Research and Innovation in Food Science and Technology
Year:2015 | Volume:4 | Issue:1|Papers Count:7

The purpose of this research was to study the effect of thin layer drying conditions (temperature at three levels of 60, 70, and 80oC, air velocity at two levels of 1.5 and 2.5 m/s, and four pretreatments including potassium carbonate and Paksan drying oil, olive oil, hot water without pretreatment (control)) on cabinet drying process of grape and color of obtained raisin. Six mathematical models were fitted on drying data and the best one was selected according to coefficient of determination (R2), Root Mean Square Error (RMSE) and coefficient of relative average deviation (P). The results showed that temperature, air velocity and pretreatment have significant effects on drying rate and color of raisin. Among these models, two term and page models showed more ability to evaluating and describing drying behavior of grape. Diffusion coefficient values were between 4.6274×10-10 to 8.6541×10-10 m/s2 and activation energy obtained 13470.83 J/mol. The best values of lightness and redness were related to dried raisin at 60oC and the maximum value of yellowness was related to dried raisin at 70oC. Drying air velocity just significantly affected the redness. Increasing drying air velocity decreased the redness. It was also found out that potassium carbonate and Paksan drying oil pretreatment caused the best raisin color.

In this study, producing flavored functional yogurt enriched with flavonoid and oil extracted from orange peel was investigated and some sensory and physicochemical properties of yogurt produced were evaluated during 15-day storage time. This study was carried out in 2 steps: the first; flavonoid and oil were extracted from orange peel, and then, flavored functional yogurt samples enriched with different percentages of flavonoid (7, 8 and 9%) and oil (0, 0.5, 1 and 1.5%) extracted from orange peel were produced. The results showed that an increase in the concentration of orange peel oil induced a decrease in acidity and synersis; and an increase in pH, fat and dry matter of yogurt samples. By increasing flavonoids content, the A parameter increased too. The yogurt sample with 8% flavonoids and 0.5 g oil/100 g yogurt received the most sensory scores.

Ultrasound is one of the emerging technologies that its application in drying foodstuffs aimed at reducing the time needed to process and improve the quality characteristics of dried product is growing day by day. In this study, the simultaneous effect of ultrasound and osmotic dehydration pretreatments on thin-layer drying kinetics of plums during drying at 80°C temperature and 1.4 m/s air velocity was examined. The pretreatments applied included ultrasound waves at two levels (10 and 30 minutes), osmotic solution concentrations at two levels (50 and 70 Brix) and osmotic dehydration time at four levels (60, 120, 180 and 240 min). The results showed that increasing ultrasound time, osmotic solution concentration and osmotic process time led to a decrease in drying time and an increase in effective moisture diffusion coefficient compared to control sample.Furthermore, in order to correctly predict the drying process, the data from the experiments were fitted with some empirical models as well as some new proposed models in this study. Then, one of the proposed models was selected as the best model (based on Coefficient of Determination, Root Mean Square Error and Sum of Square Error) to describe the drying process of plums under the selected experimental conditions. Through multiple regression analysis, the relations between the coefficients of the models with the variables used were obtained.

Whey is one of the major dairy wastes which is rich in organic compounds. These compounds reduce oxygen dissolved in water, inactivating the active water ecosystem and cause the loss of aquatics. An optimized composite formula of coagulator concentrations including Pectin, Sodium alginate, Aluminum sulfate and Iron chloride and coagulation temperature was determined to reduce biological oxygen demands in whey. Experiments designing was done using fraction of full factorial statistical method and Qualitek-4 software and Taguchi approach was applied for results analysis. Optimal conditions was obtained in Aluminum sulfate, Sodium alginate, Iron chloride and Pectin concentrations equal to 2, 0.02, 1.5 and 1 g L-1, respectively and temperature as 25 degree centigrade. The expected reduced percentage in biological oxygen demands in optimal conditions was estimated as 33.722%.Coagulating temperature was recognized as the most effective factor to reduce organic load of whey with a contribution share equal to 63%. Aluminum sulfate concentration changes showed less effectiveness (1.7%) and Iron chloride concentration changes had a negligible impact as 7%. The changes of Sodium alginate and Pectin concentrations were effective as 18 and 10%, respectively in reducing the biological oxygen that is needed.

Application of non-sugar sweeteners and bulking agents in food products is effective in lowering calories; however, it is often come with some changes in the texture and sensory characteristics of products. In this research full replacement of sugar in fruit jelly powder was investigated using sucralose as a high intense sweetener and isomalt as a bulking agent. Fruit jelly powder was prepared using different percentages of isomalt (0, 20, 30, 50, 75 and 100) together with high intensity sugar of sucralose, in an adjusted amount to replace sucrose.Physical, chemical and microbial characteristics of jelly samples were then analyzed and sensory quality of the product was evaluated. Results showed that sugar replacement with proper proportion of 50% isomalt and 0.13% sucralose causes in strengthening the gel texture with no significant change in quality and rheological properties. Microbial characteristics of sugarless sample was also in accordance with standard limitations. Organoleptic analysis was representing the acceptance of jellies having isomalt compared to sugary one. Based on this study, it is feasible to replace sugar by isomalt and sucralose in low calorie jelly, with no significant change in the quality, rheological properties, and sensory acceptance of product.

Freeze drying in particular is the preferred method for transporting and storing vast culture collections of micro-organism strain types. The main disadvantage of this method is cell damage induced through freezing. The usage of cryoprotectants due to the formation of glassy state would decrease cell damages through this stage. In this study, optimization of freezing media containing protective agents of nanocellulose, skim milk and trehalose was done using statistical design of response surface methodology (Central Composite Design). To determine the size of nanocellulose particles produced from cotton linter, atomic force microscopy and scanning electron microscopy were used. Nanocellulose particles had a width of less than 50 nm and length of hundreds of nanometers to several micrometers. Indigenous Lactobacillus brevis isolated from traditional dairy products were selected as target cells. By solving the regression equation, and analyzing the response surface plots, the optimal concentrations of the agents to maximize cell viability were determined as: Nanocellulose 13.75%, trehalose 20.5% and skim milk 13.75%. It seems that nanocellulose can be adsorbed on the surface of micro-organisms and form a viscous layer, preventing the growth of ice crystals by increasing the viscosity of the solution, and also keeps glass structure of ice near the cells. The results showed that RSM could effectively assess the main and interaction effects of protective factors on cell viability.

In this research, Iranian Peas were dried with the use of spouted bed dryer, in order to investigate the operation of Spouted Bed Dryer system, evaluating the effects of temperature on drying rate, and Rehydration ratio, and the parameters of the final product’s color at three temperatures: 45, 60 and 75oC. The Spouted Bed Dryer used, is a conical-cylindrical kind with a mutual symmetry which had the ability to dry the samples in different temperature and flow rates. Rehydration ability, color, and drying rate of the final product were compared with the peas which were dried through sun drying and thin layer dryer. Drying was done in spouted bed dryer and thin layer dryer at three levels of temperature: 45, 60, 75oC and rehydration ability of the dried product was assessed through putting the samples in distillated water in a 30oC oven, within the period of 320 minutes. The results showed that the designed spouted bed dryer system is able to dry the Iranian peas in a shorter time and with higher quality. In this system, increasing the temperature of drying has a significant effect on drying rate ability, rehydration ability and parameters of the product’s color.