نشریه نوآوری در علوم و فناوری غذایی
پیاپی 20 (تابستان 1393)

Osmotic treatment is based on placing foods into a hypertonic solution that has higher osmotic pressure and lower water activity than the foodstuffs. Food dehydration process in several reasons, causes deteriorate qualitative characteristics in final products. So it is necessary to use some pretreatments such as osmotic dehydration. The Major limitation with commercial production of osmotically dehydrated products is the high solid uptake by the texture and lack of proper management of osmotic solutions. Use of edible coating with reused of solution is important. In this research, during osmotic dehydration of pear rings, the effects of concentration of sucrose solutions of 50 percent (w/w), the CMC 0.5 percent (w/w), as in edible coat, in constant temperature of 30ºC, and reconstitution of osmotic solutions (until 5 times), were investigated on mass transfer phenomena including of the water loss (WL), solid gain (SG) and productivity ratio (WL/SG) of osmotic process. The result showed that use of edible coat and reconstituted osmotic solutions, increases the productivity ratio of process. The results present the osmotic coated samples were obtained after 5 times reconstitution of osmotic solution, as the superior samples.

The aim of this study was to produce solid nano-particles by tristearin. For this purpose, the combination of tristearin with surfactant, solvent and water was used using solvent injection method. Dynamic light scattering (DLS) was used to measure the size of produced particles. The results of DLS showed diameters about 100 nm for produced particles. The results showed that mixing speed affected the solid nano-particles diameter, as their sizes were reduced with mixing speed. The relation between particle diameters and their transmittance were modeled. The results of SEM confirmed the DLS results and showed that the produced nano-particles had spherical shapes.

Bene hull antioxidant activity is mainly related to polyphenolic compounds. One of the new methods to extract polyphenolic compounds is subcritical water extraction. The present study focused on modelling the amount of bene hull (Pistacia atlantica) polyphenolic compounds extracted with subcritical water method, using back propagation neural network. Process modelling is done with 27 sets of experimental data and temperature (110-200°C), process time (30-60 min) and solvent mixing ratio (1:10 - 1:50) were selected as neural network input variables. Also, the amount of polyphenolic contents (mg gallic acid/kg) was considered as the output of the process. The results showed that Back propagation Neural Network (BPNN) with 12 neurons in the hidden layer by sigmoid activation function, as the best network, could predict the amount of polyphenolic compounds with a correlation coefficient of 95%. In the next stage developed model was optimized using Enumeration method. Optimization results indicated that phenolic compounds extraction process can be achieved at 166 °C for 60 min and the ratio of 36:1 for water to Bene hull (w/v). Experimental results obtained from experiments with optimal conditions indicates proper function of the proposed method.

In this study, finding optimal processing conditions of carrot juice in relation to the effect of blanching on antioxidant compounds have been examined. Blanching was conducted through three immersion in water, citric acid 0.21 % solution and immersion in water and subsequently heating with microwave and were compared with the unblanch sample as the control sample. The tests applied are: extraction efficiency, measurement of ascorbic acid, anti radical activity (antioxidant characteristics), phenolic compounds contents and Carotenoids. The tests were conducted in four stages of pre-pasteurization, postpasteurization and after 15 days and 30 days of storage in the fridge. The experiments were done in completely random factorial form with three repetitions in each experiment. In order to compare the means, Duncan test at level of 0.05, was used. The statistical results indicated the blanching process and storage period have a significant effect on the antioxidant characteristics of carrot juice at the level of 0.05. Three methods used for comparing blanching anti-radical activity, phenolic compounds and ascorbic acid in the citric acid treatment of 0.21 % significantly was more than the other two methods. There is a strong correlation between the antiradical activity with β-carotene content, vitamin C and phenolic compounds (R2=0.9343).

Wheat in the most parts of Iran due to the soil type and climate is not proper to produce good quality bread flour. Control the climate changes and other factors affecting on wheat quality is difficult, so at most of the time the quality of flour is not good and many defects in bread will be observed. One of the most common problem of Iranian wheat bread is low activity of α- amylase enzyme in wheat flour which makes problems in bread industry. One of the way to adjusting is adding fungal amylase to flour. In this study the effect of fungal α- amylase on rheological characteristics of dough measured with Farinograph and specific volume and sensory evaluation has been determined after bread baking. Results showed that adding these enzymes lead to decrease in dough development time, dough stability, water absorption, quality number of Farinograph and increase in degree softening of the dough. Specific volume and total score in sensory evaluation increased in comparison with the control bread. In this research, 5 ppm of α-amylase selected as the best treatment after measuring by falling number.

Wheat germ is one of the crucial side products of milling wheat. This component is an inexpensive protein resource that could be used in food products. In this research due to high nutrition properties of wheat germ flour, the possibility of this substitution in sausage was examined. In this research, defatted wheat germ flour used for protein enrichment, texture improvement and fat reduction in substitution at levels of 50, 75 and 100%. Control sample was produced with wheat flour. Different samples were evaluated in terms of their chemical (fat, protein, moisture, ash, pH and cooking loss), physical (texture and color) and sensory properties. Addition of wheat germ flour resulted increasing the protein, ash and moisture contents, but decreasing the fat content and cooking loss, there was no significant difference (p˃0.05) among samples in terms of pH. Lightness (L*) of Samples was significantly decreased on additions of wheat germ flour, but redness (a*) and yellowness (b*) of samples did not significantly changed (p˃0.05) and the highest intensity of color (ΔE) was observed in samples with 100% of wheat flour. Samples containing wheat germ flour showed lower values for hardness, gumminess and chewiness, but cohesiveness and springiness had no significant effect by addition of wheat germ flour. There was no significant difference (p˃0.05) in flavor, odor and color. There was no significant difference (p˃0.05) among samples in terms of tenderness.

