This study investigates the effects of five drying methods-freeze, vacuum, microwave, convective, and natural-on the nutritional and visual quality of kiwifruit, focusing on the vitamin C, B-group vitamins, fat-soluble vitamins, and carotenoids. Fresh samples contained 5.57 mg/g ascorbic acid, and freeze drying retained the highest level (3.13 mg/g), followed by vacuum drying (2.63 mg/g), while natural and convective drying resulted in severe reductions (1.06 and 1.21 mg/g). Riboflavin, initially 1.59 mu g/g, decreased to 0.91 mu g/g after freeze drying, 0.82 mu g/g after vacuum drying, and 0.54 mu g/g under natural drying. Carotenoids followed similar trends, with beta-carotene declining from 2.88 mu g/g in fresh samples to 2.24 mu g/g after freeze drying and below 1 mu g/g with natural drying. Freeze and vacuum drying best preserved vitamin content and color by minimizing oxidation and thermal damage, whereas natural and convective drying led to greater losses due to prolonged heat exposure and oxidative stress. Color changes strongly correlated with nutrient degradation. Notably, Delta E was negatively associated with ascorbic acid (-0.96) and thiamine (-0.95), while hue angle correlated positively with carotenoids and fat-soluble vitamins. These results show that color parameters reliably indicate nutritional retention, offering a practical approach for quality assessment in dried fruits.

In the study, medlar samples were dried using natural drying in the shade at 25 °C, convective drying at 40, 50, and 60 °C, microwave drying at 200, 400, and 600 W, and combined drying with a combination of convective drying temperatures and microwave output powers. In order to precisely determine the effect of the method used, each drying technique was considered in a comprehensive framework. The moisture content of medlar was reduced from 74.07 to 11.75%. While the drying process took the longest time in shade drying, the drying process took the shortest time at 600 W–60 °C. The closest results to fresh product in terms of total protein content were found at 400 W. In addition, phosphorus, potassium, sodium and copper contents were maximised at 600 W–60 °C. The maximum contents for magnesium and manganese were 400 W–40 °C, while for zinc, it was 600 W–40 °C. After fresh products, the highest calcium was obtained at 600 W, and the highest iron was obtained at 200 W. The bioactive potential of medlar samples was evaluated in terms of extractable, hydrolysable and bioaccessible phenolic fractions by total phenolic content and antioxidant capacity assays. In terms of TPC, the bioaccessibility of the samples was highest when natural drying was used. The highest bioaccessibility values for ABTS, DPPH and CUPRAC were obtained at natural drying, 200 W–50 °C and 400 W–60 °C, respectively. As a result, DPPH was the most suitable antioxidant capacity determination method due to high results.

Food constituents, particularly antioxidants, vitamins, proteins, fibers, and macro-and micronutrients, are closely linked to the superior quality and desirable sensory attributes of food products, and their composition is influenced by drying methods. Food quality is traditionally assessed using chromatography or chemical analysis methods.Although these techniques provide accurate results, they are time-consuming, labor-intensive, costly, and produce chemical waste. The food industry demands rapid, cost-effective, non-destructive, and chemical-free analytical techniques. Color parameters linked to food quality have contributed significantly to the advancement of colorimetric analytical techniques. This study evaluated the effects of microwave (MD) (0.5 and 1.5 W/g), convective (CD) (50 and 80 degrees C), and vacuum (VD) (100 mmHg at 60 and 80 degrees C) drying methods on the final quality and color of chili peppers. In addition, the potential of predicting the nutritional composition of the dried samples through their color parameters was assessed. Results demonstrated that the highest values for color parameters, vitamins B1, B3, B5, B6, beta-carotene, lutein & zeaxanthin, vitamin c, as well as for protein, P, Ca, Mg, Cu, and Zn, were obtained with MD at 1.5 W/g. Successful PLSR models were developed for predicting vitamins, proteins, and macro-and micro-nutrients using L * a * b * Ch color models. The highest prediction accuracies were found for vitamin K (R2val = 0.86, RMSEP = 0.07 ppm), vitamin B6 (R2val = 0.83, RMSEP = 2.58 ppm), and Cu (R2val = 0.82, RMSEP = 0.64 ppm). Consequently, drying processes have a significant impact on both the final food quality and color parameters; moreover, quality parameters exhibit a strong correlation with color values. The study results indicated that determining food quality parameters through color measurements represents a promising approach.

