Study of the parameters' variation in the vegetables drying process (original) (raw)
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Determination of Drying Characteristics of Some Vegetables
Global Journal of Agricultural Innovation, Research & Development, 2015
Drying is, removing the water effect of distorting structure, from the food products with the effect of heat. Direct sun drying, greenhouse drying and supported by solar panel greenhouse combinations were done for drying vegetables. Eggplant, cauliflower, leeks, broccoli were dried. Dry matter and water activity values were measured for each of products on the systems of directly in the sun drying, drying in the greenhouse, the panel + greenhouse. Improvements of the conditions in the greenhouse and then with some modifications should be established such as optimization of the air velocity is thought to be achieved by faster drying.
Determination of the Coefficient of Initial Drying Speed of Selected Vegetables
Farm Machinery and Processes Management in Sustainable Agriculture, IX International Scientific Symposium, 2017
Efficient production of safe, high quality food is an important element of sustainable agriculture. Fruits and vegetables belong to an exceptional group of materials in food processing, and one method of preservation of growing production of fruits and vegetables is drying them. The work analyses the dependence of the initial drying speed coefficient in the first stage of drying on the initial moisture content in the process of convective drying, using cruciferous (root vegetables), namely, carrot, parsley, celery and beet. Samples of three different thicknesses (3, 5 and 7 mm) were dried at three different temperatures (50, 60 and 70°C), with the constant flow speed of the drying agent. The results were presented graphically, in the form of charts. As expected, the analysis of the results showed that the drying process is faster for materials with higher initial water content. The coefficient of initial drying speed reached lower values for thicker slices, and increased together with the temperature of the drying agent.
Utazi (Gongromena ratifolia) and Nchuanwu (Occimum americanus) were dried using solar dryer and open-air sun drying methods. 200 g of each sample was used. The weight losses were used to determine the reduction in moisture content. Drying was assumed to have taken place in the fallingrate period, which enabled the use of only one drying rate constant, K. Graphs of ln(M0-M) versus time were used to obtain the drying rate constants, K for the two drying conditions. All analyses were done using standard procedures. The drying rate constants for the solar dryer and open-air sun dried Utazi were 0.8 and 0.7, respectively. Similarly, the values for Nchuanwu were 0 2 and 0.3, respectively. Moisture versus time graphs of both samples showed that the assumption of one falling-rate period is justifiable. The solar dryer was more efficient and would be more appropriate to industrial application. Both the nutritional and sensory qualities of the dried products were enhanced by the process.
Scientific Research and Essays, 2014
Utazi (Gongromena ratifolia) and Nchuanwu (Occimum americanus) were dried using solar dryer and open-air sun drying methods. 200 g of each sample was used. The weight losses were used to determine the reduction in moisture content. Drying was assumed to have taken place in the fallingrate period, which enabled the use of only one drying rate constant, K. Graphs of ln(M0-M) versus time were used to obtain the drying rate constants, K for the two drying conditions. All analyses were done using standard procedures. The drying rate constants for the solar dryer and open-air sun dried Utazi were 0.8 and 0.7, respectively. Similarly, the values for Nchuanwu were 0 2 and 0.3, respectively. Moisture versus time graphs of both samples showed that the assumption of one falling-rate period is justifiable. The solar dryer was more efficient and would be more appropriate to industrial application. Both the nutritional and sensory qualities of the dried products were enhanced by the process.
International journal of molecular sciences, 2016
The seasonality of fruits and vegetables makes it impossible to consume and use them throughout the year, thus numerous processing efforts have been made to offer an alternative to their fresh consumption and application. To prolong their availability on the market, drying has received special attention as currently this method is considered one of the most common ways for obtaining food and pharmaceutical products from natural sources. This paper demonstrates the weakness of common drying methods applied for fruits and vegetables and the possible ways to improve the quality using different drying techniques or their combination with an emphasis on the microwave energy. Particular attention has been drawn to the combined drying with the assistance of vacuum-microwaves. The quality of the dried products was ascribed by chemical properties including the content of polyphenols, antioxidant capacity and volatiles as well as physical parameters such as color, shrinkage, porosity and text...
