Banana Slices Research Articles

Effect of Gradient Vacuum Pressure on Quality Parameters of Vacuum‐Fried Bananas Chips

ABSTRACTThe effect of vacuum pressure mode has not been studied depth yet. Effect of vacuum pressure on the quality of vacuum‐fried banana slices was studies in this work. Three vacuum frying processes were conducted and tested. Classically, two constant vacuum pressures 80 (CVF‐80) and 180 mmHg (CVF‐180) were applied in the frying process at 90°C. One novel frying method with gradient vacuum pressure (GVF) changed from 760 to 80 mmHg was conducted and adapted. The frying temperature was kept at 90°C. The frying processes were monitoring by moisture contents and 4% was generally accepted as moisture content of final product. Meanwhile, the frying times of CVF‐80, CVF‐180 and GVF were 50, 80 and 60 min, whereas the brightness values (L*) were corresponded to 71.07, 71.36, 67.25, respectively. The GVF samples were brightest with lowest hardness value (30.8 N) and the CVF‐180 was darkest with highest hardness value (36.87 N). The microstructure analysis showed that the GVF increase in both size and number of pores in comparison with CVF. Additionally, based on the paired comparison sensorial test the GVF fried banana slices were crisper than CVF samples. Our results revealed that the GVF method improves the quality of vacuum‐fried banana slices, thus it can be good alternative method for production of banana snack.

Banana slice drying using waste heat from an air conditioner for enhancing performance and sustainability

AbstractAs waste heat dryers (WHD) exhibit conservation of energy with environmental and economic benefits, the direct use of waste hot air rejected from the outdoor unit of a window air conditioning (AC) unit for drying banana slices is demonstrated experimentally in the present research work. For this purpose, a drying chamber was directly coupled to an AC unit (AC‐WHD) and analyzed its performance during banana slice drying by revisiting the concepts of generalized drying curve and drying performance index (DPI). The experimental data set of moisture content ratio obtained with AC‐WHD matched well with the generalized drying curve and the DPI value was found to be 0.999. It was found that the waste air supplied by the AC unit to the drying chamber was hot (≈ 50°C) and 28% dry, which aided the drying process. The thermodynamic performance of AC‐WHD was also evaluated using warm and wet exergy to provide insight into the mechanism of AC‐WHD drying. The exergy based sustainability index was higher while the exergetic destruction coefficient and environmental impact factor were lower for AC‐WHD when compared to literature values of the solar drying method. The findings of this research work indicate the practicality of coupling AC units with dryer units to address sustainable development goals (SDG).

Effect of Ultrasound and Osmotic Dehydration as Pretreatments on the Infrared Drying of Banana Slices.

There is a growing interest in foods with added nutritional value and extended shelf life. This study investigates the use of infrared technology in the drying of banana slices to improve their stability and quality by minimizing moisture content and water activity. The drying experiments were carried out at a temperature of 70 °C, using the following pretreatments: ultrasound-assisted (UA) immersion in water for 20 and 30 min, osmotic dehydration (OD) and ultrasound-assisted osmotic dehydration (UAOD) for 20, 30 and 40 min. The osmotic process consisted of immersing the samples in the isomaltulose solution (40.0 g/100 g deionized water) for 60 min. All mathematical models used to describe the drying process showed a good fit with high R2 values (>0.98) and low value of the relative mean error E (%), the sum of squared error and the root mean squared error. The Fick's diffusion coefficient (D eff) was higher for the samples previously treated with ultrasound for 20 and 30 min. The ultrasonic treatment resulted in shorter drying times with a reduction in average time of up to 29 %. OD was not efficient in reducing drying time, resulting in samples with lower drying rates. The samples treated with ultrasound showed less isotropic shrinkage and better color parameters. The osmotic process resulted in samples with greater rehydration capacity. The impregnation of a carbohydrate with low glycemic index in banana slices was achieved by the osmotic pretreatment, resulting in a new food product with attractive nutritional properties. This advancement represents not only a significant step in the development of functional foods, but also a major innovation in terms of processing technologies. The OD was combined with infrared drying, a method known for its superior drying rates, high heat transfer coefficient and energy efficiency. The synergy of these promising techniques not only shortens the processing times but also ensures more uniform dehydration of food products, resulting in end products that not only maintain but also optimize their nutritional value. These advances offer innovative solutions to improve food quality and also minimize environmental impact through low-energy technologies such as ultrasound and infrared treatment.

