Drying Of Apricots Research Articles

Machine learning approaches for estimating apricot drying characteristics in various advanced and conventional dryers

AbstractDrying plays a crucial role in preserving the quality of agricultural products. Nevertheless, suboptimal conditions in drying systems have an adverse effect on drying characteristics and energy efficiency. Machine learning approaches are innovative and reliable that have been successfully used to solve such challenges and achieve optimization in drying processes. In this study, five machine learning approaches (multilayer perceptron [MLP], gaussian processes [GP], support vector regression [SVR], k‐nearest neighbors [kN], and random forest [RF]) were used to estimate moisture content and moisture ratio of apricot in five various dryers (convective [CV], microwave [MW], infrared [IR], microwave‐convective [MW‐CV], and infrared‐convective [IR‐CV]). Also, the values of specific energy consumption (SEC) and effective moisture diffusivity (Deff) were calculated in these dryers. Accordingly, the best result of the Deff (3.14 × 10−10 m2/s) and the minimum value of the drying time (130 min) and SEC (18.67 MJ/kg) were obtained using MW‐CV hybrid dryer. While the lowest values of Deff (2.09 × 10−11 m2/s) and highest drying time (18.5 h) and SEC (209.34 MJ/kg) were detected in CV dryer at 50°C. The best correlation coefficients (R) for the estimation of moisture content were gained using RF technique for k‐fold cross validation and train‐test split with the values of 0.9908 and 0.9912, respectively. Moreover, moisture ratio results showed that the MLP achieved the highest R value over 0.9985 for both validation methodologies. In the discrimination of the drying methods, the MLP had the greatest accuracy as 82.00% and 86.00% for k‐fold cross validation and train‐test split, respectively. The results showed that the RF and ML models could potentially be used for estimation and discrimination for drying applications.Practical ApplicationsRecently, there has been an increased interest in healthy food choices such as foodstuffs, snacks, and dried products. This trend has captured the attention of both dietitians and conscious consumers. Apricots are a prime example of a valuable dried product that can be dry in various conditions. Machine learning techniques can be used for rapid and non‐destructive determination of drying characteristics and such techniques yield objective and accurate results. Present findings revealed that texture machine learning models could be used as an effective and reliable discrimination tool for dried products.

Sodium metabisulfite dipping, hot water blanching and sulfur fumigation impact on the nutritional quality of dried apricot (Prunus armeniaca L.) cultivars

Background: Fruit postharvest loss has become a major concern for apricot growers. Under this situation, fruit valorization will continue to challenge agricultural sustainability. Aims: The study aimed to evaluate the nutritional and sensorial quality of fresh and dried apricot fruits cultivars (Amr Leuch, Bayoudhi, Canino, Khad Hlima, Khit el Oued, and Sayeb) harvested from private orchards in Hajeb Laayoun- Kairouan Tunisia, during two growing seasons (2018/2019). Material and Methods: The pre-treatments consisted of sulfur fumigation, sodium metabisulfite dipping, and hot water blanching whereas the distilled water was used as a control. Fruit pomological traits, physic-chemical and biochemical parameters were evaluated in fresh and dried apricot fruits. Sensorial analysis (color, texture, taste, aroma and consumer satisfaction) was performed in fresh and dried apricot fruits. Results: Results showed that the drying process decreased the antioxidant compounds content in the apricot fruits. Conclusions: The sensorial analysis measured in global satisfaction showed that the cultivars Bayoudhi and Khit el Oued possess higher consumer acceptability as fresh fruits whereas the cultivars Canino and Khad Hlima were found to be promising varieties for apricot drying. The sulfur-fumigation and sodium metabisulfite dipping were efficient pre-treatments as it improved the color of the dried apricot fruits. Keywords: Apricot, drying, color, antioxidants, sensorial quality.