Drying of foods is a complex process where heat and mass transfer occur simultaneously, accompanied by a reduction in volume. The penetration of continuous heat energy applied during food drying plays a significant role in inducing thermal stresses in the food. Moreover, drying is crucial in removing water with a heterogeneous distribution from the food, impacting the final food quality. Therefore, it is essential to assess and validate the effects of drying practices on the quality of foods with high nutritional value and economic significance foods obtained by organic farming are more nutritious and of higher quality compared to conventional. Although the regulations define certain rules and limits in the cultivation stage of organic foods, there are deficiencies in the definitions and rules regarding the sustainability of quality in the processing stage of these foods. This review article aims to examine the physical and chemical traits of dried organic foods, including their vitamin content, antioxidant properties, color, and texture components. The available evidence on the beneficial effects of different power and temperature levels applied with various drying systems on quality parameters in foods is reported and discussed. The results of this research indicate that the use of freeze, infrared, and intermittent microwave drying methods can lead to improved quality of the final dried foods. However, it is crucial to emphasize that the effectiveness of these techniques may vary depending on the physicochemical properties of the foods and the specific drying conditions employed. This review highlights the various drying methods that can be employed to enhance the quality of organic foods, while considering the experimental factors that can impact their processing characteristics and quality attributes.

This study focused on the change in the quality parameters of rosehip fruits by different drying methods selected in a broad spectrum ranging from very long to concise duration. While natural and convective drying methods had a very long duration, with 9360 and 1080 min, respectively, microwave drying at 100 W had a relatively long duration, with 364 min. Microwave drying at 300 and 500 W represented medium-duration drying methods with 162 and 77 min; however, 700 and 1000 W were referred to as short-duration drying methods with 45 and 21 min. Among the drying methods, the highest concentrations of K, Mg, Na, Fe, total protein, ascorbic acid, niacin, and pantothenic acid were obtained with 10730, 1867, 446, 27.5, 53596, 10590, 63.1, and 35.1 mg/kg at 500 W, defined as a short duration method. For P, Ca, Cu, Mn, Zn, thiamin, pyridoxine, beta-carotene, tocopherol, lycopene, lutein, and zeaxanthin, 700 W, that is the concise duration technique, was the closest drying method to fresh samples with 1382, 6480, 4.19, 76.3, 8.09, 0.78, 75.3, 238, 278, 60.1, and 17.5 mg/kg, respectively. Unlike short-duration methods, natural drying, convective drying at 50 degrees C, and microwave drying at 100 W caused extreme decreases for all biochemical parameters. Consequently, microwave drying at 500 and 700 W was highly convenient for maintaining the quality parameters at the maximum level and saving time in drying the rose hips, which took a short time to harvest.

