Mohammad Javad Golieh; Mohammad Goli
Abstract
Introduction: Recently, the prevalence of diseases related to diabetes, hypertension, and obesity, due to high and persistent consumption of sucrose is increasing rapidly. Concerns about the adverse effects of sugar consumptionon one hand, and manufacturers and consumers attention for natural sweeteners ...
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Introduction: Recently, the prevalence of diseases related to diabetes, hypertension, and obesity, due to high and persistent consumption of sucrose is increasing rapidly. Concerns about the adverse effects of sugar consumptionon one hand, and manufacturers and consumers attention for natural sweeteners to replace sugar, on the other hand, reveal that innovative approaches are needed to help develop a healthy diet which prevents such diseases. Stevia can be introduced as a good replacement for sucrose. Corchorus olitorius L. is a rich source of bioactive compounds such as protein, fiber, vitamins, minerals, sterols, tocopherols, and carotenoids, which has significant antioxidant, antibacterial, antifungal, antiviral, anti-inflammatory and anti-cancer properties. This study aimed to reduce the sugar level in Luz preparation and produced a high nutritive product by using Corchorus olitorius. Materials and methods: Materials used in Luz formulation consisted of isomalt, sorbitol, coconut powder, pistachio powder, cardamom, cinnamon and chlorophyll, stevia, and Corchorus olitorius were supplied from Salamat-gostaran arayan Co. All chemicals were from Merck Co. The formulations of Luz include sorbitol (29.68%), sugar (25.85%), coconut powder (38.75%), cardamom (0.3%), cinnamon (0.26%) and chlorophyll (58.5%). 2) were selected, and isomalt was used as filler. To produce Luz, the mixture of sorbitol and isomalt was heated to reach boiling temperature and complete dissolution. After the heat treatment (126°C for 1h), the mixture was cooled to 40°C and the other materials were added and mixed. The prepared samples were molded and placed at 15°C for 3 h. Moisture, ash, protein, fat, and sugar were determined according to AACC standard numbers. The density was also determined according to AACC standard number 54-21. Textural properties were determined using a texture analyzer. Atomic Spectroscopic measurement of minerals was performed according to Devatkal et al. (2004). The color evaluation was performed by the Image Processing method. In this study, the effects of Stevia replacement with sugar (0-100%), Corchorus olitorius replacement with pistachio powder (0-100%) and cooking temperature (50-70°C) on physical and textural properties (density, hardness) of Luz were investigated. Formulation optimization of enriched dietary Luz was performed using Response Surface Method in the form of a central composite design with 6 central points and two replications (α=2) in other locations. In optimum condition, the results of physicochemical, textural and color properties were analyzed by SPSS software. Results and discussion: The linear model was suggested for density changes, and independent effect of variables (stevia replacement, Corchorus olitorius replacement, cooking temperature), interaction effect of Stevia and Corchorus olitorius replacement, interaction effect of Corchorus olitorius replacement and cooking temperature, the quadratic effect of Stevia replacement and the quadratic effect of cooking temperature were significant on density (P <0.05 or P <0.001). The density of all treatments increased with increasing the levels of Stevia and Corchorus olitorius replacement. An increase in density was observed with increasing cooking temperature. The interaction effect of Corchorus olitorius and cooking temperature caused a significant (P<0.05), decrease in hardness. A reduction in the level of stevia replacement resulted in a decrease in hardness. The optimum formulation of dietary Luz was introduced containing 25% Stevia, 25% Corchorus olitorius and cooking temperature of 65°C, and 55% Stevia, 75% Corchorus Olitorius and cooking temperature of 55°C. Overall, the nutritional value of dietary Luz containing Corchorus olitorius was improved in terms of protein, ash, magnesium and calcium content. The total sugar content of the optimum samples was significantly lower than the control. The textural characteristics of the optimum samples had not changed significantly.
