مجله تحقیقات مهندسی صنایع غذایی
سال نوزدهم شماره 2 (پیاپی 69، پاییز و زمستان 1399)

Physical instability and cohesion of fat-based filling in baking products have long been one of the major problems in the food industry. Since the continuous phase of these fillings is fat, the desired thermal stability can be achieved by selecting the appropriate oil. Palm oil and its products are oxidation resistant and stable for a long time at high temperatures. In this study, in order to achieve heat stable oil in the formulation of cake filling, palm oil was fractionated at two temperature levels of 5°C and 17°C, by solvent method and using pure acetone, and physical chemistry tests including determination of combination of fatty acids, solid fat content, thermal behavior analysis, melting point, saponification index, iodine index, peroxide number, acid number were performed. Palm olein oil of 17°C was used in the filling formulation and the effects of cooking temperature and storage time on the sensory, physical and rheological properties of the filling (hardness, cohesion, adhesion, gummy state) were evaluated. By reducing the fractionation temperature, in stearin fractions, the percentage of unsaturated fatty acids decreased and the percentage of saturated fatty acids increased. The palm-olein fraction of 17°C was suitable for using in formulation of filling due to fast melting profiles and relatively high solids content in 20°C, and uses in formulation of filling have affected all texture factors. Temperature and time alone did not make difference (P> 0.05) in the rheological, physical and sensory characteristics of the filling, but at the same time caused a difference (P ≤ 0.05) in the factors mentioned. The palm olein fraction of 17 °C in the formulation produced a thermal stability in the cake.

An investigation was conducted to evaluate the effects of feed composition, feed moisture content and screw speed variables on the physicochemical, textural, visual, acoustic and sensory properties of flaxseed puffed snacks, produced by the extrusion processing. The flaxseed mixed with corn grits at three ratios: 7, 14 and 21 percent, the water was added to the mixture to bring the moisture content of the samples of feeding to 12, 15 and 18%. The mixtures were extruded at screw speeds of 120, 150 and 180 rpm, at 140°C. Experiments on the samples showed that increasing in moisture content of the samples led to increase in water absorption, particle density and hardness, and also led to decrease water solubility and texture sensory scores.  Increasing in screw speed led to increase the water solubility and to reduce particle density, radial expansion, hardness, and sensory scores of appearance, color, texture, and overall acceptance of samples. Increasing the ratio of flaxseed in samples, led to increase particle density and to reduce radial expansion and sensory scores for the appearance, color and overall acceptance of the samples. In order to produce the optimum sample with the highest expansion ratio and brightness and the lowest hardness and density, containing 14% of flaxseed, the screw speed and feed moisture content must be  selected at  180 rpm and 14.42%, respectively.

Steaming is a shortened method of processing that is applied to improve the quality of rice. A two factorial experiment in completely randomized design (CRD) was used to investigate the effects of steaming on bending strength, head rice percentage and color of Gohar rice variety. In this study, two selected factors were as follows: initial moisture content (IMC) at 3 levels (14, 17, 20 percent, wet basis) and steaming duration at 5 levels: without steaming (control) and steaming in atmospheric pressure with duration of 5, 10, 20 and 30 min. The results showed that with increasing the steaming duration from 5 to 30 min, bending strength increased from 24.3 Mpa to 31.4 Mpa for paddy with IMC of 17% and from 24.8 to 32.2 Mpa for paddy with IMC of 20%. In both IMC (17 and 20 %), steaming for 30 min led to increase head rice, 47.53% and 49.09 % respectively, compared to control. Rice whiteness decreased and rice yellow index (b) increased. Regarding color changes and for Gohar, the high yield rice variety, steaming for 10 min can be proposed for paddy with IMC of 20±1% and 20 min for paddy with IMC of 17±1%.

The application of solar energy and sun dryers in food drying is increasing. Low efficiency is the main problem of this apparatus. To solve this problem, a new heat collector and drying chamber were made and assessed. The cover of the collectors was double glazed and consist of many slats and assembled in such a way that it formed a stair step fashion and made many slots through which inlet air was sucked into the collector to reduce total heat loss. The theoretical and practical efficiency of the dryer was calculated during the grape drying. The thermal efficiency of the new 10-step collector and control at low ambient wind speeds was calculated to be 65% and 56%, respectively. Increasing the ambient wind speed to 10 meters per second and more reduced the thermal efficiency of the matching collectors to 35%. The use of the new collector is recommended only if the ambient wind speed is less than 1 meter per second. The drying time of grape in the solar dryer was significantly - around %108 - shorter than that at similar time for the sun-drying method. The time required for fruit drying in the middle tray was 10 to 14 hours longer than that in other trays. In terms of overall acceptance, the raisins produced at different trays of solar dryer had a similar quality, but all were significantly superior to the traditional (sun-dried) product.

