Insight into the changes in active metabolite profiles of noni (Morinda citrifolia L.) fruit subjected to different drying treatments

Noni fruit is renowned for its abundance of bioactive compounds. Drying is an important method for processing functional products derived from noni. However, limited information exists on how drying methods affect the active metabolite profiles of noni fruit. This study investigated the impact of four common drying methods, including hot-air drying (HAD), vacuum freeze drying (VFD), microwave drying (MWD), and far infrared drying (FID), on the physicochemical indexes, bioactive components, and functional properties of dried noni fruit slices using targeted and untargeted metabonomics analysis. The results showed significant variations in appearance, water migration, and microstructure of dried noni fruit slices subjected to the four drying methods. VFD treatment yielded better dried noni fruit products when compared to other drying methods. The superiority of VFD treatment was due to its uniform stratification, reduced collapse, better retention of bioactive components and antioxidants, and higher enzyme inhibitory rates. These findings suggest that VFD method is ideal for obtaining premium bioactive profiles and maintaining the biological activity of noni fruit.

Drying kinetic, thermodynamic and quality analyses of infrared drying of truffle slices

Kinetic and thermodynamic parameters are the most important part for making a suitable tool for drying agricultural products. Moreover, calculation of the energy required for the drying of product, the properties of the rehydration ratio, the food appearance changes, and the evaluation of the microstructure of food are crucial. Since the thermodynamic properties of truffle slices have not yet been reported, this study aims to establish a mathematical model to describe drying process of agriculture product, evaluate the effective moisture diffusion coefficient (Deff), determining the activation energy (Ea) to elucidate the thermodynamic characteristics, measure color characteristics, and rehydration ratio (RR) during the drying process of truffle slices. Truffle slices were dried in an infrared (IR) dryer at four temperatures of 50-80°C and two thicknesses of 0.5 and 1 cm. The best model to describe the drying process of truffle slices was Midilli et al.'s model. The value of Deff, SEC, and RR were in the range of 3.06 × 10-8 to 2.48 × 10-7 m2/s, 79.68-191.271 kWh/kg, and 5.99-7.49, respectively. The Deff of truffle slices increased with the above-mentioned parameters of the samples. The Ea obtained was 26.62-27.43 kJ/mol. The results indicated that enthalpy and entropy decreased with increasing drying temperature, while Gibbs free energy improved. The enthalpy, entropy, and Gibbs free energy values changed between 24.48-25.28 kJ/mol, -130.47 to -122.63 J/mol °K, and 63.97-70.17 kJ/mol, respectively. In addition, the results of color attributes decreased with increasing temperature, while chroma oppositely increased.

A study into how thickness, infrared intensity, and airflow affect drying kinetics, modeling, activation energy, and quality attributes of apple slices using infrared dryer

Drying is a widely recognized process that reduces the need for storage and shipping weight, keeps free water out of the product, and prolongs its shelf life. An infrared dryer was designed to dry apples under different drying conditions. Apple slices of 6-, 4-, and 2-mm thicknesses were dried at intensities 0.130, 0.225, and 0.341 W/cm2 and airflow 1.0, 0.5, and 1.5 m/s. The dehydrating period was prolonged with higher airflow and shortened with higher infrared intensity (IR). The shortest dehydrating period was verified by 190 min at 0.341 W/cm2, 0.5 m/s under 2 mm thickness. Increasing the sample thickness from 2 to 4 mm and then to 6 mm resulted in an 84% and 192% increase in drying time, respectively. Dehydrated apples had water activity values ranging from 0.30 to 0.40. The shrinkage ratio increased with an increase in infrared radiation intensity. However, it decreased with an increase in air velocity, while the rehydration ratio decreased with an increase in radiation intensity and increased with an increase in air velocity. Regarding total color change, apple slice thickness was a major factor. The effective diffusivities varied between 2.6 and 9.0 𝗑10-10 m2/s under different drying conditions. The dehydrating curves of apples were best described by the model developed by Midilli et al.