Shima Nasiri; Saman Abdanan; Mokhtar Heidari
Abstract
Introduction: Texture represents one of the four principal factors defining food/fruit quality, together with appearance, flavour and nutritional properties (Bourne, 2002), and plays a key role in consumer acceptability and recognition of quince. Textural characteristics of quinces defined by “crispness”, ...
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Introduction: Texture represents one of the four principal factors defining food/fruit quality, together with appearance, flavour and nutritional properties (Bourne, 2002), and plays a key role in consumer acceptability and recognition of quince. Textural characteristics of quinces defined by “crispness”, “juiciness”, “hardness”,“firmness” and “mealiness” are often key drivers of consumer preference. Many non-destructive methods, including image analysis, spectroscopy, ultrasound and sound techniques, have been developed to diagnose internal and external defects in fruits and vegetables. Cheng and Haugh (1994) used a frequency of 250-kHz, rather than 1-MHz, to detect hollow heart. They were not able to transmit successfully the ultrasound wave through the whole tuber using 1-MHz transducers but found the 250-kHz transducers to be practical for a transmission path length of up to 89.7 mm. In a research an acoustic setup was developed to simultaneously detect the resonant frequencies from equator and from calyx shoulder of pear. The researchers proposed index based on these two frequencies was used for firmness evaluation of non-spherical pear; Compared with two types of single frequency-based indices, the firmness sensitivity of the dual-frequency index is mostly close to that of MT penetration test. The firmness index can classify pears with a high total accuracy (93.4%), making it suitable for nondestructive detection of firmness of differently shaped pears (Zhang et al., 2018). The goal of this study was to develop a nondestructive method based on acoustic impulse response of quince fruit using genetic programming and artificial neural network during storage. Materials and Methods: In the experiment 120 quince fruits (Cydonia oblonga) were harvested from a field near Isfahan 181 days after full flowering of the trees. For each cultivar, only samples of similar size and without visible external damage were chosen. The samples were packed in sterile nylon bags and stored at 4°C. Non-destructive test (acoustic response) as well as destructive test (chemical measurement and penetration test) were performed every 15 days for 4 months (Akbari Bisheh et al., 2014). Total soluble solids (TSS) were determined by a hand refractometer device (model: MT03 Japan) and expressed as °Brix. Ascorbic acid of the juice was measured by titration with copper sulfate and potassium iodide based on the Barakat et al. (1973) procedure. Titratable acidity was measured according to the AOAC method. To determine the total phenol content of juice, the Waterhouse method (2000) was used. Determination of the pH of the fruit extract using a pH meter (Portable Model P-755, Japan). Physical attributes of the samples including volume as well as major, minor, intermittent diameters and mass were calculated using the relations proposed by Stroshine and Hammand (1994). Penetration test was conducted by the material test machine (SANTAM, STM-20 model, Iran).In order to analyze the response sound signal of quince in time and frequency domain, a system equipped with a sample holder with foam rubber covered surface, an impact mechanism, a microphone and an electronic circuit was utilized. To record impact sound features a microphone was positioned next to the fruit and was hit at three speed level (0.3, 0.9 and 1.5 m/s). After recoding sound, five features (acoustic peak, maximum acoustic pressure, mean acoustic pressure and natural frequency) were extracted and used as inputs for models. In order to predict the stiffness, four methods of genetic programming, neural network and existing mathematical models (FI and SIQ-FT) were used. In order to carry out statistical analysis, analysis of variance (ANOVA) and Duncan's multiple range test at 5% probability level were performed according to the completely randomized design (CRD). Results and discussion: In this study, Duncan's multiple range comparison test was used to investigate the significant difference between destructive and non-destructive parameters at 5% probability level. According to the results, acoustic peak, maximum acoustic pressure, mean acoustic pressure and natural frequency were decreased by increasing storage time. Statistical analysis of the destructive tests also showed a decreasing trend at the 5% level. In several papers, two mathematical equations have been used to obtain the relationship between the mass resonance frequency and the sound of impact. In this study, genetic programming and neural network modeling were used to compare the results of these relationships. The regression coefficients between the actual and the predicted values for the resonance-mass relation and the effect of the sound from the collision were R2= 0.601 and R2= 0.754, respectively. Also, the regression values obtained from genetic programming and neural network modeling were R2= 0.9567 and R2 = 0.933, respectively. In a research, the overall R2 value amounts for stiffness prediction was reported to be 0.79 (Schotte et al., 1999). Abbaszadeh et al. (2013) evaluated watermelons texture using their vibration responses. They declared their proposed method could predict textural acceptability of watermelons with determination coefficients 0.99. According to the obtained values, the best methods for stiffness prediction were genetic programming and f neural network methods, respectively.
