Zahra Karimivaloujaei; Mohammad Hossein Abaspour fard; Mohammad Hosein Aghkhani; Saeid Tarighi
Abstract
Introduction: Packaging is one of the effective ways to increase the storage life and quality of the food products. Nowadays, most of the materials used in packaging are fossil origin and usually non-degradable and hardly dissoluble. Also biodegradable films, due to their fragility and poor resistant ...
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Introduction: Packaging is one of the effective ways to increase the storage life and quality of the food products. Nowadays, most of the materials used in packaging are fossil origin and usually non-degradable and hardly dissoluble. Also biodegradable films, due to their fragility and poor resistant to gas exchange are in limited use. It is possible that by employing nanotechnology, some particles on nano scale may be added to these polymer composites to improve the mechanical properties and permeability of the biodegradable packing films. Silver nanoparticles and zinc oxide have been incorporated in polymers individually by researchers. The objective of this study is to compare the effect of incorporating the mixture of silver and zinc oxide nanoparticles with the case of adding them separately into poly vinyl alcohol matrix, on some relevant mechanical and physical properties of the outcome Nono-composite films. Materials and methods: To make polymer films polyvinyl alcohol, solvent (deionized water) and glycerol (as softener) were used. Then, zinc oxide and silver nanoparticles at 3% by weight, were added to the polymer solution in two different ways, separately and in combination. To specify the pattern of nano-particles size distribution, transmission electron microscope (TEM) test was performed. To determine the characteristics of the films’ surface scanning electron microscope (SEM) was employed. To investigate the bondings between the components of nono-composite films, FTIR was employed.For identification of matrix structure and formation of nano-composite, the XRD was performed. To measure the infiltration of water vapor, the approved E96 ASTM method was used. Also, for measuring the color and transparency of films, the HunterLab test and for mechanical properties of the films, Instron Universal Testing Machine (H5 KS, England) were used (considering the ASTM standard for tensile tests - D88201). For statistical analysis and comparison of means, variance analysis and Dunkan test were performed, using SPSS software. Results & discussion: SEM, XRD and FTIR tests showed that nanoparticles were distributed uniformly within the polymer matrix, and react well with the polymer chains. Besides, the effect of adding silver and zinc oxide nanoparticles on the relevant properties of the films was significant. By individual adding of these nanoparticles on polyvinyl alcohol matrix, the tensile strength and the elongation of films increased. On the other hand, their transparency and water vapor permeability decreased. The results also showed that the combined incorporation of silver and zinc oxide nanoparticles into the packing films can significantly affect their mechanical properties and permeability. Hence, due to the high prices of silver nanoparticles than zinc oxide nanoparticle, the combined incorporation of these two nano-particles is recommended, while maintaining the properties of the nano-composite films in a reasonable level. It can be implied that the combined use of silver and zinc oxide nanoparticles in the polymer provides a more affordable Nano-film with good enough quality. It may also reduce their mutual side effects.
Maryam Naghipouzade Mahani; Mohammad Hosein Aghkhani; Khalil Behzad; Abbas Rohani
Abstract
Introduction: Conventional technology of sugar production from sugar beet roots consists of the next subsequent steps: sugar beet slicing, thermal denaturation of the sliced beet roots followed by diffusion in hot water at 70–75 _C, purification of extracted juice by lime, concentration of purified ...