Development and quality evaluation of polyphenols enriched black carrot (Daucus carota L.) powder incorporated bread

Black carrot is a prominent source of polyphenols and the cheapest source of anthocyanins in India. In this study, an attempt has been made to examine the feasibility of black carrot powder as an ingredient in bread. Black carrot bread was prepared by incorporating different concentrations of black carrot powder (BCP) at 2.5, 5.0, 7.5 and 10 %. The developed bread samples were analyzed for physical and textural quality, proximate composition, bioactive compounds, antioxidant properties, sensory characteristics, mineral content and storage quality. The results revealed that loaf volume and specific volume decreased (1995-1254 mL, 5.25-3.28 mL/g) with the incorporation of BCP into bread. Textural analysis revealed that the addition of BCP led to increased hardness in the bread (0.110-12 0.151 N), whereas the resilience (43.64-35.10 %), cohesion and springiness (89.930-13 82.146 %) decreased significantly. The content of bioactive compounds such as total phenols, anthocyanins (29.63-112.68 mg/100 g) and flavonoids increased to exceptionally high levels in BCP-incorporated bread and showed high antioxidant activity. Incorporation of BCP up to 7.5 % showed the most acceptable sensory analysis score (7.85) with a significant increase in dietary fiber (40 %) and total mineral content (50 %), which revealed that black carrot powder could be used up to 7.5 % as an ingredient into bread with high acceptability. The present study revealed significant enhancement in bioactive compounds and mineral content of bread after the incorporation of black carrot powder, which supports its immense potential in preventing hunger and oxidative stress-induced disorders in developing countries.

Heat source replacement strategy using catalytic infrared: A future for energy saving drying of fruits and vegetables

Drying is an important process for fruits and vegetables, which requires a lot of heat and the heat sources are mainly coal, electricity, natural gas, and solar energy. Most of the heat is usually wasted due to the long drying process and poor transfer efficiency. The use of coal also pollutes the environment. The national electricity curtailment policy regulates the drying industry. Therefore, the fruits and vegetables drying industry is facing new challenges due to its own development needs and external factors. Catalytic infrared drying (CIR) technology brings solutions to these problems. Compared with other drying technologies, CIR has a high drying efficiency and can effectively reduce the use of electric energy, avoid waste, and minimize pollution of water. However, improper processing conditions still cause quality deficits such as severe browning, and the drying is difficult due to weak infrared penetration. Although CIR has shortcomings, it is still expected to establish an energy-saving and efficient fruit and vegetable drying system.

Advances in prepared dish processing using efficient physical fields: A review

Prepared dishes are increasingly popular convenience food that can be eaten directly from hygienic packaging by heating. Physics field (PF) is food processing method built with physical processing technology, which has the characteristics of high efficiency and environmental safety. This review focuses on summarizing the application of PFs in prepared dishes, evaluating and comparing PFs through quality changes during processing and storage of prepared dishes. Currently, improving the quality and extending the shelf life of prepared dishes through thermal and non-thermal processing are the main modes of action of PFs. Most PFs show good potential in handing prepared dishes, but may also react poorly to some prepared dishes. In addition, the difficulty of precise control of processing conditions has led to research mostly at the laboratory stage, but as physical technology continues to break through, more PFs and multi-physical field will be promoted for commercial use in the future. This review contributes to a deeper understanding of the effect of PFs on prepared dishes, and provides theoretical reference and practical basis for future processing research in the development of various enhanced PFs.