Farhad Fatehi; Asghar Mahmoudi; Adel Hosseinpour; Hadi Samimi Akhijahani
Abstract
Introduction: Strawberry is one of the native and small fruits of moderate regions, which its cultivation has been increased in all over the world including Iran. Due to the abundance of vitamin C and mineral materials, it is very useful for some diseaseses. Lack of the knowledge in production ...
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Introduction: Strawberry is one of the native and small fruits of moderate regions, which its cultivation has been increased in all over the world including Iran. Due to the abundance of vitamin C and mineral materials, it is very useful for some diseaseses. Lack of the knowledge in production management, harvesting, cooling, transportion, storage, marketing and processing equipments and connection between these different parts are the main problems throgh industrial production of strawberry fruit (Salami et al., 2010). According to the various studies, the parameters such as color, shape, size and mass are not sufficient for the consumer to purchase the fruit (Abbot, 1991). They would like to have more information about the fruit which is supposed to be purchased (Voca et al., 2008). Several researchers have been investigated physical and chemical properties of different varieties of strawberry fruit (Wojdylo et al., 2009; Salamat, 2011; Nemzer et al., 2018). According to the litrature, any international standard classification for Parus strawberry (which is mostly cultivated in Iran) based on physical and chemical was not found. In this study, some physical, mechanical and chemical properties of strawberry fruit Parus variety, as well as the relationship between them, were investigated. The classification was performed based on the appearance features including color and size with the opinion of the expert in six classes. Materials and methods: In Kurdistan province strawberry fruit is often grown in open area and cultivated areas of Parus variety due to many reasons are increasing. To classify the strawberries, six classes were considered. Physical and mechanical properties such as dimensions, density, porosity, stiffness and biological yield point were measured at least at five replications. The porosity of the strawberries was also calculated through the division of the difference between actual and apparent density to actual density. Also, the stiffness and biological yield point were measured using Universal Instron Testing Machine (Zwick/Roll). Chemical properties of Parus strawberry including vitamin C, acidity, total soluble solids and flavor index were investigated at five replications. Results and discussions: The analysis of variance showed that all chemical properties including ascorbic acid, acidity, total soluble solids, and flavor index, were strongly influenced by the class. The LSD mean comparison showed that the highest levels of vitamin C were related to the ripe fruits which had a direct relationship with fruit size. The acidity values between the classes varied from 0.55 to 1.08, and the lowest value was related to the first, second and third classes, respectively. The total soluble solid material (TSS) was affected by some factors: sugar (as main part), organic acid and organic pectins and was increased by growing strawberries and increasing the amount of sugar. For the first, second and third classes, TSS was higher than those of the fourth, fifth and sixth clases. The flavor index value for the lower classes (first, second and third) is higher than the higher classes (almost 2 times). The analysis of variance for all physical and mechanical properties indicated that all parameters are affected by the classes. Due to its more soluble materials, the maximum value for actual density was related to the third and second classes, respectively. The apparent density of agricultural products depends on various factors such as geometric shape, size, surface properties, moisture content and measurement method. The apparent density for the first and fourth classes were 561.743 and 498.408 gr.mm-3, respectively. The maximum and minimum value of stiffness was related to first (about 5.2 N.mm-2) and fourth (about 28.2 N.mm-2), respectively. For biological yield the maximumvalue was related to the fourth class, as well. Conclusion: In this study, the classification of strawberry, variety of Parus was investigated based on physical, mechanical and chemical properties. All properties were affected by changing the classes. The results of this research can be used to design and construct post-harvest and sorting mechanisms of agricultural products which require comprehensive information about physical, mechanical, chemical properties.