Experimental Characterization and Mathematical Modelling of Natural Drying of Apricots at Low Temperatures

To mitigate reduced apricot fruit quality due to mildew, browning and sand dust from natural drying under low temperatures and humidity, we determined the characteristics of three different methods of drying (via hanging) and further established their mathematical models. Various comparative analyses of natural drying by laying apricots in an area of the Gobi Desert, subjecting them to ventilated drying in an air-drying house, and hanging them on trees were conducted. The least and most efficient methods were hanging on trees (302 h) and laying them in an area of the Gobi Desert (>192 h), respectively. The loss rate and the total sugar content were 5.26% and 70.16%, and up to 18.31% and 68.54% for fruits dried by ventilated drying in an air-drying house and those hung on trees, respectively. Fruits dried by ventilated drying in an air-drying house showed the least loss and the best comprehensive quality. Using experimental data from assessments of the drying methods, mathematical models were constructed and fitted to drying mathematical models of seven kinds of porous media. The Wang and Singh model had the best fitting degree, an error value of less than 0.05, and the regression that most accurately explained the drying mathematical model for apricots under natural conditions.

A potential application on reducing microorganism load in apricot drying: Ultraviolet C (UVC) + Hot air drying

Amaç: Bu çalışmada ultraviyole ışık ve sıcak havayla kurutma uygulamalarının üç farklı kayısı çeşidindeki (Prunus armenica L., var. Hacıhaliloğlu, Prunus armenica L., var. Kabaaşı, Prunus armenica L., var. Şekerpare) yüzey mikroorganizma yüküne (psikrofilik ve mezofilik aerobik bakteriler, maya ve küf) etkileri araştırılmıştır. Materyal ve Yöntem: Ultraviyole ışık ortalama doz oranı 6.70 W/m2 ve ışıma maruziyeti (dozaj) 2.01 kJ/m2 olarak uygulanmıştır. Kurutma 70 °C de kayısıların nem içeriği %19’a düşünceye kadar yapılmıştır. Araştırma Bulguları: Çalışma sonucunda Şekerpare çeşidinin diğer iki kayısı çeşidine göre başlangıç mikrobiyal yükünün açıkça daha yüksek olduğu görülmüştür. Ultraviyole ışık ve sıcak hava ile kurutma uygulamaları kayısıların yüzeyinde bulunan doğal mikroflorayı azaltmıştır. Bu azalma, sıcak hava ile kurutma uygulaması için sadece Şekerpare çeşidinde önemli bulunmuştur. Ultraviyole ışık uygulamasının etkisi maya ve küf açısından tüm çeşitlerde önemsizken, mezofilik ve psikrofilik aerobik bakteriler için sadece Şekerpare çeşidinde, toplam mikrobiyal yük için ise Şekerpare ve Hacıhaliloğlu çeşidinde önemli olmuştur. Ultraviyole ışık ve ardından sıcak hava ile kurutma uygulanması durumunda ise meydana gelen azalma mezofilik aerobik bakteriler ile maya ve küf sayıları açısından Şekerpare çeşidinde, psikrofilik aerobik bakteri sayıları ve toplam mikrobiyal yük açısından ise tüm çeşitlerde önemli bulunmuştur. Sonuç: En etkili yöntem UVC ve sıcak hava ile kurutma uygulamasının birlikte uygulanması olduğu sonucuna varılmıştır. Bu yöntemlerin ayrı ayrı kullanılması durumunda etkinlik sırasının değiştiği ve yapılan uygulamaların en fazla psikrofilik aerobik bakteri sayınının azaltılmasında etkili olduğu da tespit edilmiştir.

Techno-Economic analysis of CAZRI Solar Dryer

Apricot (Prunus armeniaca L.) is one of the major horticultural produce and an important source of income as well as livelihood in Ladakh, Himachal Pradesh and North-eastern part of India. However, it is also full of nutritional and functional health benefits. Despite all the advantages associated with the fruit, shorter shelf life is major hindrance in attaining its potential economic benefit to the farmers. Apricot drying is most common in these regions t raditionally done by the farmers. Solar dryer developed by ICAR-Central Arid Zone Research Institute (CAZRI) at its regional station, Leh is helping in extending shelf life of apricot and its availability throughout the year. This study was carried out during 2017–19 aimed to estimate the techno-economic benefit on adoption of the dryer by individual farmer or processor. It is found that adopter need to make investment of `1.10 lakh in fixed capital and requires `1.22 lakh annually to process one metric tonnes of the fruit. The annual cost of production was determined as `133,000 with depreciation of `11,000 for project of 1 metric tonne fresh fruit. Estimates indicate that adopter could generate net income of `78,000 annually. Profitability analysis yielded net profit ratio, pay-back period, benefit-cost ratio and break-even point of 37%, 1.23 years, 1.52, and 123.50 kg, respectively.