Comparison of ultrasound and ethanol pretreatments before catalytic infrared drying on physicochemical properties, drying, and contamination of Chinese ginger (Zingiber officinale Roscoe)

This study aimed to investigate the effects of different pretreatment methods on the drying process and quality of catalytic infrared dried ginger slices, particularly the safety quality. Four different pretreatments strategies were used: sample submerged in distilled water, water + US pretreatment, ethanol pretreatment, and ethanol + US pretreatment. The results showed that all pretreatments reduced drying time, and sample pretreatment by ethanol + US had the highest drying efficiency, hardness, highest total phenolic content, and total flavonoid content retention. However, these pretreatments slightly decreased the rehydration ratio and gingerol content. The possible explanation for these results has been put forward by microstructure analysis. CIR-dried ginger samples were pretreated by four methods required by the agricultural standards of China. This study provides a new perspective on the commercial application of ethanol + US pretreatment for CIR-dried ginger slices.

Short- and Medium-Wave Infrared Drying of Cantaloupe (Cucumis melon L.) Slices: Drying Kinetics and Process Parameter Optimization

The main objective of the present work was to study the drying kinetics and obtain the optimum process parameters of cantaloupe slices using short-and medium-wave infrared radiation (SMIR) drying technology. The effect of three independent variables of infrared radiation temperature (55–65 °C), slice thickness (5–9 mm) and radiation distance (80–160 mm) on the L value, color difference (∆E), hardness and vitamin C content were investigated by using the Response Surface Methodology (RSM). The results showed that the Page model can adequately predict the moisture content between 55 and 65 °C (R2 > 0.99). The effective moisture diffusivity (Deff) varied from 5.26 × 10−10 to 2.09 × 10−9 m2/s and the activation energy (Ea) of the SMIR drying was 31.84 kJ/mol. Infrared radiation temperature and slice thickness exerted extremely significant effects on L value and color difference (ΔE) (p < 0.01), with higher infrared radiation temperature and thin slice thickness leading to a decrease in the L value and an increase in ΔE. Hardness and vitamin C content were significantly affected by infrared radiation temperature, slice thickness and radiation distance, of which the slice thickness was the most distinct factor affecting the hardness value. Higher infrared radiation temperature and larger slice thickness and radiation distance resulted in higher vitamin C degradation. For the given constraints (maximized vitamin C content and L value, minimized ΔE and hardness value), the optimum drying parameters were infrared radiation temperature 58.2 °C, slice thickness 6 mm and radiation distance 90 mm. Under the optimum drying combination conditions, the experimental values were 65.58 (L value), 8.57 (∆E), 10.49 N (hardness) and 106.58 mg/100 g (vitamin C content), respectively. This study is beneficial to the development of the cantaloupe food processing industry and provides more insights for the application of SMIR drying technology to improve the drying rate and product quality of cantaloupe.

Tri-frequency ultrasound as pretreatment to infrared drying of carrots: impact on enzyme inactivation, color changes, nutrition quality parameters and microstructures

The effects of tri-frequency ultrasound as pretreatment on the peroxidase (POD) inactivation and infrared drying attributes of carrots were studied in the temperature range of 60–80 °C. Thermosonication (TS) treatment reduced 65.21, 73.33 and 81.43% POD activity after 5 min for the temperatures at 60, 70 and 80 °C, respectively, which were all higher than hot water (HW) blanching treated samples. The first-order kinetics fitted well for the POD inactivation curves. Similar retention ranges of vitamin C (VC) were observed after TS (88.41–82.51%) and HW (91.91–88.75%) treatments at the studied range of temperatures. Compared to HW treated samples, drying times of thermosonicated carrot slices were shortened by 13.6, 15 and 15.8% for blanching temperatures at 60, 70 and 80 °C, respectively. The aid of ultrasound showed a positive effect on the rehydration ration (RR) of samples. Sonicated dried samples exhibited higher hardness compared with thermal dried samples. No significant variation (p > 0.05) in the total color difference (ΔE) was attained for dried carrot slices pretreated by TS and HW processes.