In the study, seven microalgae species called Nitzschia sp., Nannochloropsis sp., Botryococcus braunii, Neochloris oleoabundans, Schizochytrium sp., Chlorella vulgaris L., and Chlorella variabiilis L. were dried by four drying methods: spray, convective, vacuum, and microwave. Biodiesel was produced from dried microalgae via transesterification.The vegetable oil yield was the maximum in spray and vacuum dried Schizochytrium with 35.50 and %34.53, respectively. Similarly, the highest biodiesel yield with 100% was obtained in Schizochytrium dried by spray technique. However, the cloud point of -1.77 degrees C was the lowest in Botryococcus braunii samples dehydrated by microwave drying. The highest pour point with -10.13 degrees C was obtained in microwave dried Chlorella variabilis samples, but the maximum freezing point was found in the microwave and convective dried samples of Chlorella variabilis with -13.60 and -13.70 degrees C, respectively. The lowest water content was measured in biodiesel samples from Botryococcus braunii, Chlorella vulgaris, and Chlorella variabilis dried by microwave technique. However, the best results regarding calorific value were found in Schizochytrium samples dried by spray and vacuum. The viscosity with 6.08 mm2 s-1 and density with 0.90 g cm-3 of Botryococcus braunii dried by the microwave method were at the maximum.Interestingly, two species commonly used in biodiesel production, Chlorella vulgaris and Chlorella variabilis, could not meet the expectations regarding quality parameters. Also, Schizochytrium and Nitzschia were determined as the most suitable microalgae species for the quality standards for biodiesel production. Compared to the others, the most successful results were obtained in the biodiesel produced from Schizochytrium dried spray drying.

Coriander leaves were weighed at 20 ± 0.02 g and dried with natural drying at shade, convective drying at 50°C and 1 m s-1 air velocity, and microwave drying at 200 and 800 W. The drying periods were led 4680, 630, 85, and 16.50 minutes for natural, 50°C, 200 W, and 800 W, respectively. Whereas energy consumption was not recorded in natural drying, energy consumption at 50°C, 200 W, and 800 W was recorded as 10.290, 0.283, and 0.220 kWh, respectively. The closest results to fresh leaves in terms of color parameters were measured at 800 W, followed by 200 W. Similarly, at 800 and 200 W, the most successful results were obtained with regard to calcium, magnesium, and iron. Also, it was analyzed that the chlorophyll content, protein, phosphorus, potassium, and zinc were preserved at the maximum level in the 800 W microwave drying method. Although all drying methods cause similar reductions for sodium, it was determined that manganese was well preserved at 200 W. Among the dried samples, the highest copper level was analyzed in natural drying and microwave drying at 800 W. To sum up, the most convenient drying technique for coriander leaves was 800 W in terms of drying and quality parameters.

In this research, persimmon samples (sliced, pureed) were dehydrated by convective (50 and 100 °C) and microwave (100 W) drying techniques with different pre-treatment combinations of sugar addition (25

In the study, we examined in detail the effect of dehydrating using natural drying in the shade, convection drying, and microwave drying, which are the most widely used techniques, especially for tea and spices, both in practice and in theory, on the protein, and mineral composition of rosemary leaves. Also, we determined the color parameters, which are the reason for the selection because it creates the allure for spices. In microwave drying at 600 W, we obtained results close to fresh rosemary in all color parameters, especially brightness and greenness. Although natural drying, which does not have any energy and investment costs, is the second-best method in terms of color, 50 °C, which is the most common drying technique in the market, caused significant color losses affecting the commercial value of the product. We reached the closest protein and P, Ca, Mg, Fe, Zn, Mn, and contents to fresh products in dried ones at 600 W. In contrast, in K only, the highest measurement was at 200 W. Strikingly, we observed dramatic losses reducing the benefit obtained from the product regarding protein and almost all nutrients in both convective and natural drying techniques, the most common methods in practice.

In this study, two different 55-kW powered agricultural tractors of the same make and model were operated for 1000 h under similar field conditions, one using diesel fuel (DF) and the other a fuel blend of 20% biodiesel-80% diesel (B20). By the end of 1000 h of operation, the performance values of the B20 fuel were determined to be 3% lower than for the DF. Although the values of CO (40%), HC (40%), and PM (46%) were lower than those of DF, the NOx (7%) was determined to be higher, as expected. Each injector needle and nozzle tip was examined in terms of a functional evaluation via visual inspection, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). According to the analyses, the B20 fuel blend C content was determined to be 73.47% and its O content 23.34%, with the quantity of the other elements lower than 1%. Similarly, for DF, the C content was determined to be 50.49% and that of O 19.95%, with the other elements in trace amounts. Furthermore, Fourier-transform infrared spectroscopy (FTIR) spectral analysis was used to examine the deposits on the injector nozzle tips and needles. Polyisobutylene succinimide (PIBSI) and inorganic components were observed on the injector needles, whereas aging products and inorganic components were seen on the injector nozzle tips. No significant difference was found between the results of the DF and B20 fuels in terms of injector nozzle function.