Mohammad Vahedi Torshizi; Mohsen Azadbakht
Abstract
This study evaluated the effect of different dynamic and static loadings and different storage periods on the firmness of pear fruit. Pear fruit was first segregated into three groups of 27 pear in order to undergo three loadings: static thin-edge compression loading, static wide-edge compression loading ...
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This study evaluated the effect of different dynamic and static loadings and different storage periods on the firmness of pear fruit. Pear fruit was first segregated into three groups of 27 pear in order to undergo three loadings: static thin-edge compression loading, static wide-edge compression loading and dynamic loading. All loaded pears were stored in accordance with three storage period designs: 5-day storage, 10-day storage, and 15-day storage. Following each period, the variations of pear texture were scanned by using the CT-Scan technique as a non-destructive test. Then, the firmness of pear texture was measured using a penetrometer. Data were simulated and evaluated using MLP and RBF artificial neural networks. The results showed that with increasing storage time and loading force , the firmness significantly decreased (1% level) in all three types of loading, In addition, pear texture was destructed under dynamic compression loading in order to compare with other two loadings. Best value artificial neural network for wide edge loading (12 neuron-RBF) was (R2 Wide edge= 0.9738– RMSE Wide edge=0.3419- MAE Wide edge =0.268) and for thin edge loading (4 neuron-RBF) was (R2Thin edge = 0.9946– RMSE Thin edge =0.170977- MAE Thin edge =0.133), also for dynamic loading (8 neuron-RBF) was (R2 Dynamic loading = 0.9933– RMSE Dynamic loading =0.230- MAE Dynamic loading= 0.187).
Hossein-Ali Tash Shamsabadi; Seyedeh Hoda Yoosefian; Ayat Mohammad Razdari
Abstract
Introduction: Tomato is one of the most important vegetable crops in Iran and is grown commercially in every state in the country. Tomatoes are climacteric in nature and climacteric fruits submitted to gamma irradiation exhibit a delay of ripening. In the specific case of tomatoes, irradiation generally ...
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Introduction: Tomato is one of the most important vegetable crops in Iran and is grown commercially in every state in the country. Tomatoes are climacteric in nature and climacteric fruits submitted to gamma irradiation exhibit a delay of ripening. In the specific case of tomatoes, irradiation generally delays ripening when the treatment is applied at the pre-climacteric stage. Mechanical properties are very important quality property in tomato. Determination of the storage time effect on the evolution of this quality is a desirable objective for producers, distributors and marketing agencies, who need reliable firmness measuring instruments for commercial purpose. Previous studies carried out by different researchers show that impact techniques can be used to evaluate firmness of fruits successfully. Quick and nondestructive methods for measuring texture are critical for controlling postharvest quality of crops and fruits. Polymer films are ubiquitous in the food industry, fulfilling a range of functions including a significant role in reducing food waste. Also, it can be possible to extend shelf-life with some coatings, including polymer films.
Materials and Methods: In this study, tomatoes were irradiated in Atomic Energy Organization of Iran. For irradiation of samples, cobalt 60 (Gamma Cell 220) was used. The samples were irradiated with doses of 0 (control), 0.25, 0.5 and 1 kG, then transferred to the laboratory and kept in a refrigerator at 6 ± 1 ° C and 65 ± 4% relative humidity for 21 days. In order to pack, polyethylene film with medium density (thickness of 0.3 mm and depth and width, respectively, 6.5 and 19 cm) were obtained from the Iranian Polymer Research Institute. Experiments were performed on samples coated with polyethylene film in 7 days intervals. Acoustic tests were performed using Impact Test System. The system was covered with aluminum chamber and inside with wood and clouds. The system was internally equipped with the sample location on the floor, the impact mechanism and the receiver of the signal. In this audio excitation system, samples were taken with the help of a blow. By applying a blow to the sample surface, the audio signal was sent to the sample and then measured by a receiver placed at a distance of 7 mm from the sample. The experiments were performed every 7 days. During the experiment period, the physical and mechanical properties of the samples were measured. Data were analyzed using SPSS.20 software. Correlation between hit parameters and firmness of penetration test were checked out using regression in Excell .2013 software, and predicted a suitable model for determining the firmness of tomato.