Honey, produced by the honeybee, is a natural supersaturated aqueous invert sugar solution, which is mainly composed of a complex mixture of carbohydrates. The diversity of the physical and chemical properties of honey depends on the nectar and pollen of the original plant, color, flavor, moisture and contents of proteins and sugars. Quality of honey is determined by evaluating physicochemical properties of different honey samples collected from Golestan province (North of Iran). The 9 samples were analyzed for parameters including moisture, specific gravity, electric conductivity, dissolved solids, ash, pH, free, lactone and total acidity, sugars, fructose/glucose and glucose/water ratio, optical rotation, ash and color. The results of study indicated that all properties and honey samples were at good quality. Parameters such as pH, conductivity, fructose content and optical rotation can be used for distinguish honeydew from other samples. Correlations observed between some parameters e.g. between electric conductivity and absorbance and between electric conductivity and optical rotation.

Sauerkraut is a cabbage fermented product that is known as a functional food because of nutritional properties.The effect of cabbage variety(red and white) and different flavoring agent(lemon powder, vinegar, dill, mint and red pepper) on chemical(vitamin C content, nitrate content, nitrite content and thiocyanate content) and sensory(flavor, appearance and total acceptance) properties of sauerkraut were investigated in this study. The results showed that the red cabbage sauerkraut has higher vitamin C content than the white cabbage sauerkraut whereas nitrate, nitrite and thiocyanate content in red cabbage sauerkraut is lower than white cabbage sauerkraut(p<0.5%). White cabbage sauerkraut prepared with lemon powder (0.1%) and vinegar (2%) has the highest score of sensory properties and sauerkraut without any flavoring agent has the lowest score in this respect. Red cabbage sauerkraut prepared with dill(0.1%) and mint(0.1%) and red pepper(0.1%) and vinegar(2%) has the highest score from the view point of total acceptance, flavor and appearance.

Traditional raw milk cheese is one of the most consuming cheeses in the world. However, pathogenic bacteria that can be transmitted through the dairy products, including cheese, are important from public health point. There have been reported some outbreaks of infection associated with the consumption of cheese and the presence of pathogenic organisms in it. Kurdish cheese is a semi-firm, traditionally made in the East of Iran. It is manufactured from raw sheep or cow milk and kept in goat’s skin bags during ripening period. As a result Kurdish cheese is often more complex in different varieties of microorganisms, which whose organoleptic properties make it highly esteemed. The aim of this study was to investigate the cheese microbiological contamination during 1, 20, 40 and 60 days of ripening periods, in local condition. Total mesophilic bacteria count; yeast and mold, coliform, E.coli, staphylococcus aureus and salmonella were enumerated according to National Standards of Iran. According to our results, After 20 day of ripening the numbers of micro-organisms reach their maximum, coliforms and E.coli were the predominant groups. But, at the end of the ripening period, No coliforms and E.coli were detected in the cheese samples, confirming that these were not contaminated with undesirable flora. The total average Moulds and yeasts of 2 white cheese samples was 4. 105 cfu/ml at first day of production but after 20 days of ripening it increase sharply and after that decrease gradually in ending days. No Coagulase positive Staphylococcus was detected at the end of the ripening period. Salmonella was not detected in any samples examined. pH content of samples decreased slowly during ripening. According to our results, the presence of high counts of pathogenic flora in cheese samples in first days of production suggests inadequate hygiene practices during transport and manufacture of this traditional food. But the optimize time for consuming kurish cheese would be after passing ripening times (60 days) due to decrease in pH, undesirable flora and increase in desirable LAB counts.

Physical and mechanical properties of agricultural products have significant effect on efficiency and performance of processing systems and machines. In this study some mechanical properties of Pistachio of Qazvini cultivar (Qazvini and Boein Zahra) such as rupture force, deformation till rupture point and rupture energy were evaluated at three levels of moisture content 3.5%, 12% and 19.5% (w.b) and in two loading directions. Results showed that rupture force of mouth closed pistachio of both cultivars by increasing moisture content at 1% probability level significantly decreased, but deformation up to the point of failure increased. Moisture content had no significant effect on the rupture energy. Loading directions and variety had no significant effect on mechanical properties. By increasing moisture content from 3.5% to 19.5%, rupture force and rupture energy for Qazvini variety decreased from 102.14 N to 54.49 N and from 22.8 mj to 20.22 mj and for Boein Zahra variety from 122.53 N to 29.25 N and from 23.17 mj to 13.18 mj, respectively. Also deformation till rupture point increased for Qazvini variety from 0.21 mm to 0.72 mm and Boein Zahra variety from 0.36 mm to 0.70 mm.

The objective of this research was to produce a dried potato product and study the effects of different drying methods (oven, microwave, and microwave-oven) on rehydration capability, vitamin C and shrinkage of the dried potatoes. Completely randomized design was used for statistical analysis of the results. The results showed that there was a significant difference between produced dried potatoes by drying methods and its justification was in applying different drying mechanisms, for example the amount of ascorbic acid (vitamin C) in the dried potatoes by microwave was significantly more than that in the dried products of the other two methods. Also starch amount of the dried cubes in microwave apparatus was higher than the other samples which this is the case of a high rehydration percentage in microwave samples. Investigating the variation of shrinkage percentage during drying by different methods showed that the lowest shrinkage occurred in the samples dried by microwave.