Quality Attributes of Dried Osmo-Dehydrated Banana Slices Using Coconut Sugar and Sucrose as Osmotic Agents

Quality Attributes of Dried Osmo-Dehydrated Banana Slices Using Coconut Sugar and Sucrose as Osmotic Agents

Low-cost solar dryer dehydrates silver banana with a prediction of diffusion approximation model

Solar dryers made from recycled materials offer a cost-effective solution for promoting the widespread adoption of this technology and reducing food production costs. In this study, a low-cost solar dryer was constructed using repurposed materials, employing indirect exposure, and its performance was evaluated through a kinetic study on banana slice drying (Musa spp.). Drying was carried out until equilibrium moisture, reaching constant mass. The drying air's temperature and relative humidity (RH, %) were monitored. Fourteen empirical models were used to fit the experimental data. The banana slices took approximately 300 min to dry, with final moisture of 1.8%. The mean operational conditions during natural drying were 59.08±9.16 °C and RH = 39±4%. The diffusion Approximation model fitted the drying curve better, as it presented the lowest reduced Chi-square (χ2 = 2.9×10-5) and a high coefficient of determination (R2 = 0.9998). The effective diffusion coefficient (Def = 5.4×10-9 m2/s, R2 = 0.9935) was determined. Thus, the solar dryer demonstrated efficient performance in the banana drying process, requiring minimal design effort. Furthermore, despite the limitations in controlling the drying conditions, most of the mathematical models successfully predicted the drying process due to the dryer's ability to maintain the continuity of the drying curve, suggesting potential viability for this low-cost dryer.

Mathematical modeling of the effects of thickness and temperature on thin-layer drying kinetics of oven-dried cooking bananas (Musa spp., sub. grp. ABB) slices

Cooking bananas is a major beneficial food in developing countries that is involved in improving human well-being and health. However, owing to its high moisture content, it quickly deteriorates. Understanding the dehydration mechanism of raw banana slices is important for subsequent processing, preservation, transportation, and product quality. Thus, this study investigates the influence of slice thickness (5, 10, and 15 mm) at varying temperatures (45, 55, and 65 °C) in a convective oven dryer on thin-layer drying kinetics and extrapolates their effect on the drying kinetics of cooking banana slices. As the temperature and slice thickness increased, the drying time also increased. Midilli’s model was found to be the best for explaining the experimental data. The effective moisture diffusivity ranged from 1.393 × 10 −8 to 8.889 10 −8 m2/s. The dependence of moisture diffusivity on temperature was described by an Arrhenius-type equation, and the activation energies were found to be 23.599, 24.804, and 24.223 kJ/mol for thicknesses of 5, 10, and 15 mm, respectively.

Experimental investigation on a solar dryer assisted with minimum phase change material (PCM) placed on the inner walls of drying chamber