Results and Discussion: The results showed that after 21 days of storage time, the amount of mass and density for irradiated sample with a 0.5 kGy dose in polyethylene film compared to control sample (uncoated) decreased to 22.53 and 12.34 %, respectively, and had more resonant frequency to 26.58%. Also, irradiated sample with a 0.5 kGy dose in polyethylene film compared to samples irradiated with doses of 1 kg and non-irradiated samples in polyethylene film had higher modulus of elasticity and firmness to 37.74, 26.48 % and 25% and 18.12%, respectively. The maximum penetration force in destructive testing had strong relationship with the parameters obtained from Acoustic test such as resonant frequency, Strength index and Modulus of elasticity with a correlation coefficient to 0.893, 0.913 and 0.886, respectively. Combination of polyethylene film with 0.5 kG irradiation on the changes in mass and volume, strength coefficient, resonance frequency, elasticity modulus and rigidity obtained from the impact test have the best results. Also, combination of polyethylene coating and 21-day storage time on mass and volume changes, strength coefficient, resonant frequency, elasticity modulus and stiffness from the impact test reduced the storage performance. According to the results of this study, by irradiation of a sample of tomatoes with a 0.5 kG and using a polyethylene film, it can be stored with a slight change in stiffness and texture for a period of 21 days, and possibly more, which causes increase the shelf-life in the warehouse, reduce storage costs in the warehouse by conventional methods and increase the possibility to export. As a summing up, irradiation in combination with Polyethylene films is a good way to preserve tomatoes tissue and Acoustic textures is a useful way to be replaced with Penetration test
Azam Ayoubi; Mahda Porabolghasem
Abstract
Introduction: Increased intake of calorie and decreasing physical activity might increase the risks for cancer, obesity, cardiovascular diseases, diabetes mellitus and hypertension. Using natural sweeteners instead of sugar in food formulations can be a good method to reduce the calorie intake. World ...
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Introduction: Increased intake of calorie and decreasing physical activity might increase the risks for cancer, obesity, cardiovascular diseases, diabetes mellitus and hypertension. Using natural sweeteners instead of sugar in food formulations can be a good method to reduce the calorie intake. World Health Organization recommends limiting added sugar intake to <10% of total energy. Many sugar substitutes were used in food products such as glucose syrup, molasses, fructose syrup, invert syrup and malt extract. Utilization of fruits in food preparation while requiring sweet taste is a wise strategy to reduce the added sugar intake. Dates are ideal fruits to substitute added sugar in foods, and they play an important role in daily nutrition of many people in the arid regions. Date fruits are rich in dietary fiber, phenolic compounds, minerals, vitamins, antioxidant and antimutagenic compounds. Date syrup that produces from date is one of the suitable replacements that can be used for substituting sugar. Date syrup is a high energy food rich in carbohydrate, a good source of minerals; but it is also contains a very complex mixture amino and organic acids, polyphenols and carotenoids. Date syrup contains fructose, glucose and small amount of sucrose. Low quality date cultivation occupies about 60% of the total plantation. These dates are poor in size and taste, unsuitable for consumption. The presence of high sugar content in these low quality varieties makes them suitable for producing date syrup. The purpose of this research was study the effects of substituting sugar with date syrup on physicochemical and sensory properties of cupcake.
