg and baking powder purchased from local market of Kerman. Sugar substitution with date liquid sugar in this research was 25, 50, 75 and 100 percent After cooking, cakes were cooled at room temperature for about one hour and then packaged in zip-kip polyethylene bags and stored at refrigerator (4-6 °C) until performing tests. The cake was evaluated in terms of physicochemical (including weight loss, pH, porosity, density, moisture, hardness of texture and color of crust and crumb) and sensory (texture, crust color, taste and total acceptance) properties. The weight loss calculated by measuring the difference of weight before and after baking. PH was measured by a digital pH meter. Cake moisture content was determined by drying samples at 105±2°C in a hot air oven. The volumes of the cake samples were measured by the seed replacement method and then density was calculated by dividing the volume by the weight (Sahin and Sumnu 2006). For determining of porosity of cake crumb, image processing technique used.Cross sectional image of cake was documented by a table top scanner (HP Scanjet 2400, China) with 300 ppi. The images were analyzed by ImageJ software and percentage of porosity was calculated (Turabi et al 2010). The hardness of the cake was evaluated in two different days, 4 and 8 days after production, using a texture analyzer machine. The first, the cake samples were cut into cubes of 25 × 25 × 20 mm then compressed by a plate probe (50 × 100 mm) at 50 mm/min speed for 10 mm (Aghamohammadi et al 2012). Color measurements were done using a Hunterlab Colorimeter (Celik et al 2007). Sensory evaluation was carried out by 5-point Hedonic Scale. The cakes were estimated for the sensory attributes by selected semi-trained panelists. The panelists were asked to evaluate the samples and score them between 1 (most disliked) to 5 (most liked). Analysis of variance (ANOVA) was conducted for data using MSTAT-C software. Differences between the mean values were also determined using Duncan’s Multiple Range test (P<0.05). The results of this research showed that date liquid sugar had a significant effect on physicochemical characteristics and sensory properties of samples. By increasing of date liquid sugar in cake formulation weight loss, pH, porosity, lightness of crust and crumb, yellowness of crust decreased and density, moisture, hardness of product texture, and redness of crust and crumb increased. The least value of weight loss (18.2%), pH (6.59), porosity (13.6%) and most value of density (0.5 g/cm3), darkness of crust and crumb of cake (respectively 33.21 and 43.62) were related to substitution level of 100%. The sensory evaluation results indicated that all sensory scores of cake decreased with increasing level of date liquid sugar. However, no significant difference was found between the crust color, texture and total acceptance scores of the low sugar cake and the control in the replacement levels of 25 and 50. Also, based on the mean comparison results, the taste score of the cake has been significant with the control just at the level of 100% replacement. Between different levels of date liquid sugar, the Levels of 25 and 50% had less negative effects on physicochemical properties of the cake. On the other hand, the low sugar cakes with 25 and 5o% date liquid sugar showed sensorial attributes similar to the control cake. It can be concluded that date liquid sugar can be replaced with sugar up to 50% to the cupcake formulation without adverse effects on the quality of cakes.

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.