جستجوی مقالات مرتبط با کلیدواژه « خواص کیفی » در نشریات گروه « مکانیزاسیون کشاورزی »

Nowadays due to the problems caused by the consumption of high fat products, the use of fat substitutes in foods such as yogurt has increased. In this study, the effect of inulin in 0, 1.5 and 3% levels and Quince seed gum in 0, 0.25 and 0.5% levels was investigated on the qualitative properties of low fat yogurt at 4°C during 14 days of storage. The results showed that addition of inulin significantly decreased syneresis (p<0.05), at higher levels of Quince seed gum (at 0.5% level), increasing the amount of syneresis was prevented during storage. Water holding capacity and viscosity increased significantly with increasing inulin and Quince seed gum (p<0.01), while maximum water holding capacity was 64% and the highest viscosity was 5500 cpoise in a sample containing 3% inulin and 0.5%  Quince seed gum powder.Hardness was increased significantly from 14N to 28N by adding inulin (p<0.01), at higher levels of Quince seed gum increasing of hardness was prevented over time. The highest color change was in the sample contained the highest amount of inulin and the lowest amount of Quince seed gum on the first day of storage. Optimum content of inulin and Quince seed gum was determined 2.5% and 0.4% respectively, in low fat yogurt. In overall acceptance, the optimized low-fat yogurt obtained a higher score than control yogurt (3% fat). The results of this study showed that it is possible to use inulin and Quince seed gum at optimal levels in the preparation of low-fat yogurt.

Introduction Material conveying in the industries is carried out in the different ways. Pneumatic conveyors are widely used in industries. The special benefits of these conveyors have led them in the short term to widely used in different industries. Transfer of materials without dust dispersion, the flexibility to choose the vertical, horizontal or diagonal tubing, low maintenance costs and manpower, adequate safety and reliability during conveying at the high amounts of materials, easy and automatic control are the some benefits of the pneumatic conveying systems Materials and Methods The mean aperture and the coefficient of variation of sugar particles were determined by sugar crystal size distribution test. It is done based on the cumulative percentages of remaining sugar content on the sieve. The mean aperture (MA) and the coefficient of variation (CV) are obtained from the chart. 7 sieves are used for testing. The percentage of remaining sugar on each sieve was calculated. The amounts of D50% and D16% were calculated following the plotting the size of the sieves versus the cumulative percentage of the remaining sugar on each sieve graph. The conveying pressure drop includes the total pressure drop required for air alone (ΔPL), the material acceleration pressure drop (ΔPA), the friction and material collision pressure drop (ΔP*z), the pressure drop due to lifting and suspension of materials (ΔPG), and bends' pressure drop (ΔPB) in Pascal. Following determination of required power (293.42 w) to run the system, with a confidence coefficient of 3, a blower with a rated power of 700 w was selected. The amount of pressure produced by the selected centrifuge fan was measured by a pitot tube embedded in the blower outlet. The outlet air velocity was measured by a pressure gauge according to the principles of the pitot tube. Results and Discussion The treatments and their levels consisted of pipe lengths at three levels (2, 4 and 6 m), inlet air velocity at five levels (13, 16, 19, 22 and 25 m/s) and mass flow rate of sugar at three levels (160, 180 and 200 kg/h). The statistical analysis was done as a factorial based on a completely randomized design. Analysis of variance and comparison of means were done using Duncan's test at 5% level in each case. Then, the effects of the factors on pressure drop, mean aperture and coefficient of variation of particle size were investigated. Analysis of variance of data shows that the effect of conveying length, mass flow rate of sugar particles and inlet air velocity as well as their interactions and the interaction of three factors on air and sugar pressure drop is significant at 1%. In all conveying lengths, an increase in air velocity and consequently increased sugar particles' velocity at each mass flow rate causes an increase in frictional pressure drop due to the particle's collision with the wall as well as air collision with the pipe wall at each length and the sugar mass flow rate level. Also, total pressure drop has increased with mass flow rate at any velocity. Analysis of variance of data shows that the effect of conveying length, mass flow rate of sugar particles, inlet air velocity, and the interaction of mass flow rate and air velocity on qualitative properties of sugar is significant at 1% level. Considering the significance of the effects of the main factors and interactions between air velocity and mass flow rate, the effect of every main factors and the interaction of air velocity and mass flow rate on qualitative characteristics of the sample was investigated. With increasing velocity in each mass flow rate, the mean aperture and coefficient of variation significantly decreased and increased, respectively. Also, with increasing mass flow at any velocity, the mean aperture decreased and the coefficient of variation increased. By increasing the mass flow rate, the effect of the air velocity on the mean aperture reduction and increase in coefficient of variation increases, and at higher velocities, the mass flow rate effect is more pronounced. Conclusion The length of the pipe with a reduction by 15% in mean aperture and an increase of 137.5% in coefficient of variations than the initial sugar sample had the least effect on these two qualitative properties of sugar. With an increase in air velocity from 13 to 25 m/s, MA and CV values decreased by 20.27 and increased by 17.22, respectively. The velocity of 13 m/s with a reduction of 5.19% in the mean aperture and an increase of 6.69% in coefficient of variation compared to the initial sugar sample had the least effect on the size and the particle coefficient of variation size of the particles among all 5 velocity treatments. With the increase in particle mass flow rate of 160 to 200 kg/h, MA and CV values decrease by 16.49% and increase by 14.75%, respectively. The particle density increases with the mass flow rate.