Solar dryers assisted with phase change material (PCM) speed up the drying process by compensating the negating effect of reduced or absence of solar energy under cloudy or non-sunshine hours respectively. The study of the relevant and recent literature indicated that the minimum quantity and proper placement of this PCM have not been explored to take full advantage of using them in solar dryers. Hence in this research work, experimental investigations on banana slice drying were carried out with 4 and 10 numbers of copper tubes filled with 176 and 494 kg of commercial paraffin wax respectively (correspondingly designated as SD-PCM1 and SD-PCM2). The copper tubes were placed in vertical and horizontal orientations on the inner wall of the drying chamber so that the upward movement of air would not disturbed. A comparison of the drying performance of a PCM-based unit with a natural convective solar dryer without PCM (SD) was also presented. As no appreciable differences between the mass loss during drying under SD and SD-PCM1 modes were observed, it was concluded that a mass of PCM greater than 176 g would enhance drying rates. Thus for the same final mass of dried banana slices, the drying time was about 15 and 9 h with SD and SD-PCM2 respectively. As the operating conditions of SD and SD-PCM vary considerably in terms of the thermal energy supplied during the drying process, the concept of a generalized drying curve with dimensionless time was used to study the drying kinetics. A close alignment of experimental data of moisture content ratio with the generalized drying curve under SD and SD-PCM modes indicates similar dryer performance irrespective of the differences in thermal energy supplied. The average exergetic efficiency of SD, SD-PCM1 and SD-PCM2 was 21, 26 and 28 % respectively. The sustainability index and environmental impact factor for SD-PCM2 were 1.41 and 2.5 respectively which was better compared to the respective values of 1.27 and 3.77 in SD mode favoring the use of PCM in solar dryers.

Preventing enzymatic browning of freshly cut green bananas through immersion in normal water, lemon juice, and coconut water

AbstractThe rising demand for freshly cut agricultural produce like bananas, apples, pears, potatoes, and roots due to health concerns and modern lifestyles has heightened awareness of their susceptibility to browning, which diminishes their appeal and contributes to food waste. The present study explored the efficacy of natural anti‐browning agents in prolonging the quality and shelf‐life of freshly cut green banana slices. The bananas underwent treatment with normal water (NW), lemon juice (LJ), and coconut water (CW), and the changes in physicochemical properties, such as browning intensity, color, firmness, total soluble solid (TSS), total phenolic content (TPC), total flavonoid content (TFC), and also microbial attributes, were evaluated during their storage at 4 ± 1°C for 12 days. The results demonstrated significant enhancements in treated samples compared to untreated ones. While normal water and lemon juice‐treated banana slices exhibited visual browning during storage, coconut water immersion proved superior in maintaining visual appeal, whiteness, and lightness while delaying yellowing and browning. Coconut water‐treated samples also displayed firmer texture (0.75 kg), lower TSS (5.67 °Brix), and reduced weight loss (9.14%) after 12 days, in contrast to samples subjected to lemon juice and normal water treatments which showed lesser texture (0.68 kg, 0.58 kg), higher TSS (5.87 °Brix, 6.10 °Brix), and greater weight loss (11.76%, 16.09%), respectively. Furthermore, coconut water‐treated samples retained higher levels of total phenols (392.67 mg GAE (gallic acid equivalent)/100 g FW (fresh weight), total flavonoids (55.67 mg QE (quercetin equivalent)/100 g FW), and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging activity (38.68%). Coconut water treatment also significantly suppressed polyphenol oxidase (PPO) activity (14 U/g) compared to lemon juice (16 U/g) and normal water (26 U/g) treatments, and untreated samples (133 U/g) after 12 days. Additionally, microbial load remained within acceptable limits for all samples, with coconut water‐treated samples showing the lowest values. Thus, coconut water is a promising natural solution for inhibiting browning and preserving the quality of fresh‐cut green banana slices during storage.

Development of advanced machine learning for prognostic analysis of drying parameters for banana slices using indirect solar dryer

In this study, eXtreme Gradient Boosting (XGBoost) and Light Gradient Boosting (LightGBM) algorithms were used to model-predict the drying characteristics of banana slices with an indirect solar drier. The relationships between independent variables (temperature, moisture, product type, water flow rate, and mass of product) and dependent variables (energy consumption and size reduction) were established. For energy consumption, XGBoost demonstrates superior performance with an R2 of 0.9957 during training and 0.9971 during testing, alongside minimal MSE of 0.0034 during training and 0.0008 during the testing phase indicating high predictive accuracy and low error rates. Conversely, LGBM shows lower R2 values (0.9061 training, 0.8809 testing) and higher MSE of 0.0747 during training and 0.0337 during testing, reflecting poorer performance. Similarly, for shrinkage prediction, XGBoost outperforms LGBM, evidenced by higher R2 (0.9887 training, 0.9975 testing) and lower MSE (0.2527 training, 0.4878 testing). The comparative statistics showed that XGBoost regularly outperformed LightGBM. The game theory-based Shapley functions revealed that temperature and product types were the most influential features of the energy consumption model. These findings illustrate the practical applicability of the XGBoost and LightGBM models in food drying operations towards optimizing drying conditions, improving product quality, and reducing energy consumption.

