IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2010 | Volume:8 | Issue:1|Papers Count:15

Dietary fiber has become a matter of considerable public interest in recent years because of its known beneficial physiological and metabolic effects. Since, fiber intake is commonly lower than recommended amount (30g daily), the fortification of bread with fiber can play an important role in achieving health benefits. The aim of this study was to add oat bran at 5, 7.5 and 10 % levels to the Sangak flour and study the rheological characteristics and quality and shelf life stability of the bread. The rheological characteristics of dough were studied on the farinograph and extensograph. Then, Sangak bread baked under standard condition and kept for 24, 48 and 72 hours at room temperature and samples evaluated by 10 trained panelists. Texture of bread samples analyzed for extensibility, sliceability and compression by Instron (Universal Testing Mashine) at 24, 48 and 72 hours at room temperature. Also, moisture of bread samples determined by standard method and compared with control. Results indicated that use of oat bran increased water absorption and weakened dough. Also, the extensograph results showed by the addition of the bran to the flour, resistance to extension increased and dough could kept the gases during fermentation. The results of the sensory test of Sangak bread showed that by the addition of oat bran to the sangak dough, the quality of the bread was low and lower quality was in the case of high percent of the bran (10%). The texture properties of the breads at 24, 48 and 72 hours, showed they were delay in staling phenomenon and the late thoughness happened. Acid detergent fiber and neutral detergent fiber values increased with increasing levels of oat bran.

In this research, the relative stability of canola, soybean, olive and corn oils in terms of the accelerated tests of rancimat at 120oC and carbonyl at 160oC was compared. The highest and lowest amount of the ratio between polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) belonged to the corn (4.74) and olive (1.03) oils, respectively. The canola (3.16) and soybean (3.38) oils, with an intermediary position, had no significant difference between their PUFA/SFA ratios. The highest amount of phenolic compounds with no significant difference was observed in the canola and soybean oils (48.19 and 45.80 ppm, respectively).Its lesser amount was found in the corn (30.80 ppm) and olive (15.27 ppm) oils, respectively.The order of the oxidative stability for the oils studied in terms of the accelerated carbonyl test (tΔCV=30) was (104.93, 77.67, 61.23, and 50.29, respectively), and the difference between the olive and corn oils here was statistically significant. The oxidative stability order of the oil samples in terms of the rancimat test was similar that of the carbonyl test (9.26, 6.89, 5.65, and 4.82 h, respectively). The comparative investigations on the ratio between the two stability indices of the carbonyl and rancimat showed more obvious differences between the oils studied in terms of the carbonyl value (1.35, 1.27, and 1.22) than in terms of the rancimat value (1.34, 1.22, and 1.17).

The adsorption and desorption equilibrium moisture contents (EMC) were determined for Estameran date fruit using saturated salt solution method at 40, 50, 60 and 70oC over the range of relative humidity from 0.05 to 0.85. Equilibrium moisture content decreased with increasing the temperature from 40 to 50°C, at water activities (aw) below 0.3, while for higher water activities, crossing phenomena of the isotherm curves was detected as the temperature increased. Furthermore, equilibrium moisture content increased due to the dissolution of crystalline sugars at higher temperatures and moisture contents. The same phenomenon took place at water activity equal to 0.05 at 60 and 70oC temperatures. GAB, modified Halsey, modified Chung-Pfost, modified Oswin, modified smith and modified Henderson models were used to fit the experimental data. The GAB model was found to be the most suitable for describing the adsorption and desorption curves. The monolayer moisture content (Mm) values at different temperatures were calculated using the GAB equation. Results showed that Mm decreased with increasing temperature. The isosteric heats of desorption and adsorption of water were determined from the equilibrium data at different temperatures by Clausius-Clapyron equation. The isosteric heats of desorption and adsorption decreased with increasing water activity.

One of the most important date producing areas in Iran is Khusestan province. Sayer, zahedi and dairi are the main date variety cultivated with a 75% fraction. Due to its arid conditions this province has the third place in date palm production after Kerman and Hormozgan with 82641 tons date production.The major components in Date palm (Phoenix dactylifena L.) are carbohydrates, which are the most important parameters for commercial quality and nutritional value in this fruit. In this study we assessed the water content, total sugar and energy content of four major date varieties (Sayer, Dairi, Zahedi and Hallawi) from the Khuzestan province. Other proximate date compositions such as the protein content, dietary fibre and essential minerals were also investigated. The mentioned date varieties have more than 65% sugar content and were found to be a good source of energy (333.82-349.68 Kcal/100g), daily recommended dietry fibre intake and mineral components such as iron and phosphorus.