Hot air-assisted radio frequency drying of apricots: Mathematical modeling study for process design.

Conventional hot air and solar energy processes have been used for apricot. These processes had adverse effects on the quality due to the longer process times, and this indicates the need for an innovative approach. Radio frequency (RF) processing has innovation potential for drying with its volumetric heating feature, but an optimal process should be designed for process efficiency in industrial-scale applications. Therefore, the objective of this study was to confirm the RF process for industrial-scale apricot drying. For this purpose, a mathematical model was developed to predict temperature and moisture content change of apricots during drying, and experimental validation study was carried out. For the RF drying process, pre-dried apricots (0.58-0.75kg water/kg dry matter, db) by solar energy were used. The purpose was to start the RF process at a suitable moisture content level as this process was not feasible to apply directly due to the high initial moisture content of apricots (up to 4kg water/kg dry matter, db). RF drying experiments were carried out in a 10kW hot air-assisted (50-60°C) staggered through electrode system. Optimum electrode gap was 81mm with 2500V potential of the charged electrode. Final moisture content of the dried apricots was 0.25-0.33kg water/kg dry matter (db). Following the model validation for temperature and moisture content change, industrial-scale apricot drying scenarios were demonstrated to confirm the RF process for feasibility and process design. PRACTICAL APPLICATION: A comprehensive mathematical model was developed for radio frequency (RF) drying of apricots. This model was experimentally validated with respect to the temperature and moisture content change. Various process design studies were carried out for an industrial-scale apricot drying process to confirm the process feasibility. With this background, the results of this study can be directly used in an industrial drying for an optimal process design and energy efficiency.

Kayısıların Farklı Ortamlarda Kurutma Kinetiğinin İncelenmesi

In this study, Çöloğlu, Hacıhaliloğlu, Kabaaşı and Karacabey apricot species grown in Malatya province of Turkey were used. The effects of various drying environment on the drying kinetics of crude and pre-treated apricots have been investigated. The experiments were conducted in the sunlight and in the shade environment with SO2 treated and untreated apricot. While the drying speed curves of the dried apricots increased rapidly at the beginning, the drying speed curve started to decrease afterwards. The data was fitted to five different mathematical models. Midilli et al. model was determined as the best one to explain drying of apricots by comparing the coefficient of correlation determination (R2), mean absolute percentage error (MAPE) and root mean square error (RMSE) between the observed and expected moisture ratios.

The suitability of apricot for dried fruit production by the combined technology

The apricot is considered as one of the most delicious temperate fruit, a highly appreciated stone fruit and a valuable raw material for processing. The Republic of Serbia is one of the leading apricot producers in Southeast Europe, but the assortment is limited by a small number of cultivars harvested, mostly in the ripening season of ?Magyar kajszi?. In order to introduce the most suitable cultivars in the production, having high yield and high quality for consumption and various forms of processing, introduced and domestic cultivars have been intensively studied. In Serbia, apricots are mostly marketed fresh and processed for jams and spirits, but demand for high-quality dried fruits is increasing. To preserve the nutritional and sensory quality of fresh apricots, choosing the best drying technique is significant, and the most preferred technique is the reduction of moisture through convective drying. The aim of the paper was to compare the potential of the apricot cultivars ?Magyar kajszi?, ?Novosadska rodna?, ?NS-4? and ?NS-6? for dried fruit production by two-phase technology - combined osmotic and convective drying, as well as the profitability of apricot drying on small family farms. Cultivars ?NS-4? and ?Novosadska rodna? were found to be suitable for combined drying technology. The highest score in the sensory evaluation of the dried apricots was given to ?NS-4?, and then to ?Novosadska rodna?. The results indicate that the combined osmotic and convective drying of apricot rather than selling fresh fruits can be a profitable and important added value tool for small family farms.