Materials and methods: Date syrup purchase from Dambaz Company and wheat flour purchase from Tavakkol factory of Kerman. Other materials purchased from local market of Kerman. In this research four different level of date syrup (25, 50, 75 and 100%) were used in cake formulations as a sugar substitution and the effects of dates syrup on the physicochemical (including weight loss, pH, porosity, density, moisture, hardness of texture and color of crust and crump) and sensory (texture, crust color, taste and total acceptance) properties of cupcake were studied. The weight loss calculated by measuring difference of weight before and after baking. pH was measured by a digital pH meter. cake moisture content was determined by drying samples at 130±2°C in a hot air oven. The volumes of the cake samples were measured by the seed displacement method and then density was calculated by dividing the volume by the weight. For evaluation of porosity used Image j method. Hardness of the cake samples were measured with Instron testing machine. Color measurements were done using a Hunterlab Colorimeter. Analysis of variance (ANOVA) was conducted for data using MSTAT-C software. Differences among the mean values were also determined using Duncan’s Multiple Range test. A significant level was defined as a probability of 0.05.
Results & Discussion: Data analysis showed that the date syrup, significantly affected the physiochemical and sensory properties of the cake. It was discovered that by increasing the percentage of date syrup in cake formulation, weight loss decreased and moisture increased. Sugars make hydrogen bonds with water molecules due to their hydroxyl groups, because of the molecular structure of the sugars like sucrose, fructose and glucose, it seems that increasing functional groups in date syrup sugars compared with sucrose, resulted in the formation of more hydrogen bonds, which caused the reduction in the mobility of free water and therefore make an increase in moisture of cake. According to the results, pH and porosity of the cake decreased as the date syrup level increased. The results showed that increasing date syrup level caused an increase in density. By decreasing the volume of cake density increased. The volume probability decreased because of affecting reduced sugars and changing viscosity and density of the cake batter. Based on the results, hardness increased significantly with increasing replacement of sugar with date syrup. The possible reason for this result was due to decreasing volume and porosity of cake with increasing date syrup content. The color of the cake is due to the Maillard and caramelization reactions during baking. A key element in Maillard reaction is reducing sugar which is abundant in date syrup and able to enhance the brown color. The results showed that the crust and crump lightness (L) decreased significantly with increasing the levels of date syrup. The crust and crump yellowness (b) were significantly less than control. With reducing sucrose level, the redness of the crust and crump increased significantly. According to sensory evaluation results, scores of crust color, texture and total acceptance of the cake remained unchanged when up To 50% date syrup was used. However, further addition of date syrup significantly reduced these scores. The results showed that the cake formulation with 100% date syrup date obtained the lowest score by panelists in terms of taste. Least value of weight loss (19/2%), porosity (19/5%) and most value of density (0/5 g/cm3), darkness of crust (32/47) and crump of cake (35/64) were related to substitution level of 100%. Present study demonstrated that the date syrup could replace up to 50% of the sugar without affecting the quality of cupcakes.
Orang Khademi; Younes Nemati
Abstract
Introduction: There are two types of Japanese persimmon (Diospyros kaki Thunb.), astringent and non-astringent, based on the degree of astringent taste at maturity state. Fruits of either type are strongly astringent when small and immature, but non-astringent type loses its astringency during development ...