Reducing the oil absorption and tailoring starch properties in banana slices by integrated ultrasound in infrared frying

The reduction of oil absorption and modifications of starch properties in infrared fried (IF) banana slices by integrated ultrasound was investigated with power levels ranged 600–1000 W. Results showed that the internal moisture migration in IF banana slices were enhanced by ultrasonication, the crust development was delayed and finally formed with a thinner layer and higher uniformity. Both the pore volume and the porosity of IF samples were reduced by the integrated ultrasound, while the accounts of pores with diameters 100–250 μm and 0.02–1 μm has been increased. The total oil uptake in IF samples was reduced by 1.5%–9.4% and both the surface and structural oil was decreased by the ultrasound. The order of starch in long range and short range in IF banana slices were reduced by the integrated ultrasound, while the formation of starch-lipid complex was increased, which leading to the prolonged starch digestion time.

Assessment of performance and sustainability of waste heat dryer coupled with air conditioner unit during drying of banana slices

The present work presents the effective application of waste heat rejected from window air conditioning (AC) in a waste heat dryer (WHD) for drying plantain banana slices. The comparison between drying with the waste heat dryer coupled with an AC unit (ACWHD) and a natural convective indirect solar dryer (SD) reveals significant differences in drying kinetics, supply air conditions, and thermodynamic performance. The drying kinetics of banana slices obtained with ACWHD and SD were validated by revisiting the concepts of dryer performance index (DPI) and generalized drying curve. The temperature of the hot air supplied to the drying chamber in ACWHD was 48 °C while the relative humidity of the supply air was below 30 %. The thermodynamic performance assessment revealed that the exergetic efficiency was about 45 % and 16 % for ACWHD and SD respectively. The results of exergy based sustainable index and environment impact factor indicated the potential application of the waste heat of residual air from AC units for drying applications. Thus, the results of the present study imply that this novel idea has appreciable potential for commercialization with large-scale central air conditioning units in commercial complexes and industries where the magnitude of heat rejection will be multi-fold.

Development of Solar PV Assisted Dryer for Cooking Banana Slice and Analysis of Proximate Properties

A solar PV-assisted dryer was developed for drying cooking banana and its performance tested. The proximate properties of the products dried in the solar PV-assisted dryer were compared to similar products dried using a laboratory oven, while open sun drying served as the control experiment. Fresh samples of cooking banana were obtained from a rural market in Ikot Akpaden, Mkpat Enin, Akwa Ibom State, Nigeria. The samples were subjected to peeling and cleaning before being sliced to a thickness of 5 mm. The dryer was embedded with a DC blower to enhance air circulation in the drying chamber. The blower was powered by a solar panel connected to a DC battery and a charge controller. 500 g of the product was loaded in the solar PV-assisted dryer, same as the other mediums. The moisture content was observed to have reduced from 67.32 to 5.80 % within 6 hours of drying as against 13 hours of open sun drying. The drying rate of the product decreased from 0.092 to 0.028 kg/hr in the solar PV-assisted dryer. The efficiency of the dryer was 40.6 %. Crude protein, crude lipid, crude fibre, and caloric value were lower in samples dried using the solar PV-assisted dryer and higher in samples subjected to drying in the laboratory oven and the control experiment. Ash content and carbohydrates were higher in products dried using the solar PV-assisted dryer than in other mediums. The study adds significant knowledge to the development of systems for post-harvest processing of cooking banana, a product highly sought for in the local market as a viable alternative to banana and plantain

