IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2011 | Volume:7 | Issue:4|Papers Count:15

A large part of produced bread in Iran is wasted every day as a result of low quality and quick staling which causes economical damage to the country. In order to reduce bread spoilage, production of part-baked bread is one of the newest techniques. With the aim of reducing bread waste and improving the quality of bread, in this study part-baked pan bread was produced. In order to produce part-baked bread, baking of the dough at 240 oC was interrupted before formation of crust color (took 15 min) and after cooling and packaging of the samples they were stored at ambient temperature (25 oC) for 0, 24, 48, 72 and 96 hr. At each of the storage time, the part-baked bread was full-baked at 210 oC for 7 min until the crust color was formed. After cooling of the samples, the effect of storage time at ambient temperature on the properties of the resultant bread was compared to those of the control (which had been produced using the common method of baking and stored at similar condition) The results showed that the quality of the control in terms of volume, crust color and general acceptability reduced during the storage time. However, after full-baking of the part-baked bread the quality parameters did not change and it had similar properties to those of fresh bread. The sensory analysis of the samples revealed that with increasing the storage time, general acceptability of the part-baked bread was higher than that of the control.

In this research, the effects of different levels of White cheese (0-30%) and tri-sodium citrate (0-2%) on chemical and physical properties of Pizza processed cheese was investigated. Adding White cheese resulted in significant decrease (p£0.05) in pH, protein and significant increase in fat and salt content.Adding tri-sodium citrate induced the increase in pH and fat and decrease in moisture. The effect of mixture components on melting degree was significant (p£0.05). Free oil was affected by tri-sodium citrate ratio in the mixture. The oiling off was decreased by increasing melting salt, Length of stretch was decreased by increasing White cheese ratio in blend. Comparison of stretch length indicated a meaningful (p£0.001) correlation between "Fork test" and "Ring & Ball" method with Pearson coefficient of 0.906. The necessity of using tri-sodium citrate as melting salt for producing a homogenous cheese mass with the ability of exhibiting smooth slices without any fracture was approved in this study. Statistical analysis using mixture design showed that the optimum formula of Pizza Processed cheese was acheived by blending 90% base, 8.6% White cheese and 1.4% tri-sodium citrate. In addition to above, two new methods for measuring physical properties of Pizza cheese were also developed.

Non-destructive methods yield a great deal of importance in agriculture since the tested product can return to the market process, together with simplicity compared to destructive ones. Therefore, the major challenge in industrial on/in line quality evaluation is to eliminate damages in fruits and vegetables. Every visible or invisible damage can be followed by problems in storage, processing and diseases. During recent years, machine vision, optical techniques such as Raman, NIR, NMR spectroscopies, acoustics and ultrasonic techniques are the main methods which have gained worldwide attention. In order to sort and grade fruits, several methods are implemented which are mostly slow, time consuming, and destructive.Yet, a rapid, non-destructive and precise measurement of qualitative factors including pH, SSC and color in tomato fruit yields a great deal of importance. For such a purpose, Raman spectroscopy is implemented to measure qualitative parameters in tomato non-destructively. Sugar components in tomato were investigated with HPLC test and spectroscopy was conducted on pure sugars. Results showed that Raman spectra highlight the major bands related to the fruit components. Lycopene and Carotene as the major cartenoeids in tomato fruit were detected explicitly through the spectra, in the way that all the three characteristic regions indexing such pigments (C-C and C=C stretching vibrations) are peaked as strong bands. Also carbohydrates could be shown by a medium band assigned to C-H vibration together with strong bands in 2300 cm-1 – 3000 cm-1 range. Thus it can be concluded that the technique is capable enough to be used in recognizing non-destructively both the external factors (e.g. color) and internal parameters (e.g. SSC) in tomato fruit.