Optimization of Convective Drying of Apricots

The purpose of this study is to realize multi-criterial optimization of the parameters of apricot drying. The drying experiments were conducted at a temperature of T=50÷80°C and velocity of ν=0.5÷2m/s of the drying agent. The dependence of the modified Page model’s parameters to the temperature and the velocity of the drying agent were obtained. The impact of the drying parameters on the quality indicators colour, β-carotene and vitamin С content in the dried apricots was studied. The optimal values of the drying parameters were determined applying different criteria: the quality of the final product, the quality of the final product and process duration, the quality of the final product and minimum energy consumption. The optimal values of the temperature and velocity of the drying agent according the criteria for the quality of the final product, the process duration and the energy consumption are T=63.5°C and ν=0.5m/s.

Influence of pre-treatment on the drying process of apricots

ABSTRACT- Drying has been used for the preservation of fruits since ancient times. Dried apricot reduces the damages, weight and volume losses, packaging space, storage and handling costs. In this paper, the effects of hot air dryer on an Iranian apricot cultivar ”Noori” have been investigated. The experiment was conducted at three temperatures (30, 40 and 50oC), three fruit thicknesses (5, 10 and 15 mm) and two pre-treatments (sulphur dioxide and water soluble sodium meta-bisulphite (Na2S2O5)). Based on the analysis of variance, the effects of temperature, thickness, pre-treatment and their interactions on drying time were significant (P<1%). It was revealed that water soluble reduced drying time more than sulphur dioxide. The data was fitted to eight different mathematical models. Page model was determined as the best one to explain thin layer drying of apricots by comparing the coefficient of correlation determination(R), chi-square ( ) and root mean square error (RMSE) between the observed and expected moisture ratios.

Improving the Sun Drying of Apricots (Prunus armeniaca) with Photo-Selective Dryer Cabinet Materials.

Photo-selective materials have been studied for their effects on the preharvest quality of horticultural crops, but little work has been done on potential postharvest processing effects. The aim of this work was to characterize the effects of 5 different photo-selective acrylic materials (used as the lid to a single-layer sun drying cabinet) on the drying rate and quality of apricots (Prunus armeniaca). Photo-selective cabinet materials that transmit light in the visible portion of the solar spectrum accelerate the apricots' drying rate in both the early period of drying and the course of drying as a whole. These materials do not significantly affect the measured quality metrics during the first day of sun drying. However, when drying is taken to completion, some minor but significant quality differences are observed. Infrared-blocking material produces dried apricot with lower red color, compared to clear, opaque black, and ultraviolet-blocking materials. Clear material produced dried apricot with significantly lower antioxidant activity, compared to black and infrared-blocking materials. Using appropriate photo-selective drying cabinet materials can reduce the required sun drying time for apricots by 1 to 2 d, compared with fully shaded drying. Ultraviolet-blocking material is recommended to maximize drying rate and minimize quality degradation.

Optimization of Hemicellulose Coating as Applied to Apricot Drying and Comparison with Chitosan Coating and Sulfite Treatment