Experimental investigation and performance evaluation of an indirect solar dryer: Effect of drying trays

Indirect solar dryers represent a clean and sustainable solution for reducing the moisture content of a variety of food and medical products. This technique enables products to be preserved over long periods, stored in compact volumes, and used when required.In this context, improving the efficiency of these systems is essential. Therefore, an experimental study of an indirect solar dryer operating with natural convection has been carried out in this paper. The experimental tests were performed at the Mechanics and Energy Laboratory at the Technopole research center,Oujda, Morocco, in August 2022. The main objective of this work is to evaluate the drying process of banana slices using three different types of drying trays, two made of wire mesh and one of perforated galvanized sheet. The evaluation of the drying system was mainly based on the variation in the moisture content of banana slices. Accordingly, five samples corresponding to different positions in each tray were examined. The obtained results show that banana slices in A-type mesh trays have a faster reduction in moisture content and a better quality than the other trays.

Arduino Based Automatic Banana Chip Slicer

Banana is a herbaceous fruit plant, in Latin banana Musa spp which belongs to the Musaceae family from Southeast Asia. What is meant by superior varieties is that banana plants are strong enough to withstand pests and diseases so they are capable of high production. Nowadays, many people who slice bananas still use simple or manual tools to slice raw bananas. An efficient machine mechanism must be needed in the manufacturing process to get these thin banana slices. This tool aims to avoid hand injuries and banana sap getting on your hands if you use a manual banana slicer. The working method of this tool is controlled by Arduino Uno R3 using an Ir sensor and with an output in the form of a relay which functions as a switch to rotate the blade. This test was carried out fifty times using three different types of bananas, namely, wak bananas, kapok bananas, and flower bananas. The results of testing three types of bananas, namely weak bananas, kapok bananas, and flower bananas, have the same thickness level, namely 1mm. This tool concludes that it makes it easier for people to slice bananas from manual to automatic so that the thickness is the same. The tool works based on input from two IR sensors using an analog signal pin connected to Arduino. The two IR sensors will detect if there is movement near the container.

Effects of pretreatments involving ohmic heating and infrared radiation on the drying process of bananas using hot air

AbstractNowadays, the hot air drying process is the most widely used method for producing dried food and agricultural products due to its suitable investment and low operational costs. However, one of the disadvantages of drying with hot air is the prolonged drying time, which sometimes leads to serious damage to the quality characteristics of the resulting products, especially at high temperatures. Therefore, there is a need to find the most suitable conditions for producing high‐quality dried products. To conduct this experiment, after determining the desired number of samples, infrared preheating and ohmic heating were performed sequentially. In the first stage of preheating, the samples were placed in the ohmic heating device, and in the second stage, they were exposed to infrared radiation. Then, the samples were transferred to a hot air dryer for complete drying. The results showed that the antioxidant content increased with the increase in the thickness of the banana slices. Moreover, an increase in the drying temperature and the number of infrared lamps led to a reduction in the antioxidant content. The slices with less thickness and higher drying temperatures had the minimum phenol content. The maximum and minimum measured values of the total phenol content were 34.51 and 37.32, respectively. The range of variation in the solid soluble content was between 11.708% and 19.5437% Brix. In addition, at the same temperature values, an increase in the thickness of the banana slices resulted in a decrease in the solid soluble content of the samples. Furthermore, with an increase in the temperature for slices of the same thickness, the solid soluble content of the samples increased.Practical applicationsThe purpose of this research is to evaluate the effect of the thickness factors of the sample pieces, the temperature of the hot air dryer along with ohmic heating pretreatments, and the infrared lamps in the hot air dryer on the quality indicators of banana.