Cornelian cherry was dehydrated using different drying techniques: namely natural, microwave, convective, and combined drying. The moisture content of cornelian cherry was reduced from 72.56% to 10.27%. The color parameters closest to the fresh samples were measured at 50 degrees C, 70 degrees C, 90 degrees C, and at 100 and 300 W. Both fresh and dried cornelian cherries show high antioxidant capacity and comprise of various polyphenolic compounds. TEACCUPRAC is the most suitable method for determining the total antioxidant capacity of cornelian cherry. We measured the total anthocyanin content closest to the fresh cornelian cherry with 2.62 and 2.11 mg (CDE) g-1 (dw) at 70 degrees C and 300 W. Also, we found the closest vitamin C to the fresh ones with values of 25.02 and 20.08 mg 100 g-1 (fw) at 300 and 500 W. Generally, the suitable drying technique in terms of physical parameters and phytochemical compounds was the microwave drying at 300 W.

In this study, blueberry fruit was dried using different thin-layer drying methods, namely, natural drying, microwave drying, convective drying, and combined microwave-convective drying. The moisture content of blueberries initially at 84.76 +/- 0.20% w. b. was reduced to 10.03 +/- 0.09% w. b. Although the drying time ranged from 340 to 3540 min in convective drying, this period was completed between 64 and 198 min in microwave drying. Also, the natural drying period continued for 22 days. It was determined that the convective drying, which was completed for the longest time, also caused the most energy consumption compared to other drying methods. The color parameters closest to fresh blueberries were obtained at 50 degrees C, 70 degrees C, 90 degrees C at convective drying, and 300 and 500 W in microwave drying. The study concludes that blueberries show a high antioxidant capacity and comprise various amounts of polyphenols compounds. Moreover, for the total antioxidant capacity, CUPRAC is the most suitable method. The anthocyanin and vitamin C content also showed high values for blueberries. In general, it was determined that the best drying method in terms of color parameters, antioxidant capacity, anthocyanin content, and ascorbic acid content was the microwave drying method at 300 W with drying time at 82 min and 500 W with drying time at 64 min.

Kuru baza göre başlangıç nemi %83,95 ± 0,01 y.b. (5,24 ± 0,003 kg su kg KM-1) olan 100 ± 0,10 g ağırlığındaki Deveci armudu dilimleri (Pyrus communis L. cv. Deveci) son nemi %11,40 ± 0,06 y.b. (0,13 ± 0,001 kg su kg KM-1) değerine ulaşıncaya dek gölgede kurutma, 60, 80 ve 100°C‘de sıcak havayla kurutma yöntemleriyle kurutulmuş ve bu yöntemlerin kurutma süreçleri sırasıyla 11150, 437, 252 ve 148 dakikada tamamlanmıştır. Çalışmada deneysel olarak elde edilen zamana bağlı ayrılabilir nem oranı değerleri yirmi farklı ince tabaka kurutma eşitliği kullanılarak modellenmiştir. Buna göre 60°C ve 100°C için deneysel verilere en yakın sonuçları veren modelin Modified Henderson & Pabis eşitliği olduğu; buna karşın gölgede kurutma ve 80°C‘de kurutma yöntemlerinde ise sırasıyla Alibas eşitliğinin ve Jena & Das eşitliğinin en iyi modeller olduğu görülmüştür. Gölgede kurutma yönteminde her hangi bir enerji tüketimi olmamasına karşın bu yöntemin oldukça uzun olması ve ürünün kalite parametreleri üzerinde olumsuz etkilere yol açması gibi nedenler Deveci armudunun kurutulmasında gölgede kurutma yönteminin kullanışlı bir yöntem olmadığını ortaya koymuştur. Bununla birlikte toplam enerji tüketiminin kurutma sıcaklığının artmasıyla yükseldiği görülmüştür. Ayrıca sıcaklık artışının kalite parametrelerini de olumsuz etkilediği tespit edilmiştir. Kurutma süresi ve özgül enerji tüketimi gibi işletim parametrelerinin yanı sıra parlaklık, kırmızılık, sarılık, kroma, hue açısı, toplam renk değişimi ve kahverengileşme indeksi gibi kalite parametrelerinin taze ürüne oldukça yakın olmasından dolayı 60°C‘de sıcak havayla kurutma yönteminin Deveci armudunun kurutulması için uygun bir yöntem olduğu görülmüştür.