Parboiled Paddy Drying with Different Dryers: Thermodynamic and Quality Properties, Mathematical Modeling Using ANNs Assessment

The effect of hybrid infrared-convective (IRC), microwave (MIC) and infrared-convective-microwave (IRCM) drying methods on thermodynamic (drying kinetics, effective moisture diffusivity coefficient (D_eff), specific energy consumption (SEC)) and quality (head rice yield (HRY), color value and lightness) characteristics of parboiled rice samples were investigated in this study. Experimental data were fitted into empirical drying models to explain moisture ratio (MR) variations during drying. The Artificial Neural Network (ANN) method was applied to predict MR. The IRCM method provided shorter drying time (reduce percentage = 71%) than IRC (41%) and microwave (69%) methods. The D_eff of MIC drying (6.85 × 10⁻¹¹–4.32 × 10⁻¹⁰ m²/s) was found to be more than the observed in IRC (1.32 × 10⁻¹⁰–1.87 × 10⁻¹⁰ m²/s) and IRCM methods (1.58 × 10⁻¹¹–2.31 × 10⁻¹¹ m²/s). SEC decreased during drying. Microwave drying had the lowest SEC (0.457 MJ/kg) compared to other drying methods (with mean 28 MJ/kg). Aghbashlo’s model was found to be the best for MR prediction. According to the ANN results, the highest determination coefficient (R²) values for MR prediction in IRC, IRCM and MIC drying methods were 0.9993, 0.9995 and 0.9990, respectively. The HRY (from 60.2 to 74.07%) and the color value (from 18.08 to 19.63) increased with the drying process severity, thereby decreasing the lightness (from 57.74 to 62.17). The results of this research can be recommended for the selection of the best dryer for parboiled paddy. Best drying conditions in the study is related to the lowest dryer SEC and sample color value and the highest HRY and sample lightness.

Mathematical modelling of infrared-dried kiwifruit slices under natural and forced convection

In this work, the effect of the radiation intensity, slice thickness, and the distance between slices and infrared lamps under natural drying air and the effect of slice thickness and air velocity under forced drying air on the moisture diffusion characteristics and the drying rate of kiwifruit slices during infrared drying were investigated. The drying of kiwifruit happened in the falling rate period, and no constant-rate period was observed in the drying curves. One hundred models were fitted to the drying data. Among the models, the exponential dsecay function model and modified two-term exponential-V model and the artificial neural networks with 4-5-7-1 and 3-5-5-1 topologies, hyperbolic tangent sigmoid transfer function, and Levenberg-Marquardt training algorithm presented the best results and showed the goodness of fit with the experimental data for the former and latter systems, respectively. The diffusivities varied between 1.216 × 10-10-8.997 × 10-10 m2⁄s and 2.567 × 10-10-10.335 × 10-10 m2⁄s for natural and forced drying air systems, respectively.

Effect of infrared drying with multifrequency ultrasound pretreatments on the stability of phytochemical properties, antioxidant potential, and textural quality of dried sweet potatoes

The study aims to determine drying of sweet potatoes using multifrequency ultrasound (US) pretreatments (20, 40, and 60 kHz) at three different infrared (IR) drying temperatures (60, 70, and 80°C) and evaluate the phytochemical and textural quality of the dried product. Drying time was significantly decreased in moderate US frequency (40 kHz) at 70°C with the increasing drying temperature. Comparing to the fresh samples, the dried samples showed the highest amount of phytochemical contents. The antioxidant activity of the samples increased especially at 60 kHz and 80°C, while US-IR treatments shown a positive impact on total carotenoids contents and β-carotene. For phenolic compounds, Ellagic acid and Rutin were quantified in higher amount while Quercetin-3-rhamnoside and Quercetin 3-β-D-glucoside were two new compounds identified for the first time in sweet potatoes. FTIR spectra showed the successful synthesis of OH group and phenolics in samples treated with the US at 20 kHz. PRACTICAL APPLICATIONS: This study investigated the effects of multifrequency ultrasound with different infrared drying temperatures. The study provides evidence that infrared drying application in synergy with ultrasonic pretreatments can improve drying efficiency and food quality much better than using each method alone. Total phenolic contents and total flavonoid contents remained stable at US 40 kHz and 60°C conditions. The findings showed that moderate ultrasound frequency (40 kHz) at 60°C improved phytochemical properties while antioxidant activities showed better preservation response at 80°C with 60 kHz. In addition, the samples treated with the same US treatment at 40 kHz showed less cell breakage in SEM analysis.