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Introduction: There are two types of Japanese persimmon (Diospyros kaki Thunb.), astringent and non-astringent, based on the degree of astringent taste at maturity state. Fruits of either type are strongly astringent when small and immature, but non-astringent type loses its astringency during development on the tree, still with firm flesh. However, the astringent type keeps its astringency and is inedible even when fully colored. It loses its astringency when becomes over-ripe with extremely soft flesh. At this stage, the fruits are usually over ripe with poor quality. Astringency in persimmon is caused by soluble tannins present in the fruit flesh. One mechanism useful in artificial removal of astringency from persimmon fruit is condensation or polymerization of soluble tannins into insoluble non-astringent forms, by acetaldehyde, which is being produced in the fruit flesh during different treatments. Acetaldehyde accumulates in the fruit flesh during its exposure to ethanol vapor or high level of carbon dioxide (CO2) gas, Hence, constant temperature and short duration (CTSD) is the preferred method of CO2 treatment used to remove astringency of persimmon fruit. It involves holding the fruits in ≥95% carbon dioxide atmosphere for a short duration at constant temperature of 20-30°C then transferring to normal atmosphere. However using CO2 treatment as gas form is expensive and needs special equipment. However, solid CO2 (dry ice) is easily available in Iran with low price. It release CO2 gas and can be used for removing astringency in persimmon fruit. The response of persimmon to de-astringent treatment depends on the cultivar. In this study two persimmon cultivars namely: ”Karaj” and ”Japanese” were harvested at maturity (full coloring) stage and treated with dry ice and ethanol vapor to remove astringency and the quality of treated fruits were evaluated.Materials and methods: Astringent persimmon fruits cvs ‘Karaj’ and ‘Japanese’ were harvested at maturity stage and transported immediately to the Department of Horticulture Science, University of Shahed and treated with either ethanol or dry ice. Both ethanol and dry ice treatmenttreatments were applied in low-density polyethylene bags with 0.05 mm thickness and polyethylene container with 3 mm thickness. In the polyethylene container, dry ice was applied at amounts of 3, 5 and 7% per kilograms of fruit and in the polyethylene bags dry ice was applied at amount of 0.16, 0.25 and 0.33 per kilogerams of fruits. For ethanol treatment, in both polyethylene bag and polyethylene container, 10 ml of 36% ethanol per kilogram of fruit was sprayed. Thereafter, bags and containers were sealed completely and kept for 48 hours at 25°C and 80% RH. After removing from the closed bags and containers, fruits were held in air at 25°C, 80% RH for completing astringency removing. After astringency removal treatmenttreatments, soluble tannin contents, astringent taste degree, fruit firmness, total soluble solid and ascorbic acid content were measured. The content of soluble tannin was determined by Folin-Denis method and the degree of astringency was determined by panel test. The experiments were conducted in a completely randomized design (CRD) and analysis of variance (ANOVA) was performed and the means were compared using LSD Test.Results and discussion: After performing the astringency removal treatment, fruits containing less than 1000 ppm of soluble tannin on a fresh weight basis showed no astringency. Results presented here showed that, dry ice treatment, especially at higher concentrations such as 7% in both cultivars, causes removal of astringency and decreases soluble tannin contents below the threshold of 1000 ppm, but ethanol treatment was effective only in Karaj persimmon for the removal of astringency. Similarly, it was indicated that CO2 treatment removed the astringency more easily in some Chinese cultivars than the ethanol treatment. The response of persimmon cv. Karaj was similar to a leading cultivar Hiratanenashi in Japan, for astringency removal by both CO2 and ethanol treatments, while, according to this results, Japanese cultivar had not shown suitable response to ethanol, while it successfully responded to dry ice treatment.Treatments to remove astringency of persimmon fruit often cause fruit softening. Astringency removal treatment induced ethylene production in persimmon which causes to the fruits softening. In this study, the firmness of both cultivars decreased significantly after treatments, however, the average of flesh firmness was significantly higher after dry ice than after ethanol treatments.Total soluble solid contents under the astringency removal treatments in both cultivars reduced significantly. This reduction is due to the removing of soluble tannins responsible for fruit astringency, since they are included in SSC measurements when not polymerized. Moreover, the results showed that ascorbic acid content is not affected by astringency removal treatments.Conclusions: The results presented here showed that removing astringency from persimmon cvs. Karaj and Japanese were achieved by postharvest application of dry ice in the poly ethylene container. Results also showed that dry ice was more effective than ethanol in astringency removal and retained higher quality of fruit. Dry ice is available treatment in Iran and it can be commercially used for removing astringency of Iranian persimmon.
