فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال سوم شماره 2 (تابستان 1393)

Microencapsulation of rice bran oil using Arabic gum and whey protein concentrate as wall material was studied through both spray drying and freeze drying methods. To this aim، oil -inwater emulsions containing 4 % rice bran oil in an aqueous solution including 20 or 25% oftotal wall material composition were produced with ultra- turrax homogenizer. The emulsion containing 100% Arabic Gum has a minimum droplet size of (0. 36 μm) while themaximum droplets size of (0. 96 μm) was obtained for the emulsion containing 100% whey protein concentrate and for other ratios of these wall materials the droplets have sizes between these two amounts. Droplet size and viscosity measurements show that the stability of emulsions was influenced by the concentration and type of wall material. Also، the method of drying of emulsion، not only was effective on the size of the microcapsules، but also ontheencapsulationefficiency and oil retention in the capsules. The results indicated that the maximum encapsulation efficiencies in the Arabic gum of 60% concentration for wall compound (the total of gum and whey protein concentrate) were 90% through spray drying and 68% through freezedryingmethod. Of the two methods، microcapsules obtained from spray drying، whilemaintaining the regular spherical structures، showed more oil retention during six weeks storage.

Sugar Beet waste is obtained from sugar industry and usually is used for animal feeding. However it is a rich source of dietary fibers that، in addition to its abundance، is cheap. Inthis study، the effect of adding fiber obtained from beet waste at levels of 0، 0. 7، 1. 5 and 2% on the rheological، physicochemical features and the viability of Bifidobacterium bifidum BB-12 in ice cream during 60 days at -18°C was investigated. All the mixes showed pseudo plastic flow behavior and the apparent viscosity decreased with increasing shear rate. Increasingtheamount of sugar beet fiber led to increasing consistency coefficient and apparent viscosity values while decreasing flow behavior index of ice cream mixes. Ice cream melting resistance improved by increasing the amount of sugar beet fiber. Increasing fiber content in ice cream had no significant effect on the viability of Bifidobacterium bifidum BB-12 cells obtained from the freezing process، but at the end of the storage period، the number of live organisms in samples containing higher amount of sugar beet fiber was more. Sensory evaluation of the samples also revealed that the application of sugar beet fiber up to 0. 7% in ice cream is acceptable.

Response Surface Method was used to determine the optimum operating conditions that yield maximum total phenol، total anthocyanin، particle size and minimum moisture content، water activity and L* value in spray drying of Pomegranate. Air inlet temperature (120 170°C)، feed rate (0. 3-1. 1 mL/s) and Pomegranate juice concentrate/maltodextrin ratio (0. 6-0. 8) were factors whose effects on dependent variables were evaluated during the spray-drying process. The second order polynomial models for all the response variables were found to be statistically significant. In the optimum conditions that are obtained، feed rate and Pomegranate juice concentrate/ maltodextrin ratio were 170 °C، 0. 55 and 0. 6، respectively. This study revealed thatby applying these conditions، pomegranate juice powder with 4. 3687% moisture content، 8. 4655 L* value، 85. 0287 total phenol، 607. 836 total anthocyanin and 41. 7944 (μm) particle size were produced.

The diffusion process in the production of sugar is a determining process which affects the final quality of sugar. The pH of water which is used in this process is being controlled by adding sulphur dioxide gas to the water. In this research، the reason of corrosion of the sulphur dioxide gas transporter pipe to the diffusion water producer tank has been studied. In this way، the quantometery analysis of the base metal and weld zone، and X-ray diffraction analysis of the corrosion products has been applied. In addition، the corrosion rate of the base metal has been determined by the potentiodynamic polarisation technique at the temperatures between 50 t 70°C and also the DLEPR method has been used for the weld zone. The Results showed that the main reason of the corrosion of the pipe was the accumulation of the gas in the bottom of the pipe and the concentrated sulphur containing droplets which led to the localised corrosion ofthe pipe. Finally، changing the position of the branch pipes، shelving the pipe and changing the material are being suggested.

Stevioside is a natural sweetener which is extracted from the leaves of Stevia Rebaudiana Bertoni plant that doesn''t have the role of calorie cleansing and doesn''t have the effect on increasing the level of blood glucose. The purpose of this research is to consider the possibility of dietary biscuit production during the substitution of stevioside in three levels of 0%، 50%، and 100% with saccharose. The results showed that the substitution of stevioside instead of sccharose hasn''t meaningful effect on the percentage of ash، fat and protein in biscuit but by increasing the percentage of stevioside in biscuit formulation، it was discovered that the moisture and product pH will increase meaningfully، also the results of calorie calculation showed that the calorie content of product will decrease 13. 3% when stevioside was substituted with saccharose by increasing the percentage of stevioside in biscuit formulation، the increasing of samples diameter and decreasing of diagonal and extension coefficient. The texture analysis of biscuit samples showed the decreasing of the hardness of product texture by increasing the percentage of stevioside (p<0. 05). The results of image processing showed the increase of parametes L٭ and b٭and the decrease of parameter a٭ during sugar deletion. Finally، sensory evaluation results of three biscuit formulations indicated more acceptance of prepared sample of steviosid 50%. Totally، prepared biscuit by using stevioside 50% can be introduced as the best sample.

Persian gum، mountain almond tree (Amygdalus Scoparia) exudate، is a transparent edible gum. This gum can have many pharmaceutical and food applications. It consists of soluble (25– 30%) and insoluble (70–75%) fractions. Therefore، with a view to utilize the gum for broader applications، the effects of different conditions of chemical modification (insoluble fraction of Persian gum concentration، acryl amide concentration، reaction temperature andreactiontime) on solubility and emulsifying capability of soluble fraction was considered using responsesurface methodology (RSM). The maximum solubility (64%) was obtained at the presence of 6% of insoluble fraction of Persian gum، 0. 08 mol acryl amide، at 60 centigrade degrees for 3 h. Intrinsic viscosity and molecular weight determination proved the significant influence of chemical modification on molecular weight. Furthermore، the chemical changes ofchemically modified gum (at optimum conditions) were confirmed by FT-IR spectroscopy. Moreover،the effect of pH and electrolytes on rheological properties of soluble fraction، separated from insoluble fraction which modified at optimum conditions، revealed its anioniccharacteristics. In addition، the emulsifying capability of this fraction was significantly lower than the soluble fraction of Persian gum.

Celiac disease is an autoimmune disorder that results in permanent intolerance to dietary gluten (especially wheat gluten). Using a gluten-free diet is the only effective remedy to this disease. The aim of this study was to evaluate the effect of xanthan gum (0. 0، 0. 3، 0. 6، and 1. 0%) and sweet almond meal (0، 5، and 10%) on physico-chemical properties of batter and gluten-free cake samples. Brightness values (L*) cake samples containing xanthan gum were in the range of 58. 4 to 64. 1 indicating that increasing levels of xanthan gum would cause an increase in the brightness of cake samples. However، increasing concentrations of almond meal significantly reduced the L* of cakes، so that L* decreased from 58. 4 to 56. 8. The addition of almond meal increased the porosity of cake samples، while the addition of xanthan gum up to 0. 3% increased the porosity، but its further concentrations negatively affect the porosity of cakes. Firmness and moisture content of cake samples and viscosity of batters were increased by adding xanthan gum. Sensory evaluation of cakes revealed that samples containing xanthan gum and almond meal were more desirable compared to the control sample.