Effect of Ultrasound on Heat Pump Drying Characteristics of Pea Seeds

For the purpose to study the effect of ultrasound treatment on heat pump drying, the experiments were conducted on pea seeds at drying temperature of 30, 35 and 40 °C , ultrasound power of 0, 60 and 100 W and frequency of 0, 28 and 40 kHz. The influence of ultrasound and temperature on the drying process was studied by analyzing the drying characteristics of pea seeds. The results demonstrated that increasing the ultrasound power, frequency and drying temperature can improve the drying rate and the Midilli model can describe the drying kinetics of pea seeds well. The effective moisture diffusion coefficient increased with the increase of ultrasound power, frequency and drying temperature, while there was no obvious trend for the change of seed activation energy under different conditions. The seed viability was promoted with the raise of ultrasound power and fell when increasing drying temperature.

Modeling of drying and ameliorative effects of relative humidity (RH) against β-carotene degradation and color of carrot (Daucus carota var.) slices

Drying and β-carotenes retention kinetics were predicted using models in relative humidity (RH) drying condition. This was achieved by drying carrot slices using RH-convective hot-air dryer at 60, 70 and 80 °C under RH (10% 20% and 30%) conditions at 2.0 m/s air velocity. Three mathematical models describing thin layer were compared to their goodness of fit in terms of coefficient of correlation (R²), root mean square error (RMSE) and reduced Chi square ( χ 2 ). The Wang and Singh model could satisfactorily describe RH-convective drying of carrot slices with R², RMSE and χ 2 in the ranges of 0.996-0.999, 5.4 × 10^-4-9.4 × 10^-4 and 0.0150-0.03353 respectively. The results reveal that a range of 3.61-8.2% retention of β-carotene was observed for every 10% increase in RH in various drying air temperature. In summary, higher temperatures were mainly responsible for β-carotenes degradation however this can be mitigated when drying is conducted under higher RH.

Effect of different drying methods on the product quality and bioactive polysaccharides of bitter gourd (Momordica charantia L.) slices

In this study, three drying methods, namely, hot-air drying, freeze drying (FD), and infrared radiation drying (ID), were applied to dry bitter gourd (Momordica charantia L.) slices. Results showed that the drying methods had significant influences on appearance, color, rehydration ratio, and microstructure of dried bitter gourd. FD provided high-quality dried bitter gourd products due to the uniform honeycomb network and less collapsed structure. Three water-soluble bitter gourd polysaccharides (BPS-H, BPS-F, and BPS-I) were obtained from the bitter gourd dried using the three drying methods. The three polysaccharides exhibited similar preliminary structural characteristics with different monosaccharide compositions and molecular weights. BPS-I obtained from ID-dried bitter gourd had higher sugar and uronic acid contents than BPS-H and BPS-F. BPS-I exhibited stronger antioxidant activities and bile acid-binding capacity in vitro than BPS-H and BPS-F. Moreover, BPS-F and BPS-I showed significant α-amylase inhibitory activities in vitro.

Drying Performance and Product Quality of Sliced Carrots by Infrared Blanching Followed by Different Drying Methods

The objective of this study was to investigate the processing parameters and quality of carrots under sequential infrared (IR) dry-blanching and (1) hot air drying (IRB-HAD), (2) infrared drying (IRB-IRD), and (3) Infrared-hot air drying (IRB-IRHAD). Water blanching at 90oC was used for comparison. The quality of dried carrot was evaluated based on vitamin C content, rehydration ratio, color, shrinkage and hardness. Applying IR dry-blanching for 15 min resulted in the reductions of about one log in peroxidase (POD) activities and 54 % in moisture reduction. A notable change in the surface color and retention of vitamin C were obtained with IR blanching. IRB-IRD and IRB-IRHAD had higher drying rates and higher quality. The recommended processing parameters for IRB-IRHAD are IR blanching for 15 min, followed by IR drying to a moisture content of 30–40 % wet basis (w.b.), and then finished by HA drying to a targeted MC (8 % w.b.).

