Food Technology
Rahman Yousefi; Mohammadreza Pourghayoumi; Seyyed Samih Marashi; Ali Ghasemi
Abstract
IntroductionDate palm (Phoenix dactylifera) is one of the most important horticultural products in arid and semi-arid regions of Iran. One of the factors affecting the quality and nutritional elements of date fruit- as an important and strategic fruit in the country, with high nutritional and health ...
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IntroductionDate palm (Phoenix dactylifera) is one of the most important horticultural products in arid and semi-arid regions of Iran. One of the factors affecting the quality and nutritional elements of date fruit- as an important and strategic fruit in the country, with high nutritional and health value- is the proper use of different nutritional elements during its growth and fruiting period. There are many reports of the negative effects of salinity on dates, both in the vegetative and reproductive growth stages. The osmotic effects limiting the absorption of water and nutrients, the specific effect of chlorine and sodium ions, nutritional imbalance and preventing the physiological processes and metabolism of nutrients and the use of high energy in osmotic regulation are some of the negative effects of salinity stress. Salinity stress negatively affected date fruit quality. Silicon is one of the essential nutrients that plays an important role in the growth and development of plants. Silicon reduces the adverse effects of abiotic stresses such as drought and salinity by affecting on the leaf and stem growth, and other plant mechanisms. Therefore, the aim of this study was to investigate the effect of foliar application of silicon on some qualitative characteristics and nutrient elements content of date fruit grown under high salinity soil. Materials and Methods This research was conducted in a randomized complete block design with 7 treatments and 3 replicates in two consecutive years. Silicon foliar spray treatments consisted of: control or no application of foliar spraying (T1), foliar spraying with a concentration of 0.1% in two stages (T2), foliar spraying with a concentration of 0.1% in three stages (T3), foliar spraying with a concentration of 0.2% in two stages (T4), foliar spraying with a concentration of 0.2% in three stages (T5), foliar spraying with a concentration of 0.3% in two stages (T6) and foliar spraying with a concentration of 0.3% in three stages (T7). The treatments were repeated in two consecutive years, and in each fruiting season, fruit quality characteristics including total soluble solids (TSS), acidity (TA), pH and total sugar content were measured. Total sugar was measured according to Iran's national standard method No. 2685 (ISIRI, 2007). The concentrations of potassium, calcium, iron and zinc were also measured at the end of the second year of the experiment. Fruit quality characteristics and concentration of fruit nutrients were measured and statistically analyzed. Results and DiscussionFoliar application of silicon fertilizer significantly increased the TSS of ‘Barhee’ date fruits while it decreased the pH of fruit juice. The lowest amount of total soluble solids was observed in T1 treatment at the rate of 63.69% and the highest amounts of fruit soluble solids were recorded in T5 and T6 treatments with values of 70.07% and 68.59% respectively. Fruit acidity and total sugar were not affected significantly by foliar application of silicon. The application of silicon significantly increased the contents of potassium, calcium, iron and zinc in date fruit, but it had no significant effect on the concentration of phosphorus in the fruit. The highest concentration of fruit potassium was observed in the T6 treatment (spraying with 0.3% silicon solution in two stages) at the amount of 1.54%. The lowest values of potassium concentration were observed in T3, T2 and T1 treatments with values of 0.89%, 1.01% and 1.06% respectively. Overall, Foliar application of silicon fertilizer can improve the quality characteristics and nutrient concentration of date fruit under salinity stress conditions. Among all the treatments, foliar application of silicon fertilizer with a concentration of 0.3% in two stages (three weeks before pollination and at the end of the Hababook stage) improved quality characteristics and the nutrient elements of ‘Barhee’ date fruit under high salinity soil.
Manoochehr Rashidi; Reza Amiri Chayjan; Ali Ghasemi
Abstract
Introduction: Tomato is one of the most valuable sources of minerals and vitamins supply in the human diet. Low shelf life of tomato and its short shelf life with inadequate processing facilities lead to heavy financial losses. Therefore, preserving and processing of tomato are of the commercial importance. ...
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Introduction: Tomato is one of the most valuable sources of minerals and vitamins supply in the human diet. Low shelf life of tomato and its short shelf life with inadequate processing facilities lead to heavy financial losses. Therefore, preserving and processing of tomato are of the commercial importance. Drying is one of the preferred methods for tomato preservation. Dried tomato products including half tomatoes, tomato slices and tomato powder, have many consumptions, compared with other tomato products. Among dried tomato products, tomato powder has a particular market. Powder production is an alternative method to extend the shelf life of foods. Usually the fruit powder is very dry, humidity absorber and has too much volume. Therefore, during storage, transportation and administration, it requires special care and heavy packaging which increase the cost. To overcome these problems, compression of the fruit powder in tablet form could be a proper solution. Tablet making of fruit powder has gained much popularity due to its ease of use, storage, transportation and product formulation. After the tablet making process, the pills contain high moisture contentwhich makes them un-suitable for transportation and storage. So, in order to prevent the tablets corruption and maintain their quality, tablet drying is one of the important steps after the tablet making process. The drying process is an important operation that affects the quality and final price of the product. Different drying methods play an important role in protecting foodstuffs. However, the effect of different drying methods on the quality of some foodstuffs is not clear. Materials and methods: In this research, after the preparation of fresh tomatoes, the primary moisture content of tomatoes was determined using hot air oven method. Then, using blanching method, the tomatoes were peeled and samples were cut using a sharp razor in thicknesses of 3 mm. Tomato slices were dried using a semi-industrial dryer in a hot air at 50 °C at an air speed of 1 m/s. Dried tomato slices were powdered using a grinder. In order to homogenize the particle size, the tomato powder was sieved by a 50 mesh (Cavity size 0.5 mm) sample. Suitable moisture content to create sufficient adhesion between the particles of tomato powder was selected at %23 d.b. Water and fructose were used as a bonding agent. The process of producing tomato spherical tablets was performed by a hydraulic press. Drying tests of wet compressed tablets were performed immediately after the end of the tabletting process using a hot air drying machine with microwave pre-treatment. In this study, the effect of drying variables,through using of microwave pre-treatment along with hot air, including air temperature in five levels (40, 50, 60, 70 and 80 °C), air velocity at five levels (0.5, 1, 1.5, 2, and 2.5 m/s) and the duration of microwave application at five levels (zero (without microwave), 4, 8, 12, and 16 s) on physical properties (shrinkage and unit density), mechanical (penetration resistance) and thermal (Effective moisture diffusivity and energy consuming drying) of compact pomegranate produced from tomato powder were studied. Statistical analysis of data and optimization of drying process were performed using response surface method and central composite design. Results and discussion: Results showed that effect of air temperature and duration of microwave pretreatment on all variables of compressed tomato tablets were significant in hot air dryers with microwave pre-treatment. Increasing temperature and time of microwave pre-treatment increased the effective moisture diffusivity and shrinkage of the final product. The temperature of the air inlet to the dryer had a negative effect on the resistance to penetration, the unit density and the specific energy consumption of the drying process. Drying under lower temperature conditions and less time for microwave pre-treatment resulted in an increase in the desirability of the drying process