We dried the orange slices massed 100 ± 0.10 g from the initial moisture content of 6.97 ± 0.02 kg water kg DM −1 to the final moisture ones of 0.12 ± 0.01 kg water kg DM −1 using two different drying methods defined as convective drying at 50, 75, 100, and 125 °C along with microwave drying at eight output power between 90 and 1000 W. In the study, we measured the drying methods' energy consumption and observed that the microwave drying method's energy consumption was very low at high and low powers. Also, we modeled the results using twenty-one different thin-layer drying equations and obtained results closest to experimental data with the modified Henderson and Pabis equation for all powers in microwave drying and all temperatures in convective drying. We calculated both effective moisture diffusivities and activation energy using the drying data. Some thermal properties such as specific heat, thermal conductivity, thermal diffusivity, and thermal effusivity were calculated and recorded to be decreasing in all thermal properties with drying. Also, we measured the color parameters known as L, a, b, C, α°, and ΔE, browning index (BI), whitening index (WI), and vitamin C (ascorbic acid) in the study. We concluded that the most suitable drying method is microwave drying at medium powers of 350 and 500 W by considering both drying and quality parameters.

Purple basil leaves dried with natural drying, which was the traditional method, convective drying at 50celcius, which was the most common method, and microwave drying at 200, 600, and 1,000 W, which were low, medium, and high powers. The drying processes lasted 4,320, 195, 48, 25, and 14 min for natural, 50celcius, 200, 600, and 1,000 W, respectively. The most convenient color parameters and chlorophyll concentration to the fresh product were obtained at natural drying. While all drying methods were very close to fresh products regarding protein content; natural drying, 50celcius, and 1,000 W were found to have the highest concentration regarding P and K. Contrarily, 200 and 600 W were suitable for Ca and Mg conservation. The drying methods in which Na, Fe, Cu, Mn, and Zn reached the maximum were natural, 1,000, 600, 200 W, and 50celcius, respectively. Novelty impact statement This study is the first and merely study in the literature that examines the effect of drying methods on color parameters, nutrients, and protein content of purple basil leaves. In this respect, the study constitutes a profile in terms of revealing the nutritional aspect of dried purple basil.

In the present study, thyme leaves weighing 20 +/- 0.02 g were dried from the initial moisture of 76.07% +/- 0.06% to the final moisture of 9.05% +/- 0.76% via natural drying, convective drying at 50 degrees C, and microwave drying at 200, 600, and 1,000 W. The closest color parameters to the fresh product were found in the natural drying, followed by 600 and 1,000 W. The highest chlorophyll content had found at natural drying, 1,000 and 600 W, respectively. Microwave drying at 600 W maximally protected the macro and micronutrients, followed by natural drying and 1,000 W. The highest total phenolic and flavonoid content was measured at 200 W, followed by 600 W and 50 degrees C, respectively. In the study, the microwave drying method at 600 W was the most successful in terms of the drying period, color parameters, chlorophyll concentration, and nutrients. Novelty impact statement For the first time, the color, chlorophyll, nutritional element, total phenolic, and flavonoids of dried thyme plants were examined in detail altogether. In the light of the quality parameters, which were examined, a data profile was created for dried thyme leaves in comparison with the fresh product.