Modeling Drying Properties of Pistachio Nuts, Squash and Cantaloupe Seeds under Fixed and Fluidized Bed Using Data-Driven Models and Artificial Neural Networks

This paper presents the application of feed forward and cascade forward neural networks to model the non-linear behavior of pistachio nut, squash and cantaloupe seeds during drying process. The performance of the feed forward and cascade forward ANNs was compared with those of nonlinear and linear regression models using statistical indices, namely mean square error ( M S E $MSE$ ), mean absolute error ( M A E $MAE$ ), standard deviation of mean absolute error (SDMAE ) and the correlation coefficient ( R 2 ${R^2}$ ). The best neural network feed forward back-propagation topology for the prediction of effective moisture diffusivity and energy consumption were 3-3-4-2 with the training algorithm of Levenberg-Marquardt (LM). This structure is capable to predict effective moisture diffusivity and specific energy consumption with R 2 ${R^2}$ = 0.9677 and 0.9716, respectively and mean-square error ( M S E $MSE$ ) of 0.00014. Also the highest R 2 ${R^2}$ values to predict the drying rate and moisture ratio were 0.9872 and 0.9944 respectively.

Electrohydrodynamic drying of carrot slices

Carrots have one of the highest levels of carotene, and they are rich in vitamins, fiber and minerals. However, since fresh carrots wilt rapidly after harvest under inappropriate storage conditions, drying has been used to improve their shelf life and retain nutritional quality. Therefore, to further investigate the potential of this method, carrot slices were dried in an EHD system in order to study the effect of different voltages on drying rate. As measures of quality, carotene content and rehydration ratio were, respectively, compared against the conventional oven drying regime. Carotene, the main component of the dried carrot, and rehydration characteristics of the dried product can both indicate quality by physical and chemical changes during the drying process. Mathematical modeling and simulation of drying curves were also performed, using root mean square error, reduced mean square of the deviation and modeling efficiency as the primary criteria to select the equation that best accounts for the variation in the drying curves of the dried samples. Theoretically, the Page model was best suited for describing the drying rate curve of carrot slices at 10kV to 30kV. Experimentally, the drying rate of carrots was notably greater in the EHD system when compared to control, and quality, as determined by carotene content and rehydration ratio, was also improved when compared to oven drying. Therefore, this work presents a facile and effective strategy for experimentally and theoretically determining the drying properties of carrots, and, as a result, it provides deeper insight into the industrial potential of the EHD drying technique.

Thin-Layer Drying Model of Rambutan (Nephelium lappaceum L.) Kernel and Its Application in Fat Extraction Process

Rambutan (Nephelium lappaceum L.) kernels contain a high amount of fat and it has a potential to be used as a new alternative source of edible vegetable fat. Drying of fat seed can improve the fat yield and prolong the seed storage shelf life. Therefore the drying behaviour of rambutan kernels was investigated using a hot air dryer for 6 h at each of three temperatures, 45°C, 55°C and 65°C. Based on the coefficient of determination (R2) and root mean square error (RMSE), modified Henderson and Pabis model was found to be the best thin-layer drying model for rambutan kernels (R2 > 0.99 and RMSE < 0.02). The effective moisture diffusivity of rambutan kernels, estimated from a modified equation of Fick’s second law of diffusion, was 2.56 × 10–10 to 3.68 × 10–10 m2 s–1. The result of fat extraction significantly indicates the effect of low moisture rambutan kernels on the fat yield enhancing (P < 0.05).