AbstractDrying of hemicellulose‐coated apricots was compared to sulfuring and chitosan coating. Air velocity, temperature and hemicellulose concentration were optimized using the Box–Behnken response surface methodology against total color change (ΔE*), yellowness (Δb*) and final moisture content. Drying kinetics were evaluated by Newton, Page and Logarithmic models. Diffusion coefficient, activation energy and rehydration rate were calculated. The optimal drying conditions were found as 1 m/s of air velocity, 80C of air temperature and 3% (w/v) hemicellulose coating, which gave values of 15.2, −8.3 and 26% for ΔE*, Δb* and final moisture, respectively. The hemicellulose‐coated apricots indicated better color values than the uncoated and chitosan‐coated samples, while sulfuring still attained the best color values. Drying kinetics were best described by the Logarithmic model at 60 and 70C and Page model at 80C for 2% hemicellulose coating. Effective diffusion coefficients ranged from 2.499 to 5.742 × 10−9 and the activation energy was calculated as 33.78 kJ/mol. The hemicellulose‐coated apricots had slightly higher rehydration rate than the uncoated and sulfured samples. In conclusion, hemicellulose coating showed a promise for use in fruit drying.Practical ApplicationsTreatment of fruits with sulfur compounds (sulfur dioxide gas, sulfite solutions, etc.) prior to drying is a common practice to minimize loss in the quality of the dried fruit. In fact, use of these chemicals in foods is limited and the allowed concentration varies with countries worldwide in the range of 300–2,000 mg/kg. Because sulfur compounds can cause health problems, use of natural, renewable and abundant preservatives will be a viable alternative. In this respect, hemicellulose extracted from agricultural and food wastes can provide a low‐cost preservative and can be utilized to preserve fruits during drying. The results of this study will also provide a basis to utilize hemicellulose in various fruits other than apricots during drying and meanwhile will help reduce the concentration of sulfur compounds in foods.

Mathematical modelling of thin layer hot air drying of apricot with combined heat and power dryer.

In this study thermal energy of an engine was used to dry apricot. For this purpose, experiments were conducted on thin layer drying apricot with combined heat and power dryer, in a laboratory dryer. The drying experiments were carried out for four levels of engine output power (25%, 50%, 75% and full load), producing temperatures of 50, 60, 70, and 80° C in drying chamber respectively. The air velocity in drying chamber was about 0.5 ± 0.05m/s. Different mathematical models were evaluated to predict the behavior of apricot drying in a combined heat and power dryer. Conventional statistical equations namely modeling efficiency (EF), Root mean square error (RMSE) and chi-square (χ2) were also used to determine the most suitable model. Assessments indicated that the Logarithmic model considering the values of EF = 0.998746, χ 2 = 0.000120 and RMSE = 0.004772, shows the best treatment of drying apricot with combined heat and power dryer among eleven models were used in this study. The average values of effective diffusivity ranged 1.6260 × 10(-9) to 4.3612 × 10(-9)m2/s for drying apricot at air temperatures between 50 and 80°C and at the air flow rate of 0.5 ± 0.05m/s; the values of Deff increased with the increase of drying temperature the effective diffusivities in the second falling rate period were about eight times greater than that in the first falling rate period.

Degradation of Carotenoids in Apricot (Prunus armeniaca L.) During Drying Process

Carotenoids are natural compounds whose nutritional importance comes from the provitamin A activity of some of them and their protection against several serious human disorders. The degradation of carotenoids was investigated during apricot drying by microwave and convective hot-air at 60 and 70 °C. Seven carotenoids were identified: antheraxanthin, lutein, zeaxanthin, β-cryptoxanthin, 13-cis-β-carotene, all-trans-β-carotene and 9-cis-β-carotene; among these, all-trans-β-carotene was found to be about 50 % of total carotenoids. First-order kinetic models were found to better describe all-trans-β-carotene reduction during drying, with a degradation rate constant (k1) that increased two folds when temperatures increased by 10 °C, in both methods. No differences were found in k1 between apricots dried by hot air at 70 °C (k1 = 0.0340 h(-1)) and by microwave at 60 °C. The evolution of total carotenoids (117.1 mg/kg on dry basis) during drying highlighted a wider decrease (about 50%) when microwave heating was employed, for both set temperatures. Antheraxantin was found to be the carotenoid most susceptible to heat, disappearing at 6 h during both trials with microwave as well as during convective hot-air at 70 °C. For this reason, antheraxanthin could be a useful marker for the evaluation of thermal damage due to the drying process. Also the degree of isomerization of all-trans-β-carotene could be a useful marker for the evaluation of the drying process.