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Introduction: Conventional technology of sugar production from sugar beet roots consists of the next subsequent steps: sugar beet slicing, thermal denaturation of the sliced beet roots followed by diffusion in hot water at 70–75 _C, purification of extracted juice by lime, concentration of purified juice and crystallization. The diffusion process is one of the most important steps that effect on product yield. The quality of cossettes is too important that increase extraction yield. Therefore the main function of the beet-slicing operation is to improve the diffusion operation. The most important factors in producing quality cossettes are the type of knives. Most knives have a V shape that cause increase of the surface area of the beets. At slicing operation, Amount of the sucrose of beet extract directly. Considering the blade edge causes the rupture of beet cell so it effects on quality of juice and yield of extraction. Also the different blades edge causes different surface areas that effect on osmotic operation. In this work, the effect of two kinds of blades (serrate and flat edge) is studied on extraction process and the juice quality. Material and method: Fresh sugar beets (Beta vulgaris) were obtained from Ferdowsi university farm and storage at 5C°. For each test run, 300gr of cossette 4mm thickness and 8cm in length were cut by cutting device with ability of blade change. The sucrose content of cossetttes was measured in ICUMSA method. These tests were organized as follows 4 steps. The first step was washing. Considering amount of sucrose of sugar beet extract directly at slicing operation, the decrease of sucrose content of cossettes and the sucrose of washing juice should be measured. For this stage, 120gr of cossettes were washed with 320gr of distilled water. After washing the cossettes, the sucrose content of cossettes was measured again and the decrease of suocrose content of cossettes was calculated and sucrose of washing juice was measured. For the thermal-pretreatment step, 130gr of sugar beet cossettes were treated with 260gr of distilled water 70C° at 7min and the sucrose of thermal-pretreatment juice was measured. In the diffusion step, 130gr of these cossettes were immersed in 260gr of distilled water 73C°. The solute concentration (Brix, g solubles 100 g_1 juice) was measured by digital refractometre (PR-101, Atago, 50 Kyo, Japan) every 5 to 10 min up to equilibrium conditions. The final step was pulp pressing. The pulps were compressed by laboratory press (2 bar) at 15min. following by the pressed pulp was weight then the sucrose content of them was measured. In the following, purity and nonsucrose of juice were determined for washing, thermal-pretreatment and diffusion steps. These parameters were measure in ICUMSA unit which is based on polarimeter method. Also extraction yield of diffusion, mass of extraction sucrose and extraction sucrose at diffusion, pressed pulp yield, extraction degree and energy were calculated. The data were analyzed in 2-sample t-test at minitab17 and the graphs were drew in excel. Results and discussion The results showed that the edge of the baled had significant effect on the juice purity (washing and thermal-pretreatment steps), non-sucrose content and sucrose of juice, extracted sucrose at cutting operation, extracted sucrose at diffusion, degree of extraction, yield of pulp, time and energy (P<0.05). The most juice purity was obtained from flat blade with 78.33%, 84.86% and 85.52% at washing, pretreatment and diffusion steps respectively. Also the least of non-sucrose content was obtained from this blade with 0.1%, 0.55% and 0.51% at washing, pretreatment and diffusion steps respectively. The serrate blade increase the tearing (rupturing) of the beet cells at slicing operation. Torn cells allow more impurities (nonsugars) to be diffused into the surrounding juice, causing an increase in nonsugars and, consequently, a reduction in juice purity. For the serrated blade, The most extracted sucrose at cutting operation and diffusion step, mass of sucrose of diffusion juice and degree of extraction were obtained 14.5%, 94.4%, 7.22 gr and 0.19 respectively that compare to another blade is more. The edge of serrate blade increases the surface aria of cossettes compare to use of flat blade. The surface area is one of the most important parameter to improve osmotic operation. The more contact area between the beet cells and the water in the diffuser cause the more movement of sugar from the cells to the diffusion juice. Therefore the use of the serrate blade improves the osmotic operation and enhances the extracted sucrose. The least of pulp yield, extraction time and energy were obtained 27.97%, 40 min and 1.7 Kw/h respectively for this blade. The increase of sucrose extraction reduces the pulp yield. As regards osmotic operation improve whit the increase of surface area cossettes, therefor the sucrose extract at lees time and the total energy decrease. Regarding to the results, both of blades improve some of the extraction parameters.
Omid Doosti Irani; Mahmood Reza Golzarian; Mohammad Hosein Aghkhani; Hassan Sadrnia
Abstract
Introduction: High percentage of orchard products, such as apples, is wasted due to mechanical damages that cause fruit quality loss. Damages due to static or dynamic pressure or impact are among very common mechanical damages that begin to bruise fruits. Post-harvest bruise damage is a major cause for ...