Drying is one of the most important steps in raisin processing. Achieving optimum drying conditions can affect the processing time and improvement of raisin quality. In this research, effect of two-temperature and pretreatments on time and drying rate of Black currant grape were studied.Drying was performed in two ways: In the first one, temperatures was constant at four levels of 50, 60, 70, and 80oC and in the second one sample were placed at two temperatures. In the latter, samples were placed at 80oC and when moisture content was reduced to 50%, temperature was set to 70, 60 and 50ºC. Four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydracids and no pretreatment were performed. According to the results of the ANOVA, factors such as temperature, two-temperature and pretreatment have significant effects on drying time and average drying rate. Drying time of grape with two-temperature comparing with drying time of constant temperature was decreased up to 67% for some pretreatment. Maximum and minimum activation energy were determined 2893.9, 4538.8 kj/kg.

With ever increasing competition, enterprises as well as researchers are focusing on consumer and its priorities and thus every day, new aspects of determinants of consumer choice become clear. One of such determinants is brand perception. Perception of consumer about technology of production-which is derived from brand and packaging-, can play a great role in the consumer choice when differentiation is little. Such role is investigated in this research work. We have studied a group of food products with very low level of differentiation and correlation between demand and technology perception is elaborated. Field study has been performed in Shahrvand department stores. Results show that in simpler, more commodity type products, technology perception has a greater role in finalizing customer choice. So making a more positive perception of technology can be considered as a rather inexpensive way for gaining competitive advantage. Additionally, based on interviews, it can be claimed that technology perception consists of sub-elements such as environment friendliness perception, healthiness perception, quality perception, etc.

Date liquid sugar (DLS) is concentrate of clear and bleached date syrup that produced after of extraction date juice with removing pectin compound, protein, fiber and color is brown to yellow. This product can be used for production of isotonic beverages, bakery products (cake and confectionary), dairy and others that also mooted for HFCS (High fructose corn syrup) and sugar replacement.In this study, DLS is used in three levels (0, 50 and 100%) replacement of invert with sugar in layer cake routine (blank) of Astane Godse Razavi factory. Then, samples are examined for sensory properties (Texture, color, moistness, mouthfeel, sweetness and total acceptance) with eight trained panelist and physical properties (aw, pH, moisture and volume).The texture of products (cake and biscuits) is examined with instron and staling of layer cake is evaluated with DSC.Results showed that pH (dough, cake) and volume of samples were replaced with invert in layer are decreased. Aw of samples with 50% replacement is decreased although replacement with 100% is increased. Also, moisture of cake with replacement is increased. Samples that were replaced with DLS show that darken color from blank. Results of panelist evaluation is shown different significant between samples. Determination starch gelatinization indicated that no difference between samples but between day’s differences is shown. Also, there is a decrease between samples ratio to blank in hardness of texture.In general, samples that replaced with invert in layer cake 50% was best sample in aw and sensory evaluation and texture.

For the determination of antibiotic residues in industrial poultry carcasses in mazandaran province, 815 carcasses are sampled from three slaughterhouses (Sari-Qaemshahr-Amol).For this purpose, the method of F.P.T (Four-Plate-Test) was used. The principle of this method is formation of pellucid halo (inhibitory zone) around the extract in agar plate that was cultured with equal layer of bacteria. Altogether from 815 carcasses, were examinated.533 carcasses (%65.4) were called for antibiotic residues, at least in one organ (muscle- liver-kidney) or tow and or all three organs. Meanwhile, kidney with the most case positive (antibiotic residues) (%52.2) and then liver (%51) and muscle (%44.5) repose.

Knowledge of physical and mechanical properties of agricultural products, such as vegetables, is needed for their processing. The objective of this study was to find the physical and mechanical properties of squash, related to head cutting process. The physical properties such as length, mass, headfirst diameters, head diameters, volume, density, sphericity and geometric mean diameter were determined. Material testing machine was used to measure mechanical properties by applying shear test on the sample. The experiments were carried out at three mass levels (m<95g, 95g120g), loading speed of 50mm/min and loading direction (vertical to headfirst diameter direction) of preprocessing squash. Mechanical properties such as maximum force and energy of shear and bioyield point were determined. Result of physical properties of squash showed that the averages of length, mass, volume, density, sphericity, headfirst diameters, head diameters and geometric mean diameter were 121.34 mm, 110.09 g, 110.77 cm3, 994.85 kg/m3, 48.72, 25.51mm, 37.48 mm, 59.05 mm, respectively. Result of mechanical properties showed that mass had significant effect on maximum shear force and energy. Moreover, the biggest squashes had the highest shear force and energy.