Apricot drying: preservation technique currently practiced in Ladakh, India

Apricot drying: preservation technique currently practiced in Ladakh, India

Determining of moisture diffusivity and activation energy in drying of apricots

In this study, Fick’s second law was used as a major equation to calculate the moisture diffusivity for apricot fruit with some simplification. Drying experiments were carried out at the air temperatures of 40, 50, 60, 70, and 80°C and the drying air velocity of 1, 1.5 and 2 m/s. The experimental drying curves showed only a falling drying rate period. The calculated value of the moisture diffusivity varied from 1.7 × 10&lt;sup&gt;–10&lt;/sup&gt; to 1.15 × 10&lt;sup&gt;–9&lt;/sup&gt; m&lt;sup&gt;2&lt;/sup&gt;/s for apricot fruit, and the value of activation energy ranged from 29.35 to 33.78 kJ/mol at different velocities of air.

Mathematical modelling of a thin layer drying of apricots in a solar energized rotary dryer

In this paper we present a mathematical modelling of a thin layer forced solar drying of apricots. An indirect forced convection solar dryer consisting of a solar heater and a rotary column cylindrical drying (RCCD) cabinet was used in the experiments. Air heated by the solar air heater was forced through the apricots by an electrical fan. Moreover, the natural sun drying experiments were conducted for the comparison at the same time. Fourteen different thin layer mathematical drying models were compared according to their coefficients of determination (r,χ2, RMSE) to estimate solar drying curves. The effects of the drying air temperature, velocity and the rotation speed of column on the drying model constants and coefficients were predicted by multiple regressions using a linear type model. Copyright © 2004 John Wiley & Sons, Ltd.

Energy and exergy analyses of drying of apricots in a rotary solar dryer

This paper presents the energy and exergy analyses of the drying process of apricots in a rotary column cylindrical drying (RCCD) cabinet. For these purposes, all stages of the drying process, considered as a steady-flow thermodynamic system, were analysed. Using the first law of thermodynamics, energy analysis was carried out to estimate the amounts of energy gained from solar air collectors and the ratios of energy utilisation. However, exergy analysis was accomplished to determine the type and magnitude of exergy losses during the solar drying process by applying the second law of thermodynamics. It was observed that the apricot samples sufficiently dried in the range 38-57.8°C drying air temperature and 20.5-49.7% relative humidity, at 2.3 ms-1 of drying air velocity and 2.25 rpm rotary speed of column in 76 h despite exergy losses of 0.1370-0.5612 kJkg-1.

Integration of a desiccant unit in crops solar drying installation: optimization by numerical simulation

An adsorption unit of silica gel is designed and integrated in a crops solar drying installation. The installation consists of a direct flat plate forced convective solar dryer connected with a similar solar collector. The daily sorption cycle of the desiccant unit is first investigated and a suitable coupling of the collector, the dryer and the adsorption unit has been selected. The coupling is numerically simulated and applied to the drying of apricots in Morocco under real climatic conditions. The mathematical model assumes non-isothermal processes and employs the basic balances of heat and mass transfer. The developed non-linear partial differential equations were solved by finite difference methods and the physical and operational parameters of the installation were numerically optimized. The integration of the adsorption unit allowed improving the quality of the dried product and permitted a cyclic operation of drying over two days by reducing the drying period from 52 to 44 h.

Drying of apricots in a rotary column cylindrical dryer (RCCD) supported with solar energy

Rapid deterioration of fruits and vegetables necessitates their consumption in a limited area. The solutions to this problem may be provided by technological precautions, which not only increase economic efficiency but also motivates agricultural developments. Among the technological operations applied to increase the market life of the foods, drying operation is of prime importance which is applicable to almost all the agricultural products. In this work, drying of apricots in a newly developed rotary column cylindrical dryer (RCCD) equipped with a specially designed air solar collector (ASC) was investigated to find optimum drying air rate and rotation speed of dryer, to maintain uniform and hygienic drying conditions and to reduce drying times. For this purpose, the changes in the moisture contents of the Sugarpiece (Şekerpare) foods were studied. Drying is an operation of prime importance used for almost all the agricultural products. Type apricots dried in the present dryer were compared to those of the same type apricots dried open on the ground. It was shown that co-operation of RCCD and ASC increased drying rate, reduced drying times and rotation of drying chamber provided gains in both time and labour.