Adding food preservatives is one of the methods for increasing shelf-life and decreasing total bacterial count. Using experimental model as liquid substance and solid substrate is necessary for survey of antibacterial and preservative effect of essential oils. In This study, effect of different concentrations of Cinnamomum zeylanicum Blume. essential oil (0.00, 0.005, 0.015& 0.03%), temperatures (8oC & 25oC) and storage time (up to 21 days) was evaluated in a food model system (Hamburger).The results showed that effect of different concentrations of essential oil on growth rate ofE. coli O157: H7 was statistically significant (p<0.01).Thus the effect of storage time on growth rate was statistically significant (p<0.01). In addition, decreasing the storage temperature (from 25oC to 8oC) affected on decrease of the growth rate of the microorganism (p<0.01). Therefore The 0.03 % of cinnamon concentration in 8oC has increasing effect in shelf-life in hamburger.Therefore using this essential oil as natural preservatives in low temperature in meat products is suggested.

In this study, the drying behavior and the effects of different drying conditions on the trend of moisture loss and effective diffusion coefficient in sweet and sour pomegranate were determined. The best drying model, energy consumption and activation energy values were also determined for the two varieties using microwave drying. Results of regression analysis of mathematical models points to the page model as the one best described the data. Effective diffusion coefficient of pomegranate arils was found to be 3.43×10−10 to 32.05×10−10 m2/s. Activation energy was determined to be 17.22 and 23.83 kJ for sweet and sour pomegranates respectively. In addition, consumed energy consumption drying of for sweet and sour pomegranate arils was 0.167 to 0.383 kW/kg respectively.

In this study two film-forming formulations were prepared. First one was prepared by slowly adding 5gr of sodium alginate & 45gr of dextrose monohydrate in 270ml of distilled water which constantly stirred. Second formulation was as the firs one, but we substituted dextrose monohydrate by maltodextrine and added 20gr glycerol in 210ml distilled water.50cc film solutions were extended on the 30*40cm polexy glass plates which covered by polyethylene selofan. Films dried after 45h in 23±2oC & RH50±5%.The dried film layers were immersed for 30" in second solution that was prepared by slowly adding 2.74gr of calcium choloride & 0.9gr of carboxy methylcellulose in 49ml of distilled water which constantly stirred. Film thickness was measured using a digital micrometer at a 0.001mm accuracy. Mechanical properties including tensile strength (TS) and elongation at break (E) were evaluated by a Instron Machin (Zwick, Model Z 2.5).Results had no statistical significant differences between 2 film formulations. Physical properties including WVP (Water Vapor Permeability) & OTR (Oxygen Transformation Rate) were measured. WVP results had no statistical significant differences between 2 film formulations but OTR in second formulation had a significant decrease. Finally, by all aspects like decrease moisture loss, lipid & myoglobin oxidation, volatile compounds loss and volatile compounds absorb during storage, we recognize second film formulation as a suitable one.

Drying is one of the best ways to decrease transport cost and increase storage life of fruits and agriculture crops. Persimmon fruit (Diospyrus kaki L.) slices with initial moisture content of 75.21% wb. Were dried to various final moisture levels and their qualitative properties were studied. These properties included sweetness, color, smoothness, chewiness, astringency and smell while the final moisture content levels were 5, 10, and 15% wb. After drying, organoleptic test was performed by 26 persons in the age range of 25-30 years old. After plotting the moisture-time drying kinetic curve which was a six degree polynomial, analysis of the test results showed that fruit slices dried to 5% received the highest scores for sweetness and the lowest for astringency, while those dried to 10% were picked as being most chewy and smooth. The 10 % moisture level with an overall score of 85.13 was selected as the best moisture content for dried persimmon slices.

The red color of pomegranate juice is primarily associated with anthocyanin pigment. Studies showed that anthocyanin has low stability during processing and storage time and color of pomegranate juice decreased significantly over time.Copigmentation between Anthocyanins and copigments such as phenolic acids and flavonoids, is the main color stabilizing mechanism and is regarded today as one of the significant factors of structure stabilization, colorant of Anthocyanin under in vivo conditions. Anthocyanin copigmentation gives brighter, stronger and more stable colors than those expressed by anthocyanin alone.The objective of this study was to compare the effects of Ferulic acid and Tannic acid in concentrations of 230, 460, and 920 mg/lit on the color stability and sensory acceptance of pomegranate juice kept in 5°C during 60 days of storage. In order to investigate the color stability, change in absorption maximum wavelength (Δlmax) and change in maximum absorbance (ΔAmax), Total color difference (ΔE), and total anthocyanin content, all treatments and control were evaluated by spectrophotometer, hunterlab colorimeter, and HPLC respectively in day 1, 10, 20, 30, and 60 in 5°C. Furthermore, the sensory acceptance level of samples was evaluated by trained panelists in first and 60th day in 5oC.The results showed that Total anthocyanin content, Redness (a*), maximum absorbance (Amax), and absorption maximum wavelength (lmax) in treated samples with 230, 460, and 920 mg/lit of Ferulic acid and in treatment with 920 mg/lit Tannic acid increased significantly (P<0.05) during storage period of 60 days compare with the control. Increase in Ferulic acid and Tannic acid concentration decreased the sensory acceptance significantly (P<0.01), Also in treatments with 230, 460, 920 mg/lit of Ferulic acid, the sensory acceptance was higher compared to similar concentrations.