Recognition performance of different artificial neural networks for distinguishing banana slices subjected to different combinations of pretreatment and microwave drying

This study was aimed at assessing the effect of microwave drying at 100, 200, or 300 W on the quality of Cavendish banana slices without pretreatment and with pretreatment using 5% ascorbic acid solution, 5% citric acid solution, 5% gum arabic solution, and ultrasound. Banana slices were imaged using a digital single-lens reflex (SLR) camera. The acquired images were processed to extract texture parameters. The classification models were developed based on image texture parameters selected from a big dataset of 2172 textures of images in different color channels using artificial neural networks. Wide Neural Network, Bilayered Neural Network, Medium Neural Network and three classifiers from the group of function, such as RBF (Radial basis function) Network, Multilayer Perceptron, and WiSARD were applied. Banana slices belonging to 15 classes with different combinations of pretreatment and microwave drying were distinguished with an average accuracy of up to 97.2% for a model built using Multilayer Perceptron. For most models, banana samples microwave-dried at 200 W without pretreatment were classified with the highest correctness. The performed study revealed that the objective, non-destructive, correct, and robust quality assessment of pretreated and microwave-dried banana slices may be performed using image processing and artificial intelligence.

Tray Dryer's Performance in the Drying of Banana Slices Using LPG and Wood Stove

An evaluation was carried out on a simple tray dryer of banana slices in the "sale pisang" production. The dryer is designed to use gas fuel and a wood-burning stove as a source of energy. The dryer's performance is analyzed to evaluate its ability to dry the product efficiently and effectively to prevent excessive heat use. The research aims to analyze the temperature distribution in the drying chamber, the profile of the product's moisture content, the drying rate on each shelf, as well as the efficiency of dryers using gas fuel and wood-burning stoves. At an air speed of 0.0176 m3/s, the drying chamber reaches a maximum temperature of 76.2 ℃ using gas and 66.23 ℃ using a wood stove. The use of Liquid Petroleum Gas (LPG) gives an average room temperature of 73.46 ℃, while the furnace gives a less stable pattern with an average temperature of 63.02 ℃. Drying using LPG occurs more quickly with a constant drying rate and a falling rate period of 0.8262%/hour and 0.01504%/hour, higher than using wood fuel which is 0.5482%/hour and 0.0098 %/hour. Within 400 minutes, the product’s moisture content reached 24.64% using LPG and 36.762 using the furnace. The efficiency for heating the drying air is 28.51% and the drying process efficiency is 27% using 8.6 kilograms of LPG as fuel. Meanwhile, using a furnace energy source, the dryer provides a heating efficiency of 15.9% and a drying efficiency of 7.37% with a fuel consumption of 34.12 kg of wood.

An experimental evaluation of drying banana slices using a novel indirect solar dryer under variable conditions

Novel thermal characteristics of drying banana slices in an indirect dryer are presented for four different experimental drying conditions in the forced convection mode. The novel characteristics include measuring the airflow velocity in the drying chamber, measuring the thermal profiles in different trays comprehensively and measuring the relative humidity under different conditions. Two tests are carried for 16 h in two consecutive days (8 h per day for each test). The first test is on acloudy day followed by a sunny day, while the second test is carried out on two consecutive sunny days. Tests 3 and 4 are 24 h tests with high (0.23 m/s) and low (0.11 m/s) average drying chamber airflow velocities under good solar radiation conditions. The maximum temperatures obtained in the collector and the drying chamber are around 80 and 48 °C, respectively, for the 16 h tests. Significantly lower collector and drying chamber temperatures are obtained due to cloudy conditions. Maximum collector temperatures are around 84 and 95 °C for the high and low average airflow chamber velocities for the 24 h tests. The corresponding maximum temperatures in the drying chamber are around 50 °C for the 24 tests. The final moisture ratios are 0.26 (cloudy and sunny days) and 0.20 (two sunny days), respectively, for the 16 h tests. These final moisture ratios are lower than those obtained for the 24 h tests which are 0.32 and 0.28, respectively. Increasing the drying chamber airflow velocity results in faster moisture removal during sunshine hours for the 24 h tests. For tests 1, 2, 3 and 4, the maximum average collector efficiencies during the sunshine period are around 60, 80, 40 and 10 %, respectively. The average drying efficiencies for the total solar drying period for tests 1,2,3 and 4 on day 1 are 6.9, 6.9, 5.5 and 5.7 % respectively. These values are comparable, suggesting that the average collector powers, airflow velocities and efficiencies have a very small effect on the average solar drying efficiency for the whole drying period. The quality of the bananas slices mainly in terms of the colour and shape is also compared with previous studies and commercially available products. A reasonably acceptable quality product is obtained.