Grape fruit set its fruits and shortly after planting and due to high nutritious value and excellent food quality has been welcomed by many people in the world, but considering its soft tissue and high softening velocity and sensitivity to fungi attack it is known as an extensively vulnerable fruit. One of the most important ways to maintain fruit quality, decrease vulnerably and assist more appropriate storage, is the use of coating method and proper packing of agricultural products and combining these procedures to decrease damages in storage. Edible coatings provide a replacement and fortification of the natural layers at the product surface to prevent moisture losses, gas aromas, and solute movements out of the food, while selectively allowing for controlled exchange of important gases, such as oxygen, carbon dioxide, and ethylene, which are involved in fruit respiration. Chitosan is the most common polysaccharide-based coatings. Chitosan films have been successfully applied as edible material in films and coatings for the quality preservation of different fruit. In this study, the effects of the application of chitosan edible coatings and storage time on some physical, chemical, mechanical and rheological properties of grape were investigated during storage. Grape fruits were screened for physical damages, fungal infections, and size homogeneity after harvesting from the farm. Then fruits were divided into without coating and fruits with coating. Fruits being coated, prepared in chitosan emulsion and submerged for two minutes and kept at 20°C for one hour for drying the surface coating via airflow. In order to calculate the weight loss, three containers of each grape fruits (treatment and control) collected and after weighing and averaging weight loss were compared to initial weight during storage expressed as a percent. Color intensities were determined using colorimeter samples. In order to determine soluble solids from each sample, refract meter was used and pH amount of each sample was determined. Mechanical traits and fruit stiffness were measured through penetration test using materials test machine Zowick/ Roell having 500 N loadcell in line with the small diameter with concave probe (5 mm diameter), the penetration depth of 2 mm and loading rate of 10 mm s-1. Mechanical traits including stiffness and elasticity module calculated from the force-deformation curve. Viscoelastic materials have the properties of both viscous and elastic materials and can be modeled by combining elements that represent these characteristics. A viscoelastic model, called the Maxwell model which can predict behavior was evaluated. In this current study, the application of chitosan coating significantly reduced the fresh grape decay. Fruit decay of grape increased with storage time, but the coating reduced the rate of decay with the length of storage. According to the results, the application of these coatings has a positive impact on yield stress and energy of rupture product texture during the storage. Results of variance analysis showed that temperature, coating and storage time has a significant effect (1% level) on some of the engineering properties of the grape. Storage time has a significant effect on elasticity, while the coating does not have a significant effect on this parameter. Finally, results showed that the application of chitosan coating has an effect on relaxation time and stress. So during storage of coated samples these parameters decreased compared to uncoated. Edible films and coatings may reduce the moisture transfer, the rate of oxidation and respiration which are considered important to prolong the shelf-life of these products. This investigation showed that the chitosan coatings are effective for grape shelf life extension and retarded the senescence process compared with control. The coat has been as a physical barrier for the gas exchange between the fruit and the environment. It was demonstrated that the coating reduced the loss of firmness and delayed the softening of fruit and texture change.

This study carried out a factorial experiment with two factors and two replicates to determine factors that improve the quality and increase the shelf life of apricots. The first factor was four levels of treatment of treatment including: the control, coated with zein, immersed in a 1% solution of calcium chloride, and coated with zein containing 1% calcium chloride. The second factor was time of cold storage at 1, 15, 30, 45 and 60 d. Statistical analysis of the results showed that, at the end of storage, the two treatments coated with zein showed higher rates of firmness, vitamin C and L* than in the control (p < 0.05). Weight loss and total soluble solids were lower. The ratings for appearance and color of the coated samples were significantly higher for the uncoated fruit (p < 0.05). The results indicate that zein coating had no adverse effect on the organoleptic properties of the apricot and improved its quality characteristics. There was no significant difference between the mixture containing zein and CaCl2 and zein alone on the characteristics of the apricot. Immersion in 1% calcium chloride solution increased firmness and vitamin C content and decreased the weight loss of apricots.

The table grape (Vitis viniferal) is a non-climacteric fruit with a relatively low rate of physiological activity and is subject to serious water loss after harvest that can result in dry brown stems, shattered grapes, and wilted and shriveled grapes. Grapes can be stored for a short time, but increasing living standards have increased the demand for fresh grapes in Iran. The possible introduction of new grape varieties of good quality with long shelf lives has been a focus of attention. The present study compared the performance of 8 Torkaman cultivars and 3 local cultivars (Koladary, Kajangor, Rezghy). The result showed that the Torkaman cultivars had good quality and quantity characteristics and, most importantly, longer shelf lives and are recommended as potential varieties for cultivation.