The seeds of two date palm (phoenix dactylifera) cultivars, kabkab and Mordasang were analysed for their chemical composition and fatty acid profiles. The average constituents were obtained as protein 5.65%, fat 9.3%, ash.1.25%, total carbohydrate 83/8%, acid detergent fibre 48.5%, neutral detergent fiber 67% (on a dry weight basis). Mineral analysis showed higher concentration of k, (300mg/ 100gr dry weight) followed by P, Mg, Ca and Na. Among the microelements, Fe was higher concentration (7.5 mg/ 100 gr dry weight) followed by Mn, Zn and Cu. Gas-liquid chromatography revealed that the major unsaturated fatty acid was oleic acid (45.36%), while the main saturated fatty acid was lauric acid (19.98%). Myristic, palmitic, linoleic and stearic acids were also found average value being 11.12, 10.81, 8.66 and 3.39% respectively. The Result showed that date seed contained large quantities of fibre and most likely, resistant starch that may have potential health benefit. Date seed oil could be used in cosmetic, pharmaceutical and food products. Further research is needed to characterization, antimicrobial, antioxidant and other health promoting activities constituents in date seed.

The storage conditions of olive fruits after harvesting are important factors which have major effects on not only oil quantyity but also quality of oil. Climatic conditions are reasons for different methods of storage in each area. In this study, two cultivars of Gorgan region consist of Mission and Roghani are selected. Then, ripend olives were stored in plastic boxes with three different storage conditions (referigeration with 5°C and 8°C temperatures and ambient condition) and quality of oils are determined after 50 days. According to the obtained results, referigration in 5oC was the most suitable treatment. The oil quality of fruits stored in 5oC and 8°C were unchanged until 30 and 15 days respectively, while in ambient condition was less than 5 days. The oil content (as %dry wt) of olives strored in 5oC and 8oC were unchanged for 50 and 30 days respectively while in ambient condition was 15 days.

Physical properties of agricultural crops are important to design of milling, planting and harvesting machines and also for reducing losses and safe quality of crops along to post harvest stage. In this study, some physical properties of three common varieties paddy rice (i. e. Khazar, Hashemy and Hybrid) including of main dimensions, geometric diameter, mathematical diameter, sphericity, area volume. weight of thousand grains, bulk density, true density, true volume, true density, angle of repose and external friction angle were determined at four level of moisture content (10, 14, 18, 22% w. b.). Then effect of grain moisture content was investigated on them. Results showed that with increasing of moisture content of grain, main dimensions, geometric diameter, mathematical diameter, sphericity, area, volume, weight of thousand grains, bulk density and angle of repose were increased significantly (p<1%) While true volume was decreased. Also external friction angle was decreased respect to increasing moisture content of grain. At all grain moisture content levels and contact surfaces, the most external friction angle allocated to black sheet. The lowest external friction angle at Khazar and Hybrid allocated to mild contact surface. Also the lowest of this factor at Hashemy variety, obtained for galvanized contact sheet.

Being biodegradable, edible and efficient have caused edible films to be widely investigated and used as a good replacement for synthetic materials in packaging of food products. Coating confectionaries, fresh fruits and vegetables, some meat products, some dairy products, chocolate, snacks, breakfast cereals, fish and poultries, frozen products, dried and freeze dried products are from those food materials that are regularly coated by edible films. The efficiency of edible films depends on their quality parameters, the latter are principally affected by the type of film-producing materials as well as its method of preparation. This article reviews quality parameters of edible films, their test methods and principal production techniques.