Food Engineering Reviews, 2015
Drying has been applied to vegetables in order to preserve, store and transport these food products. However, drying implies not only physical changes, easily detectable by the consumer through visual assessment, but also chemical modifications. These are not always visible, but are responsible for alterations in colour, flavour and nutritional value, which compromise the overall quality of the final product. The main chemical changes associated with drying are related to the degradation of phytochemicals, such as vitamins, antioxidants, minerals, pigments and other bioactive compounds sensitive to heat, light and oxygen. Moreover, nutrient losses are inevitably associated with leaching as a result of the water removal from the vegetable during the drying process. In order to prevent or reduce nutrient losses and thus improve the quality of dried products, pretreatments are often applied. In this review, an overview of the procedures developed for dehydration of vegetables applying heat by convection, conduction or radiation is presented. The influence of pretreatments on nutritional and bioactive characteristics of dried vegetables is discussed. Blanching with steam, water or chemical solutions is the most commonly used, but power ultrasound, ohmic blanching, osmotic and edible coatings pretreatments have also been reported. The influence of the drying processes and conditions on nutritional contents and bioactive characteristics is also presented.
Drying kinetics of some vegetables
Journal of Food Engineering, 2003
The effect of air conditions (air temperature, air humidity and air velocity) and characteristic sample size on drying kinetics of various plant materials (potato, carrot, pepper, garlic, mushroom, onion, leek, pea, corn, celery, pumpkin, tomato) was examined during air drying. A first-order reaction kinetics model was used, in which the drying constant is function of the process variables, while the equilibrium moisture content of dried products within the range of 0.10-0.90 water activity at two temperatures (30 and 70°C
Quality Attributes of Some Vegetables and Fruits Preserved by Sun and Oven Drying Methods
Alexandria Science Exchange Journal, 2018
Drying is one of the most appropriate techniques for producing of shelf stable food products. However, drying can result in significant loss of available bioactive compounds. This study investigated the effect two methods of drying (sun and oven) on the quality characteristics of vegetables (onions and garlic) and fruits (dates and figs). The vegetables and fruits of both types were dried by the two methods. In comparative to the fresh sample, the dried samples showed a highly significant (P˂ 0.01) difference was observed in moisture between fresh and dried vegetables and fruits. The oven dried samples had the lowest moisture. In contrast, protein, ash, crude fat, fiber and carbohydrates of fresh samples exhibit the least among the three samples in each type of vegetables and fruits. Also, the results showed a highly significant (P<0.01) difference between fresh, sun and oven dried date in potassium and slightly significant (P<0.05) in fig but no significant difference in garlic and date regarding potassium. Sodium content recorded highly significant difference (P<0.01) between the three crops (onion, date and fig) except garlic. Also, iron content the highest value revolved significant only in the oven drying. There was generally significant (P<0.01) difference between the three types in each vegetables and fruit in phosphorous. Physical evaluation showed significant differences among sun and oven drying in all samples except in onion. In this study observed the oven dried vegetables and fruits were rated lowest by the panelists in all the sensory attributes and overall acceptability. However, there was significantly difference (P<0.05 and P<0.01) between the sun and oven drying from the fresh vegetables and fruits in all the sensory attributes. Sun and oven drying have a significant effect on water absorption capacities (WAC) of dried samples except the fig. The highest value of oil absorption capacities (OAC) and swelling capacity was noticed in oven dried samples followed by the sun dried samples. All sun dried samples have low foaming properties compared with oven dried samples. The drying techniques did not significantly (P>0.05) affect the bulk density of drying samples. Dried vegetables and fruits showed low emulsion properties in which oven drying slightly improved the emulsion activity and emulsion stability over sun drying. Sun drying samples formed gel quickly at low concentration while oven dried samples formed gel at high concentration. The highest gelatinization temperature was observed for oven dried samples and the lowest for sun dried samples.
Foods, 2020
Drying is known as the best method to preserve fruits, vegetables, and herbs, decreasing not only the raw material volume but also its weight. This results in cheaper transportation and increments the product shelf life, limiting the food waste. Drying involves the application of energy in order to vaporize and mobilize the moisture content within the porous products. During this process, the heat and mass transfer occurs simultaneously. The quality of dehydrated fruits, vegetables, and aromatic herbs is a key problem closely related to the development and optimization of novel drying techniques. This review reports the weaknesses of common drying methods applied for fruits, vegetables, and aromatic herbs and the possible options to improve the quality of dried products using different drying techniques or their combination. The quality parameters under study include color, bulk density, porosity, shrinkage, phytochemicals, antioxidant capacity, sugars, proteins, volatile compounds,...
Technological Revolution in Drying of Fruit and Vegetables
Historical evolution of different drying methods for drying fruit and vegetables was evolved gradually with time. Nowadays, every form of fruit and vegetables slices, chunks, paste, puree, solution can be dried using different available dryers. Recent research on drying methods focuses on the advancement in of energy consumption, product recovery and preservation of nutrients. Different combination dryers are also used as advancement for a particular dryer. Technological advancements in drying methods were triggered by the shortcomings of the existing one. This revolution clearly indicates that drying not only reduces moisture content to a safe storage level but also provides different edible forms