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Introduction: High percentage of orchard products, such as apples, is wasted due to mechanical damages that cause fruit quality loss. Damages due to static or dynamic pressure or impact are among very common mechanical damages that begin to bruise fruits. Post-harvest bruise damage is a major cause for the loss in fruit quality. Bruising means damaging fruit tissue and consequently physical changes resulting in fruit color and chemical changes resulting in fruit tastes (Xing and Baerdemaeker, 2005). Most research projects conducted on apple bruising have focused on the use of image processing techniques for detecting apple surface defects from images. In addition to images taken in visible spectral range, thermal images have been also used for this purpose. Having reviewed the literature and research gaps in this area, we set two hypotheses for this research project: first, the color characteristics of bruised tissue would change over time and these changes would be detectable on the images taken from the affected fruits. Second, there would be a significant difference between the surface temperature of bruised and sound tissues. The distribution of temperature on an impact-caused bruised tissue would change over time in a different manner compared with that for a sound tissue. The color and temperature variation is particularly related to the intensity of impact caused bruising and where the impact is applied on apples. Therefore, the first objective of this paper was to study the color changes on the tissues bruised from the impacts with three energy levels applied on three locations on apple surface with different curvatures: top, middle and bottom. The second objective was to investigate the temperature variation on the surface of the bruised apples and to examine the capability of visible and thermal imaging in detecting bruised tissues at different times after bruising occurred. Materials and Methods: For these purposes, the experiments were conducted on sixty apples of Golden Delicious variety. From sixty samples, five apples were used for determining apples ripeness index and five apples were used for determining emissivity factor which was used later in calibrating fruit surface temperatures on thermal images. Bruising was simulated by an impact pendulum. Bruising was conducted at three impact energy levels of 200, 700, 1200 mJ and applied at three locations on apple surfaces: top, middle and bottom. The samples affected by bruising-simulated impacting device were kept in a refrigerator at 5°C and were individually imaged in a regular basis until 624 hours after impact application. At the time of imaging, both visible and thermal images were taken from each sample. Samples visible images were taken in an imaging box with uniform controlled lighting. Thermal images were taken while samples were placed in a box that was thermally insulated from surrounding temperature. A newly defined color factor, named excessive yellow index (EYI) was extracted from visible color images. The EYI index formula is EYI = 1.5r+b-1.5g where r, g and b are red, green and blue color values, respectively. Factorial experiment was conducted for the assessment of EYI. This experimental design looked at the effects of three factors of time, impact energy and impact landing location on EYI. Result and discussion: The results showed that time passed after impact and the location of impact application had significant effect on EYI at 95% confidence interval. The apples EYI index decreased until 15 days after impact application and started increasing thereafter. Surface temperatures were extracted from the thermal images of samples. The results of processing thermal images showed that the bruised tissue was cooler than the sound tissue until 48 hours after impact application. Both tissues had the same temperature from 56 to 96 hours and then the bruised tissue started becoming warmer by 0.5-1°C after 96 hours. The color variation of bruised region was not detectable from visible images within the first 48 hours after impact application, while these regions were cooler than undamaged region and detectable from thermal images. The bruised regions started to turn dark brown at 48 hours after impact application. However, there was no temperature difference between bruised and sound regions on fruit surface for the period of 56-96 hours. The bruised brown regions paled after 360 hours. As a result, this reduced the capability of visible images for discriminating bruised apples from sound ones. Conclusion: The results of this research show that both the visible spectrum and thermal imaging systems can record the changes in color and temperature at different times after the bruising in apples. Therefore, these methods can be used as an efficient methods for grading apples.
Reza Abolghasemi; Bagher Emadi; Mohammad Hosein Aghkhani; Shahram Beiraghi-Toosi
Abstract
The tissue of fruit varies at different stages of growth and storage and by determining its characteristics; the stage of fruit maturity can be found. Depending on the type of tissue, the ultrasonic waves will attenuate and its speed will change too while crossing the fruit tissue. Thus, by calculating ...
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The tissue of fruit varies at different stages of growth and storage and by determining its characteristics; the stage of fruit maturity can be found. Depending on the type of tissue, the ultrasonic waves will attenuate and its speed will change too while crossing the fruit tissue. Thus, by calculating the attenuation coefficient value and its speed in no destructive way, the characteristics of fruit tissue and the rate of its maturity will be determined. In this study, peach fruits -the Tabrizi variety- were classified in ripen, semi-ripen, large and small groups and the validity of ripen and semi-ripen groups were confirmed by taste panel. Then, in addition to measuring the attenuation coefficient and velocity of ultrasonic wave parameters, the physic-chemical parameters of fruit, including dimensions, mass, density, hardness, reducing sugar, acidity, pH, dry weight and soluble solids contents, which are the maturity indices of peach, were measured and compared with ultrasonic parameters. Results showed that fruit size and degree of maturity significantly affect on the wave attenuation and wave velocity, respectively. The correlation coefficients between attenuation coefficient and hardness (without skin) in ripen and semi ripen groups were higher than 0.8 and also the correlation coefficients of attenuation coefficient in relation with the hardness (by skin) in ripen and semi ripen groups were higher than 0.7. Also, the correlations for both attenuation coefficient and wave velocity in relation with the pH were higher than 0.8 as well as correlation between wave velocity and acidity.
Key words: Chemical, mechanical and physical characteristics, Ripening, Ultrasound, Peach