In this study, basil leaves were dried using natural, microwave-, and convective-drying methods from an initial moisture content of 90.90 +/- 0.1 % to a final one of 8.21 +/- 0.12 %. The natural drying was done in a controlled room at a temperature of 25 +/- 1 degrees C and relative humidity of 60 +/- 5 %. The microwave-drying processes were performed using 100, 300, 500, 700, and 900 W microwave output powers, while 50 degrees C was used in convective-drying. The drying periods of different drying methods lasted between 16.5 and 1620 min. Consequently, the best drying method regarding drying period, energy consumption, protein amount, macronutrients (Cu, Zn, Fe, Mn and B), micronutrients (Cu, Zn, Fe, Mn and B), water-soluble vitamins (ascorbic acid, Vitamin B3 and Vitamin B6), fat-soluble vitamins (beta-carotene, Vitamin E, and Vitamin K), color parameters (L, a, b, C and alpha) and chlorophyll concentration was determined to be microwave-drying at 700 W.

Green apple peels, (25.06 +/- 0.06 g) with the moisture content of 3.05 +/- 0.02 [kg (moisture) kg(-1) (dry matter)], were dried using two dehydration methods, microwave, and natural drying until moisture content of apple peels was reduced to 0.092 +/- 0.001 [kg (moisture) kg(-1) (dry matter)]. Microwave drying periods at 1,000, 800, 600, and 400 W lasted for 17, 21, 27, and 33 min, respectively; whereas, natural drying lasted for 66 hr. The scope of this study, a comparison of measurements of moisture with that of the predicted results was made, obtained from 21 thin layer drying models. For both 600 and 800 W microwave drying, Modified Henderson and Pabis's model; whereas, at 1,000 W, Alibas's model, and at 400 W, Modified Jena and Das's model were considered to be the most appropriate models. The most suitable drying process according to color parameters, chlorophyll content, and nutrients was obtained at 400 W microwave drying. Practical applications The herbal tea industry is growing globally and it is constanrly looking for new flavors that can attact consumers' attention. Herbal teas, in addition to being delicious, are required to meet the daily nutritional needs of the consumers. One of the drawbacks of drying is the loss of aroma and nutrients, moreover, drying operations carried out in open fields, such as sun drying, leads to contamination and can cause more harm than benefit. Thus, for food safety, it is very essential for herbal tea production facilities to use appropiriate methods to produce high-quality products. The present study on drying of apple peels for herbal tea contains important data on the selection of the most suitable drying method for the preservation of nutrients.

Parsley leaves (Petroselinum crispum L.) weighing 100 ± 0.09 g were dehydrated from moisture content of 82.24 ± 0.07% to 10.01 ± 0.02 % (wet basis) using the microwave (MD), convective (CD), solar oven (SOD), sun (SD) and natural (ND) drying. Drying in MD, CD, SOD, SD, and ND was completed at 18±1.15, 61±0.58, 255±10, 330±5.29, and 1530±11.55 min, respectively. The energy consumption of MD and CD was measured as 0.213±0.009 and 0.427±0.015 kWh, respectively. In microwave drying, 700 W microwave output power was applied while convective drying was used with 50°C temperature and 1m/s air velocity. The sun and solar oven drying processes were carried out under the same conditions at the same time. The average temperature of the system during the solar oven drying was 81.7±1.5°C whereas the airflow in the system was 0.5 m/s. The data obtained from the experiments were also modeled using twelve different thin-layer drying equations, and thus the theoretical data were obtained. According to these theoretical data, the best model in the microwave and natural drying was Alibas‘s equation while the most suitable model in the solar and convective drying was modified Henderson and Pabis‘s model. On the other hand, it was seen that the best model in the solar oven drying was the Page equation. As a result, considering both quality and drying parameters, it was determined that MD and SOD were the most suitable method for drying of parsley leaves.