In the present study the effects of extract from the peels ofRamus potato variety as a natural antioxidant in refined soybean oil were investigated using the Schaal oven and Rancimat methods.Phenolic antioxidants of potato peels were extracted by two different solvent extraction methods (Solvent with methanol and ultrasound-assisted method with different solvents including methanol, ethanol, hexane, acetone and water). The total phenolic compounds were determined according to the Folin–Ciocalteu method. Maximum amount of extract was obtained with water, followed by methanol and ethanol but maximum amount of phenolics was obtained with methanol, followed by water and ethanol by ultrasound method. Sonication improved the total phenolic compounds of the potato peel extract and shortened the extraction times.After 16 days storage at 63oC, soy bean oil containing 200, 800, 1600, and 2400 ppm of methanolic extract of potato peels, attained lower peroxide values (PV, 42.67, 37.35, 24.65 and 19.09 meq/kg, respectively) than the control sample (PV, 64.08 meq/kg) indicating strong antioxidant activity. Oils treated with 200 ppm of BHA, BHT and TBHQ attaind PVs of 33.20, 28.88 and 9.96 meq/kg, respectively, after 16 days storage at 63oC. Also, results Rancimat (at 90, 120, 150 oC) showed that potato peel extract, at concentrations of 1600 and 2400 ppm exhibited strong antioxidant activity which was almost equal to synthetic antioxidants (BHA & BHT).

In this study, physicochemical (pH, acidity, brix, vitamin C, SO2 and formalin number) and sensory properties of PET containers packed Lemon juice were evaluated. The samples were stored at 20 and 40oC. During the ten weeks of preservation, physicochemical and sensory properties were measured in three replicates every two weeks. The results showed that the two storage temperatures (20 and 40oC) had not any significant effect on pH, acidity, brix and formalin number (p≥0.05). The amount of vitamin C and SO2 were less in the 40◦C stored samples compare with the 20oC stored samples. The results of sensory evaluation indicate that the PET containers packed samples are acceptable in both storage temperatures (20 and 40oC) during the ten weeks of storage.

In this work the effect of roasting temperature and storage on the moisture content, texture and sensory attributes of pistachio nuts were investigated. Pistachio nuts were salted and then roasted using conventional method at 90, 120, and 150oC for 30 min. The changes occurred in the moisture content, textural properties (hardness and fracture force), and sensory attributes (firmness and total acceptance) of salted roasted pistachio nuts were determined during 3 months of storage. The textural properties were correlated with sensory attributes. Multiple linear regression was used to predict the effects of roasting temperature and storage time on textural properties. Hardness and fracture force as well as firmness increased across the storage time for all roasted pistachio nuts. Furthermore, during the storage, the moisture content of roasted pistachio nuts increased. By increasing the roasting temperature, moisture content, hardness and fracture force were significantly decreased. In addition, using high temperature of roasting led to less firmness. Higher total acceptance obtained for samples roasted at temperature of 120oC. The results indicated that the correlation between instrumental and sensory properties was significant.

Phenolic compounds, especially those of plants origin, are an essential part of the human diet, and are of considerable interest due to their antioxidant properties. The total phenolics content (TPC) and antioxidant and antimicrobial activities of pistachio green hull methanolic extracts of five different cultivars (Fandoghi, Kaleghochi, Ahmadaghai, Forotani and Seyed ali aghai) were studied. TPC ranged from 15.3 mg/g of GAE (cv. Kaleghochi) to 31.1 mg/g of GAE (cv. Ahmadaghai). The antioxidant capacity of extracts was assessed through DPPH and ABTS methods. A concentration-dependent antioxidative capacity was verified in both methods for all the cultivars. Antioxidant activity of Ahmadaghai cultivar in both methods was more than the other cultivars. The antimicrobial capacity was screened against Gram positive and Gram negative bacteria, and fungi. All the extracts inhibited the growth of Gram positive bacteria ofBacillus cereus and Staphylococcus aureus. Bacillus cereus was more susceptible thanStaphylococcus aureus for all the extracts. The results obtained in this study showed that pistachio green hull can be used as a cheap and easily accessible source of natural bioactive compounds.