Drying banana slices using photovoltaic ventilation solar dryer

The economic value of bananas is quite low due to the high volume of production and the short shelf life of the fruit. One of the popular methods of preserving agricultural produce is drying. The objectives of this research include determining the drying kinetics curve profile of banana slices and the drying rate using a solar dryer, analyzing the profile of incoming and outgoing air temperature, solar intensity, air humidity in the solar drying device, evaluating the performance of the solar dryer in terms of drying efficiency, as well as measuring the quality and comparing the solar-dried banana product with the open sun method. The temperature profile of the drying chamber remained relatively stable, throughout the drying process due to the addition of photovoltaic panel to generate electrical energy to run the D.C. fans and electrical heater. The fastest drying occurs in solar drying of photovoltaic ventilation with temperature of 60oC with a drying time of 8 hours and resulting in moisture content of 8.57%. The drying rate in solar instruments of photovoltaic ventilation at variable temperatures of 60oC, 50oC, 40oC and open sun drying has an average drying rate of 0.0921 g/min, 0.0784 g/min, 0.0653 g/min, and 0.0529 g/ min, respectively. The drying rate decreases as the drying time increases. The average efficiency of the dryer at 40°C, 50°C and 60°C, were 3.109%, 3.393% and 3.915%, respectively. For the quality analysis of the dried banana slice, the structure of dried banana slices with SEM analysis tends to be irregular and the surface was smooth. There were 20 compounds detected by GCMS method in dried banana slices, where there were five compounds that had the widest area or the largest presentation, namely 26.22% hexadecanoic acid, ethyl ester (CAS), 24.59% ethyl oleate, 5.47% silan, triethyl-fluoro-, 5.05% bis(2- ethylhexyl) ether and 4.83% ascorbaric acid (Vit-C).

Impact of ultrasound pretreatment on banana chip production by convective drying using hot air: Consideration of shrinkage and variable effective mass diffusivity in the process description

AbstractIn this study, we used experimental analysis and numerical simulation to describe and compare the convective drying (CD) of banana slices, without and with pretreatment with ultrasound (US) at 25 kHz. Banana slices, with an average initial thickness of about 6.60 × 10−3 m and an average diameter of about 3.01 × 10−2 m, were subjected to CD at temperatures of 60, 70, and 80°C, with air speed of 1.5 m s−1. Considering such dimensions, the one‐dimensional diffusion equation in Cartesian coordinates was numerically solved by the finite volume method, using a fully implicit formulation (direct problem). A solver with a numerical solution was developed for the direct problem. This solver was coupled to an optimizer to determine the parameters a and b of functions that relate the effective moisture diffusivity (D) with the local moisture ratio, and also to determine the convective mass transfer coefficient (h) (inverse problem), considering the shrinkage. The proposed model was used to describe the data obtained. The results revealed that the drying rate increased in samples that were subjected to pretreatment with US, for each drying temperature. The best‐simulated results were those that related D to the local moisture ratio by means of a bcosh (aMR2) function. It could be observed that pretreatment with US allowed saving of time (and consequently energy) of 28.3%, 16.0%, and 12.4% at drying temperatures of 60, 70, and 80°C, respectively.Practical applicationsThe main contribution of this paper is to present a solver and an optimizer to determine the mass transfer properties considering the shrinkage during convective drying of banana pieces pretreated with ultrasound by the inverse problem. With the information obtained for the mass transfer properties and the proposed numerical model with a hyperbolic cosine type function for the effective moisture diffusivity, it is possible to more accurately determine the time and, therefore, the energy savings of processing banana chips pre‐treated with ultrasound.