In this study, the effects of fat content (0.2-5.8%) and temperature (5-35°C) on viscosity, density, color, and the friction pressure drop per unit length of pipe flow of camel milk were investigated by using response surface methodology (RSM) based on the central composite design (CCD). The results showed that increasing the fat content decreased the density of samples with high-fat content, while increasing the temperature decreased the density, but it had no effect on samples with 0.2% fat. The results of the viscosity analysis also showed that increasing the temperature decreased the viscosity of samples containing high-fat. Also, the viscosity of the samples increased with increasing the fat content, although the increase in viscosity by increase in fat at low temperatures was much higher than that at high temperatures. The results of color measurement also showed that increasing in fat content increased only b* parameter and temperature had no significant effect on other color parameters. According to the results of ANOVA, none of the linear, quadratic and interaction effects of fat and temperature on the friction pressure drop per unit length of pipe were significant (p> 0.05).

In this research, the effects of ultrasound and microencapsulation on quantitative and qualitative characteristics of bioactive compounds extracted from red grape of Roshe Sardasht cultivar were investigated. Response surface method was used to study the effects of intensity and process time of ultrasound. Independent variables included ultrasound intensity at three levels 20, 60 and 100% and process time also at three levels 5, 10, and 15 minutes. The results showed that with increasing ultrasound intensity, total phenolic compounds, Ferric reducing activity of plasma (RRAP) and DPPH free radical-scavenging assay increased, but then decreased (p < 0.05). Also with increasing the process time, the RRAP and DPPH assay decreased (P <0.05). , Ultrasound intensity at level of 60% and process time at level of 8.78 minutes were determined as optimum conditions for extraction of aqueous grape pomace. In this condition, the extraction efficiency, total phenolic compounds, the RRAP and DPPH assay were obtained 14.99%, 55.56 mg/g, 1608.94 μmole Fe2+/L and 78.80% respectively.  Using the mixture of calcium alginate (0.1%) and maltodextrin with three concentration (5, 10 and 15%), the optimal extract of red grape pomace was microencapsulated by freeze drying method.  The results of statistical analysis of the data showed that encapsulation yield, moisture, bulk density and particle size of the microencapsulated powders increased (P <0.05) with increasing the concentration of wall materials. The glass transition temperature of all microcapsules was higher than the ambient temperature. Microencapsulated powder with 15% maltodextrin had the highest phenolic content, FRAP, DPPH assay and glass transition temperature.

Food industry produces a large amount of onion skin wastes. Due to the high amount of bioactive compounds found in such by-product, developing a method for the recovery of these biological lesions is important to benefit from them as a source of biologically active compounds.  The aims of this research were to compare the two methods, ultrasound and microwave, for extraction the phenolic compounds of red onion skin wastes and also to investigate the drying pre-treatment with conventional or infrared oven. The investigation the total phenolic compounds and anthocyanin content of extracts showed that use of ultrasonic method caused significantly (p < 0.05) enhanced extraction efficacy of phenolic compounds and anthocyanins. Additionally, drying by infrared oven caused significantly (p < 0.05) increase in total phenolic compounds and anthocyanins extraction. The antioxidant activity analysis of extracts showed that antioxidant capacity of samples extracted by ultrasonic method were significantly (p < 0.05) higher than that extracted by microwave method. As a result, the ultrasonic extraction by pretreatment applying infrared oven may be recomended as a suitable technique to extract phenolic compounds found in red onion skins to benefit from the nutritional potential of these biological wastes.

This study aimed at investigating the effects of drying temperature, heat treatment and gum concentration on emulsifying properties of Farsi gum, extracted from Amygdalus scoparia Spach. For this purpose, solutions of 3, 3.5, 4 and 5% concentration of Farsi gum were prepared. These solutions were heat treated at 65, 75 and 85 °C for 1 minute. Then, they were dried by spray dryer at 120,150, 165 and 180 °C. The 20% sunflower oil emulsions were prepared at 0.5, 1, 1.5, 2 and 3% concentration of Farsi gum. The results showed that a decrease in drying temperature made improvement in the emulsion ability and emulsion stability of Farsi gum; but heat treatment and gum concentration had no significant effect (p < 0.05) on the emulsifying properties of Farsi gum. Emulsions contained 1% Farsi gum were stabled after a week and creaming was not observed, also after a month, emulsion contained 2% Farsi gum was stabled. By increasing the drying temperature, creaming index decreased but gum concentration and heat treatment had no significant effect (p < 0.05) on creaming index. The average size of droplets of emulsion decreased with increasing concentrations of Farsi gum from 0.5% to 1.5%-2% but with increasing concentrations of Farsi gum to 3%, the average size of droplets of emulsion increased. Among the factors involved, only drying temperature had significant effect (p < 0.05) on size of droplets of the emulsions. Consequently, the average size of droplets increased with increasing drying temperature.

Disinfection of dry and semi-dry date palm cultivars are carried out with methyl bromide gas, but applying of this gas is restricted by international protocols. In this study, the combined effects of modified atmosphere, heat and packaging as a substitute for methyl bromide were investigated. The fruits were packed by vacuum packing machine. Atmospheric treatments were replaced with four combinations: 70%, 80% and 90% carbon dioxide and 90% nitrogen. The carbon dioxide treated packages were incubated at 35°C, 40°C and 45°C and the Nitrogen treated packages at 40°C and 45 °C for 24 and 48 hours, respectively. Traits including sugar content, relative humidity, soluble solids content and fruit pest infestation were measured. The results showed that there were significant differences between samples in terms of mean infestation by saw- toothed beetle at 1% probability level and for total sugar and total solids content at 5% probability level. The highest pH values were observed at the highest CO2 concentration in combination with the highest temperature. The pest control was completely done in samples treated with 90% carbon dioxide at temperature of 40°C and 45°C, 80% carbon dioxide at temperature of 45°C, and 90% nitrogen at temperature of 45°C. The results revealed that the placing of date fruits in polyethylene packages using (5%O2+90%CO2) and (5%O2+90%N2) treating at 45°C for 24 hours were suitable for disinfection of dates fruits.

Russian olive, Elaeagnus angustifolia, is used in the treatment of various diseases because of its nutritional and pharmaceutical properties. The aim of this study was to evaluate the effect of using various amounts of Russisn olive powder on physicochemical, texture and sensory properties of set-type yoghurt produced from non-fat milk. Five yoghurt samples were manufactured from full-fat milk, non-fat milk and with addition of Russian olive powder in three different amounts of 10, 20 and 30 g/L to non-fat milk. Yoghurt samples were then stored in a refrigerator (4±1°C) for 22 days and their physico-chemical, texture and sensory properties were evaluated during storage. The results showed that using Russian olive powder caused significant changes (p<0.05) in physicochemical, texture and sensory properties of yoghurt samples. With addition of Russian olive powder, acidity, viscosity and water holding capacity decreased significantly in yoghurt samples, while pH and syneresis increased (p<0.05). On the other hand, while acidity and viscosity increased significantly during storage in all samples, pH, syneresis and water holding capacity decreased (p<0.05). In conclusion, using 10 g/L of Russian olive powder had the best physicochemical, texture and sensory result in manufacturing of non-fat yoghurt.

Considering the health benefits of acorn and its effects on the digestive system, this study was conducted to introduce acorn or Persian oak fruit consumption, especially for people who suffer from digestive problems. In this study, acorn flour with different percentages (0, 6, 8, 10, 12 and 14) were added to wheat flour and then texture, sensory and chemical properties of the product were studied.  Results from penetration tests indicated that there were significant difference in samples with 14% acorn flour with other samples which can be related to reduction of the wheat protein content and increase acorn flour. Results  gained from stress relaxation tests showed that the control samples had significant differences with samples containing 8, 6, and 12 percent of acorn flour, and also the texture of the samples turned more dense and less flexibility as the percentage of acorn flour in bread samples were increased. Sensory test results showed that from the first day through sixth day all samples, except the sample with 14% acorn flour, were acceptable. On the eighth day, and from that day on, a part of samples lost their acceptability. The results of chemical analysis showed that with increase in acorn flour, the protein content, humidity and wet gluten content decreased, but the ash increased.

Maillard reaction, or non-enzymatic browning, usually occurs during the thermal processing, storage, and other food processing operations, which can lead to the formation and retaining of Maillard reaction/non-enzymatic products reaction in foods. Food producers usually implement Maillard 's reaction products to improve the color, texture, and aroma of the various food products, leading to high acceptability and popularity. Nevertheless, the Maillard reaction products may induce mutagenic, carcinogenic, and cytotoxic effects; for instance, Acrylamide, furan, and 5-Hydroxymethyl furfural are identified as potential harmful Maillard-forming compounds. Different groups of food products which are analyzed toxinogenetically, have a high consumption rate in the human societies and therefore the strategies for the minimization of these compounds should be prioritized in the production process of food products. Thus, in this revision, the antinutritional compounds produced via the Maillard reaction in industrial and traditional food products of different countries are studied.